Archive for the ‘Weather and History’ Category

The Prospect of a Cold Guarantee is a Stone Cold Lock
January 23, 2011

Does This Look Like the Coldest Place in the United States?

Alaska Jan. Mean Min Temperatures 1971-2000

On This Date in History:  At this point in the winter season, data from the National Snow Analysis reveals that 49% of the nation is covered in snow.  Last month, that total was 44.8% but, in between, I’ve noted some days where the snow cover was as high as 70%.  We are in a weather pattern that has been persistent with a general ridge in the west and a trof down through the front range of the Rockies or through the midwest.  While there have been some big storms on the West Coast, most of the action seems to be riding up the northern part of the Rockies and then down deep, often way deep, into the South with the base of the mean trof generally in the heart of Dixie.  The mean long wave has been such that it tends to take storms just off the East Coast.  The East Coast has dodged a bullet for the most part because, while there have been a couple of big boppers nail New England, much of the Eastern Seaboard has missed out on several systems that, had they been about 100 miles further west, would have buried the I-95 corridor from North Carolina to Maine.  It’s pretty cold now but a super cold outbreak has for the most part been avoided.  While some records have no doubt been set, certainly no one has come close to all-time low temperatures recorded  in history.

Back in late 1970, there was a big high pressure ridge situated over Hawaii but, by early 1971, that big ridge shifted to the East.  A new mean ridge set up over the Bering Sea and created a strong blocking pattern over the Central Pacific. Northerly flow across the Bering Sea remained persistent but the southern part of the December trof moved east to set up a strong, broad cyclonic circulation across the Mississippi Valley to the Atlantic.  All of Alaska was much colder than average that January with Fairbanks, Alaska not getting above 22 F degrees below zero for 18 consecutive days, which is a record for such cold of such duration.  The record-setting cold month in Fairbanks resulted in an average temperature for that month in that city of 31.7 F degrees below zero. 

The Prospect Creek Camp was located down this road at the bottom of the valley

About 200 miles Northwest of Fairbanks and 25 miles Southeast of Bettles, AK, one will find tiny Prospect Creek, Alaska.  It was first settled as a mining camp in the gold rush days.  Most notably, a camp was built there for the builders of the Trans-Alaska Pipeline in 1974.  The near ghost town was transformed into the residence for some 27,000 workers and to serve pipeline station number 5.  There is not much at the location and the camp was little more than housing with some washrooms.  When the pipeline was completed in 1977, Prospect Creek was once again abandoned, though in 1992 it did serve as a base of operations for some people working on the rebuilding of a bridge along the Dalton Highway.  Not only did it serve to house workers but also their families and I’m sure that mom was happy to bring the kids along to live in the wilderness north of the Arctic circle at about 67 degrees North Latitude.  It’s so far north and so cold that it’s really more or less a desert as it only gets between 0 and 10 inches of precipitation per year.  June and July aren’t too bad with average highs of 71 and 73 respectively.  But, January and February average highs are 2 and 10 degree respectively and 6 months out of the year, the average high is below freezing.  In spite of the cold, you can find Black and Brown bears in the area as well as Bald Eagles.  But, you probably won’t find Sarah Palin wandering about as it’s about 530 miles North of the former governor’s home town of Wasilla.

Airstrip at Snag, Yukon Territory Where Lowest North America Temperature was Recorded

Aside from all of this, it’s tough to find much about Prospect Creek and most likely would not be found anywhere on the internet or in encyclopedia’s if it were not what happened there on January 23, 1971.   The big fat ridge that parked itself over the region in January 1971 and brought Fairbanks such frigid conditions affected the entire state.  I suspect that the center of the high pressure ridge must have moved directly over Prospect Creek because, on this date in 1971, the mercury at Prospect Creek, Alaska fell all the way to 79.8F degrees below zero, giving it the record for the coldest temperature ever recorded in the United  States.  For all of North America, the low that day is second only to Snag, Yukon Territory, Canada that hit minus 81F degrees on February 3, 1947.  But, Snag’s elevation is 2100 ft while Prospect Creek is somewhere in the neighborhood of 1000 feet above sea level. 

