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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Quoting VAbeachhurricanes:


North South?


I'm thinkin he meant "No S***"
Member Since: September 12, 2007 Posts: 0 Comments: 725
Quoting superweatherman:
LOL... I think you should recount the 13 States.
forgot the ?mark sorry. I see now.
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2854. xcool
texascoastres you think
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Let me correct myself... the Original 13 Colonies. LOL...

EARL may swallow DE,NJ,CT,RI,NH and even possible MA.LOL
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2852. Zeec94
Quoting TampaFLUSA:

926.4 mb with that pressure why not. Also the wind field should expand as it moves pass North Carolina.


Remember wind takes time to reach the pressure. We have to see where the winds are at 2AM compared to the pressure.
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Quoting VAbeachhurricanes:


North South?


Yes, ok, that was it :)
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Its popcorn and beverage of choice time! Gonna be a long night!
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2849. 34chip
Quoting reedzone:
So far, Earl is following the NHC very nicely!
Is it me or is it a little east of the points?
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Quoting Orcasystems:


NS


North South?
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2847. Ryuujin
Quoting reedzone:
So far, Earl is following the NHC very nicely!


Cept a little west of where they're thinking. look at what Orca said. he's port of the line where they thought he'd be. (Port is left, just to make sure)
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Quoting philliesrock:

If you take those points and the NHC 11pm points, it clearly shows a more NW than NNW motion.

27.8N 73.8W
28.4N 74.3W


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Quoting Halyn:



What did you do with Vermont .. right up there next to New Hampshire .. looked for it on the map
That does not have a Cost to it.. LOL
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So far, Earl is following the NHC very nicely!
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Quoting superweatherman:
LOL... I think you should recount the 13 States.


no there are fourteen
GA, SC, NC, VA, DE, MD, PA, NY, CN, Mass, RI, NH, NJ, MA. Its cause Maine wasnt its own colony
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Quoting Zeec94:


Nice to meet you Linda. Apologies. I'm just on the wrong foot tonight. That's how I get when I go three days with only 16 hours of rest.


I understand perfectly
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Quoting reedzone:
I wonder if Earl could make it to Category 5 tonight.. That would be interesting.

926.4 mb with that pressure why not. Also the wind field should expand as it moves pass North Carolina.
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2840. Halyn
Quoting SaoFeng:


actually maine was part of massachussets back then... weird isnt it?
I saw that .. and looks as if Vermont was part of New York .. :)
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Quoting Orcasystems:
Time: 05:29:00Z
Coordinates: 28.4333N 74.3W
Acft. Static Air Press: 696.1 mb (~ 20.56 inHg)
Acft. Geopotential Hgt: 2,540 meters (~ 8,333 feet)
Extrap. Sfc. Press: 926.5 mb (~ 27.36 inHg)

If you take those points and the NHC 11pm points, it clearly shows a more NW than NNW motion.

27.8N 73.8W
28.4N 74.3W
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2838. xcool
btwntx08 5lol
Member Since: September 26, 2009 Posts: 2 Comments: 15626
They will probably use around 928 for the vortex. 125 knots SE flight winds SE Quad.

Peak (10s) Flt. Lvl. Wind: 125 knots (~ 143.8 mph)
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2836. Zeec94
Quoting texascoastres:
ZEEC94


by the way its not man, its Linda
Nice to meet you!


Nice to meet you Linda. Apologies. I'm just on the wrong foot tonight. That's how I get when I go three days with only 16 hours of rest.
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Whoa. Earl has to be close to Cat 5 if not already there.
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Quoting VAbeachhurricanes:


74.3W and still not at center? uh oh...

that is the Centre
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2832. HadesGodWyvern (Mod)
Severe Tropical Cyclone EARL AL072010
=====================================

2010SEP02 044500

CI: 6.6
931.0
129.6
Initial 6.5
Adjusted 6.5
Raw 6.5

----
T6.5/130 knots...
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hi, long time lurker. wondering what is happening to the west side of earl at end of loop, it looks like it has hit a wall?
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2830. leo305
Quoting Orcasystems:


PORT of track, straight as an arrow... no turn






just as I suspected..

