Earl a Category 4 storm again

By: Dr. Jeff Masters , 9:23 PM GMT on September 01, 2010

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Hurricane Earl has regained Category 4 strength this afternoon, and continues on a steady northwest path towards the North Carolina coast. Recent satellite imagery shows that Earl has become more symmetrical, with improved upper-level outflow and no signs of dry air wrapping into the core. The improved appearance is probably due to lower wind shear. Latest wind shear tendency imagery from the University of Wisconsin CIMSS group shows that shear on the southwest side of Earl has fallen by about 10 knots over the past 24 hours.


Figure 1. Afternoon satellite image of Earl.

Forecast for Earl
The latest set of model runs from 8am EDT (12Z) this morning shows little change to Earl's track. Thus, my write-up of the possible impacts to North Carolina, New England, and Canada in this morning's post remain unchanged. The latest SHIPS model forecast shows wind shear will remain moderate, about 15 knots, through Friday afternoon. This should allow Earl to maintain major hurricane status as it passes North Carolina early Friday morning. By Friday night, as Earl gets caught in the jet stream and accelerates to the northeast, wind shear will rise to 20 - 30 knots and ocean temperatures will plunge to 20°C, resulting in considerable weakening. Earl will still probably be a Category 1 or 2 hurricane early Saturday morning, when it will make its closest approach to New England. Earl is more likely to be a strong tropical storm or weak Category 1 hurricane early Saturday afternoon, when it is expected to make landfall in Nova Scotia, Canada.

Earl is a large hurricane, which gives it a higher potential for storm surge damage than a smaller hurricane with the same top winds. One measure of a storm's power, useful for gauging storm surge threat, is to measure the speed of the winds and multiply by the area over which those winds blow. This total is called the Integrated Kinetic Energy (IKE). Based on the storm's IKE, one can come up with a scale from 0 - 6 rating the storm's destructive power from its storm surge. A separate rating can be given to the destructive potential of the storm's winds. The IKE value of 112 Terrajoules for Earl, at 3:30pm EDT today, gives its storm surge a destructive power of 5.0 on a scale of 0 - 6. Earl's winds have a lower destructive power, 3.4 on a scale of 0 - 6. Let's hope the right front quadrant of Earl, where the main storm surge would occur, stays offshore! For comparison, the small Category 5 Hurricane Camille of 1969 had an IKE of 80 Terrajoules, and the very large Category 2 Hurricane Ike of 2008 had an IKE of 116 Terrajoules--similar to Category 3 Earl's.

Fiona
Tropical Storm Fiona is struggling due to high wind shear, courtesy of strong upper-level northerly winds from Hurricane Earl's outflow. The latest Hurricane Hunter center fix at 1:29pm EDT found Fiona had weakened some, with a central pressure of 999 mb. This is a rise of 1 mb from this morning. The wind shear analysis from the University of Wisconsin CIMSS group shows that shear has increased to a moderately high 15 - 20 knots this afternoon. Satellite loops show the classic signature of a tropical storm experiencing high wind shear--an exposed center of circulation, and all the heavy thunderstorms pushed to one side (the south side in this case). Martinique radar shows that the outer bands from Fiona are bringing heavy rain squalls to the same islands of the northern Lesser Antilles that were affected by Earl. Our wundermap for the northern Lesser Antilles shows no stations recorded winds over 20 mph this afternoon, though there was no reporting station on Barbuda, the island closest to Fiona.

Forecast for Fiona
Moderate wind shear and dry air should keep Fiona from attaining hurricane status over the next two days, as big brother Earl continues to bring high wind shear. The shear may be strong enough to destroy Fiona, as predicted by the NHC. However, by this weekend, Earl may pull far enough away for shear to drop and Fiona to survive. The 4 - 5 day track forecast is highly uncertain, as there is a large spread in the model solutions. It is possible Fiona may pose a threat to Bermuda on Saturday or Sunday, and the storm could wander for a week or more in the waters between Bermuda and the U.S. East Coast.


Figure 2. Afternoon satellite image of Fiona.

