Earl significantly weakening

By: Dr. Jeff Masters , 9:54 PM GMT on September 02, 2010

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Hurricane Earl has significantly weakened today. The Hurricane Hunters found a central pressure of 948 mb at 4:06pm EDT, a large 20 mb rise from the 928 mb pressure of the 5am EDT advisory this morning. The aircraft found flight level winds at 10,000 feet of 124 mph, which translates to surface winds at the boundary between Category 2 and Category 3 strength, 112 mph. However, the SFMR instrument on the aircraft saw top surface winds of just 98 mph. Satellite imagery shows that Earl is no longer as impressive--the eye is less distinct, and the hurricane has a lopsided appearance. Dry air and wind shear of 15 - 20 knots have chewed away at Earl's southwest side.

Earl has made its turn to the north, and is headed for a close brush with North Carolina's Outer Banks. Rain bands from the hurricane have reached the coast, as seen on long-range Cape Hatteras radar.


Figure 1. Afternoon satellite image of Earl.

Forecast for Earl
If you're wondering about your chances for receiving hurricane force or tropical storm force winds from Earl, I highly recommend the NHC wind probability product. The highest odds of hurricane force winds for any location on the U.S. coast are for Nantucket--25%. Yarmouth, Nova Scotia has the highest odds for Canada, 15%, and Cape Hatteras has the highest odds for North Carolina, 19%. The latest set of model runs from 8am EDT (12Z) this morning show little change to Earl's track, and the latest SHIPS model forecast also shows no surprises. Wind shear will remain moderately high, 15 - 20 knots, through Friday morning. This should allow Earl to maintain Category 2 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 hurricane early Saturday morning, when it will make its closest approach to New England. Earl is more likely to be a strong tropical storm early Saturday afternoon, when it is expected to make landfall in Nova Scotia or New Brunswick, Canada. The expected impacts on the coast should somewhat less than what I outlined in this morning's blog post, because of Earl's recent weakening.


Figure 2. Wind field analysis of Hurricane Earl from 3:30pm EDT Thursday, September 2, 2010. Note the asymmetry in Earl's wind field, caused by the storm's forward motion of 18 mph to the north at the time. The highest contour has top winds of 80 kt (92 mph) surrounding the "+" on the NNE side of Earl--the strong right front quadrant of the storm. However, winds in the left front quadrant (on the west side) were just 75 knots (87 mph.) The asymmetry is not nearly as great as what was observed at 9:30am this morning. Image credit: NOAA/AOML/Hurricane Research Division.

Fiona
There is little change in the forecast for Tropical Storm Fiona, which is struggling due to high wind shear, courtesy of strong upper-level northerly winds from Hurricane Earl's outflow. 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). Wind shear from Earl and dry air should keep Fiona from attaining hurricane status, and the shear may be strong enough to destroy Fiona.

Gaston dies
Tropical Depression Gaston lost its battle with dry air. Satellite imagery shows that Gaston no longer has a surface circulation, and NHC has declared the system dead. The latest SHIPS model forecast predicts shear will remain low to moderate, 5 - 15 knots, for the next five days, so it is possible Gaston could regenerate.


Figure 3. Afternoon satellite image of Gaston (left) and the latest tropical wave to move off of Africa (right).

New tropical wave
A large and well-organized tropical wave moved off the coast of Africa last night, and this wave has the potential to follow the pattern set by Danielle, Earl, Fiona, and Gaston. Several models do develop this system into a tropical depression early next week, and NHC is giving the wave a 10% chance of developing by Saturday afternoon. Wind shear is currently too high, 30 - 40 knots, for the wave to develop. However, once the wave reaches a point a few hundred miles southwest of the Cape Verdes Islands two days from now, wind shear will drop and development will be more likely.

There is also a tropical wave over Central Africa which will emerge from the coast in 4 - 5 days. Some of the models are predicting development of this wave, 7 or so days from now.

Links to follow today
Cape Hatteras weather
Cape Hatteras radar

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

Jeff Masters

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Quoting washingtonian115:
So many floridians in here I can't even count them.Their all over the place like roches.lol.


Do not bring up roaches around Floridians...You'll get the spray.
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Look washingtonian, if you want me to strap you to a cash register during hurricane season at Publix I would be more than glad to do that.
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Quoting 757weather:
people who might get hit tonight maybe
I was humoring you 757...This happens ALL the time here. The People on this blog are extremely intelligent. They are not losing sight of our potentially dangerous hurricane. The storm has weakened considerably and is making the forecasted turn, that does free up the blog a little to make observations on other systems that are occurring.
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convection is coming back with gaston....
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lol 757
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Quoting 757weather:
If earl was about to brush Florida, I wouldn't even be able to mention Gaston without the wrath of god coming down on me.
So many floridians in here I can't even count them.Their all over the place like roches.lol.
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Who would have thought relief was spelt "STBD" of track.



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Quoting KanKunKid:


Uh, what about Hermine?
I haven't foregotten about hermain?.she will probally follow in the footsteps of her older brother Gaston.
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If earl was about to brush Florida, I wouldn't even be able to mention Gaston without the wrath of god coming down on me.
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Quoting KYDan:


Whoa! Thought I was having a flashback there for a minute - that is some image!
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Quoting Flyairbird:
Thats a good question, it isnt all about the Carolinas.
You tell em F.A.B...The Carolinas will feel some stormy weather for sure, but there are other states that will be affected besides the Carolinas...The Carolinas are beautiful tho.
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I dont know but BP swears up and down it aint oil...

