Ex-Dorian Attempting a Comeback off the Florida Coast

By: Dr. Jeff Masters , 1:44 PM GMT on August 02, 2013

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After a long trek over the Atlantic Ocean from the coast of Africa, the remains of Tropical Storm Dorian (now called Invest 91L) have finally arrived at the shores of North America. Ex-Dorian is nearly stationary, and is situated over the Northwestern Bahama Islands, just off the coast of Southeast Florida. Satellite loops and Melbourne, Florida radar images show that ex-Dorian has only a limited amount of heavy thunderstorms, which are not well-organized. There does appear to be a surface circulation center trying to form just north of the storm's heaviest thunderstorms, about 70 miles east of Vero Beach, Florida. However, dry air to the northwest, as seen on water vapor satellite loops, is inhibiting development. WInd shear is moderate, 10 - 20 knots, but is expected to rise to the high range, 20 - 30 knots, by Saturday morning. Ex-Dorian is expected to move slowly northwards and then north-northeastwards on Saturday. This motion will get ex-Dorian tangled up with a cold front that extends from Northern Florida northeastwards, just offshore from the Southeast U.S. coast. Before it merges with the front, ex-Dorian has some potential for regeneration into a tropical depression, and in their 8 am Friday Tropical Weather Outlook, NHC gave ex-Dorian a 30% chance of becoming a tropical cyclone by Sunday. Ex-Dorian will likely bring heavy rains to the Northwest Bahamas on Friday, and these heavy rains may also clip the coast of Southeast Florida. However, the bulk of ex-Dorian's rains should stay offshore.


Figure 1. Morning radar image of ex-Dorian from the Miami radar.

Jeff Masters

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1478. emguy
Quoting 1468. sar2401:

They pretty well telegraphed it in the 0200 TWO if you're at all familiar with reading between the lines on those things.


Actually, I'm more than familiar with their language...In the past...I participated in pretty much every NHC Conference Call during the 2004, 2005 Hurricane seasons, plus many others since.

When the 2 AM came out, there was not much to read between the lines...they identified the parameters for development. That's all.

Since then...that low level center ejected north quickly. Even on Long Range Melbourne Radar...it is evident that there is no Low Level Center where they say it is. Actually, the thunderstorms that are northeast of their estimated center are in fact moving well away to the northeast (toward the true low that was Dorian and has departed). It makes no sense. LINK

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1477. sar2401
Quoting OminousCloud:
Like two days ago, our local met said that Dorian could split into two entities. One would drift northeastely as forecasted, but the other would move west-ish. Does anyone still see this scenario possibly play out?

No. The "west" part is off the coast now and will be slowly moving NNE of the area. The only thing left behind will be the usual sea breeze thunderstorms. Local mets tend to make stroms do as many things as possible so they have a greater chance one of them will be right. Today, you'll here him say that the west section of Dorian is moving away after a narrow escape with death and destruction on the coast. :-)
Member Since: October 2, 2004 Posts: 0 Comments: 16023
Wow. Now I realize how close Dorian is to the Gulf, and I realize how pissed off it's making me.

I was looking forward to the potential for a tropical cyclone chase. Even had the days off for it.

Ugh. >_>
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Quoting 1466. sar2401:

LOL, I love the headline:

DORIAN REGENERATES INTO A TROPICAL DEPRESSION EAST OF FLORIDA

Not strengthens but "regenerates"...



It appears the death of Dorian has been somewhat exaggerated...
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Lol why is it a circle instead of the normal TD symbol?

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It really would be a head scratcher if the LLC raced ahead like that, considering it's sitting in <10 kt steering. I don't think I could believe that until visible stuff is out. If it is the case though, what's interesting is that the MLC would likely be in place for a long time, as the mid level winds would favor it being more stationary. Also, for the LLC to have moved off but not being the source of convection would be new - each time the LLC has gotten far away from the LLC, it has let the MLC die and went off with its own convection.
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1472. sar2401
Quoting emguy:
I've mentioned the struggles in renaming cyclones, and that NHC will only retain the name of a system if it retains it's trackable low level center. Here is an example of what has occurred in the past.

