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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NIght all!
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Looks like the invest should be a Tropical Depression by now. A passing remark, as I have to go in ten miniutes
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L92 must be watched..very closely ..all the time..storms this time of year are very crazy!predicting is very hard to do.. been watching them for 40 years.
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Look at the hurricane hunter data in the wunderground tropical report. Peak winds of well over tropical storm force already detected. Still not convinced that this is a warm core yet though. That being said, I personally expect this to be a named storm by sometime this afternoon/evening. Also the Nam has recently come inline with the western-most track scenario, which is interesting. GFS is like a rock predicting the storm to remain an open wave and basically stay as far off the coast as Bill did. I don't buy the GFS, however the westerly track originally showed up on the Canadian model and the Canadian model was too far west with Bill. We will see what happens. One way or the other there is a heavy rain event possible for New England. Firstly if this system does impact the area. And secondly, even if it misses there will be an abundant rain storm caused by an approaching front and strong jet dynamics. Enjoy the nice weather while it lasts!
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Quoting weathermanwannabe:
OK...I'll try again (with a better question). Last time I looked at 92L, yesterday around 4:00 PM, it was just North of PR and now, 9 hours later, just slightly to the West and not much movement. The NHC two does not mention speed (not a TD yet) but the system seems to be kind of stalled to me, which, would throw off any timetables suggested by the current models......Any Thoughts?
Here is what I do know..1 -Convection has been persistent,but keeps shifting position and has not been over the top of any of the circulation centers(which it seems to have 2 or 3 depending when you look at it).2. Movement--circulation centers keep reforming in the same general area, but the last advisory has the center 350 miles north of Hispaniola.3--Shear-it has been fighting the shear before it was even an invest.,4--It is a really disturbed weather system.
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I'm out too......good nite WW
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Well; just checking in and have a great day to those on....I'll check back on Friday or Saturday.....WW
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Quoting TampaSpin:


I would say the slower it goes the more likely out to sea it goes as the trough will pick it up before getting to the ConUs.


Morning to you; makes sense although some folks earlier today were thinking that the Trof might weaken and dissipate at bit...
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Quoting weathermanwannabe:
OK...I'll try again (with a better question). Last time I looked at 92L, yesterday around 4:00 PM, it was just North of PR and now, 9 hours later, just slightly to the West and not much movement. The NHC two does not mention speed (not a TD yet) but the system seems to be kind of stalled to me, which, would throw off any timetables suggested by the current models......Any Thoughts?


I would say the slower it goes the more likely out to sea it goes as the trough will pick it up before getting to the ConUs.
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Quoting hydrus:
-That sounds relaxing anyway,no matter how this turns out I believe we will have plenty to watch next 14 days.Have ya seen some of those models? JEEZ!


Morning; seems like lots on the horizon, model wise,for September; once some the persistent sheer dies down, we could see a nice jump in activity...
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OK...I'll try again (with a better question). Last time I looked at 92L, yesterday around 4:00 PM, it was just North of PR and now, 9 hours later, just slightly to the West and not much movement. The NHC two does not mention speed (not a TD yet) but the system seems to be kind of stalled to me, which, would throw off any timetables suggested by the current models......Any Thoughts?
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Quoting weathermanwannabe:
Early Morning Folks.....Serious case of insomnia (first time in a long time) and going to Orlando for a conference tommorow...Thought I would have a beer, check in, and see if I can get to sleep....... 92L looks like crap this am.......You folks, and the models, sure this thing is going to make it?...... :)
-That sounds relaxing anyway,no matter how this turns out I believe we will have plenty to watch next 14 days.Have ya seen some of those models? JEEZ!
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Quoting TampaSpin:
Actually i'm beginning to think the ULL is working its way down to stack on top of 92L. It that happens 92L will intensify very very quickly.
Earlier I saw the regional weather map of 92L,it showed a gale center,a low and the invest all crammed together. Well alright already it,s a :Upper Level Sub Tropical Gale center: I just can,t Imagine whats going to happen when it intensifies rapidly.Possibly a convective hybrid cold core meso-galecane.
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Early Morning Folks.....Serious case of insomnia (first time in a long time) and going to Orlando for a conference tommorow...Thought I would have a beer, check in, and see if I can get to sleep....... 92L looks like crap this am.......You folks, and the models, sure this thing is going to make it?...... :)
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Quoting KoritheMan:


Steering analysis from CIMSS suggests that the upper low will eventually move away from 92L.


Look at the WaterVapor loop and the RGB loop! You can see that 92L is moving nearly Due WEst while the ULL is moving NW. It appears to me the ULL lost part of its midlevel and is now stacked on 92L. If you go to my website and look at the different levels of Vorticity. You will see that 92L is now stacked all all levels.....its getting ready to blast off.
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723. 7544
Quoting btwntx08:
000
ABNT20 KNHC 260534
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT WED AUG 26 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT THE AREA OF
DISTURBED WEATHER...ACCOMPANIED BY GALE FORCE WINDS...IS NOW
CENTERED ABOUT 350 MILES NORTH OF HISPANIOLA. THERE HAS BEEN LITTLE
IN CHANGE IN ORGANIZATION DURING THE PAST FEW HOURS BUT UPPER-LEVEL
WINDS ARE FORECAST TO BECOME MORE CONDUCIVE FOR DEVELOPMENT. THIS
SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL STORM AT ANY TIME AS
IT CONTINUES MOVING WEST-NORTHWESTWARD AROUND 20 MPH
. THERE IS A
HIGH CHANCE...GREATER THAN 50 PERCENT...OF TROPICAL CYCLONE
FORMATION DURING THE NEXT 48 HOURS. INTERESTS IN THE BAHAMAS
SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

ADDITIONAL INFORMATION ON MARINE WARNINGS ASSOCIATED WITH THIS
SYSTEM CAN BE FOUND IN HIGH SEAS FORECASTS ISSUED BY THE NATIONAL
WEATHER SERVICE...UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER
FZNT01 KWBC.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$


maybe at dmax one hour from now
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Quoting TampaSpin:


I don't think so. LOOK at this RGB loop. The RGB is the best loop to look at during the night when you don't have a visible.