It's Cold at Amundsen Scott but the Aurora Can Make It Worth the Trouble

 Mt. Washington, NH has the distinction of having the lowest annual mean temperature of 26.5F and the lowest mean summer temperature (51.6F) in the lower 48.  In 1954, a big old 1070mb high settled in over Montana and on January 20, the temperature at Rogers Pass in Lewis and Clark County fell to -69.7F to set the coldest temperature ever recorded in the lower 48 states. Rogers Pass sits about 150 feet below the Continental Divide at around 6000 ft in elevation.  It’s interesting that just 11 days before, the lowest temperature on the Greenland Icecap was recorded at -86.6 degrees. That is nothing compared to the all-time planet low temperature of -128.6F on July 21, 1983 at the Amundsen-Scott Station,which is just a few hundred yards from the geographic South Pole in Antarctica.  With all of this, it’s no wonder that Prospect Creek has zero population today.  But, you can mail a letter there, if you like.  The zip code is 99726.  I suppose the postal carrier that gets that mail-route is being punished because “nor rain, nor snow, nor dead of night” does not include “nor 79 degrees below zero.”  By the way, in case you are interested, you can take a tour that includes Prospect Creek.  I might suggest June or July.

Weather Bottom Line:  Well…after reading all of that, you should feel down-right warm.  Maybe not.  We have a hint of a warm up in the week ahead but it’s not much of a hint and it won’t last long.  First, we have a little disturbance wandering across that is damping out, or weakening so we may have some snow showers today and tomorrow.  Then another system comes across the south and an accompanying disturbance coming out of the midwest will also get damped out so we may have some snow showers Tuesday and Wednesday too but I don’t think it will be all that terrific.  We warm up slightly to the mid 30’s by the end of the week and may even hit 40 on Saturday but that’s about it because on Sunday, we’re back down to highs in the 20’s.  Break out the tanning butter on Saturday.

Being Covered in Molasses Seems Like a Lousy Way to Die
January 15, 2011

100 Years Later, Some People Still Claim that the Area Smells of Molasses

On This Date in History:  In Boston, MA near Kearny Square at 529 Commercial Street you will find the New England Aquarium, which is now located officially at 1 Central Wharf.    But, nearly 100 years ago, that was the location of a Molasses production factory.  On January 13-15 1919, local temperatures rose from near zero into the 40’s.  Perhaps the locals might have called it a “false spring” or maybe they were just happy to have a typical brief winter warm up to have a day or two to thaw out.  But, it apparently wasn’t such a good thing for the Purity Distilling Company.  It is thought that their 50 foot tall, 90 foot in diameter holding tank was poorly constructed.   The man who oversaw construction of the tank, Arthur Jell, determined that there was no need to perform basic safety checks when he built the tank as he never even filled the tank with water just to check for leaks.  It is said that the tank leaked so badly that it was painted brown to hide the leaks.  One would think that the owners would do more than just slap on some paint.  I mean, if I had all that money invested, I’d want to avoid the cost of a cleanup and disruption of operations.  But, obviously, they preferred to try to pull the wool over the eyes of any pestering bystanders.  Passers-by may have been fooled but it didn’t solve the problem.    

This Train Would Not Be Running on Time For Quite Some Time in 1919

In the early 20th century, the primary sweetner in the United States was molasses.  It also could be fermented to produce rum and ethyl alcohol which was quite important in pre-prohibition America.  Beyond that, ethyl alcohol was a key component in the production of munitions of the day.  Now, the tank had been in use for a few years and over that time it had been filled to capacity 8 times.  On the one hand, that might suggest that proved the tank was sturdy.  However, on the other hand, the filling and emptying also would have caused the tank to expand and shrink, which would tend to increase the liklihood of fatigue on the hoops holding it together, much like metal fatigue is a concern on a frequently used aircraft.   On that warming winter day, fermentation may have been causing a buildup of carbon dioxide inside the tank.  The exact cause of what happened next might never be known but what is a fact is that on this date in 1919, a manhole cover near the base of the tank ruptured, perhaps caused by a fatigue crack.  A wave of molasses cascaded through the neighborhood at 35 mph taking the lives of 21 people and injuring 150.  It is known as the Boston Molasses Disaster.