IVAN 2004:
Full Discussion Link
Exerpt from Discussion, "AFTER CONSIDERABLE AND SOMETIMES ANIMATED IN-HOUSE DISCUSSION OF THE DEMISE OF IVAN...IN THE MIDST OF A LOW-PRESSURE AND SURFACE FRONTAL SYSTEM OVER THE EASTERN UNITED STATES...THE NATIONAL HURRICANE CENTER HAS DECIDED TO CALL THE TROPICAL CYCLONE NOW OVER THE GULF OF MEXICO TROPICAL DEPRESSION IVAN. WHILE DEBATE WILL SURELY CONTINUE HERE AND ELSEWHERE...THIS DECISION WAS BASED PRIMARILY ON THE REASONABLE CONTINUITY OBSERVED IN THE ANALYSIS OF THE SURFACE AND LOW-LEVEL CIRCULATION.

Ivan was a big deal storm, and the boys get a lot more excited about names and continuity for them. Dorian is a dud, and I'd be amazed if they just didn't carry on with Dorian until it finally gets out into the mid-Atlantic and becomes extra-tropical.
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Like two days ago, our local met said that Dorian could split into two entities. One would drift northeastely as forecasted, but the other would move west-ish. Does anyone still see this scenario possibly play out?
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Yeah... What if its already happening as we speak?!?

AN ALTERNATIVE SCENARIO IS THAT DORIAN COULD SHEAR APART AND
WEAKEN SOONER THAN FORECAST.
Member Since: March 19, 2010 Posts: 0 Comments: 1147
Quoting 1404. ecflweatherfan:


I used to know it as the NCEP. Check on this site: http://mag.ncep.noaa.gov
There you will see a global map, select "model guidance", and then from there, select the region you want to see. It will give you the models available and their range of outlook.


Hmm, didn't quite find what I was looking for but I guess this will have to do for now. It's not bad either though. Also didn't see the Euro on there but oh well.
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1468. sar2401
Quoting emguy:
Personally...I'm pretty shocked that they redesignated it. Wow.

They pretty well telegraphed it in the 0200 TWO if you're at all familiar with reading between the lines on those things.
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Quoting 1465. scott39:
It is good to know that my family in Melbourne, is not dealing with any threat, from this new TD.


Errrr... Dorian the resurrected... Not really new, per se. But shocked that they are writing advisories on it to be honest. I wonder what they make of that swirl out in front of it. Can't wait to see the discussion the NHC puts out.
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1466. sar2401
Quoting fsumet:
Dorian is back. TD Dorian to be exact.

LOL, I love the headline:

DORIAN REGENERATES INTO A TROPICAL DEPRESSION EAST OF FLORIDA

Not strengthens but "regenerates". I get the feeling even the forecaster are getting sick of 11 straight days of this. They pretty much had to go to a TD at 0500 given the winds already seen on satellite. As stated previously, no watches or warnings, which is confirmed by land station observations. Looks like they carry it as a TD all the way out in the mid-Atlantic, well north of Bermuda. I tend to think an increase to a TS is inevitable somewhere along the line, just because every TD that hangs around the open ocean long enough becomes a TS. Now I wonder if they will decide to fly it today or tomorrow? Might give them some interesting data, and it's not awfully far away.

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1465. scott39
It is good to know that my family in Melbourne, is not dealing with any threat, from this new TD.
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MAX WINDS 35 MPH... LITTLE CHANGE IN STRENGTH FORECASTED
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1463. emguy
Personally...I'm pretty shocked that they redesignated it. Wow.
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1462. scott39
Quoting 1459. ecflweatherfan:


This may sound funny, but you may have better waves on the Gulf Coast side today.
Looks like it.
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NHC UPGRADED TO TD DORIAN... Not expected to last long though
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1460. emguy
I've mentioned the struggles in renaming cyclones, and that NHC will only retain the name of a system if it retains it's trackable low level center. Here is an example of what has occurred in the past.

