Hurricane Earl Set For Brush With US Coast From Hatteras to Cape Cod September 2, 2010

Hurricane Earl IR Rainbow Image 1915Z 09.02.10 Click for real time loop

Hurricane Earl Spaghetti Model 18Z 09.02.10

If you recall a few days ago I had talked about the challenges for Hurricane Earl maintaining its ferocity.  One of the main concerns that I had was a huge amount of dry air that Earl was getting ready to move in to.    I was a bit surprised that the NHC didn’t mention it more often and it appeared that Earl was able to fend off the dry air.  However, it seems apparent now that dry air did indeed work its way into the storm and Earl rapidly decreased in intensity on Thursday evening.   The dry air intrusion seems to have coincided with what so often seems to be the case which is that Hurricane Earl began an eyewall replacement cycle during the late morning on Thursday, prior to a potential Outer Banks of North Carolina landfall.   Most likely, Earl yesterday reached its maxima when it topped out at 145 mph with gusts to 165 and a central pressure somewhere in the neighborhood of 930 mb.  If you look at the satellite loop, you will note that the eye seems to fill in.  That was not an indication that the storm is dying, but instead was indicative of a very healthy hurricane.  What typically happens with an eyewall replacement cycle is that the maximum winds near the eye decrease somewhat, but the overall energy gets dispersed throughout the storm.  Hence, a broader field of strong winds results.  At 3:30 PM EDT Earl essentially had two eyes.  The old eye was collapsing and a new, much larger,  eyewall was developing around it.  So, winds decreased and the pressure rose to 943 mb but its a much larger storm.  By 5 pm Earl’s maximum winds had dropped to 115 mph and the pressure was up to 947 mb.   We saw that with Hurricane Katrina.  As it made landfall, the winds dropped off to 125 mph in far western Mississippi and near the mouth of the Mississippi River yet, all the way east over to Mobile, AL winds were in excess of 100 mph.  So, regardless of exactly where the eye of the storm runs in relation to North Carolina, the winds on the Outer Banks and even for some distance inland will be hazardous.

Hurricane Earl Spaghetti Model Intensity Forecast 18Z 09.02.10

On Thursday afternoon, another potential problem was that, if the replacement cycle was complete before it got to North Carolina, then it could have been in a re-intensification stage and perhaps deepening back toward a category 4 hurricane.   At this point, that is not only unlikely but also rather irrelevant.  As of 3:30 pm EDT on Thursday, Earl was moving at about 355 degrees, or just slightly west of due North.  It had crossed just west of 75 degrees West Longitude.  Cape Hatteras is at 75 degrees 15 minutes W. Long and 35 degrees 30 minutes North Latitude.  I believe that there is a fair chance that Cape Hatteras will take a direct hit though if Earl is just off shore, then it could be in the western eyewall.  If you look closely at the 2PM forecast discussion, the NHC forecast position at 2AM is 75 degrees West Long and 33.5 degrees North Lat, or right over Cape Hatteras.  At two AM on Saturday, the storm is forecast to have maximum winds of nearly 100 mph and is located at 40.o N and 75.8 W or almost exactly over Marthas Vineyard.   Keep in mind a wobble to the right by 25 miles would spare the eye passing over these locations but it would still be close enough to be potentially destructive.  By 8PM EDT Earl’s maximum winds had decreased to 110 mph and the liklihood of the trend of winding down is rapidly diminishing.  It would appear from the satellite depiction that upper shear is starting to work on Earl as well as dry air from the Eastern United States.

N. Atlantic IR 1945Z 09.02.10 Click For real time loop

Hurricane Earl NHC Forecast Track 2PM 09.02.10

Once it passes Cape Hatteras, three things will start to work in conjunction to turn it North Northeast and then Northeast.  First, there is the Coriolis Force, which is the force that wants to turn a cyclone to the right of its path in the Northern Hemisphere.  That force increases as the storm moves poleward.  Then there are the mid lattitude prevaling westerlys.  That is the general persistent wind flow in the mid lattitudes of the Northern Hemisphere.  Finally, there is a frontal boundary that is progressing Eastward.  As of 3:30 PM EDT it was just west of the Ohio Valley.  That is some distance from the coast and not moving as fast as we might like.  But, as it approaches, winds ahead of the front or trof will increase from the Southwest.  That will increase Earl’s forward speeed and also serve to knock up the upper air support of the hurricane.   As mentioned earlier, by 8PM EDT the satellite imagery appears to indicate that the southwesterly shear was already taking a toll on Earl.

Structure of a hurricane

Essentially, a hurricane is a warm-core area of low pressure that is a giant heat engine, drawing its energy from warm ocean water.  The ocean has to be at least 80 F.  Not every surface low over the ocean becomes a hurricane though.  It is essential that a hurricane get what I call a “hat” or an anticyclone aloft.  That would be a big area of high pressure.  That is why when you look at a satellite loop, you see clouds going clockwise, yet at the surface, the hurricane winds go counter clockwise.  The upper level high serves to vent the storm.  The structure of a hurricane is such that, at the surface, the flow is toward the center in a counter clockwise fashion.  When the air reaches the center it has nowhere to go but up.  Aloft, the high pressure features air that sinks and goes outward in a clock wise fashion.  The high aloft helps push out the rising air below and as it does, it allows for a more even flow of air rising from below.  When these winds from the southwest kick in, it will disrupt the ventiing flow aloft which will limit the rising air below.  All of that should start to occur in earnest once Earl gets past the Outer Banks.  At that same time, it will start to cross over water that is either near or below 80 F and eventually will get over water that is definitely too cold to support a tropical system.

Atlantic Sea Surface Temperatures-Click for Loop

So, look for rapid weakening of the storm beginning off the North Carolina coast and thereafter.  It will also lose its tropical characteristics probably before it gets to Cape Cod.  Nevertheless, winds of at least hurricane force will continue as the storm moves north.  The forecast track takes it very close to Long Island and even over Cape Cod.  While it may lose its hurricane classification, it will also provide a very healthy storm surge and a high tide will only aggravate the situation.  Click here to find the storm surge forecast for your location.  The storm will also be moving very very quickly so, on the one hand, the effects will not last as long but the conditions will also deteriorate very rapidly.  No one can tell with exact certitude where the center of Earl will travel.  That should not surprise anyone when one considers that the earth is 25,000 miles around;  a margin of error of say 50 miles represents just a fraction of a percent but, it can be the difference between terrible conditions and horrific conditions.  Most of the time, people who try to ride out a storm vow they will never do so again.  Sometimes, they lose their lives and by that time it is obvious they made a mistake.  With hurricanes you do not get a second chance.  Getting out of the way is the better part of valor.  Also, Earl’s interaction with the front may enhance rain fall inland greatly.  Flooding will be a concern from not only the surge, but also rainfall.

N. Atlantic Basin Total Precipitable Water Image-Click For Loop That Clearly Indentifies Cyclone in the N. Atlantic

Gaston NHC Forecast Track 2PM 09.02.10

Gaston Spaghetti Model 18Z 09.02.10

Behind Earl is Fiona which should not be an issue for the United States and perhaps no one.  What is of greater concern is Tropical Storm Gaston.  It is much farther south than Danielle was, or Earl or Fiona.  Fiona will get picked up by the same trof that is picking up Earl and Danielle also got picked up by a trof.  But, Gaston is so far south that it will most likely sneak under any trof and westerly flow around  an Atlantic high should drive Gaston in a westerly fashion.  Most models put Gaston either near or South of the Dominican Republic in about a week and most develop it into a hurricane.  It will not be traveling over any water that has been worked over by Danielle, Earl or Fiona so it should be plenty warm enough and conditions should be conducive for development, perhaps even enough to support a major hurricane.  Its location will offer scenarios for it to enter the Gulf of Mexico as well as potentially affecting the East Coast. 

HURRICANE EARL DISCUSSION NUMBER  34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
500 PM EDT THU SEP 02 2010

DATA FROM A RECONNAISSANCE PLANE INDICATE THAT EARL HAS WEAKENED A
LITTLE BIT THIS AFTERNOON.  THE CENTRAL PRESSURE ROSE TO 947
MB…AND A BLEND OF THE SFMR MEASUREMENTS AND FLIGHT-LEVEL WINDS
SUGGEST THAT THE INITIAL INTENSITY HAS DECREASED TO 100 KNOTS. EARL
SHOULD CONTINUE TO WEAKEN GRADUALLY AS THE SHEAR INCREASES AND THE
HURRICANE SHOULD WEAKEN EVEN FASTER AFTER 24 HOURS AS IT MOVES OVER
A COLDER OCEAN.  AFTER CROSSING CANADA IN 48 HOURS…EARL SHOULD
BECOME POST-TROPICAL/EXTRATROPICAL AND THEN DISSIPATE AS IT IS
ABSORBED BY A MUCH LARGER EXTRATROPICAL CYCLONE.

SATELLITE AND RECONNAISSANCE FIXES SHOW…AS ANTICIPATED…THAT EARL
HAS TURNED NORTHWARD AND IS MOVING 360 DEGREES AT 16 KNOTS. THE
STEERING PATTERN CONTROLLING THE MOTION OF EARL…AND THE
CONSISTENCY IN TRACK GUIDANCE…HAVE BEEN ADEQUATELY DESCRIBED IN
PREVIOUS DISCUSSIONS. EARL IS ABOUT TO BECOME EMBEDDED IN THE
MID-LATITUDE FLOW AND IT IS READY TO GRADUALLY TURN TO THE
NORTH-NORTHEAST AND NORTHEAST WITH AN INCREASE IN FORWARD SPEED.

ALTHOUGH THE MAXIMUM WINDS IN THE CORE HAVE DECREASED…EARL
CONTINUES TO BE A LARGE AND POWERFUL HURRICANE.

FORECAST POSITIONS AND MAX WINDS

INITIAL      02/2100Z 32.5N  75.2W   100 KT
12HR VT     03/0600Z 34.8N  74.8W    95 KT
24HR VT     03/1800Z 38.0N  72.7W    85 KT
36HR VT     04/0600Z 41.7N  69.0W    75 KT
48HR VT     04/1800Z 46.5N  64.5W    50 KT…POST-TROP/EXTRATROP
72HR VT     05/1800Z…DISSIPATED

$$
FORECASTER AVILA

Hurricane Earl Eyes US: Hurricane Warning Flags Flying on East Coast September 1, 2010

Hurricane Earl 1915Z IR Rainbow Image 09.01.10-Click Image for Real time Loop

Click Here For The Most Recent Update Regarding Hurricane Earl’s Brush with the US East Coast

Hurricane Earl 1915Z Visible Satellite Image 09.01.10-Click Image for Real Time Loop

If you recall, yesterday I mentioned that one aspect of the forecast regarding Hurricane Earl was the dry air in which Earl was moving into.  I had thought that perhaps dry air might work its way into the circulation of the hurricane and perhaps limit its intensity potential or even bring it down a notch or two.  At 5 AM on Wednesday September 1, 2010 the National Hurricane Center included this bit of information near the end of it’s discussion: ” …WATER VAPOR IMAGERY SHOWS A TONGUE OF MID/UPPER-LEVEL DRY AIR WRAPPED MORE THAN HALFWAY AROUND THE CYCLONE.”  I honestly had been surprised that they had not mentioned that potential earlier because the the scale of the dry air ahead of the storm was rather large.   Nevertheless, by Wednesday afternoon, the outflow symmetry of Earl looks to have improved  and the dry air looks to have been absorbed without a whole lot of disruption; perhaps it hurt Earl a bit.  But, Earl overcame the dry air and at 5pm EDT on Wed Sept 1 had maximum winds of 135 mph with gusts to 160 mph.  Central pressure was 941mb and was moving at 310 -320 degrees (NW) at 17 mph.    The dry air was one of the “challenges” that I referred to that I felt Earl would face in maintaining its intensity.  There are other issues at play as well that suggest the storm has seen its better days and its ferocity will not be as great as it once was, or even feared it would be, when it affects the US Coast.  Nevertheless, I would not take the storm lightly and it would be advisable to get out of its way if you may be in the path of Earl.

