Category 3 Hurricane Earl pounding northern Lesser Antilles and Puerto Rico

By: Dr. Jeff Masters , 2:40 PM GMT on August 30, 2010

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An intensifying Hurricane Earl is pounding Puerto Rico and northern Lesser Antilles Islands with heavy rain and high winds this morning. The eye of Earl passed just north of Anguilla at 9am EDT, and Juliana airport on neighboring St. Martin Island recorded sustained winds of 47 mph, gusting to 68 mph at 8am EDT before going silent. An Air Force Hurricane Hunter aircraft currently in Earl just found a central pressure of 960 mb at 9:42 am EDT. This is a significant drop of 25 mb in 25 hours. Top flight level winds at 10,000 feet seen by the Air Force aircraft were 128 mph. Using the usual rule of thumb that the surface winds are 90% of the 10,000 foot flight level winds gives one surface winds of 115 mph, which is right at the border of Cat 2/ Cat 3 strength. Top winds seen at the surface by the Air Force's SFMR instrument were lower, 104 mph. Recent satellite imagery shows that Earl is not perfectly symmetrical--there is still fewer heavy thunderstorms on the hurricane's north side, suggesting that upper-level northerly winds are bringing 5 - 10 knots of wind shear to the storm.


Figure 1. Radar image of Earl taken at 7am EDT 8/30/10 from the St. Maarten radar. Image credit: Meteorological Service of the Netherlands Antilles and Aruba.

Outlook for the Caribbean islands today
Latest radar animations out of Puerto Rico and St. Marten show that the eye of Earl is on track to pass just to the northeast of the islands of Anguilla, St. Maarten, and The Settlement in the British Virgin Islands today. The periphery of Earl's southern eyewall will probably bring Category 1 hurricane conditions to some of these islands today. NHC is giving its highest odds for hurricane-force winds to Saint Maarten--a 99% chance. These odds are 4% for St. Thomas in the Virgin Islands, and 2% for San Juan, Puerto Rico. The main threat to Puerto Rico will be heavy rains--up to eight inches in isolated areas. Earl's rains, in addition to causing flooding and dangerous landslides, will also help alleviate drought conditions that have affected many of the islands this year.

Intensity forecast for Earl
Wind shear as diagnosed by the latest SHIPS model forecast is nearly non-existent over Earl--just 3 knots--put is probably higher than that, based on the fact that the northern portion of Earl cloud pattern is ragged. Further evidence of this is the fact that Earl's eyewall had a gap in its west side, according to the latest report from the Hurricane Hunters. Ocean temperatures are a near-record 30°C, and very warm waters extend to great depth, resulting in a total ocean heat content highly favorable for rapid intensification. These nearly ideal conditions for intensification should bring Earl to Category 4 strength by Tuesday morning, and Category 5 is not out of the question. Earl should be able to maintain major hurricane status through Thursday, when it will make its closest approach to North Carolina. Sea surface temperatures are very warm, 29°C, along the U.S. East Coast, and wind shear is expected to remain low through Thursday. By Friday, when Earl will be making its closest approach to New England, wind shear will rise to a high 20 - 30 knots and ocean temperatures will plunge to 20°C, resulting in considerable weakening. Earl will still probably be a Category 2 hurricane on Friday, when it could potentially make landfall in Massachusetts or Nova Scotia, Canada.


Figure 2. Swath of surface winds from Earl predicted by the 2am EDT Monday August 30, 2010 run of NOAA's GFDL model. Hurricane force winds (yellow colors, 64 kt and above) are predicted to stay off the coast and tropical storm force winds (light green colors, 34 knots and above) are predicted to stay off the U.S. coast, but affect the coast of Canada. Image credit: Morris Bender, NOAA/GFDL.

Track forecast for Earl
Once Earl passes the Lesser Antilles, steering currents favor a northwesterly course towards North Carolina. History suggests that a storm in Earl's current location has a 25% chance of making landfall on the U.S. East Coast, and Earl's chances of making a U.S. landfall are probably close to that. None of the computer models show Earl hitting the U.S., but the storm will likely come uncomfortably close to North Carolina's Outer Banks and to Massachusetts. The latest set of model runs (2am EDT, or 6Z) project Earl will miss North Carolina by 200 - 300 miles on Thursday, and Massachusetts by a similar distance on Friday. Keep in mind that the average error in a 4 - 5 day NHC forecast is 200 - 300 miles, so the East Coast cannot breathe easily yet. The Outer Banks of North Carolina and Cape Cod, Massachusetts are both at the edge of the cone of uncertainty. NHC is giving Cape Hatteras a 9% chance of receiving hurricane force winds. These odds are 14% for Nantucket, 4% for Boston, and 2% for New York City. The main determinant of whether Earl hits the U.S. or not is a strong trough of low pressure predicted to move off the U.S. East Coast Friday. This trough, if it develops as predicted, should be strong enough to recurve Earl out to sea late in the week, with the storm just missing landfall in the U.S., but possibly making landfall in Nova Scotia, Canada.

