93L near tropical depression strength

By: Dr. Jeff Masters , 2:31 PM GMT on June 25, 2010

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The first tropical depression of the 2010 Atlantic hurricane season appears imminent in the Western Caribbean, as the areal coverage and intensity of heavy thunderstorm activity associated with the tropical wave (Invest 93L) continue to increase. The storm has developed a surface circulation near 16.5N, 82.5W at 8am EDT, about 100 miles northeast of the Nicaragua/Honduras border. This is far enough from land that development will be slowed only slightly. Satellite loops show a poorly organized system, with only a modest amount of heavy thunderstorm activity near the center. However, the developing storm is affecting the weather across the entire Western Caribbean, and bands of heavy thunderstorms are quickly building over a large region. Pressures at ground stations and buoys all across the Western Caribbean have been falling significantly over the past day (Figure 2.) Water vapor satellite loops show that moist air surrounds 93L, and there is not much dry air to slow down development. There is an upper-level high pressure system a few hundred miles west of 93L, and the clockwise flow air around this high is bringing upper-level winds out of the northwest of about 10 - 15 knots over 93L, contributing to the 10 - 15 knots of wind shear observed in this morning's wind shear analysis from the University of Wisconsin's CIMSS group. Sea Surface Temperatures are very warm, 29 - 30°C. The Madden-Julian oscillation (MJO) currently favors upward motion over the Caribbean, which will act to increase the chances of tropical storm formation this week. The main negative for 93L is a combination of lack of spin and wind shear. Last night's pass of the ASCAT satellite showed a broad, elongated circulation, which will need to tighten up in order for 93L to become a tropical depression. The Hurricane Hunters are scheduled to fly into 93L at 2pm EDT this afternoon to see if a tropical depression has formed.


Figure 1. Morning visible satellite image of the central Caribbean disturbance 93L.


Figure 2. Combined plot of wind speed, wind gusts, and pressure at buoy 42057 in the Western Caribbean. Pressure (green line) has fallen significantly over the past two days, and winds are beginning to increase.

Forecast for 93L
The greatest risk from 93L to the Western Caribbean will be heavy rainfall, and the nation most at risk is Honduras. The counter-clockwise flow of air around 93L will bring bands of rain capable of bringing 4 - 8 inches of rain to northern Honduras over the next two days. Heavy rains of 3 - 6 inches can also be expected in northeast Nicaragua, Cuba, Belize, the Cayman Islands, and Mexico's Yucatan Peninsula. The storm is moving west-northwest at about 10 mph, and this motion is expected to gradually slow over the next five days to about 6 mph. I expect that by tomorrow, 93L should be closer to being directly underneath the upper level high pressure system to its west, which would act to lower wind shear and provide more favorable upper-level outflow. NHC is giving 93L a 70% chance of developing into a tropical depression by Sunday morning, which is a reasonable forecast. The storm will probably be a tropical depression or tropical storm with 40 mph winds when it moves over Mexico's Yucatan Peninsula on Sunday. The storm will probably spend a day or so over the Yucatan, resulting in significant weakening. Once 93L emerges over the Gulf of Mexico, it will take the storm 24+ hours to recover its strength.

A trough of low pressure is expected to swing down over the Eastern U.S. on Monday. If this trough is strong enough and 93L develops significantly, the storm could get pulled northwards and make landfall along the northern Gulf of Mexico coast. This is the solution of the GFDL and HWRF models. If 93L stays weak and/or the trough is not so strong, the storm would get pushed west-northwestwards across Mexico's Bay of Campeche and make landfall along Mexican coast south of Texas, or in Texas. This is the solution of the NOGAPS, ECMWF, and Canadian models. A likely landfall location is difficult to speculate on at this point, and the storm could hit virtually anywhere along the Gulf of Mexico coast given the current uncertainty in its development. The amount of wind shear in the Gulf of Mexico next week is also highly uncertain. There is currently a band of high shear near 30 knots over the Gulf. The GFS model predicts that this band of high shear will lift northwards, keeping low wind shear over the Gulf next week. However, the ECMWF model keeps high shear entrenched over the Gulf of Mexico, which would make it unlikely 93L could intensify into a hurricane. In summary, I give 93L a 60% chance of eventually becoming Tropical Storm Alex, and 10% chance of eventually becoming a hurricane.

Elsewhere in the tropics
A tropical wave a few hundred miles northeast of the northernmost Lesser Antilles Islands is producing a modest amount of heavy thunderstorm activity. This system was designated Invest 94 by NHC this morning, and is passing beneath a trough of low pressure that is generating 30 - 40 knots of wind shear. However, by Sunday, the storm will be in a region of much lower wind shear, and NHC is giving the storm a 10% chance of developing into a tropical depression by Sunday morning. We do have one model, the GFS, which develops the system early next week. The GFS model takes the storm to the northwest and then north, predicting it will be very close to Bermuda on Tuesday.


