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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1831. srada
Quoting HurricaneIsabel:
with each update on earl, the more westerly track it takes :(


I agree..first it was 384 miles off the NC coast just yesterday in our local advisory..now its 200 miles off the NC Coast..and we aint even On Tuesday yet and this storm gets here on Thursday??..
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I'm continuing to watch Earl for any impacts, despite living in south-central PA.
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Quoting washingtonian115:
We have Fiona finally...well can't ask any questions since the arrogant ones are on,Where's storm, levi,or miami09 anyway the wave behind Fiona needs to be mentioned because that could indeed develop.

***

And not long for this world if it catches Earl's wake. . . . and looking at sat imagery, I think it will.
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1825. markot
look at satt.photos moving west...thnxxx
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Quoting HurricaneIsabel:
with each update on earl, the more westerly track it takes :(


So far, yes. But only very small adjustments.
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1823. GetReal
Quoting K8eCane:
Im in Wilmington NC...How Worried should I be...anybody?


I would say "highly interested" in future movements....
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Quoting Stoopid1:
Wobbles taken into account, Earl's motion is still around 285-290 degrees.


Anybody know what causes a storm to randomly wobble like Earl?
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Quoting iammothernature:


Idk, but does this count? lol


I suppose, just have to wonder if they will merge, rotate around a common center, or the weakest one dies by getting absorbed. Just goes to show you how fascinating the weather can be.
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I don't see what's supposed to be pulling earl north? Looks like giant high pressure parked over the east coast and not wanting to move (It's so hot...)

http://www.ssd.noaa.gov/goes/east/natl/flash-wv.html
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1818. KEEPEROFTHEGATE (Mod)
NMFC Norfolk Tropical Feed
As of MON 30 Aug 2010 22:20:02Z
Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico
06L (DANIELLE) Warning C1
MAJOR HURRICANE 07L SEVEN (EARL) C3
Atlantic Tropical Cyclone Formation Alert (TCFA) 97L
Active Tropical Warnings in the Northwest Pacific, North Indian Ocean, Central Pacific, Eastern Pacific, or Southern Hemisphere
09W.NAMTHEUN
08W.KOMPASU
07W.LIONROCK
2010 Storms
All Active Year
Atlantic
08L.EIGHT
07L.EARL
06L.DANIELLE
East Pacific

Central Pacific

West Pacific
94W.INVEST
93W.INVEST
93C.INVEST
09W.NAMTHEUN
08W.KOMPASU
07W.LIONROCK
Indian Ocean

Southern Hemisphere
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Quoting TampaTom:


Hmmmm.... Donna, 1960...



Yeah, that's not happening.
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Wobbles taken into account, Earl's motion is still around 285-290 degrees. And, it appears as if we have TS Fiona finally.
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1812. Skyepony (Mod)
fnmoc has 08L up
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1811. Morgana
LAT LONG

08/25 21 GMT 14.40 -32.20 40 1006 Tropical Storm


08/29 15 GMT 17.20 -58.40 75 985 Category 1 Hurricane
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Quoting CaicosRetiredSailor:

very impressive!!!
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Quoting Drakoen:
Much of the guidance on the western side of the current NHC track:

Especially through the first 72 hours.
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1807. Drakoen
Quoting MiamiHurricanes09:
10 minutes ago:



Stadium effect
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one thing before I leave is that Fiona could become a threat down the road,and the wave behind it.And another thing is that I'm proud of the blog for not including that mans name on the here.....the three initial one.Later weather fantics!.
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Quoting hurricaneman123:


Earl is on its way to becoming a CAT 5... maybe tomorrow morning


we in pr came that close. that close

i am trying to get anguila and anegada weather see how they fared, they reared the worst, yet i havent been able to pull info. any news?
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I'm really anxious to see what central pressure recon will find. By the time they get in there, it could have dropped 10 mb since the last fix.
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Quoting MiamiHurricanes09:
10 minutes ago:


It's got that classic, signature shape. So far the 3 hurricanes we've had this season have all looked great on satellite.
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1800. Skyepony (Mod)
Earl intensity chart

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Quoting GTcooliebai:
Just a random question: Has a fujiwahra ever happen between 3 storms?