N. Atlantic Basin Total Precipitable Water Image-Click For Loop That Clearly Indentifies Cyclone in the N. Atlantic

18Z Hurricane Earl Spaghetti Model Track 09.01.10-Note Model track or two suggest a mainland landfall

As of 5 PM EDT Wednesday, Hurricane Warning flags have been hoisted from  Bouge Inlet, North Carolina to the North Carolina/Virginia.  A Hurricane Watch extends from the North Carolina/Virginia border to Cape Henlopen, DE and from Woods Hole, MA to Sagamore Beach, MA.  Tropical Storm Warnings are posted from the North Carolina/Virginia border to Sandy Hook, NJ.  A Tropical Storm Warning means tropical storm conditions are likely within 36 hours, A Hurricane Watch and a Tropical Storm Watch means that those conditions are possible within 48 hours.  A Hurricane Warning means that hurricane conditions are expected in the warned area with the onset of tropical storm force winds expected within 36 hours.  Tropical Storm winds are considered to be 40 to 73 mph and winds are considered hurricane force at 74 mph.  Remember, these are sustained winds, not gusts.  Winds can gust to at least 20% higher than the sustained winds.  It is not uncommon with a hurricane for a region to experience continuous hurricane force winds for many hours.  Most people who survive “riding out” a hurricane swear they will never do so again.  Wind is only part of the story as torrential rain is always a part of a hurricane and the storm surge associated with any hurricane is typically the gravest life taker.  People generally have no idea just how powerful the sea can be.  Click here for to find the storm surge probability forecast for your region.

Note the Trof in N. Central US on 1845Z Atlantic IR Rainbow Image 09.01.10-Click Image for Real Time Loop

18Z Hurricane Earl Spaghetti Model Intensity Graph 09.01.10

By midday on Wednesday,  Hurricane Earl had continued its gradual curvature around a big fat ridge extending from the Atlantic.  As the ridge continues to move eastward,  Earl will continue its right hand shifting and will eventually be moving due North.  By late Thursday, the long anticipated trof moving across the northern United States will be close enough to pick up Earl.  The result will be an increase in forward speed as well as a turning of the storm; first North-Northeast and eventually Northeast.  The timing of the trof will be the determining factor as to the precise track of Earl up the East Coast, particularly off of New England.  The variable is so slight that no one can say with certainty how it will play out.  An hour or so timing difference of the trof’s influence on Earl can make the difference between the storm staying offshore or running over land.  Suffice it to say, it will be at least a close call and no one along the NE Coast of the United States will escape some affect of Hurricane Earl. 

Atlantic Sea Surface Temperatures-Click for Loop

While the shearing winds from the Southwest ahead of the trof and the dry air trying to work its way into Earl may serve to limit its intensity,  forecasts continue to call for a major hurricane with winds of 100 to 120 mph running just off the North Carolina, Virginia, Maryland and Delaware coasts.  By the time its off the New England coast, it will be probably scooting along at least at 30 mph and winds will have diminished from weakening due to the shearing winds that mess up its upper support as well as colder water. Tropical Cyclones need surface water temperatures of at least 80 F current coastal conditions from off of Delware northward fall below that level.  Farther out though, in the Gulf Stream, waters remain above 80 F extend a shade farther north.   However, hurricane conditions may still be probable for Long Island and Cape Cod, if not the mainland of the New England states.  The official track keeps the storm offshore but it would not take much of a deviation, say 20 miles, for the eye of the hurricane to run right over Long Island and perhaps Cape Cod or Nantuckett Island.  While its not entirely likely, it is not totally out of the question for Earl to actually make at least a partial landfall on some portion of the mainland. 

NHC Hurricane Earl Forecast Track 5PM EDT 09.01.10

While the winds may back off as it heads farther North, the increase in forward speed may serve to enhance the storm surge to the right of the storm.  Further, given that Earl was a big bopper, the sea will not necessarily react as quickly to diminishing winds so the surge may be on the top end of the normally expected storm surge associated with a minimal hurricane running up the East coast.  So, when you hear the forecasts call for a category 1 hurricane off the Jersey shore of off of the New England coast, it would be advisable not to pooh-pooh it as the destructive potential of a  category 1 hurricane can be somewhat excessive. 

18Z Tropical Depression 9 Spaghetti Model Track 09.01.10

Behind this is Tropical Storm Fiona which has been experiencing some difficulty as the outflow from Earl has been disrupting its outflow.  Aside from its intensity, the same trof that is picking up Earl will most likely pick up Fiona as well, regardless of its strength, and should turn it north well before it threatens the US coast.  Behind Fiona is a Tropical Wave (Invest 98) and Tropical Depression 9 which was designated at Tropical Storm Gaston at 5pm EDT September 1.  Invest 98 appears to be running over the same worked-over water as Danielle, Earl and Fiona and may have a difficult time developing.  However, Tropical Storm Gaston is farther south and the initial modeling data suggests its track will be more westerly and as it will be far enough south as to not be influenced by any trofs farther North.  While there is no data currently showing a rapid intensification, a few models do indicate that it will develop into a hurricane and the general track would suggest the potential exists for it to some day affect the US coast from the Gulf of Mexico to the East Coast.  It’s a long way out and there are many scenarios so there will be time to monitor its development. 

HURRICANE EARL DISCUSSION NUMBER  30
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
500 PM EDT WED SEP 01 2010

VISIBLE SATELLITE IMAGES INDICATE THAT THE EYE HAS BECOME VERY
DISTINCT…WITH OJECTIVE T-NUMBERS OSCILLATING AROUND 6.0 FOR THE
PAST FEW HOURS. AN AIR FORCE PLANE MEASURED FLIGHT-LEVEL WINDS OF
138 KNOTS AND A MINIMUM PRESSURE OF 941 MB IN THE LAST FIX.
HOWEVER…SFMR MEASUREMENTS WERE A LITTLE LOWER. A COMPROMISE OF
THESE DATA SUPPORTS AN INITIAL INTENSITY OF 115 KNOTS.
HOWEVER…EARL COULD FLUCTUATE IN INTENSITY DURING THE NEXT 12 TO
24 HOURS BUT SHOULD BEGIN TO GRADUALLY WEAKEN AS IT REACHES
COOLER WATERS AND MOVES INTO HIGHER SHEAR BEYOND 36 HOURS. BY DAY 5
THE HURRICANE SHOULD HAVE BEEN ABSORBED BY A LARGE EXTRATROPICAL
CYCLONE WELL NORTH OF CANADA.

SATELLITE AND RECONNAISSANCE AIRCRAFT FIXES INDICATE THAT EARL
HAS BEEN MOVING RELENTLESSLY TOWARD THE NORTHWEST OR 310 DEGREES
AT 15 KNOTS. THE HURRICANE IS ABOUT TO REACH THE WESTERN EDGE OF
THE SUBTROPICAL RIDGE AND SHOULD BEGIN TO TURN MORE TO THE
NORTH-NORTHWEST AND NORTH LATER TONIGHT AND THURSDAY. IN ABOUT 36
HOURS OR SO…THE HURRICANE WILL ENCOUNTER THE BASE OF THE
MID-LATITUDE WESTERLIES AND SHOULD BEGIN TO RECURVE OR TURN TO THE
NORTHEAST WITH AN INCREASING FORWARD SPEED. THIS IS THE SOLUTION
CONSISTENTLY PROVIDED BY TRACK MODELS…WHICH HAVE EARL PASSING TO
THE EAST BUT NOT FAR FROM THE OUTER BANKS OF NORTH CAROLINA ON
THURSDAY NIGHT. ONLY A SMALL WESTWARD DEVIATION OF THE TRACK TO THE
WEST WOULD BRING THE CORE OF THE HURRICANE TO THE COAST.

GIVEN THE FORECAST TRACK…THE LARGE SIZE OF THE WIND FIELD…AND
THE EXPECTED INCREASE IN FORWARD SPEED WATCHES AND WATCHES HAVE
BEEN EXTENDED NORTHWARD ALONG THE EAST COAST OF THE UNITED STATES.

FORECAST POSITIONS AND MAX WINDS

INITIAL      01/2100Z 26.3N  73.3W   115 KT
12HR VT     02/0600Z 28.4N  74.7W   115 KT
24HR VT     02/1800Z 31.7N  75.4W   110 KT
36HR VT     03/0600Z 35.1N  74.7W   100 KT
48HR VT     03/1800Z 38.5N  72.2W    90 KT
72HR VT     04/1800Z 46.5N  63.5W    60 KT
96HR VT     05/1800Z 58.0N  57.0W    40 KT…POST-TROP/EXTRATROP
120HR VT     06/1800Z…DISSIPATED

$$
FORECASTER AVILA

Hurricane Earl Faces Challenges, Still Major Threat to US East Coast August 31, 2010

Hurricane Earl Visible Satellite 1945Z 08.31.10 In Midst of Eyewall Replacement Cycle; Dry Air May Be Trying to Work In-Click Image for Real Time Loop

Note Great Lakes Trof and Huge Area of Dry Air Over Mid Atlantic States: Click Image for Real Time North Atlantic IR Rainbow Loop

CLICK HERE FOR MORE RECENT UPDATE CONCERNING HURRICANE EARL, HURRICANE WARNINGS AND WATCHES ALONG THE US EAST COAST AS FAR NORTH AS MASSACHUSETTS

Hurricane Earl has been behaving like a well developed hurricane as during the day on Tuesday it has been going through an eyewall replacement cycle.   Typically, the old eyewall collapses and a new eyewall forms.  During this time, any given storm’s maximum winds will typically decrease in response to a rise in the central pressure.  However, the energy tends to get dispersed throughout the storm, thus winds in the extremities may be higher than normally expected as the gradient is not quite as steep.  This is what happened with Hurricane Katrina:  it was going through an eyewall replacement cycle when it made landfall and so it was only a category 3 hurricane but, winds in excess of 100 mph were experienced well away from the center.  I believe that the winds were about 125 mph at the point of landfall in Western Mississippi but winds of 108 mph were felt near Mobile Alabama.  In any event, Earl should complete this cycle by Tuesday afternoon and thereafter some moderate strengthing is possible, though most models do not take it to category 5 status.    So, it may max out at around 140 mph and not 155.  What’s 15 mph amongst friends?  It’s still an extremely formidable storm.