It's Amazing What Happens When You Release Tons of Molasses

The 8 to 15 high wave of molasses had sufficient force to break the girders of the Atlantic Avenue portion of the Boston Elevated Railway.  A train was lifted off the tracks.  Buildings were swept off their foundations and city streets for blocks were left with 2-3 feet of molasses.  I’m not sure if a Humvee of today could make it through that.  Apparently, the molasses itself wasn’t the sole killer that day as the Boston Globe reported that people “were picked up by a rush of air and hurled many feet.”   The Globe also told the story of  “Anthony di Stasio, walking homeward with his sisters from the Michelangelo School, was picked up by the wave and carried, tumbling on its crest, almost as though he were surfing. Then he grounded and the molasses rolled him like a pebble as the wave diminished. He heard his mother call his name and couldn’t answer, his throat was so clogged with the smothering goo. He passed out, then opened his eyes to find three of his sisters staring at him.”  A truck was tossed into the Boston Harbor.  Aside from the deaths and injuries from people being crushed by the force of the air, flying debris and drowning in molasses, people continued to suffer from the after-effects.  Family pets and horses were counted among the dead and injured which brought grief and economic despair for their owners.  Fits of coughing were common among the residents of the area for days after the disaster. 

When Visiting the Aquarium in Boston, Sniff for Molasses in the Air

It has been speculated over the years that the Purity Distilling Company had overfilled the tanks in late 1918 in an attempt to produce as much ethyl alcohol and rum as they could in anticipation of Prohibition.  While it is true that the 18th Amendment was ratified the day after the disaster,  it must be noted that President Woodrow Wilson opposed the Volstead Act because it did not exempt industrial alcohol and that was needed for armaments in World War I.  Beyond that,  the Volstead Act was the legislation that actually enforced the 18th Amendment which was not to take effect until January 20, 1920 and it was not passed by the Congress, after over-riding a presidential veto, until October 1919.  State prohibition laws of the time exempted industrial alcohol and the final version of the Volstead Act  eventually exempted such useage.  So, it was possible the company wanted to sell as much booze as possible but it’s not like the company’s viability rode on Prohibition.   Either way, getting taken out by a flood of molasses is a crappy way to die.  Wonder what those 21 tombstones say?  And it’s foolish, arguably criminal, behaviour by companies of yesterday that has led to the regulation of corporate America today.  Some of those regulations are probably un-necessarily constraining, are politically motivated, cost companies and shareholders money and also cost jobs.  But, one has only to look at the results of foolishness by companies like the Purity Distilling Company to lead one to conclude that the fault can be found corporate America’s mirror and those ghosts found in the background.

Nebraska School Kids From the Past Could Tell You that Winter Blizzards Happen
January 12, 2011

Blizzard Before Global Warming

Blizzard Before Global Warming

Blizzard Before Global Warming

Nebraska School Kids January 1888

On This Date In History:  Last year, the East Coast, most famously the Washington DC area, had a few giant snow storms.  Some folks blamed Global Warming.  Around Christmas this year, the northeast got slammed by a big old system that dropped 20 inches on Central Park and gave the mayor a big headache.  Now, there is another similar system that has dumped a bunch of snow and ice in the South and promises to adversely affect the northeast again.  My bet is that New York will get a significant amount of snow but I suspect that Boston will be closer to the target of the 2-foot-type snow totals and blizzard warnings.  In between these events, we had a tornado outbreak in the Ozarks and parts of the Midwest.  Ironically, parts of Arkansas that got whacked with twisters a couple of weeks ago have now had to deal with the snow and ice.  I have fully expected Global Warming articles but haven’t seen much yet.  But, you know what?  It is not unprecedented.  I recall a January  tornado that caused fatalities in Owensboro not too many years ago.  This is a La Nina year and that may have more to do with the persistent pattern we’ve had and when you get a change in the pattern, well, then severe weather can occur in between the wintry stuff.  At this point, the models way out are suggesting another potential severe outbreak in the Ozarks in a couple of weeks.  Not sure if it will happen, but its out there.

