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 954FtLCane:

no no no we're still here and it's usually a 75-25 Fins split when they aren't 1-15.

now that's depressing...cured only by excessive amounts of etoh and perhaps a squeeze toy.
Member Since: July 11, 2006 Posts: 14 Comments: 11180
Long range models put a storm into the gulf, is it Gaston?
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Somebody asked, "What's next?"

Well, here's a hint: RL Gaston is the least impressive feature in this image. If everything goes as it's been going these past 12 days, this may be the cyclogenesis equivalent of ultrasounds for Hermine, Igor, and Julia:

Click for larger image:
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3 minute blog lag right now
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting ElConando:


Excuse me missy.


Sounds like the Dolphins, Bucs, and Lightening have a lot in common :)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
819. xcool
F4PHANTOM ;)
Member Since: September 26, 2009 Posts: 2 Comments: 15625
Quoting Orcasystems:


Yes, that island off of Newfoundland belongs to France.
I know...i was joking...that would make for a great model over to france and back!...lol
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Quoting ElConando:


Excuse me missy.


I think she has the wrong Florida team... there are no BUCS fans left!!! (I still love the fins)
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Quoting KanKunKid:


I don't think I wanna see Gaston's balls, just let me know when it's a TD again. Then I can see bands instead of balls.
Lord! Imagery totally uncalled for. Still, hard not to take a shot at a dangling participle.
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Meanwhile in Oklahoma we had a line of storms with straight line winds gusting to 87MPH with sustained winds at 50-60MPH move through OKC and making its way south. Some shingles off, a Church steeple down..typical Okie storm...hows the Cape holding up?
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Quoting pottery:

There are fools born every minute....
It is scary when they converge together like that.
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XCOOL, yeah, I saw the GFS runs.
But I dont want to think that they are correct.
In any case, thats a long way out.
Would be interesting though....
Member Since: October 24, 2005 Posts: 0 Comments: 24060
Quoting StSimonsIslandGAGuy:


I did. And at 8 pm the center was at 74.7 W, which is already 50 miles east of Cape Hatteras's longitude. Cape Hatteras is at 75.5 W. By the time Earl makes it to Cape Hatteras's latitude, it may well be east of 74 W. Which means the core of strongest winds will be well offshore.


oh because orca's post shows the center post of track, and likely to pass 50 miles east or less of cape hateraus if it continues the movement shown in his post, which is assembled by hurricane hunter vortex messages
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Quoting StormJunkie:
Michael just said "cane" .. Ie. hurricane :) And he's only 21 months old!!!
Quoting CosmicEvents:
That's cute.
See if you can get him to say fish...


roflmao!
Member Since: July 11, 2006 Posts: 14 Comments: 11180
Quoting Orcasystems:


Yes, that island off of Newfoundland belongs to France.


Actually it belongs to France because they say it is I believe there is another claim to it.

Or am I thinking or another island?
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Quoting Chicklit:

I didn't know there were any of those left.
The Jets play in Dolphin stadium and it's a home game for them.

no no no we're still here and it's usually a 75-25 Fins split when they aren't 1-15.
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LOL! Now that is funny!
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Quoting Chicklit:

I didn't know there were any of those left.
The Jets play in Dolphin stadium and it's a home game for them.


Excuse me missy.
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Gaston in Cloak Mode

Member Since: July 11, 2006 Posts: 14 Comments: 11180
Quoting atmoaggie:
Not bad. Not bad at all.

Full cycle of NHC forecasts from TD to now.
pretty pretty good
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http://www.esl.lsu.edu/webpics/goes/Storm/AOI0/latest.wv.gif
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Quoting btwntx08:
just rubbimg it in on the dolphin fans :)


Preseason is preseason, not the real deal. They'll be a lot better this year. BTW, I see Gaston has made it back. Need to watch it as this looks like a westward tracker.
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Quoting CosmicEvents:
Post 708: That's the ICTZ, but in that shot you can clearly see Gaston's balls of competing mid-level convection. Similar in structure to Earl when he went through this stage, just that these balls are smaller than his. Especially the right one.

Can we give Gaston the Undead a little privacy??
Sheesh!
He isnt even cold yet....
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I LOVE to quote "My Cousin Vinny"....regarding Gaston TD again...."Is this your opinion or is it a fact"??