Steering analysis from CIMSS suggests that the upper low will eventually move away from 92L.
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Quoting hydrus:
I cannot see it now,but earlier it seemed to have 3 spins at different heights,what a difficult system to forecast.:|


Strange but your correct. It almost appears the ULL has dropped part of it on top of 92L while the main ULL is moving to the NW.....really crazy stuff when a surface low ducks under an ULL. We don't see that often occur.
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Quoting 7544:


but isnt the ull moving west now and 92l is wnw tia


I don't think so. LOOK at this RGB loop. The RGB is the best loop to look at during the night when you don't have a visible.
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Quoting TampaSpin:
Actually i'm beginning to think the ULL is working its way down to stack on top of 92L. It that happens 92L will intensify very very quickly.
I cannot see it now,but earlier it seemed to have 3 spins at different heights,what a difficult system to forecast.:|
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Quoting TampaSpin:


Chuch your analysis there isn't too far off......It probably is more like a Sub-Tropical storm with the ULL dumping cold air on top of 92L! Your not too far off bases at all with that thinking.
cool i was just being facetious,but i knew no closed circulation means no name blob or Gale.
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715. 7544
Quoting TampaSpin:
Actually i'm beginning to think the ULL is working its way down to stack on top of 92L. It that happens 92L will intensify very very quickly.


but isnt the ull moving west now and 92l is wnw tia
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Actually i'm beginning to think the ULL is working its way down to stack on top of 92L. It that happens 92L will intensify very very quickly.
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Quoting chucky7777:
Actually i would call it a Mid Level Sub-tropical Storm,lol just kidding


Chuch your analysis there isn't too far off......It probably is more like a Sub-Tropical storm with the ULL dumping cold air on top of 92L! Your not too far off bases at all with that thinking.
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709. 7544
23/67 could this be the spot that wins to form center
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Quoting scottsvb:



Not you....now 45mph happens all the time in a tropical wave...also normal severe thunderstorms on land... they dont make a system a TD or TS until there is a full 360dg circulation... now that guy who wrote a Cat 1 Hurricane invest is a idiot!
Actually i would call it a Mid Level Sub-tropical Storm,lol just kidding
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Quoting KerryInNOLA:
Latest CMC continues to show a major hurricane hit for Saturday to entire East coast from North Carolin to Long Island, includng NYC. Are you getting prepared?


http://www.youtube.com/watch?v=Kw_Lf-JhdSU
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705. 7544
well if this criiter has 45mph winds as a invest and get it together in 24 hours this will skip td status and just be calleed ts danny
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Quoting Orcasystems:
Latest updates... and I am off to bed :)



AOI

AOI

AOI

AOI



Nice pic update........LOL
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If CMC is right it's an ObamaCane

Link
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700. 7544
looks like 92l wants to follow what the cmc shows
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Quoting Prgal:

Hmm, why "an idiot"? It says 45mph winds and its still an invest.



Not you....now 45mph happens all the time in a tropical wave...also normal severe thunderstorms on land... they dont make a system a TD or TS until there is a full 360dg circulation... now that guy who wrote a Cat 1 Hurricane invest is a idiot!
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Quoting btwntx08:
am back hows everything going this evening/morning



same has a few hrs a go and befor that and for that not march new going on
Member Since: May 21, 2006 Posts: 5091 Comments: 114792
Quoting KoritheMan:
Additionally, 92L is going to be hard-pressed to develop a low-level warm core with that ULL nearby, due to its baroclinic nature.

There are also appear to be at least two distinct areas of vorticity within the system.



this storm will take some time i see
Member Since: May 21, 2006 Posts: 5091 Comments: 114792
Quoting stillwaiting:




thanks dude!!!,was up until 1:30am last night,atleast I can go to bed now,until tomorrow:see ya!!!!


Per NasaTV, the shuttle is going to try another launch around 12:22AM on Friday.
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Quoting stillwaiting:




thanks dude!!!,was up until 1:30am last night,atleast I can go to bed now,until tomorrow:see ya!!!!



the shuttle was haveing some bugs with so they could not launch it tonight so am hoping that they get the bugs fixs soon
Member Since: May 21, 2006 Posts: 5091 Comments: 114792
Additionally, 92L is going to be hard-pressed to develop a low-level warm core with that ULL nearby, due to its baroclinic nature.

There are also appear to be at least two distinct areas of vorticity within the system.
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Quoting Tazmanian:
guys 92L has no SFC low with no SFC low they cant name it a TS the wind dont care how strong it is NO sfc low NO name storm


Indeed. It will be at least another 24 hours before the system organizes enough. A closed surface circulation cannot form with such significant shear in the area, because the convection is what sustains the circulation. The convection is consistently being pushed off to the northeast by strong southwesterly upper flow associated with the nearby upper level low.

Until this eases (and it is, albeit gradually), 92L cannot become a tropical depression.
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Quoting Tazmanian:




its a no go tonight they will try on wed night




thanks dude!!!,was up until 1:30am last night,atleast I can go to bed now,until tomorrow:see ya!!!!
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Retracted the dumb question.../
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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.