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 leo305:


what do you mean nothing is expected of development now? The TUTT is over cuba and in the southern gulf.. there is a huge anticyclone over 93L, How can it not develop, it's firing up convection as DMIN takes place too


he is talking about 94L, not 93L

either way though once 94L gets on the northern side of the TUTT it will have favorable conditions
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Quoting robie1conobie:
yeah, and when you think about it; La, Miss. and Ala. are the one's who allow drilling off the coast. Florida has been in a constant battle to stop it. So, they wanted oil, they can have it!
Whos they?
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Quoting weatherblog:


Exactly, I don't know where he's getting subtropical from..
It is unlikely but considering that it could run into some cold waters into the mid to long term you aren't going to get a warm cored system.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I have no doubt theres a closed low

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Quoting leo305:


what do you mean nothing is expected of development now? The TUTT is over cuba and in the southern gulf.. there is a huge anticyclone over 93L, How can it not develop, it's firing up convection as DMIN takes place too


Wrong system Dude....He's talking about 94L....:)
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273. IKE
From the Jackson, Mississippi weather office....

"A POTENTIAL FORECAST UNCERTAINTY EXISTS FOR NEXT WEEK...AND IT IS IN
REGARDS TO THE TROPICAL WAVE CURRENTLY TRACKING WESTWARD ACROSS THE
WESTERN CARIBBEAN. A CLOSED CIRCULATION HAS RECENTLY BECOME ROOTED
AT THE SURFACE...WITH A 1006 MB SURFACE LOW IDENTIFIED ALONG THE
WAVE APPROACHING NICARAGUA AND HONDURAS. RECENT INFRARED SATELLITE
IMAGERY INDICATES MULTIPLE BANDS OF CONVECTION ALONG AND JUST TO THE
EAST OF THE SURFACE WAVE AXIS. THE CONVECTION HAS BECOME MORE
PERSISTENT IN CLOSER PROXIMITY TO THE LOW-LEVEL CIRCULATION DURING
THE PAST DAY. SIMILAR CONVECTIVE TRENDS ARE EXPECTED TO CONTINUE
DURING THE COUPLE DAYS AS THE SYSTEM ENCOUNTERS WEAK VERTICAL WIND
SHEAR AND SLIGHTLY DIFFLUENT UPPER-LEVEL EASTERLY FLOW. THIS COULD
AID IN ADDITIONAL CYCLOGENESIS. THE NHC IS CURRENTLY INDICATING THAT
THERE IS A HIGH CHANCE...60 PERCENT...OF THIS SYSTEM DEVELOPING INTO
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS THE LOW DRIFTS SLOWLY
NORTHWESTWARD. MOST OF THE NHC TRACK MODELS TAKE THE LOW INTO THE
NORTHWEST CARIBBEAN THROUGH THE WEEKEND...BUT SIGNIFICANTLY DIVERGE
THEREAFTER INTO TWO MAIN GROUPS. ONE GROUP OF MODELS TAKES THE LOW
TRACK NORTHWESTWARD ACROSS THE YUCATAN PENINSULA INTO THE WESTERN
GULF OF MEXICO NEXT WEEK. THIS GROUP OF MODELS IS LIKELY RESPONDING
TO GREATER MID/UPPER-LEVEL RIDGING BETWEEN THE SYSTEM AND A LESS-
AMPLIFIED MID-LATITUDE TROUGH. THE OTHER GROUP OF MODELS INDICATES
THE LOW TRACK CURVING NORTHWARD AND THEN NORTH-NORTHEASTWARD FROM THE
YUCATAN CHANNEL INTO THE CENTRAL GULF NEXT WEEK IN RESPONSE TO
GREATER AMPLIFICATION OF THE UPPER TROUGH. THE OVERALL EVOLUTION OF
THIS SYSTEM REMAINS VERY UNCERTAIN...ESPECIALLY GIVEN UNCERTAINTIES
IN THE DEGREE OF AMPLIFICATION OF THE MID-LATITUDE TROUGH.

HOWEVER...BOTH GROUPS OF TRACK MODELS SUGGEST SOME POTENTIAL FOR THE
LOW TO AFFECT THE WEATHER ACROSS THE ARKLAMISS REGION NEXT
WEEK...WITH HIGHER PRECIP CHANCES.?
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting unf97:
The TUTT in place right now is not going to move out very fast for 94L to develop. Now, I have been long enough to know that these forecasts can change, so if the TUTT can get displaced enough in the next couple of days and if indeed the shear can relax enough, then 94L can possibly get its act together by the first of next week.