IVAN 2004:
Full Discussion Link
Exerpt from Discussion, "AFTER CONSIDERABLE AND SOMETIMES ANIMATED IN-HOUSE DISCUSSION OF THE DEMISE OF IVAN...IN THE MIDST OF A LOW-PRESSURE AND SURFACE FRONTAL SYSTEM OVER THE EASTERN UNITED STATES...THE NATIONAL HURRICANE CENTER HAS DECIDED TO CALL THE TROPICAL CYCLONE NOW OVER THE GULF OF MEXICO TROPICAL DEPRESSION IVAN. WHILE DEBATE WILL SURELY CONTINUE HERE AND ELSEWHERE...THIS DECISION WAS BASED PRIMARILY ON THE REASONABLE CONTINUITY OBSERVED IN THE ANALYSIS OF THE SURFACE AND LOW-LEVEL CIRCULATION.
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Quoting 1453. scott39:
Bummer


This may sound funny, but you may have better waves on the Gulf Coast side today.
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1458. scott39
Quoting 1454. sar2401:

Here's the Melbourne Surf Report. Don't get your hopes up for any great shots. :-)
I played in those when I was 5 years old. Lol Not much too old ex Dorian.
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Td forms.
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1456. fsumet
.
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Tropical Depression DORIAN Forecast Advisory
Home Fcst Adv Archive


000
WTNT24 KNHC 030831
TCMAT4

TROPICAL DEPRESSION DORIAN FORECAST/ADVISORY NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
0900 UTC SAT AUG 03 2013

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL DEPRESSION CENTER LOCATED NEAR 28.7N 79.2W AT 03/0900Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE NORTH OR 10 DEGREES AT 5 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1013 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 45 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 28.7N 79.2W AT 03/0900Z
AT 03/0600Z CENTER WAS LOCATED NEAR 28.3N 79.5W
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1454. sar2401
Quoting scott39:
I was born in Melbourne Fl, and lived there as a kid. My dad still lives there. Im going to give him a call today, and see if he can get us some good pictures of the Atlantic waves.

Here's the Melbourne Surf Report. Don't get your hopes up for any great shots. :-)
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1453. scott39
Quoting 1450. ecflweatherfan:


I was out at Cocoa Beach earlier this evening... Waves weren't impressive at all. Surf zone was maybe knee high at best.
Bummer
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1452. emguy
As reference earlier...maybe the piece of mid level energy remains stationary under the more favorable area for development and develops a new "E" named storm with time.
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what is going on here maybe this ri!!
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Quoting 1447. scott39:
I was born in Melbourne Fl, and lived there as a kid. My dad still lives there. Im going to give him a call today, and see if he can get us some good pictures of the Atlantic waves.


I was out at Cocoa Beach earlier this evening... Waves weren't impressive at all. Surf zone was maybe knee high at best. We are expecting offshore winds today, with MAYBE a late afternoon seabreeze.
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1449. emguy
Dorian is clearly done...

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Quoting 1443. VR46L:


It depends what you mean, as SAR pointed out its going to be in warm water for a while , As a threat to Florida it would appear to be done but there is a good chance of it becoming a fish storm IMO


Not gonna develop in a high shear environment that it is entering. Sure, it will be over warm water, but it takes more than warm water to develop these things. Needs convergence in the low levels, divergence aloft, light upper level winds to keep its column stacked and to keep outflow from being disrupted.

In other words, the big piece here is shear. We have plenty of that from 29N and points northward. It WILL NOT develop under that environment.
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1447. scott39
I was born in Melbourne Fl, and lived there as a kid. My dad still lives there. Im going to give him a call today, and see if he can get us some good pictures of the Atlantic waves.
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1446. sar2401
If you use the national mosaic radar here, and scroll over to Florida, you get as wide a picture as you can get of all the combined radars in the area. It's very useful in situations like this. The striking thing about 91L is this low is as close to both Florida and the northern Bahamas as you can get and have virtually no effect on either of them. Even worse, areas of central Florida and the northern Bahamas that could have used the rain are going to get very little. A stronger low, better steering patterns, a trough not approaching from the north, and everything could be a lot different. Weather stories are made from a couple things happening in just the right place at the right time.
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1445. VR46L
Quoting 1434. Gearsts:
Interesting


I never know what that graph means....
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1444. emguy
Quoting 1441. yankees440:


I believe NHC retains same name as long as it either has MLC or LLW. correct me if im wrong


It's required to retain a trackable low level feature to retain its name...and this feature has now departed. Those thunderstorms if they developed would not be Dorian.