While its been snowing in Atlanta, its been in the upper 70’s to near 80 in South Florida, that is about normal. As I alluded, it’s not out of the question that we get a warm up for a few days in the South in a couple of weeks.   Winter weather is not unusual and neither are warm ups, which are  so common that it is known as a “false spring”.  In the Midwest, January 11,888 had been unseasonably warm as had the morning of January 12. A cold front came barreling down with air that dropped temperatures well below zero with high winds. Some reports of the day say that the mercury fell 100 degrees in 24 hours. ..while its possible, that may be an exaggeration.

You Can Read The Book

You Can Read The Book

You Can Read The Book
When the mercury fell, the snow began to fall. Most likely a shortwave blew up from the southwest and grabbed all of the warm moist air to the south and threw it over the cold air. People who had gone to work and especially school children had not dressed for the extreme cold as the whole thing was a total surprise. 235 people died that day, many of them school children trying to get home. Hence, on this date in 1888, the Midwest of the United States suffered from what is now known as either the “Schoolhouse Blizzard,” “The Big Brash Blizzard of 1888″ or the “Schoolchildren’s Blizzard.” One story holds that a teacher was trapped in her schoolhouse with 3 children and by 3 pm they had run out of heating fuel. She tried to lead them 82 yards to her boarding house. Visibility was so poor that they got lost in the short distance and the 3 kids died. She survived but lost her feet to frostbite. There are many other tales of rescues using rope to tie children together as they tried to get to safety.  The meteorological details surrounding the 1888 blizzard are interesting and the individual stories quite harrowing.

Extreme weather changes have gone on in this country in the winter for a long long time….long before anyone thought of global warming. Its just that now we have better forecasts to be able to prepare.

Wall Street March 1888

Not A Good Trading Day on Wall Street

It was a tough winter in 1888. In March, New York City had one of its greatest snowfalls and blizzards. From March 12-14, about 50 inches fell and wind drifted the snow to up to 40 feet. The city came to a standstill.  The storm adversely affected cities all up and down the East Coast, including Baltimore, which had temperatures in the mid 40’s the day before the storm hit.   And that winter of 1888 was well before anyone suggests that climate change had any effect on the weather.

Weather patterns really haven’t changed all that much, it’s just that forecasting has gotten so much better as well as communications.  But, snow forecasting remains very difficult and the TV honchos who aren’t on the air insist on public relations campaigns that elevate their tv weather folks to mythical proportions.  Even if a station has a top shelf Meteorologist like Jay Cardosi or Matt Milosevich, Kevin Harned or Marc Weinberg, it’s far from perfect.  It doesn’t help when a tv outfit hires a broadcaster and then labels them as  a Meteorologist. It’s really not fair to that person. Either way, snow/sleet/ice forecasts can be really beyond human abilities and so they change.  The difference between an inch of snow and 5 inches is not much.  And when you throw in ice potential, it really creates a challenge.  Be thankful for what we have today.  Those kids in Nebraska in 1888 could only dream of having someone alert them to the potential danger as did the people along the East Coast later that year.

A Christmas Thought
December 24, 2010

nativity2

So, This is Christmas: This time of year, Christmas becomes a focus of attention. Sometimes, we hear about the scrooges out there. Sometimes we hear about the sad stories. Other times, we hear of heartlifting stories of people serving their fellow man, giving others a hand or stories of families making long overdue reunions. It used to be heard more often on public airwaves, but still we do hear the Christmas story of which the entire holiday has been based. Oh….there are the fights about communities and their “holiday parades” and the politically correct argument about saying “happy holidays” as opposed to “Merry Christmas,” or the annual fight about public displays. But, still the majority of Americans accept the basis of the holiday.