Like I mentioned earlier, nothing is expected in development now, but we all will closely monitor it during this weekend.


what do you mean nothing is expected of development now? The TUTT is over cuba and in the southern gulf.. there is a huge anticyclone over 93L, How can it not develop, it's firing up convection as DMIN takes place too
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Quoting extreme236:


It would be very unlikely to see anything subtropical since the formation of this system is in part due to a tropical wave.


Exactly, I don't know where he's getting subtropical from..
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Quoting hurrkat05:
hurricanjun negative if it goes east of biloxi it will pull all the oil out of se la but it will increase the threat to the florida beaches and will get in the gulf stream not good for florida..
yeah, and when you think about it; La, Miss. and Ala. are the one's who allow drilling off the coast. Florida has been in a constant battle to stop it. So, they wanted oil, they can have it!
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Recon is on the way

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Quoting IKE:
Birmingham,AL weather office on the trough/cold front....

"BY MON...OUR 2ND FRONTAL SYSTEM MAKES ITS WAY INTO KY/TN/AR
AREAS. BY THIS TIME...WEAK SRLY FLOW IN THE UPPER LEVELS WITH
TRANSITION AS THE BASE OF THE UPPER LONGWAVE TROUGH MOVES ACROSS
THE SE STATES WITH A COUPLE OF EMBEDDED SHORTWAVES AS WELL...STILL
WITH GOOD LOW LEVEL INFLUX OF MOISTURE. BY TUE...FRONT IS EXPECTED
TO MAKE ITS WAY INTO AL SLOWLY MEANDERING THROUGH THE STATE AS
UPPER FLOW CHANGES TO NW TO HELP KICK IT THROUGH BY WED. NOT ALL
MODELS ARE AGREEING TO THIS CONSENSUS...BUT LEANING TOWARD FRONT
MAKING IT A GOOD WAY INTO THE STATE WITH DECENT UPPER LEVEL
SUPPORT...MOST LIKELY STALLING ALONG THE COAST WED...ON INTO THE
LATTER PART OF NEXT WEEK."
what does this mean for the track of a possible future developed TC?
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266. Gorty
How come the SHIPS model is always so intense with an invest? It seems to always show an invest strenghining rapidly.
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recon on the way . two hours out
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Quoting PensacolaDoug:



Dude! Not here.......
LMAO!!
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting CaptainUnderpants:
are there any girls on this site interested in dating a 24 year old single weather guy?


Talk about a tropical depression?
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Quoting CaptainUnderpants:
are there any girls on this site interested in dating a 24 year old single weather guy?



Dude! Not here.......
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L symbol looks about right. Still a broad circulation, look at the band all the way by the Yucatan.

Probably be a TD tonight. Obviously depends on recon.
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One thing is certain; the tropical atlantic is starting to wake up, and, in accordance with the MJO pulse mentioned by others and Dr. M....I think the most interesting question, as Dr. M and others have mentioned that current conditions appear several weeks ahead of schedule, is whether we might see a higher number of storms, than the climatological average, in late-June/early July; that would be a really bad sign for the peak of the season come August and September if this happens.
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Latest coordinates on Recon:

15:25:00Z 27.633N 88.900W 376.2 mb
(~ 11.11 inHg) 8,070 meters
(~ 26,476 feet) - 454 meters
(~ 1,490 feet) From 144° at 11 knots
(From the SE at ~ 12.6 mph) -21.9°C
(~ -7.4°F) -21.9°C
(~ -7.4°F) 11 knots
(~ 12.6 mph) - - - -
Member Since: September 2, 2009 Posts: 130 Comments: 21194
257. unf97
The TUTT in place right now is not going to move out very fast for 94L to develop. Now, I have been around long enough to know that these forecasts can change, so if the TUTT can get displaced enough in the next couple of days and if indeed the shear can relax enough, then 94L can possibly get its act together by the first of next week.

Like I mentioned earlier, nothing is expected in development now, but we all will closely monitor it during this weekend.
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I don't think this thing is going to make landfall anywhere east of Pensacola, and I'm tending to support TX. It's difficult to believe in an intense trough this time of year. Maybe that is wishcasting, in fact I'm sure it is, but I just do not want to forecast a direct TS/Hurr "OIL"ex strike on the central Gulf Coast when there is another possibility.
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Quoting ATL:

Basis for this? All model guidance is pointing to a Yucatan crossing.


