92L very disorganized, but a long-range threat to develop

By: Dr. Jeff Masters , 2:05 PM GMT on June 18, 2010

Invest 92L, which yesterday became severely disrupted by wind shear and dry air, is generating a large area of rain showers over the northern Lesser Antilles Islands today. Infrared satellite loops show that the tops of the thunderstorms associated with 92L have warmed in recent hours, and these thunderstorms are weak and disorganized. Water vapor satellite loops show that there is a large amount of dry air in the storm's environment, and this dry air is getting sucked into 92L's thunderstorms, where the dry air is sinking to the surface and creating surface "arc clouds"--arc-shaped clouds that spread out away from 92L's thunderstorms. With wind shear at 20 - 30 knots today, no signs of a surface circulation, and plenty of dry air around, 92L is not a threat to develop into a tropical depression today or Saturday. The National Hurricane Center is giving 92L a low (20% chance) of developing into a tropical depression by Sunday morning. I put the chances at 1%. You can track the progress of 92L today by looking at our wundermap for the region, with weather stations turned on. Antigua recorded sustaiined winds of 20 mph this morning from 92L.

A slight chance 92L could develop next week
Today and Saturday, 92L will encounter 20 - 40 knots of wind shear as it plows though a region of strong upper-level winds associated with the subtropical jet stream. The disturbance will also encounter the mountainous terrain of Hispaniola. These factors should significantly disrupt the disturbance. If there's anything left of 92L by Sunday, when it will be over eastern Cuba, the storm may have the opportunity to develop. At that time, 92L will have passed through the core of the subtropical jet stream and entered a region of lower shear (15 - 20 knots.) For the latest round of 00Z and 06Z model runs, the HWRF is the only reliable model calling for 92L to develop; that model predicts that 92L will organize into a tropical depression on Wednesday over the Lower Florida Keys, and head into the Gulf of Mexico. The obstacles that 92L must overcome to do this are great, and I give 92L just a 10% chance of eventually developing into a tropical depression by Wednesday next week.


Figure 1. Morning satellite image of Invest 92L. Dry air is getting sucked into 92L's thunderstorms, where the more dense dry air creates downdrafts. When these downdrafts hit the surface, the air spreads out creating surface "arc clouds"--arc-shaped clouds that spread out away from 92L's thunderstorms. This puts stable air into the storm's low level environment and blocks inflow of moist air into the core of the storm, weakening it. These arc clouds are a telltale sign that dry air is significantly disrupting the disturbance.

Elsewhere in the tropics
The NOGAPS model is calling for a tropical disturbance to form off the coast of Nicaragua on Monday and push ashore over that country on Tuesday, bringing heavy rains.

Wind and ocean current forecast for the BP oil disaster
Light and variable winds less than 10 knots will blow in the northern Gulf of Mexico for the next five days, according to the latest marine forecast from NOAA. The winds will tend to have a westerly component through Saturday, which will maintain a threat of oil hitting beaches as far east as Panama City, Florida, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Ocean current forecasts for early next week show a weakening of the eastward-flowing currents along the Florida Panhandle, which would limit the eastward movement of oil so that it would not move past Panama City. The long range 8 - 16 day forecast from the GFS model indicates a typical summertime light wind regime, with winds mostly blowing out of the south or southeast. This wind regime will likely keep oil close to the coastal areas that have already seen oil impacts over the past two weeks.

Resources for the BP oil disaster
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's new interactive mapping tool allows one to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

I'll have an update on Saturday.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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2506. txsweetpea
4:58 PM GMT on June 19, 2010
I hate to ask...BUT what does the 12z gfs @ 156 hours show? What looks so bad that we hope dont pan out?
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2504. GainesvilleGator
4:37 PM GMT on June 19, 2010
Dr Masters posted a new blog.
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2503. hydrus
4:36 PM GMT on June 19, 2010
Quoting IKE:
12Z GFS @ 156 hours...

Now that looks bad. Hope that model does not pan out.
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2502. Drakoen
4:36 PM GMT on June 19, 2010
Quoting extreme236:
00z ECMWF at 48 hours (not the same system as the one it develops later on)



It is
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2501. Tazmanian
4:34 PM GMT on June 19, 2010
2495. StormSurgeon 4:31 PM GMT on June 19, 2010
Quoting Tazmanian:
92L my be drop later today


It will be, just a bunch of T-storms now. What's up Taz?


not march
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2500. IKE
4:34 PM GMT on June 19, 2010
GFS continues to develop, to a point, a system in the Bahamas in about 4 days. Moves the area of disturbed weather across southern Florida and into the SE GOM where a low pressure system forms and moves toward the north-central GOM...aka...oil spill.