Tropical Storm Gaston forms
Tropical Storm Gaston developed enough heavy thunderstorms near its center this afternoon to get a name, and appears destined to become Hurricane Gaston by early next week. Water vapor satellite images show a large area of dry air to the north and west of Gaston, and this dry air will be the dominant inhibiting factor for development. The latest SHIPS model forecast predicts shear will remain moderate, 10 - 15 knots, for the next four days, and perhaps fall to the low range 4 - 5 days from now. Gaston is over warm 28°C waters, and should be able to steadily intensify into a hurricane by Saturday or Sunday, as predicted by the many of the intensity models. Gaston may threaten the northern Lesser Antilles Islands as early as Tuesday.

Next post
I'll have an update in the morning, and Dr. Rob Carver will have a late night update tonight.

Jeff Masters

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1456. canehater1
1:46 AM GMT on September 02, 2010
Quoting stormwatcherCI:
I don't know anything about ridges or anything else but I make sure I pay attention when you say something because so far you have been on the mark to me. I have asked you in the past couple years about systems reaching us and when you told me not a chance you have been right. If you say there is a chance for this to track in the Caribbean you can bet your bottom dollar I will pay attention.


Yep, StormW and Levi have been hinting at this pattern change for awhile now as well... This may be one year that a long track CV storm makes it all the way across to the Carib. or beyond..That being said..I Love fish, always have!
Member Since: September 8, 2008 Posts: 1 Comments: 1050
1455. OBXNCWEATHER
1:46 AM GMT on September 02, 2010
Quoting hydrus:
Dont tell me.....Your on the Outer Banks.


Um... Yeah...
Member Since: June 30, 2010 Posts: 0 Comments: 113
1453. robj144
1:46 AM GMT on September 02, 2010
Quoting HaboobsRsweet:
What is scarey is how well the GFS has been doing and look at the GFS track for Gaston. Whew man once Earl passes in the next 72 hours this blog will go nuts with Gaston.


Didn't the GFS have Earl hitting Daytona and then New Orleans the next day, a few days ago though?
Member Since: August 19, 2008 Posts: 0 Comments: 825
cat 4 for how much longer?
Member Since: August 24, 2010 Posts: 19 Comments: 4357
If Earl makes like a donut with teeth on the outside run for the hills.
Member Since: August 19, 2006 Posts: 0 Comments: 15798
Quoting Chicklit:

Here's your chance:


And here's your intensity:


Of course all this is subject to change.
REALLY don't like the looks of that.
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1446. BigToe
Quoting amd:
Latest Dropsonde Information through Northwest Eyewall

945mb (Surface) 40° (from the NE) 107 knots (123 mph)
943mb 40° (from the NE) 110 knots (127 mph)
939mb 45° (from the NE) 107 knots (123 mph)
936mb 40° (from the NE) 122 knots (140 mph)
932mb 45° (from the NE) 127 knots (146 mph)
929mb 50° (from the NE) 142 knots (163 mph)
926mb 50° (from the NE) 147 knots (169 mph)
916mb 55° (from the NE) 140 knots (161 mph)
907mb 60° (from the ENE) 142 knots (163 mph)
895mb 60° (from the ENE) 173 knots (199 mph)
892mb 65° (from the ENE) 162 knots (186 mph)
886mb 70° (from the ENE) 153 knots (176 mph)
881mb 75° (from the ENE) 153 knots (176 mph)
878mb 80° (from the E) 157 knots (181 mph)
874mb 75° (from the ENE) 145 knots (167 mph)
871mb 75° (from the ENE) 148 knots (170 mph)
868mb 75° (from the ENE) 144 knots (166 mph)
860mb 75° (from the ENE) 153 knots (176 mph)
844mb 80° (from the E) 145 knots (167 mph)
834mb 90° (from the E) 122 knots (140 mph)
819mb 95° (from the E) 141 knots (162 mph)
762mb 110° (from the ESE) 116 knots (133 mph)
740mb 115° (from the ESE) 123 knots (142 mph)


Oh snap...
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Quoting cYcLoN1C86:


Gaston could take a path similar to Hurricane David of 1979
gets us thinking.
Member Since: October 19, 2005 Posts: 0 Comments: 234
I'm back! Reporting from eastern nc!
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1442. Max1023
According to that Dropsonde the surface winds have not caught up to the flight level, in the eyewall that reading of 145 at about 850mb would correspond to 125 knots at the surface against 107. Also this is the NW quadrant, on the "weak" side of the storm.
Member Since: July 22, 2008 Posts: 1 Comments: 286
last sat image at 8:31PM damn near perfect hurricane. Eye is perfectly circular. Deep reds completely envelope the CDO.
Member Since: July 14, 2008 Posts: 1 Comments: 9628
Quoting MiamiHurricanes09:
They are, it came from a dropsonde.