Figure 3. Hurricane Celia as a Category 4 storm at 20:55 UTC Thursday, June 24, 2010, as captured by NASA's MODIS instrument.

Impressive Hurricane Celia hits Category 5
The first Category 5 hurricane in the Northern Hemisphere this year is Hurricane Celia in the Eastern Pacific. Celia's 160 mph winds make it tied with Australia's Tropical Cyclone Ului as the strongest tropical cyclone in the world so far in 2010. Celia has likely peaked in intensity, and is not expected to threaten any land areas.

Wind and ocean current forecast for the BP oil disaster
East to southeast winds of 5 - 15 knots will blow in the northern Gulf of Mexico today through Tuesday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should push the oil to the west and northwest onto portions of the Louisiana and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. I would expect Mississippi to have its most serious threat of oil yet early next week as these winds continue. The longer range outlook is uncertain, and will depend upon what 93L does.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
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 interactive mapping tool 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

Jeff Masters

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1379. Levi32
Yeah I don't buy the 12z ECMWF. That's almost ridiculous right there.
Member Since: November 24, 2005 Posts: 628 Comments: 26454
1378. Drakoen
93L would almost have to head due west for the ECMWF to verify
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Quoting kmanislander:
The critical thing is that the low is sitting right underneath that deep convection which is not showing any sign of warming cloud tops in the middle of the day. That is a sure sign of a system that is on the upswing.

If the HH does not find a closed low now one will not be many hours away. They will likely stick around for some time if necessary and do runs again in an hour or so. They are close to us and can refuel here with ease.


How big is the island? About the size and population of a Nuc Carrier? Can't sink it. Be a Handy Thing to have. Now I see why we bothered with Granada.
Member Since: September 9, 2007 Posts: 36 Comments: 4687
I have yet to find evidence of a closed low, so in my mind as of now we do not have a TD
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1375. GBguy88
Quoting CaneWarning:
Bad news coming out of the gulf...

According to the St. Pete Times, if a hurricane threatens the gulf, oil will gush freely for 2 weeks.

Link


Of course it will. Can't very easily pump oil to a surface ship in an angry, pitching ocean.
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1374. Patrap

93L swinging in the Mo..


93L NASA Viewer
Member Since: July 3, 2005 Posts: 414 Comments: 125429
On what website can i directly look at the HH info as it comes in??
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Quoting MiamiHurricanes09:
No not Grand Cayman, I think Honduras and Belize are the countries that warrant a watch or warning.


If the NW motion holds I don't see any watches until much later in the timeline and then possibly for the N end of the Yucatan and/or Western Cuba. Too early to worry about for now.
Member Since: August 19, 2006 Posts: 0 Comments: 15671
any more reports of stronger west winds from recon
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Quoting Drakoen:
ECMWF 12z is way too far south and west
Bad initialization and track, imo.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
1369. leo305
Quoting Hurricanes101:


actually no it doesnt, I have the track plot up on hurricane tracking softward, if it stays NW it still goes over the Yucatan just south of Cozumel


yes but as it strengthens, the NW motion will start becoming more northerly
Member Since: April 17, 2010 Posts: 0 Comments: 1753
1367. Levi32
Quoting saintsfan06:
Levi, Is there a correlation between size during the consolidation of 93L and the final storm??


Well a large disturbance is usually likely to form into a larger tropical cyclone. Some don't, however, like 92L, which reduced its size greatly after leaving the ITCZ. 93L should remain a pretty decent size. Tropical systems generally like to get large in the western Caribbean.
Member Since: November 24, 2005 Posts: 628 Comments: 26454
1366. xcool
Hurricanes101 yep . I have to throw it out the window now .
Member Since: Posts: Comments:
Hey guys,
I need your honest opinion on that wave with a 20% chance of development. I live in south florida and will be away on a trip for two weeks starting next tuesday. Should I be worried? I appreciate your opinion since I am not an expert but realize that some of you really know your stuff. Thanks
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Quoting Jeff9641:
93L looks to go right through the Channel if it stays on this coarse.


actually no it doesnt, I have the track plot up on hurricane tracking softward, if it stays NW it still goes over the Yucatan just south of Cozumel
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Quoting Grothar:
This is what is called ein Klecks in German:



Einer groissen Schmutz?
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Bad news coming out of the gulf...

According to the St. Pete Times, if a hurricane threatens the gulf, oil will gush freely for 2 weeks.

Link
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Of highest interest to me right now is this current NW motion to the storm.

It's headed straight for the anticyclone.

They will embrace each other, the minimal shear it is experiencing will decrease, and then you should really begin to see that 93L is so much more than just a slow moving headache.
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1360. leo305
Quoting Floodman:


Looking at a longer loop, it does appear to show NW in the last few frames...


the stronger it gets, the further north it will move
Member Since: April 17, 2010 Posts: 0 Comments: 1753
1359. Skyepony (Mod)
1005.3mb, little lower.
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1358. bappit
Quoting sonofagunn:


I think it's large size will prevent it from spinning up too quickly.

Good point.

