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