Regardless of Earl's exact track, the U.S. East Coast can expect a long period of high waves beginning on Thursday. Significant beach erosion and dangerous rip current will be the rule, due to waves that will reach 10 - 15 feet in offshore waters (Figure 3.)


Figure 3. Wave forecast for 8am Friday, September 3, 2010, as produced by the 8pm EDT August 29 run of NOAA's Wavewatch III model. The model is predicting waves of 4 - 5 meters (13 - 16 feet) in the offshore waters from North Carolina to New Jersey.

Hurricane History for the northern Lesser Antilles
The last Cape Verdes-type hurricane to affect the Barbuda and the surrounding northern Lesser Antilles Islands was Hurricane Debby of 2000, which passed over the islands on August 28 as a Category 1 hurricane. Damage was less than $1 million, and no fatalities were reported. The last hurricane of any kind to pass through the northern Lesser Antilles Islands was Category 4 Hurricane Omar, on October 16, 2008. Omar took an unusual track, moving towards the northeast, and the storm's eyewall missed all of the islands. Omar did $80 million in damage to the Caribbean, mainly on the islands of Antigua, Barbuda, Dominica, the SSS Islands (Saba, St. Eustatius, and St. Maarten), and the U.S. Virgin Islands. No direct deaths were attributed to Omar, and the name Omar was not retired from the 6-year rotating list of hurricane names.

Links to track Earl
Wundermap of the northern Lesser Antilles Islands
Long range radar out of San Juan, Puerto Rico
Visible rapid scan satellite loop

97L
The tropical wave (Invest 97L) now 1000 miles east of the Lesser Antilles Islands has a well-defined surface circulation and enough heavy thunderstorms to be classified as a tropical depression, if it can maintain that state for another six or so hours. Satellite loops show the surface circulation clearly, but also that heavy thunderstorm activity has been slow to build. The storm is experiencing low wind shear of less than 5 knots, and is over warm 29°C waters. The main impediment to development continues to be dry air associated with the Saharan Air Layer (SAL) surrounding the storm. The latest SHIPS model forecast calls for shear to stay in the low range, 5 - 10 knots, through Tuesday, and this should allow 97L to organize into a tropical depression today or Tuesday. NHC is giving 97L a 90% chance of developing into a tropical depression by Wednesday.

97L is moving quickly to the west, at about 20 mph. This means it is catching up to Earl, which has slowed down to 14 mph. By Tuesday night, Earl is expected to be a large and powerful major hurricane with a well-developed upper-level outflow channel heading clockwise out from Earl's center at high altitudes. These strong upper-level winds will bring high levels of wind shear, 20 - 30 knots, to 97L, and probably arrest the storm's development. The most likely scenario depicted in the computer models is for 97L to be drawn into the low pressure wake of Earl and pass to the northeast of the Lesser Antilles. Earl would then eventually destroy 97L through high wind shear, and by robbing the storm of its moisture. An alternative scenario is that 97L will stay far enough away from Earl that it will be able to pass through the northern Lesser Antilles islands as a tropical storm on Wednesday and Thursday, then bend northwestwards to potentially threaten the Bahamas and U.S. East Coast. There is a very high degree of uncertainty on what may happen to 97L. History suggests that a storm in 97L's current location has a 25% chance of making landfall on the U.S. East Coast.


Figure 4. Morning satellite image of 97L.

Danielle
Hurricane Danielle is on its way to oblivion over the cold North Atlantic waters, and is only of concern to shipping interests.

Elsewhere in the Tropics
Over in the Western Pacific, tropical cyclone activity is ramping up, with two named storms expected to affect land this week. As is typical in a La Niña year, these storms have developed close to mainland Asia, and don't have a lot of time over water to intensify into strong typhoons. The storm of most concern is Typhoon Kompasu, which is expected to hit Okinawa today and recurve northward into Korea on Thursday. It now appears the Kompasu will not have major impacts on China's largest city, Shanghai. In the South China Sea, the fearsome sounding Tropical Storm Lionrock is forecast to hit the Chinese coast near Hong Kong on Tuesday, but is not predicted to develop into a typhoon.

The GFS model is predicting formation of a tropical depression off the coast of Africa about seven days from now.

