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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Quoting RecordSeason:
I'm about to go to sleep...in the middle of the day.

This storm is a complete waste of time.

T number 1.0...

Pathetic 93L, pathetic.


have a nice nap
Member Since: March 10, 2010 Posts: 1 Comments: 7353
1277. scott39
NW and going slow-----Not Good IMO
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Quoting StormChaser81:


Calling for landfall areas is a good way of getting people in a panic.


It isn't even a TD yet. Anyone that would panic over a comment on a blog, about a system that hasn't become anything yet is just looking for something to panic about. If they don't panic about this, they will find something else.
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Tried to steal a page from the Book of Levi, but alas, how come no one near the coast around there has an anemometer?

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1274. Patrap
Quoting Floodman:


How much you pay for dat poboy? I hear dey runnin' t'rough da roof...


Classified.

Guy's Po-boy on Magazine made me sign a paper.
Member Since: July 3, 2005 Posts: 420 Comments: 127520
1273. leo305
Quoting Drakoen:
Circulation seen on GOES hiresolution imagery is clearly closed.


yep..
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Quoting Drakoen:
Circulation seen on GOES hiresolution imagery is clearly closed.


well based on the google overlay orca just showed, they have not gotten through the center yet
Member Since: March 10, 2010 Posts: 1 Comments: 7353
1271. Levi32
Quoting Drakoen:
Circulation seen on GOES hiresolution imagery is clearly closed.


That's what I thought too until seeing the recon obs.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
1269. Levi32
Look at how much 93L dwarfs Hurricane Darby in the eastern Pacific. There is a lot of energy being consolidated in the western Caribbean right now.

Member Since: November 24, 2005 Posts: 635 Comments: 26547
1245. StormW 2:34 PM EDT on June 25, 2010

Great shot....Does anyone have an "educated - informed" guess of where the COC might be located at the moment?
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1267. Drakoen
Circulation seen on GOES hiresolution imagery is clearly closed.
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Quoting Hurricanes101:


I didn't think it was closed, could be we dont have a TD at all at 5pm lol
I believe that for a tropical depression to be classified it doesn't need to have closed consolidated low.
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Quoting Tropicaddict:


kman....refresh my memory what the T1.0/1.0 means again....


Typically we look for a T # of 2 for a TD

Take a read of how the Dvorak technique is used and what different T numbers mean

Link
Member Since: August 19, 2006 Posts: 0 Comments: 15707
Looks like they found some Circulation

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Quoting neverfollow:
Stage going on the beach in Gulf Shores for the Jimmy Buffet concert next Thursday.


Maybe not, now...
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1262. leo305
Quoting stormpetrol:
This 93L , this is really starting to look like TD/TS( best it ever looked imo) is also creeping NNW at the moment don't like that speed at all, and getting so close to our neck of the woods.


yep
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HPC has the front hitting the gulf coast on tuesday..so that gives the storm approx 100 hours to reach the n gom..or be shunted to the ne or back to tex/mex. Now if the fron t slows down or speeds up by 12 hours...that will mean a lot where it lands. http://www.hpc.ncep.noaa.gov/medr/nav_conus_pmsl.php?fday=5&fcolor=wbg
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Quoting Patrap:
Oyster Po-Boy, a Barqs Root beer

Dr. Jeff Masters on the Spud Show soon.

93L

Recon

Itsa good Friday.
afternoonm,,mmm,scuse,drip..Tabasco



How much you pay for dat poboy? I hear dey runnin' t'rough da roof...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1259. GBguy88
Quoting neverfollow:
Stage going on the beach in Gulf Shores for the Jimmy Buffet concert next Thursday.


Grossly off topic, but a couple family members just got a job at his new resort on the beach here. Full benefits, paid vacation, chances at free stay throughout the year, and that's for a food service position. He definitely sets people up pretty well.
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1258. bappit
Quoting StormW:


Doesn't have to be a hurricane to have a CDO.


I would think a CDO is persistent, new cirrus replacing cirrus carried away by outflow. Seems premature to talk about a CDO. Got some cirrus in the last few hours near the center. Wait and see if it persists. Then I'll call it a CDO.
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Quoting kmanislander:


Yes, NW, just posted on WU home page


that is not necessarily good.
Member Since: July 17, 2008 Posts: 0 Comments: 1242
Hi! If anyone has the coordinates handy for the COC, I'd welcome it -thanks. :)
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Quoting Levi32:
This looks like a very amplified open wave with a weak low center that you almost can't call closed but it is very close.. I don't see it remaining this way very long.....it should close off by the end of the day. It has done nothing but become better-defined since yesterday.