NAM 850mb 12Z Thu 09.02.10 Note Movement of Trof East

NAM 12Z 850mb Wed 09.01.10 Note Trof Over Great Lakes

We had a big high pressure ridge over the Eastern United States last week and another ridge in the Atlantic with a trof in between.  Hurricane Danielle followed the trof that split the two ridges and stayed well out in the open waters of the Atlantic.  By this weekend, that weakness between the two ridges filled in and formed generally one large ridge from the mid Atlantic to the Eastern US with a slight weakness in the ridge along the US East Coast.  Now, as hurricanes traverse farther north from the equator, the coriolis parameters become greater.  The coriolis force is the apparent motion caused by the rotation of the earth.  Any hurricane in the Northern Hemisphere will want to move to the right due to the rotation of the earth.  Until the last day or so, the ridge to the north was strong enough to for the most part overcome the coriolis parameters and keep Earl moving generally westward.  However, as Earl moved north of the Virgin Islands, it began to get toward the edge of the strongest part of the ridge and now is moving to the right of a westward track.  Midday Monday it had a vector of 285 degrees and by the evening it was running at 300 degrees.  This however is not the expected turn north.

NAM 12Z Fri 850mb 09.03.10 Note Relation of Trof on East Coast Vs. Earl Position

That turn north will not occur until a trof moving across the northern part of the United States moves eastward to the US East Coast.  When it does, it will provide the channel for Earl to turn north and run up the trof.  A c0uple of things will happen at that time.  The southwesterly flow ahead of the trof will pick up the storm and turn it north and then eventually north-northeast and then northeast and the forward speed of Earl will also increase.  By the time its up to about 35 degrees North Latitude, it will most likely be scooting along at about 30 mph.  That southwesterly flow will not only turn it and increase its forward speed, it should also disrupt the outflow aloft and that would tend to limit any intensification potential or even lead to a decrease in intensity.  Even though there is a high probability of that coming about, it will still be a very strong storm with a high storm surge potential and its even possible that the forward speed might enhance the surge potential in the front right quadrant. 

1845Z Water Vapor-Huge Area of Dry Air Looks As if it is trying to wrap into Earl: Click Image for Real Time Loop

With regard to the intensity there is another potential fly in the ointment that could prove beneficial.  I noticed yesterday a huge area of dry air on the water vapor imagery to the north of Earl.  That dry air is not quite as large in scale today but it’s still there and is moving south.  Earl will be moving right into that environment and I think that there is a fair chance that Earl may have some of that dry air wrap into it.  If that happens, then the dry air will tend to weaken the storm.  Hurricane Opal got a shot of dry air and it actually acted as a steroid shot for a few hours and the intensity jumped unexpectedly but then it fell quickly when that dry air got into the core.  I believe that there is a chance that some dry air intrusion may take place. If so , that  would be good news.  Nevertheless, I believe the big story with Earl will be the ultimate track.

08.31.10 18Z Hurricane Earl Spaghetti Models Intensity

The spaghetti models have been consistently keeping the storm off the coast, though some recent runs had a model or two taking the storm inland in Maine or one even had it going in farther south in New England.  The National Hurricane Center has been inching the official forecast ever so slightly westward for each of the most recent forecast tracks and has been pretty consistent in keep their forecast track  to the left of the model consensus track.  No one can say for certain at this point because it comes down to a matter of hours in regard to the trof digging into the East Coast.  6 hours difference in the timing would result in the difference of a major hurricane running right along the coast or running up say 80 miles offshore.  While both scenarios would bring significant effects to the East Coast, a storm running just off the coast would be probably the worst case scenario.  In that worst case scenario in my mind, the eye of the hurricane would remain over water so the intensity would not drop all that quickly.  Meantime, coastal residents from North Carolina to Maine would feel the effects of a major hurricane, storm surge, winds and all. 

18Z 08.31.10 Hurricane Earl Spaghetti Model

There remain many scenarios as there are still several days for this to play out.  However, I think its safe to say that residents of the Eastern Seaboard will feel the effects of a hurricane by the end of the week.  The question is how much of an effect and no one can say with certainty what the answer to that question is.  However, places like the outerbanks of North Carolina, the Virginia Coast, Long Island and Cape Cod will get the worst of whatever Earl has to offer.  The history of hurricanes running up the East Coast is filled with examples of storms that weren’t too terrible, but there are also some glaring examples of storms that brought extreme devastation and loss of life.  While we can’t avoid any devastation, there is no reason for loss of life as the potential is great enough with this storm for everyone to know that the better part of valor is to get out of the way.  Remember, estimates suggest that a hurricane at its peak can release 10 to the power of 15 watts of total energy which equates to about 500,000 Hiroshima-type atomic bombs every day.  Hurricane Earl quite literally is the most powerful force on the face of the earth right now and that is a battle man cannot win.

Hurricane Earl NHC Forecast 5PM 08.31.10

WTNT42 KNHC 312043
TCDAT2
HURRICANE EARL DISCUSSION NUMBER  26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
500 PM AST TUE AUG 31 2010

ALTHOUGH THE SATELLITE PRESENTATION IS NOT AS IMPRESSIVE AS IT WAS
EARLIER...A RECONNAISSANCE PLANE AROUND 1700 UTC REPORTED A MINIMUM
PRESSURE OF 940 MB AND MAXIMUM FLIGHT-LEVEL WINDS OF 128 KNOTS.
THESE DATA SUPPORT AN INITIAL INTENSITY OF 115 KNOTS.
CURRENTLY...THERE IS SOME SOUTHWESTERLY SHEAR DISRUPTING THE
UPPER-LEVEL OUTFLOW OVER THE WESTERN SEMICIRCLE OF EARL.  THIS SHEAR
IS CAUSED BY A WEAK UPPER-LOW OR TROUGH OVER THE EASTERN BAHAMAS AS
OBSERVED ON WATER VAPOR IMAGES.  HOWEVER...MODELS WEAKEN THE UPPER
LOW AS EARL MOVES AROUND IT...RESULTING IN A MORE FAVORABLE
ENVIRONMENT. EARL IS EXPECTED TO MAINTAIN ITS CATEGORY FOUR
INTENSITY FOR THE NEXT DAY OR TWO.

EARL HAS BEGUN TO MOVE TOWARD THE NORTHWEST OR 305 DEGREES AT 12 OR
13 KNOTS DURING THE PAST FEW HOURS. THE SUBTROPICAL HIGH THAT IS
STEERING EARL TOWARD THE WEST-NORTHWEST OR NORTHWEST IS FORECAST TO
GRADUALLY SHIFT EASTWARD AS A BROAD TROUGH BECOMES ESTABLISHED OVER
THE EASTERN UNITED STATES. THIS PATTERN WILL FORCE EARL ON A MORE
NORTHWESTERLY AND NORTHERLY TRACK FOR THE NEXT DAY OR TWO.
THEREAFTER...EARL WILL REACH THE BASE OF THE MID-LATITUDE WESTERLIES
AND WILL LIKELY TURN SHARPLY TO THE NORTHEAST WITH AN INCREASE IN
FORWARD SPEED.  THIS IS THE SOLUTION UNANIMOUSLY PROVIDED BY TRACK
GUIDANCE.  ONCE AGAIN THE OFFICIAL FORECAST HAS BEEN SHIFTED A FEW
MILES TO THE WEST BEFORE 48 HOURS FOLLOWING THE TRENDS OF THE ECMWF
AND THE GFS.

GIVEN THE LARGE AREA OF TROPICAL STORM FORCE WINDS ASSOCIATED WITH
EARL...AND THE NEW DEFINITION OF WATCHES AND WARNINGS...A HURRICANE
AND TROPICAL STORM WATCH HAS BEEN ISSUED FOR A PORTION OF THE MID-
ATLANTIC COAST.

INTERESTS FROM VIRGINIA NORTHWARD TO NEW ENGLAND SHOULD MONITOR THE
PROGRESS OF EARL. 

FORECAST POSITIONS AND MAX WINDS

INITIAL      31/2100Z 22.0N  68.8W   115 KT
 12HR VT     01/0600Z 23.3N  70.5W   115 KT
 24HR VT     01/1800Z 25.6N  72.8W   115 KT
 36HR VT     02/0600Z 28.0N  74.5W   115 KT
 48HR VT     02/1800Z 31.0N  75.5W   115 KT
 72HR VT     03/1800Z 36.0N  73.5W    95 KT
 96HR VT     04/1800Z 44.0N  65.0W    75 KT
120HR VT     05/1800Z 56.0N  55.0W    50 KT...POST-TROP/EXTRATROP

$$
FORECASTER AVILA

Major Hurricane Earl Posing Real Threat to US East Coast August 30, 2010

Click on Image for Latest Satellite Loop

Earl Visible 1945Z 08.30.10 Click for Loop

CLICK HERE FOR MORE RECENT UPDATE

Hurricane Earl will pose a threat to residents along much of the eastern coast of the United States later this week.  If you recall, last week we had Hurricane Danielle that became a powerful hurricane but turned north from the tropical regions into the Central North Atlantic and really was nothing more than a concern for shipping, though it may eventually raise issues along the SE Greenland coast, Iceland, England or mainland Europe.  Danielle turned north because there was a trof in between ridge in the North Atlantic and a ridge over the eastern third of the United States.  Since that time, the trof lifted up and out and the ridge has filled in to a large degree.

Click on Image for Water Vapor Loop

Consequently, Earl has been traveling more westward around the expanding Atlantic ridge at the lower latitudes of teh North Atlantic than Danielle did.  The idea has been that this storm would turn north by now but the models did a lousy job of anticipating the expansion of the Atlantic ridge.  However, each model run from the last 48 hours have been taking the track of Earl farther and farther west.  At this point, none of the hurricane models that make up the spaghetti model depiction take Earl into the United States but does bring it close enough to cause an increase in tides and also provide windy weather in squalls.  However,  midday Monday, Earl was passing North of the Virgin Islands with a vector of 285 degrees, or just 15 degrees north of due west, which means that Earl has not begun its turn.

Hurricane Earl 18Z Spaghetti Intensity Model 08.30.10

Remember, coriolis parameters will want to turn Earl north but the ridge is preventing that.  Any weakness in that ridge will allow Earl to turn.  As it stands, the ridging along the US East Coast is not all that strong so some turning northwest  is anticipated.  But the major turn will come when a trof digs in from the Great Lakes and down the East Coast.  If that happens, then Earl will turn north and increase in forward speed.  There should also be some decrease in intensity as shearing with the trof will tend to mess up the upper support.  However, Earl will remain a significant hurricane.  At 5pm, winds were estimated at 135 mph with gusts to 155 mph.  Several models take Earl to Category 5 status on the Saffir Simpson Scale over the next few days before backing off. 