Not all of it. The HRWF has it threading the needle between cuba and the yucatan. Models aren't very reliable at this point, they are more useful once it develops.
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254. IKE
Birmingham,AL weather office on the trough/cold front....

"BY MON...OUR 2ND FRONTAL SYSTEM MAKES ITS WAY INTO KY/TN/AR
AREAS. BY THIS TIME...WEAK SRLY FLOW IN THE UPPER LEVELS WITH
TRANSITION AS THE BASE OF THE UPPER LONGWAVE TROUGH MOVES ACROSS
THE SE STATES WITH A COUPLE OF EMBEDDED SHORTWAVES AS WELL...STILL
WITH GOOD LOW LEVEL INFLUX OF MOISTURE. BY TUE...FRONT IS EXPECTED
TO MAKE ITS WAY INTO AL SLOWLY MEANDERING THROUGH THE STATE AS
UPPER FLOW CHANGES TO NW TO HELP KICK IT THROUGH BY WED. NOT ALL
MODELS ARE AGREEING TO THIS CONSENSUS...BUT LEANING TOWARD FRONT
MAKING IT A GOOD WAY INTO THE STATE WITH DECENT UPPER LEVEL
SUPPORT...MOST LIKELY STALLING ALONG THE COAST WED...ON INTO THE
LATTER PART OF NEXT WEEK."
Member Since: June 9, 2005 Posts: 23 Comments: 37858
There is one thing about this setup that is the wildcard for 93L.

If it can organize quickly into TS Alex AND if it can somehow manage to only cross a small portion of the YucPen AND if the storm is not too disrupted and can reform into a very organized system THEN since the GoM is hot water, Alex's intensity level at landfall could still be as a major category hurricane.
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Quoting Stormchaser2007:
Thats a developing TC if I've ever seen one...
93L or 94L? Lol, 93L definitely improving on sat.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Jeff9641:


Hey buddy thanks for unpoofing me. Things look interesting down the road my friend as to where he will go east or west seem to be the model camps.


And we have 94L
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Quoting WinterAnalystwx13:


For all we know, it could very well be 40 m/h. We will have to see what they find.

I see we have 94L now...Not a major threat to land besides Bermuda. We'll see 95L eventually, likely from the tropical wave off the African Coast. Rotation is already evident, and a broad area of Low Pressure was found yesterday. Hurricane Season 2010 has officially started...

Morning All
Yup.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
12Z NAM is starting to hint on the trough being strong enough to stall 93L in the Central Gulf and possibly in induce a more NNE to NE movement.

Will be interesting to see how 12Z GFS/ECMWF deal with this trough and 93L strength.

One thing is for sure... 00Z runs should be more accurate as to the initialization of 93L (possibly TD#1), so definitely looking forward to those.
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Quoting Stormchaser2007:
Thats a developing TC if I've ever seen one...


ECMWF deserves huge props, pegged development from long range
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Thats a developing TC if I've ever seen one...
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http://www.ssd.noaa.gov/goes/flt/t1/flash-vis.html
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Quoting extreme236:


Well it will be interesting to see how strong the HH find 93L. Based on the available data, it's organization isn't terribly impressive yet. 17:45utc numbers should be higher though.
I would expect so. Satellite presentation has improved somewhat in the past couple hours and in my opinion should see a T-number of 1.5 at 17:45 UTC.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I am sorry, I meant if it goes west of us.
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not all the model are pointing to the yucatan a few are pointing betwwen the yuc and cuba and the models are more and more shifting to the east plus this time of year you would expect tracks like this and head to Fl
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94L

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Quoting MiamiHurricanes09:
We would need a very consolidated closed low for a TS. Pressure is that of TS status but winds are only at 35mph.


Yes. We need a closed low. Winds are at TD strength though, so that is taken care of.
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Reconnaissance aircraft coordinates as of 15:15 UTC (11:15 AM EDT) are:

28.450N 89.200W
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting ATL:

Basis for this? All model guidance is pointing to a Yucatan crossing.


bases? Look at the visible satellite, its moving N/NNW right now.. btw.. this thing is over VERY HOT WATERS, once it gets a tight closed low... there is nothing that will stop this from becoming a hurricane.

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Quoting MiamiHurricanes09:
We would need a very consolidated closed low for a TS. Pressure is that of TS status but winds are only at 35mph.


Well it will be interesting to see how strong the HH find 93L. Based on the available data, it's organization isn't terribly impressive yet. 17:45utc numbers should be higher though.
Member Since: August 2, 2007 Posts: 19 Comments: 19234

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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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