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 hydrus:
Africa.....Says he wants a souvenir from the good ole U.S of A. Dont know if he wants Carolina Crab Cakes or some New England Clam Chowder or both.
Maybe some saltwater taffy.
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Quoting Alockwr21:
What's the margin for error this far out with Earl?
about 3 ft.
Member Since: August 23, 2005 Posts: 0 Comments: 285
Station 41047
NDBC
Location: 27.469N 71.491W
Conditions as of:
Thu, 2 Sep 2010 02:50:00 UTC
Winds: SSE (160°) at 44.7 kt gusting to 54.4 kt
Significant Wave Height: 29.2 ft
Dominant Wave Period: 11 sec
Mean Wave Direction: SSE (167°)
Atmospheric Pressure: 29.64 in and rising rapidly
Air Temperature: 83.5 F
Dew Point: 77.5 F
Water Temperature: 83.1 F
View Details - View History

NE Bahamas buoy..still kickin out there!
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3:31UTC 11:31PM EDT. NW movement
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That turn keeps getting later and later....i don't like it.
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What does it mean when you say the hurricane is becoming "annular"?
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Quoting PrivateIdaho:


I suspect that the water level rise due to atmospheric pressure is very small compare to that water pushed by the wind...correct?


Yes and a post-Cat5 will have had (at some point)stronger winds to push water in its path than a Cat3 storm that never reached 145mph in its lifetime.
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2399. Dunkman
Quoting DestinJeff:
should see a clear miss of eye at 30hrs frame soon


Yeah it appeared to move due north from 18h to 24h.
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Quoting CosmicEvents:

.
.
.
Not really wrong. It's such a close call at an obtuse angle to the coast, like Charlie. It's all in the timing AND the exact orientation of the trough. Impossible to predict. All the models can and probably will in tandem shift 50-200 miles as they all pick up on the progress and orientation of that trough as we go through the next 36 hours. It's a fluid situation.


I agree.......always does.
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I think the overall message is this, the NHC said in there public advisory at 11pm NOT TO FOCUS ON THE TRACK... Unless Earl went to school, He is not reading the NHC Track map following through. The NHC took the line out of there map to prevent people from focusing on the "PATH", they would much rather that you focus on the cone and pay attention to your local Emergency Management Agency. Hurricane forecasting with the scientific study and data still has an element of art to it. Preparedness means paying attention, heeding the warnings and responding appropriately. If you live on the East Coast, let me clue you in, there is a threat to your area. FEMA has already begun positioning people and supplies for a possible response. Anyone know why they are doing that, because there is enough concern with Hurricane Earl that it may impact the East Coast. The bottom line is this, ARE YOU READY? DO YOU HAVE A PLAN? WHAT IS YOUR LIFE WORTH? if the NHC is right, then so bi it and you have just had an opportunity to exercise your plan. If the NHC is off, then you are going to be well ahead of the curve by executing your plan when the local Emergency Management Agency alerts you to the threat. If you do not have a plan IT IS TIME TO MAKE ONE AND BE PREPARED TO INITIATE IT, it may just save your life.....
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2395. leo305
so GFS is calling for a landfall now?
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting Orcasystems:




Brings new meaning to flying squirrel.
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Quoting floridiancanuck:


I realize this was mentioned awhile ago but THANK YOU! I keep hearing mention of Bay of Fundy being high risk for a devastating storm surge, but that makes no sense for the exact reason you mentioned, the area is used to huge volumes of water pushing in and out every day.


High tide... add 10-20 feet of surge... you could almost flood to the other side.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting 1900hurricane:
!!!!!



Not good news at all...
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Quoting floridiancanuck:


I realize this was mentioned awhile ago but THANK YOU! I keep hearing mention of Bay of Fundy being high risk for a devastating storm surge, but that makes no sense for the exact reason you mentioned, the area is used to huge volumes of water pushing in and out every day.


good point...a 2 foot tidal range on the La delta is on the high side...just sayin'
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What's the margin for error this far out with Earl?
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Quoting DestinJeff:
hmmmmm.....+24 will be landfall or near-miss


Super close... Shouldn't they be putting up high wind warnings well inland???
Member Since: April 26, 2009 Posts: 3 Comments: 3667
2386. hydrus
Quoting atmoaggie:
Whoa. Where did that come from?
Africa.....Says he wants a souvenir from the good ole U.S of A. Dont know if he wants Carolina Crab Cakes or some New England Clam Chowder or both.
Member Since: September 27, 2007 Posts: 1 Comments: 21409
Quoting TampaSpin:
Not much Consensus doubt it stays off shore. That would be a lot of wrong model runs....