Hopefully it's wrong.
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2499. hydrus
4:33 PM GMT on June 19, 2010
Quoting Drakoen:
The MJO looks very chaotic.
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2498. AllStar17
4:33 PM GMT on June 19, 2010
NEW BLOG!
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2497. Tazmanian
4:32 PM GMT on June 19, 2010
looks like per 93L is looking a little better then a few hrs a go but whats wait and see
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2496. IKE
4:32 PM GMT on June 19, 2010
12Z GFS @ 156 hours...

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2495. StormSurgeon
4:31 PM GMT on June 19, 2010
Quoting Tazmanian:
92L my be drop later today


It will be, just a bunch of T-storms now. What's up Taz?
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2493. aspectre
4:30 PM GMT on June 19, 2010
Thanks, extreme236, that did roll quite a bit west since I last saw it.
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2492. extreme236
4:28 PM GMT on June 19, 2010
00z ECMWF at 48 hours (not the same system as the one it develops later on)

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2491. AllStar17
4:28 PM GMT on June 19, 2010
Quoting Tazmanian:
92L my be drop later today


I don't think so. It looked much worse yesterday and it was not deactivated.
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2490. Tazmanian
4:27 PM GMT on June 19, 2010
92L my be drop later today
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2489. hydrus
4:26 PM GMT on June 19, 2010
Link.............. Here is a better link Skye. This is small potatoes compared to past floods, but deadly none the less.
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2488. extreme236
4:25 PM GMT on June 19, 2010
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2487. AllStar17
4:25 PM GMT on June 19, 2010
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2486. AussieStorm
4:24 PM GMT on June 19, 2010
nice little rain core
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2485. Drakoen
4:23 PM GMT on June 19, 2010
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2484. Drakoen
4:23 PM GMT on June 19, 2010
Quoting MiamiHurricanes09:
CMC, GFS, NOGAPS, and ECMWF all develop it. The ECMWF had the most intense solution.



GFS and CMC solutions are associated with 92L. The ECMWF is associated with a southern Caribbean disturbance
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2483. aspectre
4:22 PM GMT on June 19, 2010
SouthWest Caribbean and not South Central Caribbean?
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2482. extreme236
4:20 PM GMT on June 19, 2010
Quoting MiamiHurricanes09:
CMC, GFS, NOGAPS, and ECMWF all develop it. The ECMWF had the most intense solution.


I assume your referring to the second system?
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2481. MiamiHurricanes09
4:19 PM GMT on June 19, 2010
Quoting extreme236:
12z GFS suggests that area of disturbed weather in the SW Caribbean now could have some potential. Doesn't appear to strengthen it much but just a little.
CMC, GFS, NOGAPS, and ECMWF all develop it. The ECMWF had the most intense solution.
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2480. Skyepony
4:19 PM GMT on June 19, 2010
Quoting hydrus:
They have been receiving well above average rainfall in some areas......Link.


Wow up to 136 dead or missing so far. It's been an odd year with those deadly land blobs rolling over that same area almost weekly. It's like they are getting the Philippines usual wrath. Weird land blobs, there had been much drought & a kick up in their weather modification program, wunder if there's any correlation.
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2478. extreme236
4:18 PM GMT on June 19, 2010
00z ECMWF shows a disturbance in the SW Caribbean at 24 hours, and forms another around 96-120 hours that it develops in the NW Caribbean.
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2477. extreme236
4:16 PM GMT on June 19, 2010
12z GFS suggests that area of disturbed weather in the SW Caribbean now could have some potential. Doesn't appear to strengthen it much but just a little.
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2476. MiamiHurricanes09
4:13 PM GMT on June 19, 2010
Quoting WinterAnalystwx13:


Leave already!!! :P lol
Someone didn't get much sleep last night...
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2475. hydrus
4:11 PM GMT on June 19, 2010
Quoting Skyepony:
Hydrus~I was just looking at that..bet China is getting some flooding.
They have been receiving well above average rainfall in some areas......Link.
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2474. Skyepony
4:10 PM GMT on June 19, 2010
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2473. Clearwater1
4:10 PM GMT on June 19, 2010
Quoting Tazmanian:
2445. RecordSeason 3:45 PM GMT on June 19, 2010
2443:

True, but 92L still has a lot of momentum already spinning. If the AOI gets any good spin, then it's going to get interesting.


ok


Would you please take a look at long range PR radar and try to spot a point of circulation. Approximate, of course. I don't see it any longer.
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2472. hurricanelover236
4:09 PM GMT on June 19, 2010
Quoting hydrus:
Link .........It looks like shear is keeping the Western Pacific calm for now.