Hurricane Earl 18Z spaghetti model 08.30.10

The issue is when does Earl turn?  If the trof does not dig as deep as the models advertise, then the turn could be a more gentle, wide turn and that would increase the possibility of it running along the East Coast.  If the trof does not come through fast enough, then the storm will be farther west when it makes its turn and then it affects the US.  None of the hurricane models at this point show the eye of Earl on land in the US.  A couple of conventional 12Z models run it along the VA coast but, in general, they too keep it off shore.  Most models time the storm as off the VA coast on Thursday night.  The majority of the 12Z hurricane models take it to 131 to 140 mph winds (cat 4) at its maxima but decrease intensity as  it runs up the coast.  What concerns me is that if you look at the spagetti models at 18Z, they initiate Earl moving in a heading something a little greater northwest than what I observe from the actual satellite loop.  It could just be a wobble but its possible that Earl may have a bit more of an initial westward motion than the models think and that could greatly affect the ultimate track, depending on how the trof shakes out.  The 5PM Discussion has the intial motion at 290 degrees, which is 5 degrees farther north than the 11AM discussion, but the NHC has once again shifted the track farther west for the first 72 hours.  Again, this bears watching on the East Coast 

National Hurricane Center Forecast Hurricane Earl 5pm EDT 08.30.10

The 18Z hurricane models also raise the stakes and  initiate Earl as a Category 4 hurricane, yet, at 3pm EDT it was only 125 mph.  Several raise its intensity to category 5 before backing it off somewhat.  Regardless, tides will be running very high later this week all along the East Coast.  Folks from North Carolina to Maine will feel some effect of Earl for the latter half of the work week…it just remains to be seen how much of an effect.  The National Hurricane Center added this last remark to its 11AM Monday discussion, which should be enough for East Coast residents to pay attention:

THIS IS A GOOD TIME TO REMIND EVERYONE THAT NHC AVERAGE TRACK
FORECAST ERRORS ARE 200 TO 300 MILES AT DAYS 4 AND 5.  GIVEN THIS
UNCERTAINTY…IT IS TOO SOON TO DETERMINE WHAT PORTION OF THE U.S.
EAST COAST MIGHT SEE DIRECT IMPACTS FROM EARL.

HURRICANE EARL DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL072010
500 PM AST MON AUG 30 2010

THE RECONNAISSANCE AIRCRAFT MEASURED 116 KT FLIGHT-LEVEL WINDS AND
108 KT SFMR SURFACE WINDS SHORTLY AFTER 1500 UTC.  THIS WAS THE
BASIS FOR THE EARLIER INCREASE IN INTENSITY.  SINCE THAT TIME…THE
PRESSURE HAS CONTINUED TO DROP AND WAS DOWN TO 955 MB ON THE LAST
DROPSONDE RELEASED IN THE EYE AROUND 1700 UTC.  SINCE THE AIRCRAFT
DEPARTED EARL…THE EYE HAS CONTINUED TO CLEAR AND IS SURROUNDED BY
CLOUD TOPS TO -70 DEGREES CELSIUS OR COLDER.  OBJECTIVE SATELLITE
INTENSITY ESTIMATES HAVE INCREASED TO JUST ABOVE 6.0 ON THE DVORAK
SCALE AND SUPPORT AN INITIAL INTENSITY OF 115 KT…CATEGORY FOUR ON
THE SAFFIR-SIMPSON HURRICANE WIND SCALE.

EARL IS EXPECTED TO REMAIN IN A LOW SHEAR ENVIRONMENT AND OVER WARM
WATER DURING THE NEXT FEW DAYS AND SOME ADDITIONAL STRENGTHENING IS
LIKELY IN THE SHORT TERM.  THEREAFTER…EYEWALL CYCLES WILL LIKELY
INDUCE SOME FLUCTUATIONS IN INTENSITY…WHICH ARE DIFFICULT TO
PREDICT.  THE NHC FORECAST IS AGAIN NEAR THE HIGH END OF THE
INTENSITY GUIDANCE. AT DAYS 4 AND 5…THE HURRICANE IS FORECAST TO
MOVE OVER COOLER WATER AND INTO AN AREA OF INCREASING SHEAR WHICH
SHOULD RESULT IN WEAKENING.

THE INITIAL MOTION IS 290/13.  THE FORECAST REASONING REMAINS
UNCHANGED AS EARL IS EXPECTED TO TURN NORTHWESTWARD IN ABOUT 24
HOURS AROUND THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE. THE
TRACK GUIDANCE HAS SHIFTED NOTICEABLY WESTWARD DURING THE FIRST
48 HOURS…WITH THE GFS AND ECMWF ON THE EASTERN EDGE OF THE
ENVELOPE.  THE OFFICIAL FORECAST HAS BEEN ADJUSTED WESTWARD…
PRIMARILY THROUGH 72 HOURS…AND LIES BETWEEN THE GFS/ECMWF AND THE
MULTI-MODEL CONSENSUS.

THIS IS A GOOD TIME TO REMIND EVERYONE THAT NHC AVERAGE TRACK
FORECAST ERRORS ARE 200 TO 300 MILES AT DAYS 4 AND 5.  GIVEN THIS
UNCERTAINTY…IT IS TOO SOON TO DETERMINE WHAT PORTION OF THE U.S.
EAST COAST MIGHT SEE DIRECT IMPACTS FROM EARL.

FORECAST POSITIONS AND MAX WINDS

INITIAL      30/2100Z 19.3N  64.7W   115 KT
12HR VT     31/0600Z 20.2N  66.3W   125 KT
24HR VT     31/1800Z 21.7N  68.1W   130 KT
36HR VT     01/0600Z 23.4N  70.1W   130 KT
48HR VT     01/1800Z 25.8N  72.1W   125 KT
72HR VT     02/1800Z 31.6N  74.7W   115 KT
96HR VT     03/1800Z 38.0N  71.0W    95 KT
120HR VT     04/1800Z 45.5N  63.0W    70 KT…INLAND

$$
FORECASTER BROWN

Always Alert, Samuel Morse’s Success Came From Unlikely Origin May 24, 2010

Finding Success can be an Enigma...ask William Tell

I guess Morse Ended Up Finishing His Lafayette Painting

On This Date in History: In 1810, a young man graduated from Yale and immediately went to England to study art. He created a giant painting and a small sculpture and called them both “the Dying Hercules.” These were his most significant works and I suppose that he figured that was the best he could do and so he came home to America. He decided to paint portraits for a living. He had some works that were considered outstanding including one of Lafayette and other historical figures that were recognized for the extreme detail. Among his portraits of famous people was one of Eli Whitney. The young man gained a pretty big reputation but also was known as a man with a small income. That makes me think that if he was such a big painter, then maybe he would figure out that he needed to charge more for his paintings. I guess perhaps his reputation was good at the price he charged. Had he charged more, then maybe he wouldn’t have been so popular. Well, its a good thing for him, and for the rest of the world, that he had other pursuits to relieve his creative mind.

Signal Flags Were Still Used in Spanish American War When Other Communications Were Not Practical

The word “telegraph” derives from the Greek word, “to write far.” Pretty good description. Before there was electricity, there was a communication system that fit that description. It was in the form of tall poles that put up different arms and other signals. It could be seen at a distance. It was used during the Battle of Waterloo to let the folks know back in London what was going on with the struggle against Napoleon. I suppose that has its use but for long distances, you probably would need a series of big poles with a guy hanging around each one and waiting for a signal to be seen from one direction so he could then relay it to someone in the other direction. I suppose it was better than nothing and probably faster than relying on a guy on a horse, like Paul Revere…though Paul was pretty fast and he could travel at night, which obviously was a limitation for this early form of “telegraph.”

1844 First Telegraph Receiver

So, along comes electricity. Now, a bunch of inventors had figured out the basic principals involved but it was left to the somewhat successful American painter, Samuel Finley Breese Morse, to understand the practical application of those principals and the first to take pragmatic steps to invent a way to take exploit those principals. While at Yale, Morse had taken a keen interest in electricity but was lured by his love for art. He studied under Benjamin West and Washington Allston, who were considered two of the better painters of the day. He got married in 1818 but, while he was working on his painting of the Marquis de Lafayette, he got news his wife died. He left the painting unfinished and became an artistic recluse in his grief. But an odd thing happened, in his grief, he rediscovered his interest in electricity. He attended some lectures of academics but eventually returned to art.

William Cullen Bryant by Morse

In 1829, he went back to Europe to study art.  Had he not done that, he may never had received the inspiration of the telegraph. You see…in 1832 he was on board a ship returning to America when he came upon some scientists who were discussing the properties of electricity. One man queried whether electricity lost its velocity over a long distance. When another remarked that in Ben Franklin’s experiments, he had noted that a captured electrical current traveled over several miles of wire without any time differential as the reaction at the end of the wire seemed to be coincidental with the intialization of the current. That statement triggered the small spark of inspiration in Sam Morse’s head.

Old Sam Looks Like a Decorated Warrior

That left Morse with a tough choice. If he wanted to immerse himself in electricity, then he had to give up painting but, with no painting, he had no income. He was already rather poor, often skipping meals for extended periods or depending on the help from friends. In 1835, he was granted a teaching position in the Art Department of the State University of New York. That gave him access to the facilities and faculty at the University and afforded him the opportunity to expand his electrical research. With the help of a colleague, he made numerous successful experiments and developed a code of communication, known today as the Morse Code. In 1842, Morse went to Washington to build a telegraph line. In early 1843, he convinced Congress to grant him $30,000 to build a line from Washington to Baltimore. And finally, on this date in 1843, Samuel F.B. Morse demonstrated his telegraph to the world. His friend, Miss Ellsworth, came up with the first words to be transmitted. It was “What Hath God Wrought?” Indeed…what? It was the beginning of the information age that eventually progressed from communications by telegraph to radio to television and now the internet. All because a painter became heartbroken by his wife’s death and because he had run off to Europe as part of his grief.

I suppose, this might be an example of “don’t give up.” Difficult situations today might make you say “why me?” or make you angry. But, it could be that circumstance that proves necessary for your later success and happiness.

Weather Bottom Line:  Everything is going right along as scheduled.  However, it got a bit warmer sooner than I expected. Snow White and I were out and about on Sunday afternoon.  Even though we officially hit 90, I think just about everyone was in the mid to upper 80′s since no one lives at the airport where they decided a few years ago to keep the official records.  Necessarily, that means that the temperatures will be hotter.  It’s going to be very difficult for Louisville to break all time low temperature records.  Anyway, my thinking was that there would be so much humidity that it would be difficult to get to 90 this week and I still think that is the case.  But…whatever.  Its going to be pretty warm and humid.  Having said that, isolated afternoon t’showers will be possible..the exception not the rule. One way you can tell if they are going to be an issue if, at noon time you see any towering cumulus clouds. If you do, then there is a good bet that there will be storms in the afternoon.  If not…if you just see puffy cumulus or ones that are kinda flattened out, that would suggest that there is somewhat of a cap and that storms aren’t likely.  Now, at the end of the week, there is a frontal boundary that will be approaching that may bring a better chance for general rain and t’storm activity. 