Idk, but does this count? lol

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1798. angiest
Quoting hcubed:
Invest_RENUMBER_al972010_al082010.ren

Doesn't this really mean we have TD8?

They'll release a seperate line that names it Fiona, won't they?


She already had winds to support tropical storm strength. And she is tropical cyclone 8L in the numbering system.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1797. Drakoen
Much of the guidance on the western side of the current NHC track:

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1796. hydrus
Quoting MiamiHurricanes09:
10 minutes ago:

Dont you have anything more recent.....sheesh..:)
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1795. angiest
Quoting clwstmchasr:


I give praise to the NHC and bash them when they miss. I believe they have missed it on Earl.


Almost five and a half days ago they say this:


THE DEPRESSION IS MOVING TOWARD THE WEST OR 275 DEGREES AT 15 KNOTS
TO THE SOUTH OF A SUBTROPICAL RIDGE. THIS GENERAL MOTION IS
EXPECTED TO CONTINUE DURING THE NEXT 2 TO 3 DAYS. THEREAFTER...THE
CYCLONE MOST LIKELY WILL DECREASE IN FORWARD SPEED AS IT REACHES A
WEAKNESS IN THE SUBTROPICAL RIDGE LEFT BY DANIELLE. BY THEN...THE
CYCLONE SHOULD BEGIN TO TURN TOWARD THE WEST-NORTHWEST. THE
OFFICIAL FORECAST IS BASICALLY IN THE MIDDLE OF THE TIGHTLY
CLUSTERED GUIDANCE ENVELOPE. MOST OF THE NUMERICAL GUIDANCE SHOWS A
PERSISTENT TROUGH OVER THE WESTERN ATLANTIC. IF THIS PATTERN
MATERIALIZES...IT WOULD STEER THE CYCLONE TOWARD THE NORTHWEST AWAY
FROM THE LESSER ANTILLES.


He should have been going WNW by at least 2 days ago. Instead, I believe it happened last night. That forecast implied he should be going NW likely by now, but still he's not. The early forecasts for Earl were not very good.

Since he became a hurricane they have been better, but that is not a very long time.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1794. HadesGodWyvern (Mod)
https://152.80.49.110/tcweb/dynamic/thumbnails/tc_thumbs/20100830.1945.goes-13.vis.1km.08L.EIGHT.35kts.1007mb.14.2N.47.7W.100pc.jpg
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1793. hcubed
Invest_RENUMBER_al972010_al082010.ren

Doesn't this really mean we have TD8?

They'll release a seperate line that names it Fiona, won't they?
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1792. K8eCane
Im in Wilmington NC...How Worried should I be...anybody?
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Quoting StormsAreCool:


F. Mississippi


Hahaha...very funny...lol...
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Ok, enough of this amateur casting. All I can say is east coast needs to be prepared regardless. All this wnw w NW crap giving me a headache
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1788. srada
I guess they finally decided to update..double whammy for the Carolinas? NWS in Wilmington, NC

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...HURRICANE EARL WILL BE MOVING NORTHWEST MAKING
ITS WAY UP INTO THE ATLANTIC WATERS OFF THE SOUTHEAST COAST OF THE
UNITED STATES. LATEST MODEL GUIDANCE SHOWS CLOSEST APPROACH TRENDING
CLOSER TO THE CAROLINA COAST. FOR LOCAL AREA IT LOOKS LIKE THE
CENTER OF THE STORM MAY REACH UP TO 200 MILES OFF SHORE AT CLOSEST
APPROACH ON THURS AS IT PASSES BY AND MOVES OFF TO THE NORTH
NORTHEAST. HAVE ADDED SLIGHT CHC OF PCP FROM CAPE FEAR COAST
NORTH...BUT OVERALL IF CURRENT FORECAST HOLDS...WE SHOULD STAY ON
THE SUBSIDENT SIDE OF STORM. MOISTURE PROFILE NOW SHOWING BETTER
SPIKE OF DEEPER LAYER MOISTURE ON THURS ASSOCIATED WITH EARL...BUT
COUNTING ON MORE IN THE WAY OF CLOUD THAN PCP OVER LAND
AREAS...MAINLY FROM CAPE FEAR NORTHWARD. GUSTY WINDS AND SHOWERS
WILL BE MORE PREVALENT OVER THE COASTAL WATERS IN POSSIBLE RAIN
BANDS FROM EARL ON THURS. MAY END UP BEING A BIGGER THREAT TO MARINE
AND COASTAL COMMUNITY WITH LARGE SEAS AND STRONG WINDS. HAVE MAXED
OUT WINDS AROUND 25 KTS IN OUTER WATERS THURS AFTERNOON AS WINDS
BACK AROUND FROM THE NORTH TO NORTHWEST AS EARL MOVES BY.