I didn't think it was closed, could be we dont have a TD at all at 5pm lol
Member Since: March 10, 2010 Posts: 1 Comments: 7353
Wow I stepped away for 20 minutes and we had over 200 new comments. LOL
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1253. Drakoen
UKMET

NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 24 HOURS
FORECAST POSITION AT T+ 24 : 18.0N 85.9W

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
12UTC 26.06.2010 18.0N 85.9W WEAK
00UTC 27.06.2010 18.6N 88.3W WEAK INTENSIFYING SLIGHTLY
12UTC 27.06.2010 20.1N 91.7W WEAK WEAKENING SLIGHTLY
00UTC 28.06.2010 20.1N 92.7W WEAK INTENSIFYING SLIGHTLY
12UTC 28.06.2010 22.3N 94.5W WEAK LITTLE CHANGE
00UTC 29.06.2010 23.0N 95.8W WEAK WEAKENING SLIGHTLY
12UTC 29.06.2010 23.3N 96.6W WEAK LITTLE CHANGE
00UTC 30.06.2010 BELOW TROPICAL STORM STRENGTH
Member Since: Posts: Comments:
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 25th day of the month at 18:26Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 302)
Mission Purpose: Investigate first suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 07

Mandatory Data...

Observation Time: Friday, 18:24Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 16.3N 83.5W
Location: 250 miles (402 km) to the SW (214°) from George Town, Cayman Islands (GBR).
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 300 meters
Flight Level Wind: 5 knots (~ 5.8 mph) (Bearing was unavailable.)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 25°C
Flight Level Dew Point: Not available, probably because the dew point hygrometer was not working.
Weather (within 30 nautical miles): Thunderstorm(s)
Mean Sea Level Pressure (MSLP): 1006 mb (extrapolated)

Optional Data...

Estimated Surface Wind: From 330° at 10 knots (From the NNW at ~ 11.5 mph)
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1251. Levi32
Don't know if this ASCAT was posted earlier, but you can see it is very close to closed for sure.

Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting reedzone:


I'm sorry, I respectfully disagree with you. There is LLC, full with convection, great outflow, spinning clouds on the visible. The storm is spinning and NOT going through RI, though I'm not ruling that out tonight.


No one is taking sides with our discussion, so we must both be wrong. It is spinning and yet it is not spinning. (Please see my YinYang post.)
Member Since: June 16, 2010 Posts: 0 Comments: 28
Quoting kmanislander:


Yes, NW, just posted on WU home page
At 5mph I believe.
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1248. Levi32
This looks like a very amplified open wave with a weak low center that you almost can't call closed but it is very close.. I don't see it remaining this way very long.....it should close off by the end of the day. It has done nothing but become better-defined since yesterday.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting Hurricanes101:


yes it is the blob to the north


Thanks!
Member Since: July 17, 2008 Posts: 0 Comments: 1242
1246. Patrap
Oyster Po-Boy, a Barqs Root beer

Dr. Jeff Masters on the Spud Show soon.

93L

Recon

Itsa good Friday.
afternoonm,,mmm,scuse,drip..Tabasco

Member Since: July 3, 2005 Posts: 420 Comments: 127520

Link
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This 93L , this is really starting to look like TD/TS( best it ever looked imo) is also creeping NNW at the moment don't like that speed at all, and getting so close to our neck of the woods.
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Quoting tennisgirl08:
Kman - agreed. that is just what i was noticing. NW motion?


Yes, NW, just posted on WU home page
Member Since: August 19, 2006 Posts: 0 Comments: 15707
Kman Bite your tongue on the move through the Straight there between the Yuca and Cuba I know that means for florida
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1240. Drakoen
Quoting atmoaggie:

That Honduras ob must be a local/land influenced thing...


I think so as well I have seen alot of westerly wind reports over Central America
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Quoting kmanislander:


Current motion is NW. This may shoot the Yucatan channel. The models will come right soon.


kman....refresh my memory what the T1.0/1.0 means again....
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Stage going on the beach in Gulf Shores for the Jimmy Buffet concert next Thursday.
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Quoting Drakoen:


Or the low is very small which is what it appears to be on visible imagery
Visible suggests that the COC consolidated a lot than from how broad it was early this morning.
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1236. Drakoen
Quoting Levi32:


That could be too, except that the WNW winds in Honduras earlier this morning suggested a larger circulation.


Possible larger west and east than it is north and south.
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Kman - agreed. that is just what i was noticing. NW motion?
Member Since: July 17, 2008 Posts: 0 Comments: 1242
1234. leo305
Quoting MiamiHurricanes09:
If it does we might have a much stronger system than what we are currently thinking, especially with those TCHP.


and a more easterly track
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Quoting tennisgirl08:


Anyone? Just wondering...because if that is so, looks to be moving in a more NW fashion.


yes it is the blob to the north
Member Since: March 10, 2010 Posts: 1 Comments: 7353
Quoting StormW:


Well, don't forget Drak and Levi too..and 456 if he is back on...wonder where he's been BTW?
sick bad i hear
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Quoting Levi32:
Recon obs south of the center showing easterly winds....perhaps weakly closed but not very well.

That Honduras ob must be a local/land influenced thing...
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1229. Levi32
Quoting StormW:


Well, don't forget Drak and Levi too..and 456 if he is back on...wonder where he's been BTW?


I really hope he's ok....don't like seeing him disappear like this. I hope he didn't get a serious illness or something.
Member Since: November 24, 2005 Posts: 635 Comments: 26547

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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.