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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97L better start moveing N or it may this get eat in up by Earl
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Quoting FLPandhandleJG:


97L is going to be destroyed by Earl's outflow... they are very close to each other
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Quoting FLPandhandleJG:
Danielle



I'll say Earl.
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97L looks like its just gonna thread the needle going straight into the Central Carribbean, probably blow up once in there.
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Quoting FLdewey:

Curious are "Downcasters" the people who DON'T think every storm is coming to Florida?
Nice +1
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Quoting Floodman:


I'm not so sure on intensity...the possibility is there but the shear appears to want to increase in the next 24 hours or so...
Yes...I see that..If Earl does not reach 5 by this time tomorrow it probably wont.
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823. xcool
very very long hurricanes season . active sep to oct ..
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Quoting FLPandhandleJG:


I know im trying to stay positive.. lol


yea hopefully they are wrong... the GFS predicts a NJ/NY graze... being one of the most densly populated places in the USA that would be disastrous... think about a 8ft strom surge in NYC... very bad
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Quoting xcool:


update. moved west Little be .

Looks like a little southwest wobble
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000
NOUS42 KNHC 301730
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0130 PM EDT MON 30 AUGUST 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 31/1100Z AUGUST TO 01/1100Z SEPTEMBER 2010
TCPOD NUMBER.....10-091

I. ATLANTIC REQUIREMENTS
HURRICANE EARL
FLIGHT 0NE -- NOAA 49 FLIGHT TWO -- TEAL 78
A. 01/0000Z A. 01/0000Z
B. NOAA9 0707A EARL B. AFXXX 0807A EARL
C. 31/1730Z C. 31/1730Z
F. 41,000 TO 45,000 FT F. 24,000 TO 33,000 FT
FLIGHT THREE -- TEAL 77
A. 01/1800Z
B. AFXXX 0907A EARL
C. 01/0115Z
D. 24.0N 69.7W
E. 01/0530Z TO 01/0800Z
F. SFC TO 15,000 FT
SUSPECT AREA
FLIGHT ONE -- TEAL 71 FLIGHT TWO -- TEAL 70
A. 31/1800Z A. 01/0600, 1200Z
B. AFXXX 01EEA INVEST B. AFXXX 0208A CYCLONE
C. 31/1600Z C. 01/0415Z
D. 15.7N 55.0W D. 17.0N 58.4W
E. 31/1730Z TO 32/2130Z E. 01/0530Z TO 01/1200Z
F. SFC TO 10,000 FT F. SFC TO 15,000 FT
2. SUCCEEDING DAY OUTLOOK: BEGIN 6-HRLYS ON EARL


Member Since: September 23, 2005 Posts: 14 Comments: 11028
817. JLPR2
I'm watching Earl closely but 97L is looking like a threat to the islands as well.

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Quoting Engine2:
Anyone know if Storm was able to finish his blog yet?
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Earl

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Quoting Jeff9641:
Where are the downcasters now. 2 major hurricanes in less than a week and just wait till we get something in the Caribbean going come SEPT and OCT.

I am wishing them away but thanks to you and all the bloggers here we will always be on top of things in the Caribbean and everywhere else.
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Quoting Tropicaddict:


Close...Katrina was 902...but who's counting! lol Tip was the lowest with 970. :)


The 882 mb pressure reported in Wilma is the lowest central pressure on record in an Atlantic hurricane, breaking the old record of 888 mb set by Hurricane Gilbert in September 1988. The central pressure fell 88 mb in 12 hours, which shatters the record of 48 mb in 12 hours held by Hurricane Allen in August 1980.

The National Hurricane Center also maintains the official Tropical Cyclone Report for Hurricane Wilma in PDF and MS-Word.

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809. xcool


update. moved west Little be .
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808. Relix
One more time:


http://radar.weather.gov/radar.php?rid=JUA&product=N0Z&overlay=01101111&loop=yes
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Quoting Jeff9641:
Where are the downcasters now. 2 major hurricanes in less than a week and just wait till we get something in the Caribbean going come SEPT and OCT.
And when that does happen, I would bet there will be a couple cat-3 or higher in the mix with all that warm water down there.jmo
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bbl. off to lunch. hang tight islanders.
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Quoting Goldenblack:
Oh but I did see the wobble...