That looks like the progression of atmosphere samples the dropsonde took as it fell. The sfc reading is 945 mb in the northeast eyewall.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
Quoting bayoubug:
pressures are rising on the east coast, the high is holding on.. any thoughts...


It makes me think no landfall. Pressure should be falling at the point of landfall.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting amd:
Latest Dropsonde Information through Northwest Eyewall

945mb (Surface) 40° (from the NE) 107 knots (123 mph)
943mb 40° (from the NE) 110 knots (127 mph)
939mb 45° (from the NE) 107 knots (123 mph)
936mb 40° (from the NE) 122 knots (140 mph)
932mb 45° (from the NE) 127 knots (146 mph)
929mb 50° (from the NE) 142 knots (163 mph)
926mb 50° (from the NE) 147 knots (169 mph)
916mb 55° (from the NE) 140 knots (161 mph)
907mb 60° (from the ENE) 142 knots (163 mph)
895mb 60° (from the ENE) 173 knots (199 mph)
892mb 65° (from the ENE) 162 knots (186 mph)
886mb 70° (from the ENE) 153 knots (176 mph)
881mb 75° (from the ENE) 153 knots (176 mph)
878mb 80° (from the E) 157 knots (181 mph)
874mb 75° (from the ENE) 145 knots (167 mph)
871mb 75° (from the ENE) 148 knots (170 mph)
868mb 75° (from the ENE) 144 knots (166 mph)
860mb 75° (from the ENE) 153 knots (176 mph)
844mb 80° (from the E) 145 knots (167 mph)
834mb 90° (from the E) 122 knots (140 mph)
819mb 95° (from the E) 141 knots (162 mph)
762mb 110° (from the ESE) 116 knots (133 mph)
740mb 115° (from the ESE) 123 knots (142 mph)


Holy Crap!!!
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1437. robj144
Quoting hydrus:
BEHOLD!!...The perfect heat engine. I just hope the perfect heat engine does not kill anyone.


Actually, I did some research on that a little while ago... they're not that efficient engines.
Member Since: August 19, 2008 Posts: 0 Comments: 825
Quoting leo305:


LOLLL WHAT??


Let me clarify. A dropsonde deployed into Earl's eyewall has registered 173 knot winds at roughly 1,000ft above sea level. That same dropsonde found winds of some 107kts at the surface. So we're not talking about the peak sustained winds. Still, a storm that's generating 173kts that close to the surface can reasonably be estimated to be producing far stronger winds than 107kts.
Member Since: August 18, 2009 Posts: 0 Comments: 460
1434. hydrus
Quoting SirTophamHatt:
Ed Rappaport on TWC

ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ



Isnt he about 95?
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On the WU site the NHC has winds of 115 MPH & pressure of 929. I take it they are not done taking wind samples. At the 8:00 PM advisory the winds were listed at 135 & Earle looks a lot better on satellite & infrared. I think this has a shot of hitting cat 5 status with this latest burst - it will take a few hrs for the winds to catch up with the drop in pressure.
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Quoting Patrap:
When Oz hits the OBX he wont be allowed on.

They notorious for keeping even the Press out.



He'll put up his Hurricane suit and rush the line.
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Quoting hurricanejunky:
Oz is broadcasting live. Leg 1 of the trip is getting on the island tonight. Think he can pull it off?

http://7674u.com


No, the cops won't let him on the island.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Gaston has a lot of dry air to its west which will slow development.
Member Since: July 11, 2006 Posts: 14 Comments: 11267
Quoting MiamiHurricanes09:
They are, it came from a dropsonde.



Hm didn't get a sonde notification.

Thanks.
Member Since: June 9, 2007 Posts: 4 Comments: 15864
What is scarey is how well the GFS has been doing and look at the GFS track for Gaston. Whew man once Earl passes in the next 72 hours this blog will go nuts with Gaston.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
Quoting 850Realtor:


Really?