Interesting and intensive NHC debates have occurred in the past on retaining names of storms...Most notably Mitch in the late 90's when it redeveloped in the Gulf (after days over Central America) and Ivan in 2004 when it redveloped near Florida (after hitting Florida the first time). If you go in the NHC archives and pull down the Forecast Discussions for these storms...they specifically mention the name was retained because the low level center remained trackable and redevloped. In this instance with Dorian...it's not the case.
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1443. VR46L
Quoting 1442. ecflweatherfan:
It looks pretty apparent to me on satellite imagery and radar, that our CoC of 91L is oval shaped, N-S, with what appears to be the center near 29.5N 79W, moving N around 10 or so. Even the deep thunderstorm activity off Cape Canaveral and the Space Coast is now nudging NE ever so slowly (not rotating around the center, but moving as a whole). I am not sure that it should get renamed at 5am, therefore I really think we are done with Dorian.


It depends what you mean, as SAR pointed out its going to be in warm water for a while , As a threat to Florida it would appear to be done but there is a good chance of it becoming a fish storm IMO
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It looks pretty apparent to me on satellite imagery and radar, that our CoC of 91L is oval shaped, N-S, with what appears to be the center near 29.5N 79W, moving N around 10 or so. Even the deep thunderstorm activity off Cape Canaveral and the Space Coast is now nudging NE ever so slowly (not rotating around the center, but moving as a whole). I am not sure that it should get renamed at 5am, therefore I really think we are done with Dorian.
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Quoting 1439. emguy:
Ex Dorian had it's opportunity to develop and is now a dead stick...at least the lower lever piece of him. That low lovel swirl has clearly ejected itself nothward on the shortwave and that is it for that development. That truely is ex-Dorian and is under an unfavorable area as it peels away.

On that note, the mid level energy is producing those thunderstorms off the east coast. As ex-Dorian's low level pulls away, time is required, but that energy is not going anywhere fast and may have a chance for something new. Maybe a new circulation develops under that mid level feature with time...time...time...but don't get over excited just yet.

If something forms of it, I would argue it is not Dorian...maybe the daughter of Dorian...but not Dorian...as the low level energy has left the scene of the crime.


I believe NHC retains same name as long as it either has MLC or LLW. correct me if im wrong
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1440. sar2401
Quoting VR46L:


Sar I was being selfish ... I see the end of tropical systems after going extrop where occasionally we get hurricane winds but not sustained . I am just wondering if he could be a wonderful fish in the North Atlantic but dies as a storm in about 5-6 days and not retain tropical characteristics later as he formed in cooler waters originally

I don't know. Wait and see. This one might surprise you. It's surprised us about everything else so we'll see.
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1439. emguy
Ex Dorian had it's opportunity to develop and is now a dead stick...at least the lower lever piece of him. That low lovel swirl has clearly ejected itself nothward on the shortwave and that is it for that development. That truely is ex-Dorian and is under an unfavorable area as it peels away.

On that note, the mid level energy is producing those thunderstorms off the east coast. As ex-Dorian's low level pulls away, time is required, but that energy is not going anywhere fast and may have a chance for something new. Maybe a new circulation develops under that mid level feature with time...time...time...but don't get over excited just yet.

If something forms of it, I would argue it is not Dorian...maybe the daughter of Dorian...but not Dorian...as the low level energy has left the scene of the crime.
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Apparently, it is the low level center getting sheared away from main convection... Lets see if we can get a new one to form.. And if it needs to reform, whats the time frame for LLC to form?
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1437. sar2401
Quoting yankees440:
A slight bend to the West b4 heading NNE doesnt seem out of the question.. Anyone agree?

It's as far west as it's going to get. The motion now is a very slow drift north that will accelerate NNE later today. Even if it moved a little further west, it wouldn't make any difference. The only station if Florida in even the remote area of the storm that's reporting any precip is Sarasota, that's reporting light rain with calm winds. No matter ow many ways yu try to dissect this storm, it's not the one that's going to flatten anything n land. Pay attention to it as it moves off and intensifies a little before it's swallowed by the trough and learn something. A storm large enough to flatten something will come, and you won't have to question every swirl and model - it will be perfectly obvious to all of us.
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Quoting 1430. KoritheMan:


Heh. That seems pretty evidential to me. Guess we'll see.

It just seems very weird for that to happen in the absence of any large-scale steering mechanisms.