This is What the actual satellite photo of the Atlantic and the disturbance looked like on May 24 2010

As mentioned yesterday, there is a little system north of the Bahamas.  I’ve seen it show up on the models for several days.  Generally they only take it to 1004 mb and keeps it meandering offshore of the SE US before it scoots away.  I found several news outlets though that, last Friday, claimed that we could have a tropical storm over the weekend.  The Palm Beach Post said “…there’s a chance the first storm of the season will form this weekend.”  That was such nonsense except that 1% chance I suppose qualifies as a “chance.”  There was nothing to suggest that.  Even the guy from the local NWS office didn’t say that. They just made it up. And they weren’t alone.  It’s headline writers and producers in news rooms that often give meteorologists a bad name because they write things that are not accurate. 

This is the photo the TV station uses in association with a story that says absolutely nothing about a tropical storm, tropical depression or hurricane. You decide using this old photo is a responsible act.

Now, WXJT in Jacksonville has one of several headlines put out by various media outlets today that are just as far off base.   They show a picture of a very mature and completely developed hurricane, which who knows when that was taken, but its not this one and they know it but a casual reader may not.  All they see is the photo and a headline that reads,  “Tropical System Brewing in Atlantic?”  If the TV station bothered to read the first sentence of the special statement put out by the National Hurricane Center (found below) it says “…the non-tropical low pressure system….”  That should answer their question mark. They suggest that there is less than a one in three chance for it to acquire subtropical characteristics in the next few days… nothing about tropical.  Now, last night, I found one model run that wanted to run this guy off the Virginia coast and then deepen it quickly to about 984mb as it ran up  just offshore the Northeast and New England coast.  Seemed a bit odd and now that abherration is no where to be found.  Every model that i looked at today still has a 1004-1008 mb low wandering about for a few days off the South Carolina and Georgia Coast before it moves northeast.  From the satellite picture,even an untrained eye like a news producer can see it looks nothing like a tropical cyclone.  Is it possible for it to acquire those characteristics?  Yes. Probable? NO.  And it would have to become a fully developed major tropical cyclone to affect the oil slick operations in the Gulf, and that seems very unlikely…though I suppose the headline writers might say there’s a chance if I said it was .00025% chance.  They like to scare people so they will buy the news paper, read their webpage or watch their news.  Don’t worry about it.  Having said all of that, I have seen in the past where an early storm of dubious distinction was given a name with the “subtropical” modifier. I have speculated that if there is an excuse for a name, they find it early on just to make people more aware of the season’s start.  I have no proof but, I have sometimes wondered if a couple of storms have actually met the criteria and qualified for a name.  So, I won’t be surprised to see a name, deservedly or not…but either way…..there is no indication at all that it will be anything but a moot point.

1. SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT THE
NON-TROPICAL LOW PRESSURE SYSTEM CENTERED ABOUT 475 MILES SOUTHWEST
OF BERMUDA HAS NOT BECOME BETTER ORGANIZED SINCE YESTERDAY.  THIS
SYSTEM IS PRODUCING A LARGE AREA OF DISORGANIZED SHOWERS AND
THUNDERSTORMS OVER THE SOUTHWESTERN ATLANTIC OCEAN ALONG WITH WINDS
TO GALE FORCE.  THE LOW IS EXPECTED TO MOVE SLOWLY TOWARD THE
NORTH-NORTHWEST AND IT STILL HAS THE POTENTIAL TO ACQUIRE
SUBTROPICAL CHARACTERISTICS DURING THE NEXT DAY OR SO.  THERE IS A
MEDIUM CHANCE…30 PERCENT… OF THIS SYSTEM BECOMING A SUBTROPICAL
CYCLONE DURING THE NEXT 48 HOURS.  FOR ADDITIONAL INFORMATION…
PLEASE SEE HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER
SERVICE…UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.
ANOTHER STATEMENT WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER
THIS EVENING.

$$
FORECASTER PASCH/ROBERTS
NNNN

Tropical Storm Ida Forecast Track Eyes Mobile Bay Landfall as it Weakens Rapidly November 10, 2009

Tropical Storm Ida Satellite Loop (click for most recent)

Tropical Storm Ida Water Vapor Loop (click for most recent)

Hurricane Ida has behaved as expected for the most part. You can access the Mobile National Weather Service Radar Here. You can also tell from the satellite loop above, it doesn’t really look like a tropical cyclone anymore but instead a run-of-the-mill area of low pressure.    In fact, if you look at the Tropical Storm Ida Water Vapor Loop to the left, it really looks like it doesn’t have much in the way of tropical characteristics.  As it moved north during the day, it ran into colder water.  By the afternoon, it was over water with a surface temperature of 26 C which is below the critical level to sustain tropical cyclones.  As it moves north, it will move into increasingly colder water.  Also, it encountered strong wind shear.  Late Sunday night, when I saw the Vortex message from the Hurricane Hunters, I noted that it was showing a rise in pressure and an open section of the eyewall and suggested that perhaps it was already beginning its demise even though the winds had increased to 105 mph.  By late Monday afternoon, Hurricane Ida was no longer and Tropical Storm Ida was back with us as winds had dropped to 70 mph, though observations showed a small area of hurricane force winds that the boys that the National Hurricane Center determined was a local anomaly and not indicative of the circulation.  The shear had become so pronounced that early afternoon observations from the Hurricane Hunter indicated that the center at 700 mb was already shifting away from the center at the surface, indicating that the shear was really ripping up the integrity of the structure.

Tropical Storm Ida Forecast Track (click for most recent)

By late afternoon/evening, Ida was located 40 miles ESE of the mouth of the Mississippi River and 125 miles South of Mobile and was moving north at 17 mph.  Much of the convection was on the north and east side of the storm, again indicative of a storm getting ripped up and perhaps transitioning to an extra-tropical cyclone.  The 00Z Tuesday Tropical Storm Spaghetti Model had more than half of the tracks now not looping back but instead are following a track that I had advocated for several days, which would be from Pensacola to Savannah, GA.  It looks like a Mobile Bay landfall,  50 miles west of Pensacola will be likely.  One thing that I did get wrong, unless it really slows down, is that I had thought that the NAM solution of a day ago of a landfall around 00Z Tue was all wrong and I liked somewhere around midday on Tuesday.  It seems more likely that an early morning landfall is in the cards, provided  that it doesn’t slow down too much and I just think with the shear increasing ahead of a trof coming across the Gulf ahead of a cold front will keep it moving along.   I also think that if the front can keep its legs, it will come and pick it up and take the remnant something north of east and I think that a lot of the models are picking up on that same line of thinking.

Atlantic Total Precipitable Water Loop (click image for most recent)

All in all, this will be a storm that will bring a minimal storm surge with some gusty winds.  I noted a buoy about 40 miles south of Orange, Alabama with winds of about 35 kts gusting to near 45 kts and seas were running about 16 ft.  The biggest issue with this will be rain, especially for areas well east of the landfall point.  Even though I would think that Ida will be off the Atlantic Coast by Thursday, I would think that an area from say Tallahassee to Savannah to Daytona and maybe as far south as Cedar Key will have 36 to 48 hours of decent rain that could accumulate and cause some problems.  The 10PM EST advisory has Tropical Storm Ida with maximum winds of 65 mph.  The central pressure is 997 mb.  24 hours ago, it was 979 mb and 105 mph winds.  So, it has weakened substantially.  Ida was located about 100 miles SSW of Mobile and had slowed a bit with a northerly track of 13 mph.  It is expected to turn NNE overnight.  At this speed, landfall would be at about 6 am EST Tuesday morning.  See discussion below the Tropical Storm Ida Spaghetti model 00Z Tue.

Tropical Storm Ida Spaghetti Model (click for most recent)

WTNT41 KNHC 100300
TCDAT1
TROPICAL STORM IDA DISCUSSION NUMBER  25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112009
900 PM CST MON NOV 09 2009

RADAR AND SATELLITE IMAGES SHOW THE CONVECTION THAT WAS NEAR THE
CENTER DURING THE AFTERNOON HAS WEAKENED AND SHEARED OFF TOWARD THE
NORTH.  THIS WAS CONFIRMED BY A RECENT AIRCRAFT FIX THAT POSITIONED
THE CENTER EAST OF SOUTHEASTERN LOUISIANA WELL SOUTH OF THE
REMAINING DEEP CONVECTION.  THE FORWARD SPEED OF IDA HAS SLOWED TO
ABOUT 11 KT.  THE DYNAMICAL MODEL GUIDANCE FORECASTS A CONTINUED
REDUCTION IN THE FORWARD MOTION OF THE STORM AND A TURN TOWARD THE
EAST AFTER LANDFALL.  THE NHC FORECAST IS CLOSE TO THE PREVIOUS
ADVISORY THROUGH 12 HOURS AND IS THEN ADJUSTED A LITTLE NORTHWARD
CLOSER TO THE MODEL CONSENSUS.

THE AIRCRAFT HAS RECENTLY MEASURED A PEAK 850 MB FLIGHT-LEVEL WIND
OF 71 KT AND A SMFR SURFACE WIND OF 51 KT.  THIS SUPPORTS AN
INITIAL INTENSITY OF 55 KT.  IDA SHOULD GRADUALLY WEAKEN THROUGH
LANDFALL DUE TO INCREASING SHEAR AND COOLER SSTS.  ONCE INLAND THE
CYCLONE WILL WEAKEN AT A FASTER RATE AND BECOME EXTRATROPICAL
SHORTLY THEREAFTER.  MOST OF THE GLOBAL MODELS SHOW THE CYCLONE
BEING ABSORBED BY A FRONTAL BOUNDARY IN 36-48 HOURS AND SO DOES THE
OFFICIAL FORECAST.

THE LOCATION AND TIMING OF IDA’S LANDFALL WILL HAVE LITTLE
SIGNIFICANCE SINCE THE TROPICAL STORM FORCE WINDS COVER A LARGE
AREA AND MOST OF THE HEAVIER RAINFALL IS ALREADY SPREADING ONSHORE.

