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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3629. scott39
Quoting MiamiHurricanes09:
Yes, why?
You seem older than your Quotes.
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3627. uplater
Quoting MiamiHurricanes09:
Yes, why?


prolly because the maturity with which you analyze trends in the ocean and on the internet seriously belies your real age! =)
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3626. Gorty
Quoting MZV:
Running out of chances to see this on visible. Looks like the CDO has been fleshing out just before sunset, though:


Wow, that TD is big! Plus, the whole thing is so organized it looks more like a TS!
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Quoting cg2916:
TD 1 is the size of a hurricane!
Stupid comment, Hurricanes come in all sizes, many smaller, some bigger.
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Quoting taco2me61:
Channel 15 News broke in on Friday Night Lights and said that about 5 min ago....


ugh, was really, really hoping you were wrong lol
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TS is pretty immanent.
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I think you will see TS Alex emerge from the intense convection currently at 16.80N 84.0W.

Very Soon!
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What I wonder is how big the wind field will be once it grows up. Hopefully not the size of Special K of 2005.
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3619. scott39
Quoting Snowlover123:


What do you think?
I think KaBoom!
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3618. MZV
Running out of chances to see this on visible. Looks like the CDO has been fleshing out just before sunset, though:
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Quoting scott39:
Are you really 13?
Yes, why?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting PcolaJess:


where did you see that?
Channel 15 News broke in on Friday Night Lights and said that about 5 min ago....
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Quoting Weather456:
I see we have TD 1.

Welcome back Weather456, I trust you are feeling better now and on your way to a speedy recovery.
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3614. scott39
Quoting MiamiHurricanes09:
Utter insanity will take over the blog.
Are you really 13?
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Quoting CybrTeddy:
TAFB gave TD-1 a 3.0
SAB gave TD-1 a 2.5

I don't know about you guys.. but I think we're dealing with a TS right now.
I would agree.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
6136 comments and 41 entries posted by all members in the last 24 hours.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting scott39:
Whats going to happen with TD/1 when it lands in the GOM and theres no land interaction?


What do you think?
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Quoting scott39:
Whats going to happen with TD/1 when it lands in the GOM and theres no land interaction?


No one knows yet. Even the NHC seems uncertain.

EDIT: Oh, you mean with regards to intensity? Still, no one knows. Probably gradual intensification, though.
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Quoting uplater:


The Rainbow show the Water Vapor in the region/AOI ( Area of Interest ), look for the funktop/IR ( infrared ) to see the temperature.


Okay, I'll go look.

Uh oh, I'm fixin' to get a storm. There are some big, black clouds to the northeast. I'll be back.

Thanks again for all your help!
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TAFB gave TD-1 a 3.0
SAB gave TD-1 a 2.5

I don't know about you guys.. but I think we're dealing with a TS right now.
Member Since: July 8, 2005 Posts: 259 Comments: 24575
3607. scott39
Whats going to happen with TD/1 when it lands in the GOM and theres no land interaction?
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Quoting Tazmanian:



this wait in tell this gets in too the gulf will have like 500 too 1,000 commets an hr
Utter insanity will take over the blog.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
3605. IKE
Junior in his prime....

Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting MiamiHurricanes09:
3,600 comments in 10 hours. If you average it out that means there was an average of 360 comments an hour and 6 comments a minute. I gotta tell ya this is gonna be one helluva year.



YAY 09 was are 3600 post commet
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Quoting weatherman566:
Just curious, but can anyone read anything I have posted? I'm starting to feel as if I am being blocked. ???

I cannot see you...
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Quoting MiamiHurricanes09:
3,600 comments in 10 hours. If you average it out that means there was an average of 360 comments an hour and 6 comments a minute. I gotta tell ya this is gonna be one helluva year.



this wait in tell this gets in too the gulf will have like 500 too 1,000 commets an hr
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Quoting bappit:


Been on some of those flights have you?
No, why?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
3,600 comments in 10 hours. If you average it out that means there was an average of 360 comments an hour and 6 comments a minute. I gotta tell ya this is gonna be one helluva year.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting taco2me61:
oh by the way BP is now stopping all collections in the Gulf due to the storm....

NOW stopping or will stop if needed?
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3598. bappit
Quoting MiamiHurricanes09:
Not when dealing with a relatively weak system like 01L, but when they send you to do those missions with strong hurricanes, then those are scary.


Been on some of those flights have you?
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The CLP5 has held it's own throughout the entire development. Corpus continues to look like ground zero for me.
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Quoting JamesSA:

This thing just keeps getting bigger. If it strengthens beyond a TS it is going to be a real problem.


Size comparison:

Ike 2008:


Bill 2009:


Compare Alex 2010:
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And to add, reedzone... pretty strong too. Some of the world's strongest tropical cyclones were formed in the WestPac
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3593. IKE
Quoting weatherman566:
Just curious, but can anyone read anything I have posted? I'm starting to feel as if I am being blocked. ???


I see em. When there's so many posts per minute on here it's hard to get questions answered sometimes.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting taco2me61:
oh by the way BP is now stopping all collections in the Gulf due to the storm....


where did you see that?
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cat 5 by morning then heading to the gulf for a oil change
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3589. uplater
Quoting weatherwart:


I was looking at the Rainbow. Which is the one I should be looking at?


The Rainbow show the Water Vapor in the region/AOI ( Area of Interest ), look for the funktop/IR ( infrared ) to see the temperature.
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Quoting extreme236:
SAB gave out a DT of 2.5, so I'd say were definitely dealing with a tropical storm now. Whether it's declared at 11 I don't know.
Could be, although unlikely.

T-Number 2.0: 30 knot winds - pressure of 1009mb.
T-Number 2.5: 35 knot winds - pressure of 1005mb.
T-Number 3.0: 45 knot winds - pressure of 1000mb.

TS Alex at 11PM or sooner is almost certain.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
talking about the Western Pacific i think this is now the 1st time the Western Pacific has not had a storm in june
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Folks the reason why TD1 is big is because it has the characteristics of a Western Pacific Storm. There was soo much energy in the Caribbean, it lead to this monsoonal depression. As with typhoon development, it takes a long time (days) for a disturbance out there to organize into a storm. This is what happened with what is now TD1. The only thing I wonder is.. Once a system forms in the West Pacific, they get going pretty quick, so TD1 comes into mind. I am treating it like a Western Pacific storm, I feel that this may be on the verge or at Hurricane strength come landfall at the Yucatan.
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Quoting taco2me61:
oh by the way BP is now stopping all collections in the Gulf due to the storm....



link please???
Member Since: August 1, 2006 Posts: 28 Comments: 3716
3583. uplater
Quoting CaneWarning:


I can't see you.


why didn't I think of that
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Quoting uplater:


Literally. you may have been looking at the water vapor images/loops. Different Subject. Colors represent diff. scale.


I was looking at the Rainbow. Which is the one I should be looking at?
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Weather456 "I see we have TD 1."

Waiting with bated breath for your return, twas 93L. And TD1 is its sigh of relief.
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Quoting weatherman566:
Just curious, but can anyone read anything I have posted? I'm starting to feel as if I am being blocked. ???


I can't see you.
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Quoting CaicosRetiredSailor:
Good Night:



How.. How is that even possible in the atlantic?
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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.

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