Earl maintaining Category 4 strength; hurricane watches for North Carolina

By: Dr. Jeff Masters , 9:44 PM GMT on August 31, 2010

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Hurricane watches are now posted for coastal North Carolina, as Hurricane Earl continues towards the west-northwest at 13 mph with little change in strength. Currently, the outer reaches of the storm are affecting the Turks and Caicos Islands, and NOAA's Wavewatch III model is predicting 15 - 20 foot waves are affecting these islands. Early this morning, waves at buoy 41043 offshore of Puerto Rico reached 31 feet. Winds at Providenciales in the Turks were only 20 - 25 mph this afternoon, though Cockburn Town and Balfour Town in the extreme eastern Turks may be seeing winds near tropical storm force--40 mph.


Figure 1. Afternoon satellite image of Earl.

Intensity forecast for Earl
Recent visible satellite loops show that the southwest side of Earl is getting eaten into by wind shear and dry air. The storm is no longer as symmetrical as 24 hours ago, and the spiral band on Earl's west side has been destroyed by dry air. Wind shear as diagnosed by the latest SHIPS model forecast shows a moderate 10 - 20 knots of wind shear, due to upper level winds out of the southwest from a trough of low pressure to Earl's west. This moderate shear is predicted to continue through Friday. Water vapor satellite loops show some moderately dry air to Earl's southwest, and very dry air to the northwest. Once Earl works its way farther to the northwest, it is possible that the persistent moderate wind shear will be able to drive this dry air deep enough into Earl's west side to significantly disrupt it. However, none of the models is predicting this, and Earl is probably large and strong enough to fend off this sort of assault. I give a 30% chance that a major dry air intrusion will significantly disrupt Earl between now and Thursday, weakening it to a Category 2 hurricane. Ocean temperatures are a near-record 29.5 - 30°C, and very warm waters extend to great depth, resulting in a total ocean heat content favorable for intensification. Earl is undergoing an eyewall replacement cycle, which may diminish its winds by 10 - 20 mph for a day or so. There is no evidence that Earl has weakened, though, based on the latest pressure of 940 mb from the Hurricane Hunters. It is likely Earl will be a major Category 3 or 4 hurricane at its closest approach to North Carolina Thursday night and Friday morning. By Friday night, 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 night, when it could potentially make landfall in Massachusetts. Earl is more likely to be a Category 1 hurricane on Saturday morning, when it could potentially make landfall in Maine or Nova Scotia, Canada.

Track forecast for Earl
The latest set of computer models runs from 8am EDT (12Z) are pretty unified in taking Earl 100 - 200 miles off the coast of North Carolina, then 150 - 300 miles off the coast of Southeast Massachusetts, then into Nova Scotia. The high degree of model unity gives confidence that this is the correct solution, but it is good to keep in mind that the average error in a 48-hour NHC forecast is about 125 miles. It is likely that Earl will bring a 15-hour period of heavy rain and tropical storm force winds of 39+ mph to North Carolina's Outer Banks, beginning on Thursday evening. NHC is giving Cape Hatteras a 15% chance of receiving hurricane force winds. By Friday evening, Southeast Massachusetts can expect a 6 - 8 hour period of heavy rain and tropical storm force winds of 39+ mph. NHC is giving Nantucket a 13% chance of receiving hurricane force winds. These odds are 5% for Boston, 6% for Providence, 8% for Eastport, Maine, and 14% for Yarmouth, Nova Scotia. 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. Keep in mind that the average error in position for a 3-day NHC forecast is 185 miles.

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 currents will be the rule, due to waves that will reach 10 - 15 feet in offshore waters. Waves from Hurricane Danielle killed two swimmers in the U.S. over the weekend and forced hundreds of water rescues along the U.S. East Coast. Earl's waves will be worse, and will likely cause millions of dollars in beach erosion damage.

Next update
Dr. Rob Carver is planning an update late tonight, and I'll have a full update in the morning.