FORECAST POSITIONS AND MAX WINDS

INITIAL      10/0300Z 29.3N  88.6W    55 KT
12HR VT     10/1200Z 30.8N  87.9W    40 KT…EXTRATROPICAL
24HR VT     11/0000Z 31.5N  86.5W    30 KT…EXTRATROPICAL
36HR VT     11/1200Z 31.3N  84.8W    25 KT…EXTRATROPICAL
48HR VT     12/0000Z…DISSIPATED

$$
FORECASTER BROWN/BERG

Hurricane Ida In Gulf with 100 mph winds; Will Be Weakening at landfall in US November 9, 2009

Hurricane Ida Satellite Loop (rainbow IR click image for most recent)

See update on pending Ida landfall near Mobile Bay. For latest satellite, radar, forecast track, spaghetti model CLICK HERE

Cancun Radar of Hurricane Ida Passing Through Yucatan Channel

Hurricane Ida is moving through the Gulf of Mexico and the Hurricane Ida Forecast Track takes it inland near Pensacola, Florida.  A Hurricane Watch has been issued for the northern Gulf Coast and  Hurricane Warning flags have been hoisted from Pascagoula, MS to Indian Pass, FL which is near Applicachicola.   A Tropical Storm Warning is in effect westward to New Orleans and eastward to Aucilla River, FL.  For the past two days, I have been suggesting that the more conventional solution should be considered rather than the forecast track established by many models which called for the storm to loop back out to sea.  In many regards, it made no sense.  The National Hurricane Center went along with the consensus modeling but I figured the models would eventually come around, and they have.  Yesterday, I had observed the satellite imagery and concluded that it was certainly possible for Hurricane Ida to be something stronger than the forecast intensity of 70 kts.  By late Sunday afternoon, Hurricane Ida had sustained winds of 105 mph.  As it came through the Yucatan Channel, Cozumel Radar showed very distinctive banning and a decen, though not perfect, circulation structure.    Even though Ida spent 48 hours over land, it is now stronger than it ever has been.

Gulf of Mexico Sea Surface Temperatures (SST) Not Conducive to Supporting Tropical Cyclones

I would think that Hurricane Ida does not have much more time to get stronger.   In the first place, if you look at the sea surface temperature analysis, you will note that the lighter orange shades in the Yucatan Channel correspond with sea surface temperatures something less than 30 degrees C but more than the minimum required of 28.5 C.  As the shading progresses farther north, it goes darker and darker toward brown.  That is representing falling water temperatures and it would appear to me that when you look at the central Gulf of Mexico about even with Tampa, the temperatures at the surface are below 28 C, which means that Ida will begin to die then.  By the time you get to about 150 miles off the US Gulf Coast, water temperatures are in the lower 20′s C.  Remember, we’ve had several strong cold fronts in the past few weeks that have reduced water temperatures in the shallower waters. 

Atlantic Total Precipitable Water Loop (click image for most recent)

The other factor in Hurricane Ida’s demise will be strong southwesterly shear ahead of a trof that is moving across the Continental United States.  That just happens to come into play in about the same spot as where the water temperature falls before critical levels.  So, while that upper wind has been serving to enhance the northern outflow of Ida and helped enhance its intensity, it will be the same factor that will help kill it.  By late Sunday, the hurricane hunter aircraft noted a central pressure of 976 mb, which is fairly impressive. However, a later recon mission revealed the pressure had risen to 980 mb, there was an 8 mile circular eye that was open to the east.  So, the Sunday night observations may be an early indication that Ida has seen its best days and the decline has already begun.   But, then again maybe not because the flight level winds were higher on this pass from the last going from a maximum flight level (700 mb) wind of 94 kts to 108 kts.  It’s kinda interesting that the hurricane hunters reported hail on their latest venture into Ida.  In any event,  in contrast to the most recent observations, the NAM, GFS and NOGAPS models have respective central pressure at landfall of 1004 mb, 1004 mb and 1009 mb.  That is pretty pedestrian and is indicative of just how far and how fast Ida is expected to fall apart.  It may indeed become extra-tropical.  That is really not an issue because that has more to do with the structure of the storm and wherever it makes landfall, residents can expect a storm surge, heavy rain and gusty winds. 

Hurricane Ida Forecast Track (click for upates)

As I outlined the previous two days, it seemed likely that this guy would get caught up in the southwesterly flow ahead of the trof and be kicked to the northeast like any other low pressure area.  While it is falling apart and becoming a run-of-the-mill low, it will still be an area of low pressure and I think will act accordingly.  If it got completely absorbed, then it wouldn’t be a distinct low and therefore no longer an entity to be tracked.  In any event, everyone seems to me on board with a landfall in the US.  The NAM wants to take it into New Orleans on Monday night.  The GFS likes Monday night around Mobile or Pensacola while the NOGAPS likes Mobile/Pensacola but is looking for a Tuesday night landfall.  The NOGAPS solution is probably more accurate as to timing and location but I bet the GFS and NAM idea of a 1004mb low is probably a better call than the NOGAPS 1009 mb suggestion.  The ultimate truth of the landfall time will probably be sometime in between the NOGAPS and GFS/NAM timing.  I’ll vote for Tuesday early afternoon.

Bottom line is this.  Hurricane Ida has been tabbed as a 90 kt hurricane with gusts to 110 kts based on the latest recon data but will be hard pressed to maintain its hurricane status at landfall.  In fact, there it may be likely that it will be considered extra-tropical.  So what.  North Florida, South Georgia, South Alabama and even perhaps South Carolina can expect gusty winds and heavy rain Tuesday into Wednesday as I would think the ultmate path may go from say, Pensacola to Savannah.  A cold front sweeps it all away and that will be the end of that by Thursday.  See the official discussion below the Hurricane Ida Spaghetti Model image that you can click on for the most recent update.

Hurricane Ida Spaghetti Model (click image for most recent)

Hurricane Watch/Warning Map

000
URNT12 KNHC 082332
VORTEX DATA MESSAGE   AL112009
A. 08/23:04:40Z
B. 22 deg 47 min N
  086 deg 25 min W
C. 700 mb 2948 m
D. 80 kt
E. 355 deg 4 nm
F. 099 deg 103 kt
G. 359 deg 8 nm
H. 980 mb
I. 7 C / 3069 m
J. 17 C / 3054 m
K. 7 C / NA
L. OPEN E
M. C8
N. 12345 / 7
O. 0.02 / 1 nm
P. AF309 0411A IDA                OB 29
MAX FL WIND 108 KT NE QUAD 22:09:20Z
HAIL AND CONT LIGHTNING  N QUAD

WTNT41 KNHC 090301
TCDAT1
HURRICANE IDA DISCUSSION NUMBER  21
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112009
900 PM CST SUN NOV 08 2009

THE SATELLITE APPEARANCE OF IDA HAS CHANGED VERY LITTLE SINCE THE
AIRCRAFT DEPARTED THE HURRICANE JUST BEFORE 0000 UTC.  DURING THE
LAST COUPLE OF PASSES THROUGH THE CENTER THE AIRCRAFT MEASURED A
MAXIMUM 700 MB FLIGHT-LEVEL WIND OF 108 KT AND A SFMR SURFACE WIND
OF 84 KT. THESE DATA SUPPORT AN INTENSITY OF 90 KT.  ANOTHER AIR
FORCE PLANE IS SCHEDULED TO REACH IDA AROUND 0600 UTC.

THE LAST FEW AIRCRAFT FIXES PROVIDE A FAIRLY CONFIDENT INITIAL
MOTION OF 345/12…A LITTLE FASTER THAN BEFORE.  IDA IS FORECAST TO
CONTINUE MOVING NORTHWARD BETWEEN A MID/UPPER-LEVEL TROUGH OVER THE
WESTERN GULF MEXICO AND A MID/UPPER-LEVEL RIDGE OVER THE EASTERN
GULF OF MEXICO AND THE NORTHERN CARIBBEAN SEA.  THE TRACK MODELS
APPEAR TO BE IN A LITTLE BETTER AGREEMENT ON A NORTH-NORTHWESTWARD
TO NORTHWARD TRACK DURING THE NEXT 24-36 HOURS.  THE 12Z RUNS OF
THE ECMWF AND UKMET ARE A LITTLE WEST OF THE REMAINDER OF THE
GUIDANCE AND SHOW A TRACK NEAR EXTREME SOUTHEASTERN LOUISIANA.
DURING THE FIRST 24-36 HOURS…THE NEW OFFICIAL FORECAST IS NEAR
THE MODEL CONSENSUS AND THE PREVIOUS TRACK…BUT IS A LITTLE
FASTER.  AFTER LANDFALL ALONG THE NORTHERN GULF COAST…THE MODELS
TURN IDA EASTWARD THEN SOUTHEASTWARD AND THE NHC FORECAST FOLLOWS
SUIT…BUT DOES NOT SHOW AS SHARP A SOUTHEASTWARD TURN AS SOME OF
THE GUIDANCE INDICATES.  THE AIR FORCE ALSO FLEW A SURVEILLANCE
MISSION AROUND AND NORTH OF THE HURRICANE THIS AFTERNOON AND THAT
DATA SHOULD BE ASSIMILATED INTO THE 0000 UTC MODELS.

IDA IS FORECAST TO TRAVERSE COOLER WATERS…AND MOVE INTO A
COOLER AIRMASS AND INCREASING SHEAR DURING THE NEXT 24-36 HOURS.
AS THE CYCLONE APPROACHES THE NORTHERN GULF COAST IT WILL ALSO
LIKELY BEGIN EXTRATROPICAL TRANSITION.  HOWEVER…IT IS BECOMING
MORE LIKELY THAT IDA WILL RETAIN ITS TROPICAL CHARACTERISTICS
THROUGH LANDFALL.  THE INTENSITY GUIDANCE FORECASTS GRADUAL
WEAKENING AND ALL SHOW IDA AROUND HURRICANE STRENGTH AT LANDFALL.
THE OFFICIAL FORECAST IS IN LINE WITH THE GUIDANCE AND KEEPS THE
CYCLONE A HURRICANE WHEN IT REACHES THE COAST.  THIS HAS REQUIRED
THE ISSUANCE OF A HURRICANE WARNING FOR A PORTION OF THE NORTHERN
GULF COAST.