Does Snoopy Have it Right?

Does Snoopy Have it Right?

Now, some naysayers like to get to the root of the holiday saying that Christmas was really derived from pagan rituals and the ancient celebration of Winter. And you know what? There is some truth to that. If you read the biblical account of the birth of Jesus, you also find that the shepherds were in their fields tending their sheep, which suggests that it was not winter. So, it seems likely that the actual birth was not on December 25th, but since no one knows exactly when the birth occured, the early Church determined that December 25th was a good time. Perhaps it was an effort by the early Church to quash the pagan winter celebrations. But, to me, that is a poor excuse to dismiss the story of Christ’s birth as false. It is simply a history of the celebratory day.

Take a look at this.

Isaiah 7:14
Therefore the Lord himself will give you a sign: The virgin will be with child and will give birth to a son, and will call him Immanuel.

Now, there is talk that this passage from Isaiah is flawed in that the Hebrew word used in the original text is “almah” and that literally means “young woman” and not “virgin.” However, the bible never refers to an “almah” in connection with a married woman and the bible is clear that an unmarried woman is to be a virgin. Therefore, the use of “virgin” as opposed to “young woman” is completely logical.

But, all of that is semantics. Let’s get to the bottom line. Ultimately, this comes down to Faith and I fully accept that my Faith is not necessarily that of others and there is no reason for people to call each other names. But, consider that the words from Isaiah were written some 700 years before the birth of Jesus. Some people are more likely to believe in the words of Nostradomus but not Isaiah even though it takes a little more imagination to create truths about the Frenchman.

As I can attest, things don’t always go the way we want them to go and we have set backs, obstacles and difficulties in life. Christmas time is not immune from that. For the past two years Snow White were in a bit of and unpleasant, unexpected circumstance.  It was tough (especially the second year) but were thankful for what we had and for each other. We feel blessed with our circumstance whether it be tough times or the many friends we have, our families and the fond memories we have and the memories still left to make. Christmas is a time of love and hope for the future.  Two years ago,  there is no way that I could ever have imagined that we would be where are we are today.  And yet,  here we are.  While I have many people to thank, I know that Providence was at work.  Nothing lasts forever and you never know what happens when you try.  Christmas is a time of gift giving.  It is ultimately the story of the ultimate gift to all who will receive.  I have found that, if I get out of the way and stop grabbing at gifts and instead let my heart be open to accept them and to give to others, then all of the issues and problems of our world suddenly aren’t so difficult.  Everything is not perfect right now but for the first time in 12 years, I get to spend 4 days in a row with just my wife and my kitty cat, and that is a gift in itself.  Snow White and I wish to extend to you and your families a very Merry Christmas and a blessed, happy new year.

Weather Bottom Line:  You know, for the majority of the dozen or so years I’ve been in Louisville, we had a White Christmas, if one considers a White Christmas as being one with snow on the ground.  Even if it has to snow on Christmas to fit the definition of the term methinks arose from the Bing Crosby movie and song, we had a number of those over the years.  This year will be no exception regardless of how you look at it. I don’t think you get snowed in on Christmas Eve but several inches will provide an opportunity for a snow angel or a snowman and then on Christmas Day look for flurries or maybe a snow shower.  Be careful on the roads and I’ll leave you with a weather Christmas story.  Whenever it snows, Snow White and I like to go out stomping about in it at about 3 AM.  We did that one time when there was about 10 inches.  When we returned to our driveway, we noticed two snow angels had been made.  By this time it was about 4 AM and we could not imagine who could have been out and about to make them.  So, I looked for footprints that might give a clue.    There were none.  I have no idea how those two snow angels got on our driveway…but I bet that it was not Nostradamus.