Jeff Masters

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Quoting StormW:


Flag thrown on the play! Earl, number AL07, offsides to the west of track, 10 yard penalty!


LOL
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18z NOGAPS is a little scary:

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recon pages not loading, what is going on?
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Personally, I think the secret deflector shield is OZ...he starts heading for somewhere and the storm turns away. ;)
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116. h0db
Quoting Flyairbird:
I wonder if you had a message in a bottle and threw it in Earl, I wonder where the bottle would wind up?

Duh. Florida.
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Destin, StormW. What do you two think of my friends thoughs on that Trof not even making it to the Midwest until late Thursday early Friday, and if that happens, how will it affect Earl's motion?

Stupid ipad
Member Since: August 20, 2010 Posts: 0 Comments: 373
Who is heading to Daytona, Melbourne area surf east of Bahamas 26 ft. North of Bahamas 13.6 ft. Calling all Surfmom's.
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Quoting StormW:


Flag thrown on the play! Earl, number AL07, offsides to the west of track, 10 yard penalty!

looks more like 10 degree penalty
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Quoting Floodman:


Never...270 is due west


315 is true NW
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Quoting PEISLANDER:

Nova Scotia
Quoting Ryuujin:


So in other words, Earl still hasn't truly turned NW yet and is still on a more WNW-NW wobble instead of a W-WNW wobble
Yes what What he/she said
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Quoting DestinJeff:


WHOA. I did it again.


I think you may need to take a break as you have begun to mind-meld with the blog.
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Quoting DestinJeff:
Local Met just said "back to you Bob".

what does that mean?


Barometric observation boy!!
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Quoting Flyairbird:
315 is true NW...slightly north of wnw is 305


So in other words, Earl still hasn't truly turned NW yet and is still on a more WNW-NW wobble instead of a W-WNW wobble
Member Since: August 20, 2010 Posts: 0 Comments: 373
Quoting Ryuujin:
Question.

When is 305 degrees on a 360 degree circle considered NW?


Never...270 is due west
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Thanks Storm, answered my ? talking to Levi lol. Thanks Levi
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Levi, Storm, beell, whoever,

what are your thoughts on 98L?
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Quoting Flyairbird:
Just hope it isn't gas itself.


There is always that possibility...unfortunate, but true
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Quoting StormW:
Levi, thanks for mentioning the mid to upper low.

Here is what should happen,

The trof/low NW of Earl should continue to back SW as indicated by the light blue arrow. This should sort of "cut" the ridge, so that the portion to the NW of Earl will be oriented in a manner, as to impart a more NW motion on him. Then, the trof out west should begin to enter the picture.



That trof has a looooong way to go
Member Since: August 20, 2010 Posts: 0 Comments: 373
Quoting StormW:
Levi, thanks for mentioning the mid to upper low.

Here is what should happen,

The trof/low NW of Earl should continue to back SW as indicated by the light blue arrow. once it backs far enough south, this should sort of "cut" the ridge, so that the portion to the NW of Earl will be oriented in a manner, as to impart a more NW motion on him. Then, the trof out west should begin to enter the picture.



...is this a forecast or a football play?

Just kidding, thanks as always Storm
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Quoting Ryuujin:
Question.

When is 305 degrees on a 360 degree circle considered NW?
315 is true NW...slightly north of wnw is 305
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Quoting Flyairbird:
I wonder if you had a message in a bottle and threw it in Earl, I wonder where the bottle would wind up?

Nova Scotia
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Quoting Chucktown:


No such thing as a weak CAT 2. Minimal Cat 2 sounds better.


Yeah, you right. Not too concerned with being politically correct here, lol.

But I'll change it.
:)
Member Since: September 11, 2007 Posts: 142 Comments: 16623
Question.