That wont be necessary. Nothing is going to happen lol. this is going to be anear average hurricane season.
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2471. CyclonicVoyage
4:09 PM GMT on June 19, 2010
As models indicate, 92L will make that northward turn sooner or later, right into the Mountains.


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2470. Patrap
4:09 PM GMT on June 19, 2010
92L is a OPEN wave at this time..
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2469. hydrus
4:08 PM GMT on June 19, 2010
............................Wide view.
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2468. Skyepony
4:08 PM GMT on June 19, 2010
Hydrus~I was just looking at that..bet China is getting some flooding.
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2467. MrMarcus
4:08 PM GMT on June 19, 2010
Quoting wunderkidcayman:
MrMarcus = big expert Downcaster = MrMarcus Ph.d in Downcasting
lol


Hardly, but I'm always amazed at how spun up some people get over a cloud formation with no spin of its own. ;-)
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2466. mrsalagranny
4:07 PM GMT on June 19, 2010
I just looked at hurricanecitys site and in the video he said 92L would be somewhere in the Northern Gulf by Saturday or Sunday.I am praying it doesnt do too much with the oil.
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2465. wunderkidcayman
4:07 PM GMT on June 19, 2010
MrMarcus = big expert Downcaster = MrMarcus Ph.d in Downcasting
lol
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2464. hydrus
4:06 PM GMT on June 19, 2010
.
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2463. Patrap
4:05 PM GMT on June 19, 2010
Computer Models Used to Forecast Hurricanes


The behavior of the atmosphere is governed by physical laws which can be expressed as mathematical equations. These equations represent how atmospheric quantities such as temperature, wind speed and direction, humidity, etc., will change from their initial current values (at the present time). If we can solve these equations, we will have a forecast. We can do this by sub-dividing the atmosphere into a 3-D grid of points and solving these equations at each point. These models have three main sources of error:

1) Initialization.We have an imperfect description of what the atmosphere is doing right now, due to lack of data (particularly over the oceans). When the model starts, is has an incorrect picture of the initial state of the atmosphere, so will always generate a forecast that is imperfect.

2) Resolution. Models are run on 3-D grids that cover the entire globe. Each grid point represents of piece of atmosphere perhaps 40 km on a side. Thus, processes smaller than that (such as thunderstorms) are not handled well, and must be "parameterized". This means we make up parameters (fudge factors) that do a good job giving the right forecast most of the time. Obviously, the fudge factors aren't going to work for all situations.

3) Basic understanding. Our basic understanding of the physics governing the atmosphere is imperfect, so the equations we're using aren't quite right.
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2462. hydrus
4:04 PM GMT on June 19, 2010
Link .........It looks like shear is keeping the Western Pacific calm for now.
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2461. MrMarcus
4:04 PM GMT on June 19, 2010
Quoting WinterAnalystwx13:
If 92L can survive tonight and tomorrow, it really doesn't have to worry about Shear anymore. Its in the 30-40 kt. range, but 20 kts. is very close.


Your kidding, right? 92L will be a non-event. Even the good doctor gives it a 10% chance of becoming a TD, much less anything significant.
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2460. smmcdavid
4:01 PM GMT on June 19, 2010
Good morning all. Can't stay to chat... just enough time to check in. Someone keep on eye on things for me. ;-)
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2458. Tazmanian
3:59 PM GMT on June 19, 2010
2445. RecordSeason 3:45 PM GMT on June 19, 2010
2443:

True, but 92L still has a lot of momentum already spinning. If the AOI gets any good spin, then it's going to get interesting.


ok
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2457. hydrus
3:58 PM GMT on June 19, 2010
Quoting AllStar17:
What's happened to the Western Pacific? It is extremely quiet.
That is interesting, I have to check the weather charts to see why its so quiet.
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2456. MTWX
3:56 PM GMT on June 19, 2010
Quoting AllStar17:
What's happened to the Western Pacific? It is extremely quiet.

Now that you say something, it has been really quiet over there...
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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