EARL WILL TRACK UP THE EAST COAST AND SHOULD REMAIN OFF SHORE FOR
THE MOST PART AS IT TRACKS OFF TO THE NORTHEAST THURS THROUGH FRI
WHILE ANOTHER SYSTEM...POSSIBLY THE FUTURE FIONA...TRACKS MORE
WESTWARD TOWARD THE SOUTHERN BAHAMAS. LOOKS LIKE THE STRONG RIDGE
OVER THE EAST COAST WILL BREAK DOWN AS EARL MOVES NORTHWEST AND A
MID TO UPPER TROUGH MAKES ITS WAY EASTWARD ACROSS THE GREAT LAKES
THURS INTO FRI.
THIS TROUGH WILL PUSH A COLD FRONT EAST INTO THE
CAROLINAS ON SAT. THE TIMING OF THE RIDGE BREAKING DOWN AND THE
TROUGH MOVING EASTWARD WILL PROVE CRITICAL TO THE MOVEMENT OF THE
SYSTEM BEHIND EARL.
AT THIS POINT THERE REMAINS ENOUGH UNCERTAINTY
TO KEEP ALERT FOR UPDATES TO THE FORECAST OF BOTH EARL AND THE
SYSTEM TO FOLLOW BEHIND EARL. ACCORDING TO ECMWF...THE FUTURE FIONA
WILL TRACK IN A SIMILAR MANNER AS EARL AND WE WILL HAVE TO WATCH OUT
FOR THIS SYSTEM BY EARLY TO MID WEEK NEXT WEEK...WHILE ITS HARD
PRESSED TO SEE ANY SYSTEM ON THE GFS.
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WU just updated five day track forecast. Manhatten is in the western edge of the cone.
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Quoting DVG:
Donna 1960 might be closer I think. Earl getting more west on it's stair step course, and then the ridge finally pulling Earl out.

Just throwing it out there as long as it's ok.


Hmmmm.... Donna, 1960...

Member Since: June 20, 2005 Posts: 22 Comments: 1054
1785. hydrus
Quoting washingtonian115:
We have Fiona finally...well can't ask any questions since the arrogant ones are on,Where's storm, levi,or miami09 anyway the wave behind Fiona needs to be mentioned because that could indeed develop.
I have to say my hat is off to Jasoniscoolman2010. He has not mentioned his spot-on forecast with Danielle. I was waiting for I told ya so for at least a couple of posts anyway.
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From the mangrove swamps in Culebra PR
right when inwas about to write things are not to bad we got our first sustained over 50knots and 2 boats in the harbor broke loose
I am in amangrove creek on C NUT tied up with about 30 lines so should be fine up to about 100 knots which we should not see.
I'm in Avery protected spot the harbor is now. Amss of white caps the ocean is
the north side of stt where my house is has not been to bad either but is now getting hit
pretty hard.
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Yep, looking at wide angle, visible Atlantic, it doesn't look good for 97 in the mid to long term, even after/if development. I think Jeff Masters first scenario about her is correct; Torn to shreds by Earl. Fiona gaining on him fast.
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10 minutes ago:

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Just a random question: Has a fujiwahra ever happen between 3 storms?
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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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