@reed

a CAT 5 nearing the south east, and hogging the east coast..

well we'll see, it seems like earl wants to make history
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Quoting Orcasystems:
Time: 05:29:00Z
Coordinates: 28.4333N 74.3W
Acft. Static Air Press: 696.1 mb (~ 20.56 inHg)
Acft. Geopotential Hgt: 2,540 meters (~ 8,333 feet)
Extrap. Sfc. Press: 926.5 mb (~ 27.36 inHg)


Looks like Earl is not gonna down without on helluva fight...
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Quoting Orcasystems:
Time: 05:29:00Z
Coordinates: 28.4333N 74.3W
Acft. Static Air Press: 696.1 mb (~ 20.56 inHg)
Acft. Geopotential Hgt: 2,540 meters (~ 8,333 feet)
Extrap. Sfc. Press: 926.5 mb (~ 27.36 inHg)


74.3W and still not at center? uh oh...
Member Since: Posts: Comments:
2826. Ryuujin
Quoting Orcasystems:
Time: 05:29:00Z
Coordinates: 28.4333N 74.3W
Acft. Static Air Press: 696.1 mb (~ 20.56 inHg)
Acft. Geopotential Hgt: 2,540 meters (~ 8,333 feet)
Extrap. Sfc. Press: 926.5 mb (~ 27.36 inHg)


WOW.
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Quoting hulazigzag:
um thats 14
LOL... I think you should recount the 13 States.
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Quoting Orcasystems:
Time: 05:29:00Z
Coordinates: 28.4333N 74.3W
Acft. Static Air Press: 696.1 mb (~ 20.56 inHg)
Acft. Geopotential Hgt: 2,540 meters (~ 8,333 feet)
Extrap. Sfc. Press: 926.5 mb (~ 27.36 inHg)


PORT of track, straight as an arrow... no turn




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I wonder if Earl could make it to Category 5 tonight.. That would be interesting.
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2822. SaoFeng
Quoting hulazigzag:
um thats 14


actually maine was part of massachussets back then... weird isnt it?
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2821. Halyn
Quoting superweatherman:

I feel like Earl may sallow some. LOL



What did you do with Vermont .. right up there next to New Hampshire .. looked for it on the map
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Hmm...center is reading around 926.5 to 929 or so
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If Earl nearly hits the Carolinas, the storm should move NNE for a while, no sharp recurve. Farther west he gets, the farther west the track could be up the coastline.
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Time: 05:29:00Z
Coordinates: 28.4333N 74.3W
Acft. Static Air Press: 696.1 mb (~ 20.56 inHg)
Acft. Geopotential Hgt: 2,540 meters (~ 8,333 feet)
Extrap. Sfc. Press: 926.5 mb (~ 27.36 inHg)
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2816. leo305
Quoting reedzone:
So Fiona got mad at all her RIPpers and is blowing some really nice convection near the center.


yes, and with a weak anticylone setting up over her... a hurricane is probable, I mean it already has 60mph winds with no convection lol
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Quoting Zeec94:


Same here...UGH. I have to get my summer paper done tonight too!


haha, that sucks at least it gives you something to do, if it makes it past 75W early they are probably gonna cancel classes
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2814. Dunkman
Take this with a giant grain of salt because it's just a forum post (granted a very well respected forum, but still.)


00z Euro tease, hr 24 about 30 miles west of GFS, odd though because midwest trough appears barely to move during that period (GFS also shows this, which I had discounted)

Explanation as to how he has Euro results when it hasn't initialized yet:


We run a parallel model as a joint effort of several agencies (within and without Europe), but only out to 48 hours...goal is to use this in contrast to the NA models, specifically the medium range (but not really as an alternative to the GFS or the other reliable medium range guidance)
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ZEEC94


by the way its not man, its Linda
Nice to meet you!
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2812. leo305
Quoting Orcasystems:
I think I should go to bed before they find it.. and update it in the morning :)


Things are too crazy for you to go to sleep!! And you know it!!!

the hunters are almost there!!

lol jk do w.e you want
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Quoting superweatherman:

I feel like Earl may sallow some. LOL
um thats 14
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So Fiona got mad at all her RIPpers and is blowing some really nice convection near the center.
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Quoting xcool:


GASTON - & 99l



that could be the H storm by then
Member Since: May 21, 2006 Posts: 5091 Comments: 114779
Agreed. It should be just about on the XTRAP line.
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I feel like Earl may sallow some. LOL
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2806. Zeec94
Quoting VAbeachhurricanes:


whatever you want orca haha no sleep for me though...


Same here...UGH. I have to get my summer paper done tonight too!
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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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