Perhaps the Most Spectacular Bridge Collapse Ever Caught on Film
November 7, 2010

A Big Mistake

Tacoma Narrows Bridge: A Big Mistake

GertiephotoOn This Date In History:   The Tacoma Narrows Bridge opened in July 1940 to great fanfare. With a span of 2800 feet, it was the third longest bridge in the world. The builder decided to save money by making the bridge only 39 feet wide to support just two lanes of traffic which seems pretty short sighted given that it was probably a pretty good bet that traffic in the years ahead would continue to increase.  Nevertheless, the bridge only had two lanes but was designed to withstand winds of 120 mph. People flocked to the bridge after it’s opening, not just because it was faster than the ferry, but also because word had traveled that the moderate winds that are common in the area would make the bridge sway and even undulate up and down.   It was pretty cool to see.  Drivers reported losing sight of the autos in front of them when the bridge waved. The bridge gained the moniker “Galloping Gertie.”

Tacoma-Narrows-Bridge

Brave (or stupid) Pedestrian

All the fun and games came to a crashing end on this date in 1940 when steady winds of just 42 mph made the bridge sway…and then leap. It continued throughout the day until the entire structure failed. The bridge had been closed but the last man let across lost control of his car and, in fear of being tossed 190 feet into the Tacoma Narrows below, he fled on foot. He tried to retrieve the family cocker spaniel from the back seat but the pup would have none of it. As he reached the end of the bridge, the bridge collapsed spectacularly with the dog as the only casualty.

The result of the collapse was analyzed and is a common subject in college physics classes. Basically, the wind was in tune with the natural harmonics of the bridge. The more the wind blew, the greater it increased the amplitude of the harmonics creating a wave. Its a similar phenomena as when a singer breaks a glass. To avoid a similar fate, bridges today, including the one that replaced “Galloping Gertie” have damping and aerodynamic features built in and wind tunnels are used to test the ability of the structure to resist wind and prevent compromise of the integrity of the structure.

Here is the 1940 Newsreel Footage of the Collapse of the Tacoma Narrows Bridge

Here is a different, color film on video of the collapse

Whatever man builds, can come down. Gravity and other forces are constantly at play. There are some things in life in which compromise can be a good thing. But engineers cannot afford to not get it right the first time. It kinda reminds me of what US Grant often said, “man proposes; God disposes.” These days we often teach our kids that close is good enough. If that is your methodology, mommas don’t let your babies be engineers.

Super Typhoon Megi Set To Strike Philippines With Extreme Intensity
October 17, 2010

Super Typhoon Megi Cast an Impressive Multispectral Image at 2330Z Oct 16, 2010

For a more recent update regarding Typhoon Megi’s approach to China CLICK HERE

Japan Meteorological Agency Forecast Track Super Typhoon Megi (Juan)

The Philippines is making preparations ahead of a powerful Super Typhoon set to strike the island nation Monday morning with effects being felt on Sunday. The storm, known locally as Juan, is feared to have the same flooding potential as Typhoon Ketsana in Sept 2009. Typhoon Megi (a.k.a. Typhoon Juan) has behaved exactly as expected and it is now a very powerful storm designated as Super Typhoon Megi, Super Typhoon Juan or Super Typhoon 15W.  Whichever moniker you choose, it is a force to be reckoned with as its energy release compares favorably to an excess of the global electric generating capacity or as an equivalent to the largest yield atomic weapon every minute.  Another estimate puts a well developed tropical cyclone energy release on par with 500,000 Hiroshima style atomic bombs per day

Super Typhoon Megi Graph of Central Pressure Progression

In any event, the inhibiting factors to the storm have gone by the wayside as anticipated and the central pressure has dropped to 908 mb, which is extremely low.  To provide a frame of reference of how that compares to intense hurricanes in the North Atlantic,  Hurricane Camille in 1969 bottomed out at 909 mb and had winds approaching 200 mph.  Hurricane Andrew in 1992 had a minima pressure of 922 mb and the lowest that Katrina had in 2005, well before landfall, was 920 mb.   Super Typhoon Megi is not too far from the all-time lowest recorded atmospheric pressure which occured in 1979 with Typhoon Tip, which had a remarkable central pressure of 870 mb.  Previously, Typhoon Ida held the record of 879 mb when it was 750 miles east of Luzon (very close to the current location of Megi-450 miles NE of Manila) in 1958.  So, extremely intense storms in the region are not totally uncommon.  The clouds that had been obscuring the center have gone by the way-side and a well defined, relatively small eye has developed. 