.
.
.
Not really wrong. It's such a close call at an obtuse angle to the coast, like Charlie. It's all in the timing AND the exact orientation of the trough. Impossible to predict. All the models can and probably will in tandem shift 50-200 miles as they all pick up on the progress and orientation of that trough as we go through the next 36 hours. It's a fluid situation.
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Quoting Flyairbird:
He's Early alright!...That's the problem!...


Unpredictable
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2381. twooks
I'd like to believe the GFS at 24hrs, but a 40mb drop in pressure that quick seems a bit too exaggerated, don't you think? In this environment? I know shear is suppose to increase, but such a drop would suggest it went into a very hostile environment, which I don't think will be the case tommrow. Am I wrong?
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!!!!!

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2377. leo305
Quoting DestinJeff:
next frame tells us if GFS gets it past 75 or not


and when is that getting posted?

btw.. you guys like my avatar? I know its offtopic but it took me months to finally get one here
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting Max1023:


Thankfully the landscape there can handle huge tides, a storm surge at any time other that high tide would have little effect in most places, at least compared to a place like NYC or NOLA. A 10 foot surge at low tide would be just another high tide there.


I realize this was mentioned awhile ago but THANK YOU! I keep hearing mention of Bay of Fundy being high risk for a devastating storm surge, but that makes no sense for the exact reason you mentioned, the area is used to huge volumes of water pushing in and out every day.
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Quoting Flyairbird:
YIKES!


How soon until that next frame?
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Quoting muddertracker:
I have no idea what that means...my nickname comes from my family's mud-racing history..yes, I know, redneck, but you can't choose your family:)


Seinfeld reference. Kramer is betting on horsesand overhear a tip. Funny episode.
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2368. Oh snap!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Flyairbird:
He's Early alright!...That's the problem!...


LOL. Oops! I just realized I put "Early". xD
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Quoting ussual:
Hey Storm Junkie was that Fadder a Mudder to a joke in reference from "Fire Fly" tv show?


See post 2335
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Quoting Dunkman:
Model question: The 6h GFS running right now has Earl at 982mb...does that impact it's ability to forecast how he will react to steering currents?
Good Question.

Any strong cat 2 and up represented in the model will get about the same steering.

Could the track be effected differently with other factors that turn our hurricanes westward or poleward, depending on strength or size? Yes, *could*.

But in a strong steering flow, generally, the steering winds trump the other factors.
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Quoting TampaSpin:
Brain is interviewing people.....LOL


Oz is FAMOUS!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting StormJunkie:


lol...Actually it has to do with that in some respect...Kramer (from Seinfeld) got a tip on a horse...The track was muddy...The horses mother was mudder and the fadder was a mudder too...Just a good Seinfeld reference.
oh yeah..lol..
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Quoting DestinJeff:
next frame tells us if GFS gets it past 75 or not
YIKES!
Member Since: August 23, 2005 Posts: 0 Comments: 285
Quoting RufusBaker:
I just emailed someone at NHC my resume. Ya just never know!


yeah maybe they won't do the background check ;)
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Looks like earl is starting to become annular -- large eye, round clouds.
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Brain is interviewing people.....LOL
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Quoting atmoaggie:
Whoa. Where did that come from?
Where's it going?
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2360. JRRP
Quoting JLPR2:


Here is the comparison:
Gaston:

Georges:


Creepy, right? XD

good one
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2359. leo305
Quoting weathercrazy40:
ok guys so if the high to the east gets strong enough what will it mean for us here in south eastern mass


that means the hurricane may move closer to the coast
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting atmoaggie:
Fitzpatrick is one (MSU, look him up).

And, yes, I did realize that, but thanks anyway.

Did you know that Ike wasn't a stronger storm offshore? Yet, had a surge not usually associated with a cat 2? All about radius of TS force winds (and wind speeds at landfall, of course). Really.
(Surge modeling is what I do. No kidding.)


You are mixing comparisons.
I was speaking on the differences in maximum intensity, and you are referring to storm-size, which also impacts surge.
I'm talking apples and you are talking oranges. Quite frankly, we're both right.
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Quoting ussual:
Hey Storm Junkie was that Fadder a Mudder to a joke in reference from "Fire Fly" tv show?
Abbott and Costello
Member Since: August 23, 2005 Posts: 0 Comments: 285

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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.