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Quoting StSimonsIslandGAGuy:
So far on Cape Hatteras, winds have not even gusted to 30 mph That will change as Earl makes its closest approach, but I am now doubting they will get sustained winds above 50 mph.
Yes media over hyped based on worst case. yesterday it started showing up just east of forecast track after days of west. No surprise to me.
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Quoting Flyairbird:
FRANCE?


Yes, that island off of Newfoundland belongs to France.
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Quoting StormJunkie:
Michael just said "cane" .. Ie. hurricane :) And he's only 21 months old!!!
That's cute.
See if you can get him to say fish...
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Ahh, my bad, I didn't see that before posting LOL!
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Quoting RecordSeason:
727:

lol. So true.

I was gonna post a set of custom Darwin Award scoring rules in response to his post, but figured I'd probably get banned if I did.


I got chastised last night for referencing Darwin on the Jersey boys that were surfing at night...... that they were "risk takers".

So now I will only reference F. Gump, "stupid is as stupid does".

Has the pier collapsed yet???? :-)
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Quoting Chicklit:
I'll be a lot of folks in the Carolinas are relieved tonight.


This morning it was a CAT4 with potential to hit the coast. Tonight Earl's a CAT2 staying off shore.


yeah, great news! This is also why people do not evacuate. They leave and then ended up not really having to leave. It is a lot of craziness and all having to evacuate. It can be frustrating when you did all that for nothing or somewhat nothing.
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Quoting aspectre:
HurricaneEarl's heading had turned eastward to 4.9degrees north of NorthEast
from it's previous heading of dueNorth
H.Earl's average speed moving between its last 2 reported positions was~15mph(~24.1km/h)

02Sep . 12amGMT - - 27.2n73.5w - - 135mph - - 941mb - - NHC.Adv.#30A
02Sep . 03amGMT - - 27.8n73.8w - - 140mph - - 932mb - - #31
02Sep . 06amGMT - - 28.6n74.4w - - 140mph - - 932mb - - #31A
02Sep . 09amGMT - - 29.3n74.7w - - 145mph - - 928mb - - #32
02Sep . 12pmGMT - - 30.1n74.8w - - 145mph - - 932mb - - #32A
02Sep . 03pmGMT - - 30.9n74.8w - - 140mph - - 932mb - - #33
02Sep . 06pmGMT - - 31.7n75.2w - - 125mph - - 943mb - - #33A
02Sep . 09pmGMT - - 32.5n75.2w - - 115mph - - 947mb - - #34
03Sep . 12amGMT - - 33.0n74.7w - - 110mph - - 948mb - - #34A

Copy&paste 27.2n73.5w, 27.8n73.8w, 28.6n74.4w, 29.3n74.7w, 30.1n74.8w-30.9n74.8w, 30.9n74.8w-31.7n75.2w, 31.7n75.2w-32.5n75.2w, 32.5n75.2w-33.0n74.7w, bwi, 33.0n74.7w-46.82n56.3w into the GreatCircleMapper for a look at the last 12hours.

Using straightline projection upon the speed&heading averaged
over the 3hours spanning the last two reported positions:
~88hours from now to St.Pierre-et-Miquelon,France
then Newfoundland, Canada
FRANCE?
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Quoting MoltenIce:
Are those area of convection south of Gaston are formerly his or part of the ITCZ?
Post 708: That's the ICTZ, but in that shot you can clearly see Gaston's balls of competing mid-level convection. Similar in structure to Earl when he went through this stage, just that these balls are smaller than his. Especially the right one.
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Quoting StSimonsIslandGAGuy:
Earl looks to be heading even further east of Cape Hatteras than I thought. The odds of hurricane force winds on the OBX are now very low.


didn't you say earlier it would be at least 75 miles away from shore? It's looking like it might pass 50 miles or less from shore
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Quoting KanKunKid:

No he isn't gone yet. No double tap for him.
He is pulling a zombie on us.


Member Since: July 11, 2006 Posts: 14 Comments: 11180
Quoting Chicklit:
I'll be a lot of folks in the Carolinas are relieved tonight.


This morning it was a CAT4 with potential to hit the coast. Tonight Earl's a CAT2 staying off shore.

Yep all in a matter of one day.
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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.