West Pacific IR Rainbow Satellite Featuring Typhoon Megi-Click Image for Most Recent Loop

Super Typhoon Megi (Juan) JTWC Forecast Track 00Z 10.17.10

A pressure approaching 900 mb can easily support higher winds than the 3 UTC (Z) Oct 17 2010 analysis of 140 kt sustained winds of 140 kts and gusts to 170 kts, which translates to sustained winds of 161 mph or 259 kph and gusts to 195 mph or 315 kph.  Some further intensification is possible as the forecast calls for sustained winds to increase to 145 kts and gusts to 175 kts.  While the pressure can support even higher winds than that, at this point, they are so strong that it almost becomes academic in relation to the destruction potential and the ultimate intensity at landfall will most likely be subject to eyewall replacement cycles.  When a tropical cyclone goes through an eyewall replacement cycle, central winds typically fall off but the breadth of gale force winds expands.  That was the case with Hurricane Katrina which “only” had winds of 125 mph at landfall as it headed  into Mississippi but 100 mph winds were felt all the way to Mobile.  Another factor that may inhibit substantial intensification would be a slight disruption of the northern outflow.  This is an example of why it is difficult for an extremely intense tropical cyclone to maintain its maxima for long as environmental conditions must be perfect and perfect conditions rarely last long.  Nevertheless, as it stands, the official forecast from the Joint Typhoon Warning Center puts the winds around 140 kts at landfall sometime after 00 UTC (Z) October 18, 2010 north of Palanan and east of Tuguegarao.  It would not be out of the question for winds to exceed forecast levels at some point in time.  The timing of eyewall replacement cycles, however, is beyond current forecast abilities until the beginning of the cycle change is actually observed.

West Pacific Total Precipitable Water Latest 72 hours-Click Image for Loop

West Pacific IR Satellite with Wind Barbs (Isotachs)

As was anticipated, the trof of low pressure near Okinawa that was causing a weakness in the steering ridge to the North has moved northeast and the ridge filled in.  Consequently, the previous west northwest track of Megi has shifted westward at 12 kts.  The ridge is expected to continue to build such that the westward track should change around the time that the storm gets to the coast of Luzon such that it moves west-southwest.  That track would take Megi over the mountainous regions of northern Luzon but well north of Manila.  The storm surge on the eastern, northeastern and northern part of the island will be extreme but exact levels will be determined by the geogrpahy of the coast.  The mountains will enhance the rain totals which will most likely be extreme.  Even as it loses intensity rapidly over the mountains, the circulation will be such that there will be an onshore flow off of the South China Sea toward Manila for a period of time so rain totals will most likely be high on both sides of Luzon. 

Super Typhoon Megi Morphed Integrated Microwave Imagery with max Wind Velocity-Click Image for Loop

If there is any good news to report it is that the forward speed may increase a bit and so the center of the storm may be over Luzon for only about 12 hours.  That’s plenty of time to do plenty of damage but at least its not going to crawl across the Philippines and extend the high risk for catastrophic flooding.  By 12UTC (Z) October 18, 2010 Typhoon Megi should re-emerge over the ocean in the South China Sea with winds forecast to have been reduced to 95 kts.  However, once over the warm waters of the ocean, Typhoon Megi will regain some strength but most likely will not get back to it’s former self…that would be extremely rare and there simply will not be time nor will the environmental conditions support such a scenario.  Even so, It is expected to get back to 115 kt sustained winds by 00UTC (Z) October 22, 2010. 

Super Typhoon Megi Graph of Wind Speed Progression

Previously, the extended forecast track had suggested a second landfall on the South China island of Hainan followed by a final landfall after crossing the Gulf of Tonkin in Vietnam.  Modeling data though has formed a consensus though of another trof coming down through Asia. 