FORECAST POSITIONS AND MAX WINDS

INITIAL      09/0300Z 23.7N  86.7W    90 KT
12HR VT     09/1200Z 25.8N  87.5W    85 KT
24HR VT     10/0000Z 28.5N  87.7W    75 KT
36HR VT     10/1200Z 30.5N  87.1W    65 KT…INLAND
48HR VT     11/0000Z 31.2N  85.8W    40 KT…EXTRATROPICAL
72HR VT     12/0000Z 30.5N  82.0W    30 KT…EXTRATROPICAL
96HR VT     13/0000Z…DISSIPATED

$$
FORECASTER BROWN

Tropical Storm Ida could soon to be Hurricane Ida again; Ida Forecast Track slightly more clear November 8, 2009

Ida IR Rainbow Satellite Loop (click image for most recent)

See latest on Cat 2 Hurricane Ida in Gulf with Cancun Radar image, sea surface temperature, satellite image, forecast track CLICK HERE

Ida Forecast Track (click image for most recent)

Tropical Storm Ida is behaving itself though it looks to be in pretty good shape.  As noted yesterday, as the storm came offshore, the convection in the center exploded and the intensity was raised to 60 kts and there was some thought that perhaps it may become a hurricane by nightfall.  But, a little southerly shearing came into play and the late night advisory kept the storm at 60 kts.  Ida appears as if it will more or less thread the needle through the Yucatan channel thus keeping its center of circulation over water between the Island of Youth in Cuba and Cozumel near the top of the Yucatan Peninsula.  As mentioned previously, the satellite image if fairly impressive and there are strong winds aloft to the north of the storm.  The official forecast reflects the potential for some good outflow that may provide for an uptick in the intensity to that of low end Hurricane status.  I won’t be surprised to see it go higher than the current forecast of 70 kts.  That same shear, however, will then serve to mess up the storm and so the forecast calls for it to fall back to tropical storm status.  Confidence is pretty high through Monday. (see discussion below)

Total Precipitable Water Loop (click image for most recent)

After that, a cold front comes down into the Gulf.  Now, yesterday I opined that the then forecast of it turning back southeast seemed a bit improbable to me.  I thought a conventional viewpoint of the storm getting caught up in the strong southwesterly flow ahead of the trof, thus shooting the storm northeast, would be something to consider.  Only two of the models though played out that scenario and the hurricane center went with the consensus of the modeling data.  However, later model runs have taken the storm farther north, then north northeast toward the Florida Panhandle.  In doing so, the storm is expected to be so influenced by the front and colder water over the northern Gulf (we’ve had a lot of strong cold fronts lately) that Ida becomes Extra-Tropical.  The official forecast then turns the storm southeast as the thinking is that it gets absorbed by the front and moves with the front to the southeast.  I know the models say that but several go ahead and take the remnant of Ida into the extreme southeastern US. 

Gulf of Mexico IR Loop

I contend that solution is still something that should be considered given that the low will have forward momentum and also there will be those strong southwesterly winds.  I mean, a conventional low moves up along a front with a strong flow and I’m not so sure that an extra-tropical cyclone is just going to get absorbed into nothing and, if it were, then there would be no center of circulation to track.  Seems to me that if it is still a distinct circulation center, it would  run up the front.  Now, its true, the models do take the storm back south, but I contend that climatology and the fact that the storm is transitioning from a tropical system that is may be possible that the models are confused.  In any event, its an interesting academic discussion.  As it stands, regardless, winds will get pretty gusty in the Florida panhandle.  I suspect that there will be pretty heavy rain along that front too, given the amount of moisture being drawn northward.  With the increase in convection with a disturbance coming from the Bay of Campeche, I would think that anywhere from New Orleans to Tallahassee will get a pretty good dose of rain.

Ida Spaghetti Model (click)

WTNT41 KNHC 080246
TCDAT1
TROPICAL STORM IDA DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112009
1000 PM EST SAT NOV 07 2009

THERE HAS BEEN LITTLE CHANGE TO THE SATELLITE APPEARANCE OF IDA
SINCE THE AIR FORCE PLANE LEFT EARLIER THIS AFTERNOON.  THE
LOW-LEVEL CENTER IS STILL EMBEDDED WITHIN A LARGE CENTRAL DENSE
OVERCAST ALTHOUGH RECENT MICROWAVE DATA SUGGEST THAT THE SYSTEM IS
BEING IMPACTED BY SOME SOUTHERLY SHEAR.  THE INTENSITY WILL BE HELD
AT 60 KT FOR THIS ADVISORY…WHICH IS SUPPORTED BY DVORAK ESTIMATES
OF 55 KT FROM BOTH TAFB AND SAB AND AN OBJECTIVE ADT ESTIMATE OF 61
KT.  ANOTHER AIR FORCE RECONNAISSANCE AIRCRAFT IS SCHEDULED TO
INVESTIGATE IDA IN A FEW HOURS TO PROVIDE UPDATED INFORMATION.

IDA HAS TURNED TO THE NORTH-NORTHWEST WITH AN INITIAL MOTION OF 340
DEGREES AT 10 KT AS IT IS STEERED BETWEEN AN AMPLIFIED TROUGH OVER
MEXICO AND A MID-LEVEL RIDGE THAT EXTENDS FROM THE SOUTHEASTERN
U.S. TO HISPANIOLA.  THE TRACK GUIDANCE IS IN EXCELLENT AGREEMENT
THROUGH 48 HOURS ON A CONTINUED NORTH-NORTHWESTWARD MOTION…AND
THE NEW OFFICIAL FORECAST IS ONLY SLIGHTLY TO THE EAST OF THE
PREVIOUS FORECAST.  THEREAFTER…ALL THE MODELS BRING IDA TO THE
COAST NEAR THE FLORIDA PANHANDLE AS AN EXTRATROPICAL CYCLONE BUT
QUICKLY TURN IT TO THE SOUTHEAST AS THE ABSORBING COLD FRONT
PUSHES SOUTHWARD OVER THE GULF.

ALTHOUGH SOME SHEAR IS AFFECTING IDA…IT IS NOT PROHIBITIVELY
STRONG.  STRONG UPPER-LEVEL WINDS NORTH OF THE SYSTEM ARE PROVIDING
SOME DIFFLUENCE ALOFT…AND THIS WILL CONTINUE TO GIVE IDA A 24-36
HOUR WINDOW TO STRENGTHEN TO A HURRICANE.  THE SHEAR IS EXPECTED TO
INCREASE AFTER 36 HOURS AND SHOULD LEAD TO SOME WEAKENING…BUT THE
NEW INTENSITY GUIDANCE INDICATES THAT THIS WEAKENING COULD BE
SLOWER TO OCCUR THAN PREVIOUSLY FORECAST.  IDA SHOULD BEGIN THE
EXTRATROPICAL TRANSITION PROCESS AROUND 48 HOURS AND BE FULLY
EXTRATROPICAL BY 72 HOURS.

A TIGHT PRESSURE GRADIENT BETWEEN IDA AND HIGH PRESSURE LOCATED OVER
THE SOUTHEASTERN UNITED STATES IS ALREADY PRODUCING STRONG WINDS
OVER THE SOUTHEASTERN GULF OF MEXICO…BUT THESE WINDS ARE NOT
DIRECTLY ATTRIBUTABLE TO THE CIRCULATION OF IDA.

FORECAST POSITIONS AND MAX WINDS

INITIAL      08/0300Z 20.1N  84.6W    60 KT
12HR VT     08/1200Z 21.2N  85.3W    70 KT
24HR VT     09/0000Z 23.0N  86.5W    70 KT
36HR VT     09/1200Z 25.4N  87.6W    65 KT
48HR VT     10/0000Z 27.7N  87.9W    60 KT
72HR VT     11/0000Z 30.0N  86.5W    45 KT…EXTRATROPICAL
96HR VT     12/0000Z 29.0N  85.5W    35 KT…EXTRATROPICAL
120HR VT     13/0000Z…ABSORBED BY FRONT

$$
FORECASTER BERG/FRANKLIN

Hurricane Ida, Tropical Storm Ida, Tropical Depression Ida; Uncertainty heading into the weekend. November 7, 2009

Ida IR Rainbow Loop (click image for most recent)

See latest as Tropical Storm Ida becomes Hurricane Ida and enters Gulf CLICK HERE

Gulf IR Loop-Note Activity in Bay of Campeche

Former Hurricane Ida is moving along as expected so far and for the next day or so, there is a pretty fair consensus on what is going to happen.  After that, well…there are a lot of scenarios.  Reports from Honduras and Nicaragua claim rain totals of up to 20 inches in some locations with some flooding and wind damage from the initial impact when Ida was a minimal hurricane.  It quickly fell back to a tropical depression and, almost exactly as forecast, moved offshore of the northeast coast of Honduras on Friday evening.  Ida emerged with a circulation but with the bulk of the convection on the northern half.  The southern half of the storm was almost void of any convective activity.  However, after just a few hours offshore, substantial convection began exploding in all sectors.  The intensity forecast is difficult to determine but this sudden burst makes me think its going to be interesting.  A couple of models suggest it becoming a hurricane again, but the NHC is dismissing those, citing an idea that wind shear will develop and prevent such an solution.

Ida Forecast Track (click for most recent update)

Over the next couple of days, Ida is expected to get a little better organized as it moves with a general northern component through the Yucatan Channel, though places like Cancuun and Cozumel will be affected.  Unlucky for tourists.  A cold front is still looking to move into the Gulf of Mexico by Tuesday and begin to influence the storm.  The National Hurricane Center has gone with the idea that the southwesterly shear from the trof will transform Ida into an Extra-Tropical Storm.  That means that the physical structure will go from a tropical low, which is a warm core low, to a cold core low.  Pragmatically, that is not so much of a big deal because extra-tropical storms can produce extremely strong winds and bring excessive rains.    I would think that the storm would get swept northeast.  But, there have been several models that want to take the storm back to the southeast once it gets into the Northwest Gulf.

Atlantic Total Precipitable Water Loop

I have to be honest.  This is extremely complex. There is another area of disturbed weather in the Bay of Campeche and the models are all over the place. I don’t think the Southwest Gulf system will do much except draw a lot of moisture into the US Central Gulf Coast but I do think its presence is helping to confuse the models.  The discussion from the NHC (see below) is no help and provides no explanation.  My maps don’t go far enough south to provide an answer as to why the storm would go back southeast instead of getting picked up by the trof and scooted northeast.  I am left to assume that the answer is that Ida gets by passed by the trof crossing the United States and leaves it behind or it gets shoved south by the front.  But, what leaves me a bit befuddled is that, if it is involved with the trof sufficiently to transform it to a extra-tropical storm, I would think that the trof would have enough influence to pick it up.  I’ve got models running deep lows anywhere from New Orleans to Tallahassee or back to the southeast with a couple taking it northeast.  This points out the difficulty of models to pick up on not fully developed tropical systems.  These models are designed for tropical cyclones and when they turn extra tropical, the models can get confused…and so am I.  Stay tuned.

Ida Spaghetti Model

WTNT41 KNHC 070233
TCDAT1
TROPICAL DEPRESSION IDA DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112009
1000 PM EST FRI NOV 06 2009

A 2302 UTC SSMIS MICROWAVE PASS INDICATED THAT THE LOW-LEVEL CENTER
OF IDA WAS LOCATED JUST OFF THE NORTHEASTERN COAST OF HONDURAS AND
WAS DISPLACED TO THE SOUTH AND SOUTHEAST OF THE DEEP CONVECTION.
NEW CONVECTION IS DEVELOPING CLOSE TO THE CENTER…AND DVORAK
ESTIMATES FROM TAFB AND SAB ARE 25 KT AND 30 KT…RESPECTIVELY.
NOAA BUOY 42057…LOCATED ABOUT 150 N MI EAST-NORTHEAST OF THE
CENTER…RECENTLY REPORTED A 1-MINUTE SUSTAINED WIND OF 35 KT…BUT
IT APPEARS THAT THIS OCCURRED WITH THE PASSAGE OF A SQUALL AND MAY
NOT BE REPRESENTATIVE OF THE OVERALL CIRCULATION.  THEREFORE…IDA
IS KEPT AS A TROPICAL DEPRESSION FOR THIS ADVISORY…BUT IT IS
PROBABLY VERY CLOSE TO REGAINING TROPICAL STORM STATUS.

