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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The Yucatan peninsula is extremely flat, and surrounded by water. It will weaken the system, but odds are against it completely falling apart.

Edit: That does depend on the speed at which it crosses though. That's assuming it continues at it's current forward speed.

Quoting sarahjola:
isn't it just going to fall apart if it makes landfall. it is a weak system and land would jusst rip it apart right?
Member Since: December 18, 2006 Posts: 7 Comments: 2686
1128. Levi32
Quoting Hurricanes101:


um dont you need a west wind to close a low though?



They found a west wind, light but they still have yet to leave the center. The next set of obs should show us a good batch of west winds if there are any.
Member Since: November 24, 2005 Posts: 635 Comments: 26647
1127. Patrap
Floater - Water Vapor Loop
Member Since: July 3, 2005 Posts: 424 Comments: 128271
Quoting StormW:


True, however one reason I'm inclined not to by the hook right now, is it appears it may cross the Yucatan Peninsula a little farther south than projected by the Dynamic model package.



Depends on the intensity. I was thinking more along the lines that a slow mover over high TCHP might ramp up quicker than forecast and a deeper system will pull up to the N sooner in a weak steering environment.

Several variables out there right now and perhaps a few surprises in store over the next 24 hours.
Member Since: August 19, 2006 Posts: 0 Comments: 15816
ECMWF mexico.
Member Since: January 30, 2005 Posts: 6 Comments: 750
Quoting ezcColony:
This system just will not spin up! Incredible!


Not spin up?? It's spinning up right now, convection around, over the center. Its probably a TD or TS by now. I'm calling for TS. Alex by 5 p.m.
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Quoting Levi32:


Still well over the criteria for a TD though.


um dont you need a west wind to close a low though?

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1120. Drakoen
Quoting StormW:


Agree! Afternoon Drak!


Afternoon StormW!
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Kman, StormW how are you all. Kman how is paradise. You were right in what you said last night. Looks like all the vegetables are in the pot and the heat is about ready to start cooking.

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1118. Skyepony (Mod)
Quoting Hardcoreweather2010:
I don't believe that I have ever seen 2 recon planes flying into an invest. One left MS and the other left Tampa. How often do they do this ?


The one from Tampa is NOAA's Kermit flying the Deepwater letting. They do it once a week, drop radio floats that helps nail the currents for oilcasts.
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Im out...

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1116. Levi32
Quoting Hurricanes101:
I dont see a pure west wind there and winds not over 30mph



Still well over the criteria for a TD though.
Member Since: November 24, 2005 Posts: 635 Comments: 26647
1115. cg2916
Did they find a non-closed area?
Member Since: December 21, 2007 Posts: 13 Comments: 3046
1114. bappit
Quoting Drakoen:
The central dense overcast of the system is really nice


Need a stronger system to talk about the CDO. Kind of meaningless right now I think.
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1112. leo305
Do you guys know how to add an avatar to your profile? A display pic?
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isn't it just going to fall apart if it makes landfall. it is a weak system and land would jusst rip it apart right?
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1109. Drakoen
Pressure 1005.5mb
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Quoting scottsvb:
HH is only looking for 35kt winds and higher right now...This will be classified @ 5pm.. probably TS Alex.Pressure is around 1004-1005mbs
bump
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93L kinda reminds me of Tropical Depression Sixteen (2008).

93L



Tropical Depression Sixteen


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This system just will not spin up! Incredible!
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1104. cg2916
Quoting Jeff9641:
Wager guys TD or TS at 5pm?


TD, 35 mph.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
1103. Drakoen
The central dense overcast of the system is really nice
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Not sure when he will be on, sometime between 1 and 4 today. www.wwl.com press listen live. Patrap do you have power? Heard most of Uptown is out.
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Quoting Jeff9641:
Wager guys TD or TS at 5pm?


neither lol
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Quoting scottsvb:
HH is only looking for 35kt winds and higher right now...This will be classified @ 5pm.. probably TS Alex.Pressure is around 1004-1005mbs
.bump
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1099. Skyepony (Mod)
Wind dropped to near nothing winds from the SE after, weak, not well stacked. Have to see if a dropsonde comes with that.
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I dont see a pure west wind there and winds not over 30mph

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HH is only looking for 35kt winds and higher right now...This will be classified @ 5pm.. probably TS Alex.Pressure is around 1004-1005mbs
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From 237° at 3 knots
(From the WSW at ~ 3.4 mph)
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1095. Patrap
Jeff Masters on the Spud Show a few weeks back talking and taking questions on Oil and Hurricanes.

Member Since: July 3, 2005 Posts: 424 Comments: 128271
Quoting Jeff9641:


Hey boss we have a strengthening storm and doing so quick now. Looks like TX or FL. What you think 50/50?


Your calling landfall areas already. That's funny...I guess your magic 8 ball is working over time.
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Quoting JamesSA:
LOL! And... how many people will die, and what are their names? We must warn them!


hahaha, now that's funny!!!
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Quoting Jeff9641:


Hey boss we have a strengthening storm and doing so quick now. Looks like TX or FL. What you think 50/50?


you need to chill out a bit, you are wishing this thing so hard into Florida, people in the Philippines can hear it lol
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1090. Levi32
Pressure was down to 1005.4mb north of the center.
Member Since: November 24, 2005 Posts: 635 Comments: 26647
Looks like they found a center
Member Since: September 23, 2005 Posts: 14 Comments: 11163
Quoting StSimonsIslandGAGuy:


I think someone's tinfoil hat is getting a bit too tight.


LOL, I am thinking of switching to a steel roof. :)
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1087. cg2916
Quoting StSimonsIslandGAGuy:


I think someone's tinfoil hat is getting a bit too tight.


LMAO
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Quoting StormW:


Hey kman! How are ya?


Pretty good today. Just watching events unfold.
Looks like a slow mover which is a worry with that TCHP. Plus, gives time for the steering to shift to the right.

Touch and go for the Northern GOM.
Member Since: August 19, 2006 Posts: 0 Comments: 15816
17:55:00Z 17.100N 83.117W 976.8 mb
(~ 28.84 inHg) 263 meters
(~ 863 feet) 1006.4 mb
(~ 29.72 inHg) - From 97° at 22 knots
(From the E at ~ 25.3 mph) 23.5°C
(~ 74.3°F) 23.5°C
(~ 74.3°F) 23 knots
(~ 26.4 mph) 22 knots
(~ 25.3 mph) 0 mm/hr
(~ 0 in/hr) 21.0 knots (~ 24.2 mph)
95.7%
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Quoting StormW:

I hear ya...I REALLY miss John Hope...he was da bomb!


Is that a good thing or bad, lol?
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1082. Skyepony (Mod)
1005.4mb with a 2 westward winds readings... 16.817N 83.117W
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Quoting cg2916:
Does anyone have a non-Google Earth version oir screenshots, I'm on my slow computer.


Link
Member Since: July 30, 2007 Posts: 76 Comments: 4063
1080. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 171 Comments: 53827
Thanks Storm, Gator, record. Hi Tex. :)
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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.