Map SE Asia

That trofiness is expected to influence Megi northwest after it enters the South China Sea.  The depth of that trof will determine the fate of Megi.  If it is slow or not so strong, then Megi may run into China south of Hong Kong, though it would still be close enough to affect that city.  If the trof is a little deeper, then it could turn Megi for a more direct affect on Hong Kong and if the trof is fast and very deep, it could conceivably turn the storm north and then northeast.  While there may not be sufficient room in the sea for this to occur without striking land, that scenario would put Taiwan at risk of a hit from the Southwest and potentially even Japan after that.  It’s way too soon to tell.  One thing seems invevitable:  the Northern Philippines will be affected adversely of the effects of a major tropical cyclone by 00UTC (Z) 18 October 2010.

Typhoon Fanapi Set To Strike Taiwan Before Weekend is Over
September 18, 2010

Click on Image for Most Recent Western Pacific Rainbow IR Image Loop

Typhoon Fanapi Forecast Track as per Joint Typhoon Warning Center

The people in Taiwan are anticipating the arrival of Typhoon Finapi.  Among other things, it is disrupting the fishing season that just started at the beginning of the month.  Perhaps more importantly, the Typhoon is packing winds that will cause concern for damage and a potentially devastaing surge.  However, the actual surge is determined by geograhpical features of the island as well as the physical features of the shelf and I am not aware of the physical features around Taiwan.  I cannot find any buoys in the region that are in operating condition but reports of 28 foot seas have been made.   While the forward speed of around 12 mph might limit the storm surge potential to a small degree, winds running at 105 kts (120 mph) will be sufficient to push a substantial amount of water up to the right of landfall.  Typhoon Fanapi’s intensity puts it as an equivalent of a category 3 hurricane.   Beyond the wind and surge threat, the topography of the island will serve to enhance rain totals and authorities are expecting up to 20 inches in some areas.  With a storm travelling around 10 mph, Typhoon conditions can be expected in several parts of the island for up to 8-12 hours.

Total Precipitable Water-Click on Image For Most Recent Loop

When you look at the satellite imagery, you find that Finapi is a well formed, compact tropical cyclone but the outflow to the north is almost absent while there remains some outflow to the south.  There is a big fat high to the north of the cyclone that is inhibiting the poleward outflow which may have inhibited the storm from becoming even more intense.   The central pressure of 935 mb has the potential to support winds higher than previous estimates.  Nevertheless, tropical storm force winds extend up to 150 miles from the center and typhoon winds some 35 to 40 miles from the center of circulation.   I suspect that there is the possibility that this storm may be getting slightly more intense as it approaches Taiwan for landfall as it appears that Fanapi has completed an eyewall replacement cycle.  An eyewall replacement cycle is a natural occurence related to a well developed tropical cyclone and typically, the maximum winds decrease as the storm goes through the cycle of replacing an eyewall, though the overall strong windfield expands.  Once the cycle is complete, then the storm returns to its previous intensity.  Hence, the satellite imagery suggests that the cycle is complete and Fanapi may be ramping up toward maximum potential just prior to landfall.

Fanapi IR Satellite 09.18.10 1732Z

For what it’s worth, Fanapi is the Micronesian name for “sandy islands” and it is expected to continue on its track generally to the west at around 10 kts and the Joint Typhoon Warning Center Forecasts points  to a landfall about 70 miles SSE of Taipei near the coastal town of Hualien.  Geographically speaking, it seems to me that the little bay to the north of Hualien may be vulnerable to an enhanced surge.  Once the storm makes landfall, the topographical features of Taiwan will disrupt the storm sufficiently that it will fall to below 100 kts when it re-emerges over the Taiwan Straits and will move into China within 36 hours with winds of around 80 to 85 kts about 150 miles Northeast of Hong Kong.  Inland flooding will be a concern for China as the storm dissipates, particularly when one considers that China has experienced flooding problems all summer long in many parts of the huge nation.

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 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

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