Hurricane Hunters find 50 - 60 mph winds in disturbance 92L north of Puerto Rico

By: Dr. Jeff Masters , 8:54 PM GMT on August 25, 2009

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The tropical wave (92L) a few hundred miles north of Puerto Rico is generating a large area of surface winds of 50 - 60 mph, according to the latest information from the Hurricane Hunters. Top winds seen so far at their flight level of 1,000 feet were 69 mph, which would make 92L a strong tropical storm if it had a surface circulation.
However, the aircraft has not found a surface circulation, and the satellite appearance shows virtually no change in the amount, intensity, or organization of the storm's thunderstorm activity. Wind shear has dropped to the moderate range, 15 - 20 knots this afternoon, but the upper low 92L is moving underneath is dumping cold, dry air into the region. Dry air continues to get ingested into 92L's thunderstorms, creating strong downdrafts that are robbing 92L of heat and moisture. These downdrafts are creating surface arc clouds that spread out from where the downdraft hits the ocean surface. NHC continues to give 92L a high (greater than 50% chance) of developing into a tropical depression by Thursday afternoon.

The forecast for 92L
As 92L moves underneath the center of the upper low on Wednesday morning, the upper low is expected to weaken, and wind shear is expected to decline to the low range, 5 - 10 knots. However, the upper-level low will continue to dump dry, cold air into 92L through Thursday afternoon, slowing down development. By Thursday night, when 92L should be several hundred miles off the coast of northern Florida, the upper-level low may be weak enough and far enough away that 92L will find itself in a region with light upper level anticyclonic winds, which would favor more rapid development. However, this favorable environment will not last long, since a strong trough of low pressure will be approaching the U.S. East Coast on Friday. This trough will bring high wind shear of 20 - 30 knots by Friday night. This trough should be strong enough to turn 92L to the north. The models disagree substantially on how close 92L will be to the coast at that time. One camp of models, including the NOGAPS, Canadian, UKMET, and ECMWF models, predict 92L will pass very close to the Outer Banks of North Carolina on Friday night or Saturday morning. The GFS, GFDL, and HWRF models keep 92L several hundred miles out to sea. Both sets of models bring 92L north-northeastwards on Saturday, with a track over Massachusetts or Nova Scotia. The intensity forecast for 92L is problematic, since it's eventual strength depends upon how quickly it manages to become a tropical depression. Given that 92L will find itself in a favorable environment for strengthening for about 36 hours this week, and marginal for the remainder of the week, I give the system these odds:

10% chance of never getting a name.
20% chance of becoming a weak tropical storm (40 - 50 mph winds).
40% chance of becoming a strong tropical storm (55 - 70 mph winds).
30% chance of attaining hurricane strength.

Elsewhere in the Atlantic
The ECMWF and UKMET models predict the development of a tropical wave coming off the coast of Africa late this week. The GFS model no longer shows this.

I'll have an update Wednesday morning.

Jeff Masters

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So what is the general consensus on here regarding development on 92L? Can we expect a ramping up off the system tonight or will development be slow to occur?
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Could someone please verify whether or not the trough is trying to slit near Jacksonville, FL?
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Quoting rmbjoe1954:


That appears to be the ULL traveling westward.

I believe the ULL is a little further north than than down by 22.5 / 67
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Quoting GatorWX:


Bastardi calling for a strong e coast storm??? NO!! I bet it'll hit NY metro area as at least a cat 2 if it forms. lol!


Hey if it wasn't for him all we would hear about is Florida and the GOM. I don't think he is that bad.
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I want to see the wind direction when they get back down to 23N.
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133. bwat
It is going to be an interesting night here on the blog, I think 92L is starting to find its groove. I think you'll see the system start to close in around 23.4N 65.5w. We'll see what happens.
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132. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting kanc2001:


Hanna part deux?


Nice avatar...
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I am not a Florida caster by any stretch of the imagination...but don't some of the models bring 92L petty close to the coast of Central Florida before turning north?
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Quoting wcoastfl:
Looks to me like the main area of circulation is to the west of the main blob, as also noted in a previous post. Best to see on wide view, satellite. We will have to wait and see if it splits away completely and heads more westward. Thoughts from anyone?


That appears to be the ULL traveling westward.
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Quoting Hhunter:
bastardi getting bullish on 92L development and possibly strong east coast storm strike..recon searching wrong spot for center...


OMG! Bastardi forecasting an east coast hit!

LOL...how you doing, Hunter?
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The area where I think the COC might be is actually moving more south.
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Quoting gatorcanefan:
Is there any possibility that the models are initializing from the wrong point?


It's not just a possibility, it's a near-certainty. Without a closed surface low there is no specific point for the model to initialize from.
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Or is that circulation the ULL that has been mentioned?
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124. edmac
Is it me, or does the S. Carrib. disturbance look as if it is moving north. Could just be my eyes playing tricks. Any thoughts
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Drak
it looks like a centre is trying to near 23n 63w
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Is there any possibility that the models are initializing from the wrong point?
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Looks to me like the main area of circulation is to the west of the main blob, as also noted in a previous post. Best to see on wide view, satellite. We will have to wait and see if it splits away completely and heads more westward. Thoughts from anyone?
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Quoting Drakoen:
The strong winds may warrant them staying in the system a bit longer than scheduled.


It really looks like 92L is going due west......for now.
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Quoting IKE:
Looks like 92L is a threat for SC/NC and points north.

2nd post. First one got lost in cyberspace.