Member Since: Posts: Comments:
Time: 18:33:00Z
Coordinates: 16.7167N 83.2167W
Acft. Static Air Press: 977.3 mb (~ 28.86 inHg)
Acft. Geopotential Hgt: 249 meters (~ 817 feet)
Extrap. Sfc. Press: 1005.6 mb (~ 29.70 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 70 at 3 knots (From the ENE at ~ 3.4 mph)
Air Temp: 23.3C (~ 73.9F)
Dew Pt: 18.0C (~ 64.4F)
Peak (10s) Flt. Lvl. Wind: 3 knots (~ 3.4 mph)

Member Since: October 1, 2007 Posts: 81 Comments: 26493
Quoting kmanislander:


For Grand Cayman ?. I wouldn't think so.
No not Grand Cayman, I think Honduras and Belize are the countries that warrant a watch or warning.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
1354. Drakoen
ECMWF 12z is way too far south and west it is almost bullish
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1353. Patrap
Quoting NOLA2005:


I didn't think Guy's had ersters on the menu. If they do, I'm headed that way right now!



Actually..the ol Lady went to Domelisi's.
Member Since: July 3, 2005 Posts: 414 Comments: 125429
Quoting MiamiHurricanes09:
You can really see the northwesterly motion.



Looking at a longer loop, it does appear to show NW in the last few frames...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting xcool:
look at ewcmf lol


barely develops it now
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Quoting Drakoen:


The OFCI which is from the NHC
drak for some reason i think its headed for the yucatan channel or near the resort areas in cancu, i just have that feeling
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1349. Skyepony (Mod)
No west wind second time through..
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could this new nw movement @6mph. keep the center over water haveing no land interaction to slow it down or keep it from getting stronger? thanks in advance:)
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1347. Max1023
Is it possible that the center is re-forming under the heavy convection?? It looked like recon investigated the area to the west of the coldest cloud tops.
Member Since: Posts: Comments:
1346. LRandyB
Quoting CybrTeddy:
From 345° at 6 knots
(From the NNW at ~ 6.9 mph)

Another west wind.
Quoting CybrTeddy:
From 345° at 6 knots
(From the NNW at ~ 6.9 mph)

Another west wind.


Depends on where they found that wind and whether or not it was a larger area. That could have been a convection induced direction.

They'll be looking for something of a more solid westerly wind to call it closed.
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Quoting Floodman:


Not a good example; too few frames and the apparent "motion" could just be convection blow up...
It was the only animation I found that I could have posted on the blog.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
1343. RJT185
stepping out of lurker mode here for a question:

StormW (or anyone that knows!) how long would it take for the models to be able to input and use the data from the recon mission?

thanks!!
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there is no 95L
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Quoting MiamiHurricanes09:
We will likely see some watches and warnings up if and when 93L gets classified.


For Grand Cayman ?. I wouldn't think so.
Member Since: August 19, 2006 Posts: 0 Comments: 15671
1340. Grothar
This is what is called ein Klecks in German:

Member Since: July 17, 2009 Posts: 63 Comments: 23676
It will be interesting to see what the winds are like. I would expect tropical storm force gusts in some of the squalls from the rainbands. Whether or not there are any sustained winds of that strength, I guess we have to wait an see.
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1338. xcool
look at ewcmf lol
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if 93L develops or not people in the northern gulf coast better get ready for some real rough weather maybe not directly but enough to move oil around and spread it out more . if there is any hope for florida 93L goes to the west of the spill and far
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Quoting stillwaiting:
anybobody see theirs 95L posted on the navy site???
LOL, no.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Jeff9641:


2pm models are showing east track. Most of them that is. We gots us a bomb on da hand. Get ready as tonight and tomorrow could be interesting.


Really? How far east?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting MiamiHurricanes09:
You can really see the northwesterly motion.



Not a good example; too few frames and the apparent "motion" could just be convection blow up...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting Patrap:


Dusk and the Low Sun Angle then should be interesting on the Viz Imagery later Kman.


Yep,just before sunset.
Member Since: August 19, 2006 Posts: 0 Comments: 15671
Seems everything got pulled up in the last couple frames looking at that...
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Quoting charlottefl:
Looks like the models are having a hard time handling the trough/high interaction in the Gulf. Should be interesting to see where/ if this storm hits the Yucatan.


You can almost count out modeling this system until it hits the BoC or the GoM. And the reason is that the models will have a very difficult time with how this system intensifies. Intensity is the driving focus right now, and unless you know exactly how big this storm is going to get in the area it now exists, there will be no way of knowing where it will go.

You will continue to see splayed model tracks for the next 48 hours minimum.
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Quoting kmanislander:


Current track would not warrant watches for us. It is already about 100 miles West in longitude.
We will likely see some watches and warnings up if and when 93L gets classified.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Patrap:


Classified.

Guy's Po-boy on Magazine made me sign a paper.


I didn't think Guy's had ersters on the menu. If they do, I'm headed that way right now!
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.