IDA CONTINUES TO MOVE NORTHWARD AT 360/6.  A MID-LEVEL ANTICYCLONE
BETWEEN JAMAICA AND HISPANIOLA AND A DEEP-LAYER TROUGH OVER MEXICO
ARE EXPECTED TO STEER IDA NORTH-NORTHWESTWARD THROUGH THE NEXT 72
HOURS.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT DURING THIS PERIOD
ALTHOUGH THE GFDL AND HWRF MODELS ARE THE EASTERNMOST MODELS AND
HAVE FORCED THE MODEL CONSENSUS A LITTLE MORE TO THE EAST.  THE
FORECAST BEYOND 72 HOURS IS STILL COMPLEX AND IS DEPENDENT ON HOW
IDA INTERACTS WITH THE FRONT AND SHORTWAVE TROUGH OVER THE GULF OF
MEXICO.  MOST OF THE GUIDANCE SHOWS IDA BECOMING EXTRATROPICAL BY
96 HOURS ONCE IT MERGES WITH THE FRONT…BUT THE SOLUTIONS VARY ON
WHERE THE LOW GOES NEXT.  ONLY THE 1200 UTC ECMWF AND UKMET SHOW
IDA BECOMING PICKED UP BY A SHORTWAVE TROUGH AND MOVING
NORTHEASTWARD OVER THE NORTHERN GULF.  THE OTHER MODELS INDICATE A
MORE PRONOUNCED SOUTHWARD MOTION AFTER 96 HOURS…AND THE OFFICIAL
FORECAST NOW SHOWS A SLOW SOUTHEASTWARD TURN AT 120 HOURS.

ALTHOUGH WATERS ARE WARM OVER THE NORTHWESTERN CARIBBEAN…VERTICAL
SHEAR IS EXPECTED TO HAMPER MUCH INTENSIFICATION OVER THE NEXT FEW
DAYS.  THE GFDL AND HWRF MAKE IDA A HURRICANE OVER THE CENTRAL GULF
OF MEXICO…A SCENARIO THAT DOES NOT SEEM PLAUSIBLE IN THE FACE OF
WESTERLY SHEAR THAT IS EXPECTED TO INCREASE TO 50 OR 60 KT BY DAY
4.  THE OFFICIAL FORECAST INDICATES SOME SLOW STRENGTHENING OVER
THE NEXT SEVERAL DAYS BUT PEAKS THE INTENSITY AT 45 KT…WHICH IS
JUST BELOW THE INTENSITY CONSENSUS.

IT IS OF NOTE THAT MOST OF THE GLOBAL MODELS ARE SHOWING A LARGE
PRESSURE GRADIENT BETWEEN A HIGH OVER THE SOUTHEASTERN UNITED
STATES AND THE TROPICAL CYCLONE.  THIS COULD CONTRIBUTE TO A LARGE
AREA OF STRONG WINDS OVER THE GULF OF MEXICO NOT DIRECTLY
ATTRIBUTABLE TO IDA.

FORECAST POSITIONS AND MAX WINDS

INITIAL      07/0300Z 16.2N  84.0W    30 KT
12HR VT     07/1200Z 17.1N  84.2W    35 KT
24HR VT     08/0000Z 18.4N  84.8W    35 KT
36HR VT     08/1200Z 19.7N  85.5W    40 KT
48HR VT     09/0000Z 21.4N  86.5W    45 KT
72HR VT     10/0000Z 25.5N  88.0W    45 KT
96HR VT     11/0000Z 27.5N  87.0W    45 KT…EXTRATROPICAL
120HR VT     12/0000Z 26.5N  85.6W    35 KT…EXTRATROPICAL

$$
FORECASTER BERG

Hurricane Ida Strikes Nicaragua; Could Re-Develop and affect United States November 6, 2009

Hurricane Ida IR Rainbow Loop (now depression)

For an update on Tropical Depression Ida as it came off the Honduran Coast, CLICK HERE

Tropical Cyclone Ida Forecast Track

Tropical Storm Ida  became Hurricane Ida before making landfall and spent the day over Nicaragua.  In the process found itself downgraded to a Tropical Depression.  Initial reports are the winds caused some damage but officials are concerned about the potential for up to 20 inches of rain to fall in Nicaragua and Honduras before Ida leaves town.  The official Ida forecast track from the National Hurricane Center calls for it to trudge across Honduras for the better part of Friday before emerging late in the day just off the northeast coast of that country.  The center of circulation is close enough to the water that perhaps it will be able to maintain its integrity sufficiently to allow it to regenerate somewhat once its back over water.  That is what the official forecast calls for as it takes the storm through the Yucatan Channel and into the Gulf of Mexico.

Total Precipitable Water Loop (click)

Now, as I mentioned yesterday, some of the models didn’t really give the cold front coming down too much credit but the spaghetti model indicates that several are now reflecting the cold front’s presence as toward the latter part of the extended tracks, you see it beginning to veer to the right.  Part of that is due to coriolis forces but much of that is a reflection of a breakdown the Caribbean ridge that has been steering the storm north as the cold front approaches.  The National Hurricane Center forecast reflects that kind of thinking and, you know what, it makes sense.  As long as the front behaves and gets into the Gulf by Tuesday, then the storm will begin to curve.  But, if the front is behind schedule, then that turn may not take place until it does.  Most data indicates that, regardless of the frontal timing, the associated trof should be deep enough to the south to pick up the storm and when it does, look for Ida to accelerate to the northeast.  One thing of interest. If you look at the Total Precipitable Water loop to the left, two things stand out. First is how subtle the circulation of Ida was as it developed off the coast. Second, note all of the extremely dry air being pushed down from North America and how far that extends into the Gulf.

Ida Water Vapor Image Loop

I would think a plausible scenario would be for the storm to move into the big bend of Florida and exit into the Atlantic somewhere between Daytona and Savannah.  But, there are many variables, not the least of which is getting Ida out of Central America in tact and then have it be in an environment to redevelop.  Those are both formidable “ifs” but most data suggests that is what will happen. However, only 3 of 17 models that make up the 00z spaghetti model intensity run take Ida back up to Hurricane status.  The NHC discussion below addresses the intensity issues.

Ida Spaghetti Model 00Z 11.06.09

WTNT41 KNHC 060241
TCDAT1
TROPICAL DEPRESSION IDA DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112009
1000 PM EST THU NOV 05 2009

SURFACE OBSERVATIONS AND CONVENTIONAL SATELLITE IMAGERY INDICATE
THAT IDA HAS WEAKENED TO A TROPICAL DEPRESSION.  WHAT REMAINS OF THE
DIMINISHING DEEP CONVECTION IS CURRENTLY CONFINED TO NORTHWEST AND
NORTHEAST QUADRANTS.  SOME FURTHER WEAKENING IS LIKELY DURING THE
NEXT 12 TO 24 HOURS AS IDA CONTINUES ON A GENERAL NORTHWARD TRACK
OVER NORTHEASTERN NICARAGUA AND EASTERN HONDURAS. AROUND THE 36
HOUR PERIOD…THE CYCLONE SHOULD EMERGE OVER THE NORTHWEST
CARIBBEAN SEA AND…ASSUMING THE CIRCULATION IS NOT TOO SEVERELY
DISRUPTED BY ITS PASSAGE OVER LAND…THE SYSTEM SHOULD RESTRENGTHEN
INTO A TROPICAL STORM.  HOWEVER…THE GLOBAL MODELS INDICATE ONLY A
MARGINALLY FAVORABLE UPPER-LEVEL WIND ENVIRONMENT OVER THE
REGION…WHICH SHOULD CURTAIL SIGNIFICANT INTENSIFICATION AS IDA
HEADS IN THE GENERAL DIRECTION OF THE YUCATAN CHANNEL.  AFTER IDA
ENTERS THE SOUTHERN GULF OF MEXICO….THE INTENSITY FORECAST IS
HIGHLY UNCERTAIN.  THE LARGE-SCALE MODELS ALL AGREE ON AN
INCREASINGLY STRONG VERTICAL SHEAR ENVIRONMENT DEVELOPING OVER THE
GULF OF MEXICO TOWARD THE END OF THE FORECAST PERIOD.  THE GFDL AND
HWRF MODELS…PARTICULARLY THE FORMER…SHOW SIGNIFICANT
INTENSIFICATION OF IDA IN THE LATTER PART OF THE PERIOD.  IT SHOULD
BE RECALLED HOWEVER THAT THESE MODELS HAVE BEEN KNOWN TO HAVE A
HIGH BIAS IN STRONGLY SHEARED ENVIRONMENTS…AS WAS THE CASE WITH
TROPICAL STORMS DANNY…ERIKA…AND HENRI OF THIS YEAR.
CONSEQUENTLY…THE OFFICIAL WIND SPEED FORECAST LEANS MORE TOWARD
THE WEAKER LGEM AND SHIPS PREDICTIONS.

THE INITIAL MOTION IS ESTIMATED TO BE 330/4…WITHIN THE SOUTHERLY
STEERING FLOW ON THE WEST SIDE OF A WEAK MID-LEVEL RIDGE. WITH THE
EXCEPTION OF FORWARD SPEED DISPARITIES…THE GLOBAL AND REGIONAL
MODELS CONTINUE TO INDICATE A GENERAL NORTH TO NORTH-NORTHWESTWARD
MOTION INTO THE CENTRAL GULF OF MEXICO OVER THE NEXT 4 DAYS.
AROUND THE END OF THE PERIOD…MOST OF THE TRACK GUIDANCE SHOWS A
TURN TO THE RIGHT AS IDA BEGINS TO INTERACT WITH THE WESTERLIES.
THE OFFICIAL FORECAST HAS CHANGED LITTLE FROM THE PREVIOUS ONE AND
IS CLOSE TO THE MODEL CONSENSUS.

THE BIGGEST IMPACT OF THIS SLOW-MOVING SYSTEM DURING THE NEXT DAY OR
SO WILL LIKELY BE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES
CAUSED BY EXTREMELY HEAVY RAIN OVER PORTIONS OF NICARAGUA AND
HONDURAS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      06/0300Z 13.8N  84.1W    30 KT
12HR VT     06/1200Z 14.4N  84.1W    25 KT…INLAND
24HR VT     07/0000Z 15.4N  84.2W    25 KT…INLAND
36HR VT     07/1200Z 16.6N  84.5W    35 KT…OVER WATER
48HR VT     08/0000Z 17.7N  85.0W    40 KT
72HR VT     09/0000Z 20.3N  86.2W    45 KT
96HR VT     10/0000Z 23.0N  87.5W    45 KT
120HR VT     11/0000Z 26.0N  87.0W    45 KT

$$
FORECASTER PASCH/ROBERTS