Hanna part deux?
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The circulation that I see on RGB imagery is near 23.4N 65.5w
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looking at steering & the front/trough expected to come through I honestly believe that 92L if it becomes anything or not will come close to the OBX but not brush them and move up the east coast maybe brushing(at best) the NE coast. I know it's too far out to make a judgment call but this is JMHO. I believe that NC has nothing to worry about and would eat crow if I was wrong.
Member Since: June 27, 2009 Posts: 0 Comments: 152
The strong winds may warrant them staying in the system a bit longer than scheduled.
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Quoting Hhunter:
bastardi getting bullish on 92L development and possibly strong east coast storm strike..recon searching wrong spot for center...


sorry it's just what Max Mayfield said while he was on local 10 at 6pm, he said that the HH were going to fly west to take a look, no one has made a bullish statement here i quite a while....
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Quoting Hhunter:
bastardi getting bullish on 92L development and possibly strong east coast storm strike..recon searching wrong spot for center...


Bastardi calling for a strong e coast storm??? NO!! I bet it'll hit NY metro area as at least a cat 2 if it forms. lol!
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Just got back and noticed our "shrimp" storm has 60+ mph gusts. Shrimpy just needs to get a circulation and we'll be in business.

Also,I just looked at the latest ECMWF and noticed a strong tropical system crossing the Atlantic at about 216 hours with a very strong ridge in place.
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Jeff Masters believes the wind readings. The wind readings were consistent over a large area with supporting flight level winds. 92L does have strong tropical storm force winds in the lower levels.
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108. bwat
Just heard the local forecast on tv here in NE NC, they talked about 92L for about 20 seconds saying that it is still a long ways out. Friday night isnt THAT far out. Well, guess they didnt want to cause panic. But 30% chance of it being a hurricane will sure keep me on my toes.
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92L looks very sloppy, so even if it had a llc and they still found winds of 55-60 mph, I doubt they'd call it anything more than a depression. I would certainly imagine they would wait until it organizes better and actually resembles a ts before they say it has 50+mph winds officially as a ts.
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Dropsonde pattern that the Gulfstream IV is currently flying for 92L.


Member Since: September 23, 2005 Posts: 14 Comments: 11274
bastardi getting bullish on 92L development and possibly strong east coast storm strike..recon searching wrong spot for center...
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104. IKE
NASA scrubs overnight shuttle launch due to bad valve...from CNN.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting extreme236:


For some freakin reason everytime I zoom in on the NASA images it closes firefox down...it gets annoying.


Sometimes it does that to me
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Quoting Drakoen:
I have a hard time believing that thing has 60mph winds


lol, no kidding, at least not at the surface. Yes, I know what it says!
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I think 92L COC maybe around 22.3N/68.5W. further south & west away from the heaviest convection, jmo.
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Quoting Drakoen:
SSD is having image issues. NASA GOES works best.


For some freakin reason everytime I zoom in on the NASA images it closes firefox down...it gets annoying.
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Thanks for updating doc.

Gotta run.
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SSD is having image issues. NASA GOES works best.
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Quoting extreme236:


I dont think it would be, not going to rule it out, but dvorak estimates show it as a tropical pattern, and convection is close to the hypothetical center.
Exactly...I was lookin at Fay and Dolly and especially Hanna from last year...they were like this...but weren't subtropical. It would be tropical...99.999999% sure.
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Quoting JeffMasters:
I updated the blog to include the high winds found by the Hurricane Hunters. I bumped up my odds of it becoming a hurricane, too. Still, there is nothing resembling a closed surface circulation that the hurricane hunters are able to find, or visible on satellite.

Jeff Masters


iam scatchin the side off my head myself doc got to be tightness of two systems the high and low causing the winds they may back off and give us a more reasonable measurement but by then it may well be on its organizing stage and spin up fast as well
Member Since: July 15, 2006 Posts: 175 Comments: 54858
Thanks for the update AGAIN Dr. Jeff.
I am curious. When I look at the computer models on the tropical page of WU I do not see the European model. Why is that? Are the other models an ensemble, or in some way dependent on the other?
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Quoting 954FtLCane:
Max Mayfield just mentioned that the hunters are going to fly west from what I can tell towards the smaller blowup to the west around 22.5 & 67, i thought that might look a little interesting but not an expert here by any stretch

That is exactly where I put the center at earlier on the blog today.
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Quoting cyclonekid:

Why Subtropical?


I dont think it would be, not going to rule it out, but dvorak estimates show it as a tropical pattern, and convection is close to the hypothetical center.
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Quoting JeffMasters:
I updated the blog to include the high winds found by the Hurricane Hunters. I bumped up my odds of it becoming a hurricane, too. Still, there is nothing resembling a closed surface circulation that the hurricane hunters are able to find, or visible on satellite.

Jeff Masters


Thanks, Doc.
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90. amd
Quoting cyclonekid:

Why Subtropical?


because the strongest winds are well away from any "center", if it exists. Personally, I think a LLC exists well to the sw of the main convection, near 23 N 68 W (or directly north of the mona passage).

Here's a real good Visible animation from LSU:

Link
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Quoting JeffMasters:
I updated the blog to include the high winds found by the Hurricane Hunters. I bumped up my odds of it becoming a hurricane, too. Still, there is nothing resembling a closed surface circulation that the hurricane hunters are able to find, or visible on satellite.

Jeff Masters


Thanks for the update Doc. Using the area of lowest pressure as the potential center, the strongest winds have been displaced to the north, similar to a subtropical system. Any chance this could be the case?
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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.