Jeff Masters

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Quoting hurricaneman123:


nice pinhole type eye on Earl


Its just cloud covered atm. Not symmetrical or small enough to be one just yet but its getting there.
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Quoting Thundercloud01221991:
Hurricane Felix.. I think had lightning in the eyewall so they had to abort their recon mission

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Quoting clwstmchasr:


I'm beginning to wonder if Fiona will develop from 97L? For 3 days now it wants to develop but it but it refuses to organize. Now it is catching up to Earl and he just might put the kibosh on 97L. Also, the latest GFS does not develop 97L.

hmmm for about 3-4 days now it has been switching between 80-90% chance of development. i`m not sure if it will develop but if it keep its current forward speed Earl for sure is going to rip it apart!
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Quoting mtyspider:
Storw i have read 3 pages about Earl hitting sflorida , Most of them guessing and wishing i even read some crazy talk that it will get to NY.

What are the actual scientific facts?
he will travel the coarse n nw of pr scrap outer bahama island as a curve n along the coast till long island where then a system coming from grtlakes curves him nne ward to skirt along ns then over central newfoundland poss cat 5 coming in towards bahamas then graual weakening to a strong 3 weak 4 storm anything else
Member Since: July 15, 2006 Posts: 171 Comments: 53838
I am wondering the same thing about Fiona. not sure if they would clash due to in 3 days Earl already turning northwest but the wind shear left behind could inhibit significant development of possible Fiona.
Member Since: July 12, 2010 Posts: 0 Comments: 1130
Quoting DestinJeff:
NW

Link

too small of a sample .. still kinda of hard to tell if thats more wnw or true nw
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Hurricane Felix.. I think had lightning in the eyewall so they had to abort their recon mission
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nice pinhole type eye on Earl
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Quoting poknsnok:
moving north of forecast points


Yes it is !!
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521. Prgal
Quoting txjac:


Stay safe PRgal!


Thanks, we will.
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Quoting IamTheCanesSurfer:


Agreed - Never seen lightning in H...only transformer blowing up and that greenish light... :)


i recall lightning in TD's, but not in Hurricanes. Is there any in TSs??
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Quoting truecajun:


at one point, Katrina had Hurricane force winds almost 200 miles across and TS force winds 350 miles across. she was one big mama. I'm guessing they are all different depending on their size.

i remember driving from LA to FL about a month after she passed. the entire drive there was destruction EVERYWHERE along the way. signs down all over the place for the entire 4 hour drive. i kept thinking in amazement of how BIG she was.


And yet, when I went down to Punta Gorda after Charley, the wind damage swath was maybe 10 miles across... It was astounding how narrow it was...
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good link in about 2-3 hours...

http://radar.weather.gov/ridge/radar.php?rid=jua&product=N0R&overlay=11101111&loop=yes
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Quoting FloridaToz:
Question: As a resident of S. Florida and Hurricane Wilma recipient, the experts in describing developing tropical systems often refer to the development of "Heavy Thunderstorm" around the eye wall. Yet, have actually been in Wilma, Jeanne, Irene and skirted by Francis, I haven't ever seen or heard thunder or lightning. Is the reference to heavy "thunderstorms" inaccurate?

Thanks in advance for an expert reply


Agreed - Never seen lightning in H...only transformer blowing up and that greenish light... :)
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511. txjac
Quoting FunkStorm:


Theres nothing on Radar for NC.


Stay safe PRgal!
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Quoting clwstmchasr:


I'm beginning to wonder if Fiona will develop from 97L? For 3 days now it wants to develop but it but it refuses to organize. Now it is catching up to Earl and he just might put the kibosh on 97L. Also, the latest GFS does not develop 97L.
it appears that some of the models are starting to hedge on what 97l will become of maybe not become.
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Quoting TampaTom:


It's tough to say there are 'standard' distances from the COC for wind fields. Hurricane Charley had a very small wind field, but Hurricane Ike was huge...

Each storm is an individual.

If you start to research some storms, look for a stat called the RMW = Radius of Maximum Winds. That will show you how large the max wind field for the storm was, which has a major impact on surge flooding.


at one point, Katrina had Hurricane force winds almost 200 miles across and TS force winds 350 miles across. she was one big mama. I'm guessing they are all different depending on their size.

i remember driving from LA to FL about a month after she passed. the entire drive there was destruction EVERYWHERE along the way. signs down all over the place for the entire 4 hour drive. i kept thinking in amazement of how BIG she was.
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Quoting katroy:
I'm looking for a site where I can get the size of various wind fields for a tropical storm/hurricane. I know the NHC puts this in their Public Advisories (example below), but for hurricane-strength winds, they don't break it out by Category (i.e., Cat 1, Cat 2, Cat 3).

Example:
HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 185
MILES...295 KM.

This example is from the latest Advisory for Hurricane Earl (a Cat 3), so I'd like to know the size of the wind fields that are Cat 1, vs Cat 2, vs Cat 3.

Hope this makes sense. Thanks!


There isn't a site out there that I'm aware of that lists that.

However, ImpactWeather had a presentation at the latest hurricane conference on their rating scale, which shows how to estimate the radius of 100 kt winds (winds at this point begin destructive damage to residences). Just open the pdf at that link. You'll need a calculator to figure it out.
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Quoting mtyspider:
Storw i have read 3 pages about Earl hitting sflorida , Most of them guessing and wishing i even read some crazy talk that it will get to NY.