I don't think that's at the surface lol.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
1425. Max1023
Quoting TerraNova:


I agree, I think a peak intensity of 140 mph/121 knots at 11 sounds reasonable followed by gradual weakening.


Celia did it with less. Where she was the SST was lower than what earl is over. Also 173 knots at 895mb is the strongest wind ever seen in this cyclone. Earl is definitely stronger now than it ever was.
Member Since: July 22, 2008 Posts: 1 Comments: 286
1423. Patrap
When Oz hits the OBX he wont be allowed on.

They notorious for keeping even the Press out.

Member Since: July 3, 2005 Posts: 423 Comments: 127803
1422. hydrus
.
Member Since: Posts: Comments:
Quoting SirTophamHatt:
Ed Rappaport on TWC

ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ





for real, geez, drink some coffee lol
Member Since: June 30, 2006 Posts: 5 Comments: 229
Quoting Stormchaser2007:
Not really looking like a Caribbean system. Maybe another system that ends up north of the islands.



GFS and CMC have a 1024-1028 ridging feature building across Bermuda through 120 hours, nothing is out of the question with Gaston.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
Ed Rappaport on TWC

ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ



Member Since: August 25, 2010 Posts: 0 Comments: 44
Quoting Stormchaser2007:
I doubt any of those readings are reliable.
They are, it came from a dropsonde.
Member Since: September 2, 2009 Posts: 130 Comments: 21098
Quoting OBXNCWEATHER:
y'all... earl is really freaking starting to scare me lookin' all doughnut-like and stuff... (lol)

honestly, though, can anyone tell me if we're trending towards an OBX strike or away (models, general thinking... ANYTHING would be appreciated).

If I wake up in the morning and the winds have responded to that drop in pressure, imma gonna pee my pants.


I hope you've already left. No need to wait until the morning.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Just for those who are interested...

Here is a Loop of Hurricane Isabel.

Link
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pressures are rising on the east coast, the high is holding on.. any thoughts...
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1411. amd
Latest Dropsonde Information through Northwest Eyewall

945mb (Surface) 40° (from the NE) 107 knots (123 mph)
943mb 40° (from the NE) 110 knots (127 mph)
939mb 45° (from the NE) 107 knots (123 mph)
936mb 40° (from the NE) 122 knots (140 mph)
932mb 45° (from the NE) 127 knots (146 mph)
929mb 50° (from the NE) 142 knots (163 mph)
926mb 50° (from the NE) 147 knots (169 mph)
916mb 55° (from the NE) 140 knots (161 mph)
907mb 60° (from the ENE) 142 knots (163 mph)
895mb 60° (from the ENE) 173 knots (199 mph)
892mb 65° (from the ENE) 162 knots (186 mph)
886mb 70° (from the ENE) 153 knots (176 mph)
881mb 75° (from the ENE) 153 knots (176 mph)
878mb 80° (from the E) 157 knots (181 mph)
874mb 75° (from the ENE) 145 knots (167 mph)
871mb 75° (from the ENE) 148 knots (170 mph)
868mb 75° (from the ENE) 144 knots (166 mph)
860mb 75° (from the ENE) 153 knots (176 mph)
844mb 80° (from the E) 145 knots (167 mph)
834mb 90° (from the E) 122 knots (140 mph)
819mb 95° (from the E) 141 knots (162 mph)
762mb 110° (from the ESE) 116 knots (133 mph)
740mb 115° (from the ESE) 123 knots (142 mph)
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Earl looking VERY impressive...don't know about annular but definitely a monster of a storm...
anyone getting current pressure readings?
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Quoting DestinDome:
wierd.....thats downright insane!


I mentioned earlier that I was on the USS Saipan and left early for the North Atlantic because of Charley in '86. I have pictures of us taking water over the bow....It's about 90' from the flightdeck to the water line.
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I doubt any of those readings are reliable.
Member Since: June 9, 2007 Posts: 4 Comments: 15864
Quoting Thundercloud01221991:
173 knt winds at 895 mb (199 mph winds)



Really?
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1406. leo305
Quoting CloudGatherer:
::Whimper::

895mb 60° (from the ENE) 173 knots (199 mph)


LOLLL WHAT??
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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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