When is 305 degrees on a 360 degree circle considered NW?
Member Since: August 20, 2010 Posts: 0 Comments: 373
Quoting Zeec94:

Attach a GPS locater to the bottle and do it. You might be surprised at where it may end up.
Quoting Floodman:


Therein lies my gastro-intestinal prognostication
Just hope it isn't gas itself.
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Quoting beell:
A secondary threat may exist for Earl to get entrained in the very strong low pressure system coming with the trough. This would pull Earl to the north or north west-closer to the coastline. Could be a stronger pull than the westerlies from the trough itself. A more or less direct landfall. Maybe Maine or the Canadian Maritimes.

Not a CAT4 at that time but consensus might suggest a strong CAT1 or weak CAT2


No such thing as a weak CAT 2. Minimal Cat 2 sounds better.
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Quoting DestinJeff:
Local Met just said "back to you Bob".

what does that mean?


Don't tell me he brought back Hurricane Bob from 1991. NOOOOOOOOOOO!!!!
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Afternoon everyone!

Storm or Levi,

With Earl pushing against the high to his northwest, shouldnt he go a little further to the east of the forcast track towards the weakness to his northeast between the two highs. He already seems to be going more north than this morning. Tia
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Quoting DestinJeff:


west.
LMAO....I think that would be the only thing going due west at the moment.
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Quoting StormW:


It should be close for the OBX/Hatteras area...but it doesn't look like a direct hit yet. Let me do up some graphics, and I'll explain what SHOULD happen, and any landfall will be based on the timing of these factors.


Euro model was the closest to Boston (hits Cape Cod)...new GFS still offshore, as is the UKMET.
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I'd like to thank the 60+ members who sent me e-mails earlier expressing their agreement and/or support. 63 to 4 is pretty good I think.
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Quoting katadman:
Plus, It isn't only Earl's current trajectory. If the trough is only a little bit slower to the coast than projected, Earl will not curve hard enough fast enough.


I was talking to my Meterologist friend and he said that he doubts that the trough will be able to move the high out of the way. We are not expected to get rain until late Thur, early Fri, and I live in Indiana. Which means the trof will be far away from the east coast still
Member Since: August 20, 2010 Posts: 0 Comments: 373
Quoting Flyairbird:
I wonder if you had a message in a bottle and threw it in Earl, I wonder where the bottle would wind up?

Attach a GPS locater to the bottle and do it. You might be surprised at where it may end up.
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High-res rapid-scan Water Vapor is great for viewing Earl's structure and tracking changes, especially now that the sun is about to set and we're losing visible light. EWRC is still incomplete, as the inner eye has not given up yet. One can see how much dry air has invaded the core, some of it due to the natural processes of an EWRC but some of it from foreign sources as well.

You can also see an upper low just west of Earl backing southwestward and allowing outflow to expand in the northwest quadrant, which is an increasingly favorable upper-level setup as time goes on. However, Earl still has a whole lot of dry air in his path. This is similar to what happened to Danielle, where an upper low backed away, outflow expanded northwestward, which helped her intensify into a Cat 4, yet dry air remained a limiting factor on her structure and intensity for her entire life. I still don't see Earl remaining a Cat 4 as long as the NHC has him, but he has proven a fighter so far judging by the vortex messages.

North Carolina outer banks and Cape Cod may still be dealing with a nasty situation if the storm track comes close enough to the coast, but I think with all this dry air getting wrapped in Earl has a chance to be only a Cat 2 when he passes the outer banks of North Carolina, but we'll see how well he fights.
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07L/MH/E/C3
MARK
22.33N/68.99w
Member Since: July 15, 2006 Posts: 171 Comments: 53827
A secondary threat may exist for Earl to get entrained in the very strong low pressure system coming with the trough. This would pull Earl to the north or north west-closer to the coastline. Could be a stronger pull than the westerlies from the trough itself. A more or less direct landfall. Maybe Maine or the Canadian Maritimes.

Not a CAT4 at that time but consensus might suggest a strong CAT1 or minimal CAT2
Member Since: September 11, 2007 Posts: 142 Comments: 16623
Quoting DestinJeff:
Earl's center doesn't hit NC, but they can see it from their house.

I wonder if you had a message in a bottle and threw it in Earl, I wonder where the bottle would wind up?
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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.