What are the actual scientific facts?


Link
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Quoting Bordonaro:

That looks BAD..
Reminds me of Hugo I hope everyone there is OK what was the predicted storm surge of Earl?
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Quoting FloridaToz:
Question: As a resident of S. Florida and Hurricane Wilma recipient, the experts in developing often refer to development of "Heavy Thunderstorm" around the eye wall of a developing tropical cyclone. Yet, have actually been in Wilma, Jeanne, Irene and skirted by Francis, I haven't ever seen or heard thunder or lightning. Is the reference to heavy "thunderstorms" inaccurate?

Thanks in advance for an expert reply
no expert, but lightning is rare in hurricanes; however recent studies have suggested open ocean lightning is a good indicator of cyclogenisis in CV storms; and with that I'm reinstituting my self imposed "e" storm ban after my complete wrong call on Danielle; good luck to everyone today in Earl's path. Stay safe.
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moving north of forecast points
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Quoting katrinakat5:
YES RELIX IT IS ITS GOING TO KOVE ON A WEST TO WNW ALL DAY LONG NO NW TURN UNTIL ITS TO LATE FOR SOU FLA AND THE BAHAMAS...THE BAHAMAS ARE GOING GET HAMMERED BY THIS SOON TO BE CAT 5..


It puts the lotion on its skin, or else it gets the hose again.
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Quoting FloridaToz:
Question: As a resident of S. Florida and Hurricane Wilma recipient, the experts in describing developing tropical systems often refer to the development of "Heavy Thunderstorm" around the eye wall. Yet, have actually been in Wilma, Jeanne, Irene and skirted by Francis, I haven't ever seen or heard thunder or lightning. Is the reference to heavy "thunderstorms" inaccurate?

Thanks in advance for an expert reply


A very cool article on lighting in hurricanes from NASA:

http://science.nasa.gov/science-news/science-at-nasa/2006/09jan_electrichurricanes/
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Quoting divdog:
wnw not west


But it is taking another leftward wobble. A few minutes ago I showed 305 degrees. Now I am seeing ~301.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting katrinakat5:
YES RELIX IT IS ITS GOING TO KOVE ON A WEST TO WNW ALL DAY LONG NO NW TURN UNTIL ITS TO LATE FOR SOU FLA AND THE BAHAMAS...THE BAHAMAS ARE GOING GET HAMMERED BY THIS SOON TO BE CAT 5..
OK , enough with the caps. CLick
Member Since: August 23, 2005 Posts: 0 Comments: 285
Quoting tornadodude:


seriously???

Carolina, Puerto Rico


Man, if only Presslord were here...
Member Since: September 22, 2005 Posts: 18 Comments: 2342
Quoting wjdow:


Sorry FH, misunderstood your post, my bad.


it is ok i am just on edge because of that first post i read this morning but everyone says not to listen to that person
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Storw i have read 3 pages about Earl hitting sflorida , Most of them guessing and wishing i even read some crazy talk that it will get to NY.

What are the actual scientific facts?
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Am I over simplifying this?

Earl is to move WNW or NW for the next couple of days...depending on how far west he gets by the time the cold front drops through will determine where he makes his Northward to eventual Northeastward turn...and geographic impact

Everything I've read this morning suggests the front may be slow to come due to the extreme high pressure over Ohio. To me the only saving grace is less of a westernly component from now until Friday/Saturday to avoid getting under the "lip" of the carolina up to the maritimes before turning.

Think we need to try out some Bugs Bunny "air brakes" right now
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Dag Nabit! I can never keep a resolution. Promised myself I was going to keep away from the ignore button this season. Oh Well . . .
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Quoting all4hurricanes:
Wow look at this
Link
major flooding in St Martin

That looks BAD..
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Quoting FunkStorm:


Theres nothing on Radar for NC.


seriously???

Carolina, Puerto Rico
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Quoting FloridaToz:
Question: As a resident of S. Florida and Hurricane Wilma recipient, the experts in developing often refer to development of "Heavy Thunderstorm" around the eye wall of a developing tropical cyclone. Yet, have actually been in Wilma, Jeanne, Irene and skirted by Francis, I haven't ever seen or heard thunder or lightning. Is the reference to heavy "thunderstorms" inaccurate?

Thanks in advance for an expert reply

Unless a thunderstorm was actually observed in the hurricane, heavy rain would be the appropriate title, not "thunderstorm".
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485. jdj32
This is the link for Google Earth Recon Data.

http://tropicalatlantic.com/recon/
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Quoting want2lrn:
TampaTom - thank you for your response earlier.


No sweat. :-)
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Wow look at this
Link
major flooding in St Martin
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.