Looking at 41002, 225 S of Cape Hatteras (far enough removed from the LLC), has south winds around 10kt, were in the 15kt range earlier in the day (all southerly or SSW winds), so gradient flow is there. And the 850-900mb wind barb on the UW-CIMSS map shows SSE winds at 30N 78W around 25kt... so it could be moving out.
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1435. VR46L
Quoting 1431. sar2401:

Take a look at the Western Atlantic AVN loop here and select the SST option. You'll see the path of 91L has lots of 29-30 degree centigrade water around it. It can remain fully tropical for at least a couple fo days, depending on how far north it eventually travels. That's why I was saying earlier today I expected a TS, just not one that was going to affect land. It's still lopsided and, even if it becomes a TS by the 8:00, there are no winds that will affect Florida or the Bahamas. The highest wind being reported by any Florida station right now is 14 mph from the West at Cocoa. The highest wind being reported in the Bahamas is a SSW wind of 10 mph. 91L is never going to get closer, so wind just isn't going to be an issue for land areas with this system.


Sar I was being selfish ... I see the end of tropical systems after going extrop where occasionally we get hurricane winds but not sustained . I am just wondering if he could be a wonderful fish in the North Atlantic but dies as a storm in about 5-6 days and not retain tropical characteristics later as he formed in cooler waters originally
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1434. Gearsts
Interesting
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Quoting 1429. KoritheMan:


I didn't say a landfall, I just said it might get close. Look at this:



Weakness has opened again compared to the 0300Z image, but still. The trough is getting reinforced by a shortwave impulse over in Quebec, but in the meantime 91L has not moved much, except for perhaps a very slow northward drift.

Even if the ridge is beginning to weaken again (as forecast), the CIMSS map I posted above implies the possibility of a more north-northeastward motion in the short-term, which can have longer-term implications.


Any chance that high builds West more, seeing how this current trough has flattened more than expected already?
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1432. VR46L
Quoting 1426. Tribucanes:
Camille33 taking this to Wilma status would be the fastest RI in the history of any storm. Shear is only going to be moderate though and being over the Gulf Stream, annular, and increasing quickly; this could RI to 60-70mph TS. Anyway you see this making it to landfall on the OBX Kori? Front should make that an impossibility, right?


Looking at the Water vapour parcels of Vapour It would appear to be a harmless fish soon .. but what do I know I thought it was going to be attracted into the gulf yesterday by the front .




Camille33 Wilma ...AYE RIGHT ...LOL!
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1431. sar2401
Quoting VR46L:
I am wondering now that it appears as though its going out to see and was a storm in cooler waters would that mean he could become quite a fish in the cooler North Atlantic and turn Extrop later than usual ?

(a selfish question I know!!)

Take a look at the Western Atlantic AVN loop here and select the SST option. You'll see the path of 91L has lots of 29-30 degree centigrade water around it. It can remain fully tropical for at least a couple of days, depending on how far north it eventually travels. That's why I was saying earlier today I expected a TS, just not one that was going to affect land. It's still lopsided and, even if it becomes a TS by the 8:00, there are no winds that will affect Florida or the Bahamas. The highest wind being reported by any Florida station right now is 14 mph from the West at Cocoa. The highest wind being reported in the Bahamas is a SSW wind of 10 mph. 91L is never going to get closer, so wind just isn't going to be an issue for land areas with this system.
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Quoting 1427. ecflweatherfan:


Buoy 41012, located 40 miles ENE of St Augustine is reporting WSW winds right now


Heh. That seems pretty evidential to me. Guess we'll see.

It just seems very weird for that to happen in the absence of any large-scale steering mechanisms.
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Quoting 1426. Tribucanes:
Camille33 taking this to Wilma status would be the fastest RI in the history of any storm. Shear is only going to be moderate though and being over the Gulf Stream, annular, and increasing quickly; this could RI to 60-70mph TS. Anyway you see this making it to landfall on the OBX Kori? Front should make that an impossibility, right?


I didn't say a landfall, I just said it might get close. Look at this:



Weakness has opened again compared to the 0300Z image, but still. The trough is getting reinforced by a shortwave impulse over in Quebec, but in the meantime 91L has not moved much, except for perhaps a very slow northward drift.

Even if the ridge is beginning to weaken again (as forecast), the CIMSS map I posted above implies the possibility of a more north-northeastward motion in the short-term, which can have longer-term implications.
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A slight bend to the West b4 heading NNE doesnt seem out of the question.. Anyone agree?
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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.