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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93L IMO has the potential to be a serious Gulf Coast threat as long as the shear remains low. I could easily see a hurricane in the Gulf.
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Quoting Stormchaser2007:
And they're off!

They're probably currently looking out of the windows commenting on the large area of oil in the water :/
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Could that 'extra' blob south of Haiti become 95L?
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Quoting extreme236:


A tropical wave interacting with the TUTT. Fairly common disturbance.


Agree...............
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Quoting Stormchaser2007:
Here we go...



A tropical wave interacting with the TUTT. Fairly common disturbance.
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we have a storm blowing up right over the center of the future TD here... watch to see how large it gets
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Recon currently 36 miles SSW of Gulfport, MS.
Member Since: July 8, 2005 Posts: 259 Comments: 23618
Quoting FLWeatherFreak91:
Right, it allows computer models run earlier and also keeps the storm out of the public's eye. No one tracks invests except us lol.
LOL!
Member Since: September 2, 2009 Posts: 130 Comments: 21091
113. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Invest 94, while firing a good amount of convection, is about to run into a wall of 30-50 knots of sheer and right on the boundry and very close to the TUTT......I would not get too excited about this one at the moment.
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And they're off!

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Remember - preliminary track and intensity forecasts are subject to large errors.

For example, the NHC only had Darby reaching TS strength, and here it is now as a major hurricane.
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109. BDAwx
Quoting sammywammybamy:
What are the Models saying about 94L , are they saying it will stay out to sea. Hopefully Away from the Us or Bermuda?


to be honest, if it stays weak please send it to bermuda - we could reeaaally use the rain...
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108. jpsb
Quoting Patrap:
That looks like the worst case scenario, tarcane. Anything but that!
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I think 94L will be orange circle at the next update with a 30% risk although it could only be 20%
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Quoting 69Viking:


Good morning Flood! Been lurking this morning for a while and I have to ask, did you give the kids at daycare access to the Blog or was that someone else?

BTW, good update Doc!


I have the little monsters in a morning long time out...must have been someone else...LOL
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Quoting cchsweatherman:


Thats most likely the reasoning behind declaring all these invests. Its not a bad idea in my opinion since it allows for computer models to be run on systems and as we have seen several times before, you just never know what systems may have in store.
Right, it allows computer models run earlier and also keeps the storm out of the public's eye. No one tracks invests except us lol.
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Recon is on! Starting to get Data
Link
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Here we go...

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99. IKE
Floater with "fronts" checked, puts the center at near 17N and about 82.2W.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Can someone tell me when recon will have data posted for the morning flight? I realize it will take them time to get there, gather the data, etc. Just wanted to know if there is an approximate time I should check back...

Thanks.
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I just posted my blog, I'm going to have to include 94L in my update later today.
Link
Member Since: July 8, 2005 Posts: 259 Comments: 23618
Invest 94
Wind: 30 MPH — Location: 17.8 57.8W — Movement: NW
This area of disturbed weather has the potential for tropical development.
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A cell is bursting very quickly right around the purported center (as per Dr. M's posting).
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Quoting Patrap:


You trying to jinx us?
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89. jpsb
Question, your home gets destroyed by a hurricane (Ike) and you collect flood insurance, basically the insurance company 'bought' your house. Then a few years later another cane hits your house will the insurance company "buy" your house again, or will it say "hey wait a minute: we paid off once we are not going to pay off twice. thx in advance.
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Quoting FLWeatherFreak91:
Yes. That is directly from 93l... See all the moisture to its east in the central Caribbean? All of that is going to be pulled northward over Florida.


Wow...that's amazing. Woulda been nicer if it happened on a Monday though! ;-)

Thanks for the response.
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Quoting extreme236:
They seem to be declaring invests much more liberally this year than most. Probably to get an early feel on these systems with potential down the road.


Thats most likely the reasoning behind declaring all these invests. Its not a bad idea in my opinion since it allows for computer models to be run on systems and as we have seen several times before, you just never know what systems may have in store.
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86. IKE
Quoting Patrap:


Being honest...that could be close to this one's landfall. Then again, it could be hundreds of miles off.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Stormchaser2007:
We have 94L

invest_al942010.invest

178N, 578W
I was thinking within 48 hours and we got it in 2, lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Stormchaser2007:
We have 94L

invest_al942010.invest

178N, 578W


Wow, two things to track.
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82. IKE
NAM also has it going just east of north on the end of the latest run.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Invest 94L

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Quoting extreme236:
They seem to be declaring invests much more liberally this year than most. Probably to get an early feel on these systems with potential down the road.


Yeah I've noticed that as well. Almost every system with a chance of 10% or higher is declared an invest.
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Quoting Floodman:
Thanks, Doc!


Good morning Flood! Been lurking this morning for a while and I have to ask, did you give the kids at daycare access to the Blog or was that someone else?

BTW, good update Doc!
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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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