Oh it has definitely wobbled more to the west. Over the last hour or so I have gone from 305 degrees to 296 or so.
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Quoting DestinJeff:
12Z CMC ... misses the coast


Whats that in the GOM?

And look at the wave train off Africa...
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Quoting DestinJeff:
12Z CMC ... misses the coast



What's that in the GOM in this image?
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Dropsonde showing 955mb
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Quoting HurricaneIsabel:
Sorry to bring Katrina up, but the most impressive pressure we've seen was 898 mb, yes? and is that the most impressive in history?


Nope 882mb by Hurricane Wilma in 2005
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798. MahFL
Our distribution warehouse just closed for the day on PR. Delivery trucks are off the road.
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Quoting hurricaneman123:


the NAM and the GFS predict it to be in NC/SC


I know im trying to stay positive.. lol
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Quoting Tropicaddict:


Close...Katrina was 902...but who's counting! lol Tip was the lowest with 970. :)


870 u mean
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Quoting DestinJeff:
12Z CMC ... misses the coast



Is that 97L in the Gulf? Or some spurious low?
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Oh but I did see the wobble...

Quoting angiest:


You need a wider field. I think the south you are seeing is an artifact of more of the eye coming into the range you are looking at. I am using 248nm and am not seeing south.
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Quoting hydrus:
Hello Flood....I believe Earl is going to be at Cat-5 strength by late tonight or early tomorrow morning....Your thoughts?


I'm not so sure on intensity...the possibility is there but the shear appears to want to increase in the next 24 hours or so...
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Quoting SavannahStorm:
Is it just me, or is the ridge building south and west on the water vapor loop?


http://www.ssd.noaa.gov/goes/east/tatl/flash-wv.html


I was noticing that too. The big "if" with Earl's track was whether the ridge would have time to build in behind Danielle. We shall see.
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Quoting HurricaneIsabel:
Sorry to bring Katrina up, but the most impressive pressure we've seen was 898 mb, yes? and is that the most impressive in history?


882 in Wilma - the Atlantic Record
870 in Typhoon Tip - the world record
Member Since: June 20, 2005 Posts: 22 Comments: 1050
Quoting VAbeachhurricanes:


dont pounce on me... but a little south of due west wobble?


You need a wider field. I think the south you are seeing is an artifact of more of the eye coming into the range you are looking at. I am using 248nm and am not seeing south.
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Hiding Jeff....very hidden....

Quoting Jeff9641:
Where are the downcasters now. 2 major hurricanes in less than a week and just wait till we get something in the Caribbean going come SEPT and OCT.
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Anyone know if Storm was able to finish his blog yet?
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Quoting MississippiWx:
It's almost impossible for major hurricanes to move in a straight line. They are going to wobble left and right, but the wobbles generally average out to be right on or close to the forecast track. In Earl's case, he is doing just that and is right on or very close to the forecast track so far. I see no reason why Earl wouldn't follow the track that is currently forecast for the 3 day time frame. After that, it's anyone's guess as forecasting a trof/ridge interaction five days in advance is a very tricky situation. As for now, most if not all of the guidance agrees on keeping Earl offshore and has agreed on that for several days. All it takes, though, is for the trof to be slower/weaker than the models believe and then Earl will be on NC's doorstep.


the NAM and the GFS predicted just that
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Quoting FLPandhandleJG:




the NAM and the GFS predict it to be in NC/SC
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Quoting FloridaHeat:


? i just got on for the first time today what are you talking about


Some folks here are just testy today. Stress high. Please don't pay attention. Just keep an eye and an ear out for the forecast, since you are new to the annual season down here. Listen to StormW, Levi, Floodman and a couple others. They will steer you right. It doesn't hurt to get together a hurricane survival kit. I think KeeperoftheGate had a very good one posted awhile ago. Read that and follow it. Your local news sources and civil defense offices should have good ones to follow. Be aware and keep calm.
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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.

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