ROFL - TK!
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Quoting hydrus:
Who cares?
people who might get hit tonight maybe
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259. KYDan
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258. HadesGodWyvern (Mod)
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Quoting KerryInNOLA:
Was Gaston murdered?



yes by dry air


the the dry air is off too jail
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Quoting poknsnok:


what is that in the gulf????
I dont know but BP swears up and down it aint oil...
Member Since: November 1, 2004 Posts: 25 Comments: 8937
253. HadesGodWyvern (Mod)
Official advisory for "Henry"

Philippines Atmospheric Geophysical Astronomical Services and Administration
Tropical Cyclone Bulletin #1
TROPICAL DEPRESSION HENRY
5:00 AM PhST September 3 2010
======================================

The Tropical Depression East of Extreme Northern Luzon has entered the Philippine Area of Responsibility and was named "HENRY".

At 4:00 AM PhST, Tropical Depression Henry located at 20.6°N 134.0°E or 1,120 km East of Basco, Batanes has 10 minute sustained winds of 30 knots. The depression is reported as moving west northwest at 12 knots.

Additional Information
======================
This weather disturbance is too far to affect any part of the country.

This tropical cyclone is expected to enhance the Southwest Monsoon and bring rains over Luzon and Visayas particularly the western sections.

The public and the disaster coordinating councils concerned are advised to take appropriate actions and watch for the next bulletin alert to be issued at 11 AM today.
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Quoting KanKunKid:


She isn't until 2013.

Been playing with the time machine again, haven't you?


LOL
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A few observations on Ex-Gaston:

There's a whole lotta CAPE to work with in the Eastern Caribbean, from 2400 to 2800 Joules.

There's a slight capping inversion out ahead of him which could prevent him from firing good cells until Sunday.

Shear forecast to start relaxing gradually starting Sunday. The map shows the TUTT in the central Carib. so we'll have to see how that goes.

Steering shows a continued danger to the Windward and Leewards and a strong ridge setting up shop smack in the middle of the Atlantic.
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Quoting challengerpr:


what is that in the gulf????
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Quoting 757weather:
How is it we have a major hurricane hours from the U.S. and the focus is on a TD thousands of miles out to sea?
Thats a good question, it isnt all about the Carolinas.
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Good sign for VaBeach - birds are back at the feeders after disappearing for most of the day. it's dusk here, and unusual for the songbirds to still be out and about, but I am glad to see them back. Doves and squirrels are scouring the ground feed as well - both of them were noticeably absent for most of the day.

For a more scientific viewpoint, the WUndermap shows the windfield to have moved the TS force winds about 20 miles to my SE - leaving me with the local mets and NWS forecast of 25-35 mph.
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Well looking a bit better for the folks from NC to New England,But I wouldn't sure holler before I get out of the woods.
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Quoting IKE:
Did he just do what it looked like he just did or are my eyes playing tricks?
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How is it we have a major hurricane hours from the U.S. and the focus is on a TD thousands of miles out to sea?
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Quoting tkeith:
He dont say much Hydrus but when he does I listen...
That is the sign of a smart and patient person.
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Jason your capslock is stuck again...
Member Since: November 1, 2004 Posts: 25 Comments: 8937
236. IKE
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sorry I meant to say north of the COC
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Quoting wunderkidcayman:
I am look at Gaston sat and I see that there is a small burst of convection where I think the COC of RL Gaston it won't bee long before gaston get reinstated as a TD/TS and Gaston should follow the southern end of the cone


Needs to reclose its circulation, but yeah, I agree with the prognostication of regeneration.
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Hey all, from Yarmouth, Nova Scotia. VERY glad to see this weakening trend in big ol' Earl. Yesterday we had 30% chance of getting hurricane force winds; now it's down to 15%. I can deal with that.
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Quoting hydrus:
Because when E.F.Hutton talks....People listen... I have not heard that in 100,000 years.
He dont say much but when he does I listen Hydrus...
Member Since: November 1, 2004 Posts: 25 Comments: 8937
230. Relix
I still say Gaston or the one behind it will be a direct impact for the islands. The setup is there. Also... Gaston WILL live. He's been knocked out a bit.
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why is no one talking about earl? did he die out and become no big deal. just getting back on from this morning. thanks in advance
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Quoting KerryInNOLA:
Was Gaston murdered?
There is no foul play suspected at this time. Stay tuned to your local media outlets for further information and updates.
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Quoting hydrus:
Because when E.F.Hutton talks....People listen... I have not heard that in 100,000 years.
He dont say much Hydrus but when he does I listen...
Member Since: November 1, 2004 Posts: 25 Comments: 8937
I am look at Gaston sat and I see that there is a small burst of convection where I think the COC of RL Gaston it won't bee long before gaston get reinstated as a TD/TS and Gaston should follow the southern end of the cone
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Quoting kmanislander:


Gaston has struggled it's true and stalling has not helped but I still think he is more likely than not to recover.

I think you're right, I fear Gaston and the wave right behind him, I can only imagine if they tap into the warm waters from Eastern to the western Caribbean, frightful and worrisome to the least!
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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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