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 Jeff9641:
For people that don't by the sharp right turn might want to look at the GFDL and HWRF which both have the best track record with tropical systems. An upper low is progged to dive SE from the Great Lakes early next week and enhance a trough in the eastern us. A Stronger system will feel this and swing N then NE as Doc mentioned. Doc hit it right on.


Their still models and its a little while out still, it will change.
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Shucks I never keep a NHC tab open,

Cuz soon as sumthing new pops up.,

We get the UPS delivery here really fast
Member Since: July 3, 2005 Posts: 423 Comments: 127803
Quoting cg2916:
The NHC site crashed for me!
Mine too.
Member Since: September 2, 2009 Posts: 130 Comments: 21098
Mine too. Not good!
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The NHC site crashed for me!
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Quoting JamesSA:

"I would like to assure you that we tested our hurricane response plan Wednesday. We unhooked everything and let the oil spew uncontrolled into the Gulf while dumping tons of toxic dispersant to hide as much of it as possible. The plan worked flawlessly.

I would like to assure everyone again that we are fully ready to execute this plan for weeks if necessary in the event of a hurricane.

Now why don't you little people leave me alone and let me get my life back."


Unless you think that helps in some way. I'm tired of it, give it a rest.

Heyward is not leading the response team any more...so who cares. All we care about down here is stop it, then clean it up. The rest, including all jokes, mockery, lawsuits, head-games, you all can have fun with that later.

Sorry if that offends..we've just heard enough.
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Quoting Drakoen:
93L continues to get better organized convectively
ASCAT just revealed a well-defined closed surface circulation. I myself would be very surprised if we do not get TD #1 today.
Member Since: September 2, 2009 Posts: 130 Comments: 21098
Models should improve after data from recon is factored in.
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CMC goes right over Patrap.
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The storm has developed a surface circulation near 16.5N, 82.5W at 8am EDT, about 100 miles northeast of the Nicaragua/Honduras border
Member Since: July 3, 2005 Posts: 423 Comments: 127803
Quoting WPBHurricane05:


Yup. Probably around the center within the next hour.


Thanks!

I fully expect they'll find a depression. If current trends continue i think we'll see this thing designated by tonight.
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GFS does have a history of over amplifying troughs. The ECMWF westerly track is a better bet in my opinion.
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Quoting WPBHurricane05:


NHC will issue an update shortly.

Hurricane Hunters are currently investigating the system. If they find a closed circulation (tropical depression) they will issue a Vortex Data Message. Should one be issued, you'll see it posted about 10 times here (lol).


LOL, true, plus the TWO.
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863. IKE
Quoting weathermanwannabe:


Thanks Ike.....Right over my house......


LOL...sorry.
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Quoting utilaeastwind:


Going to watch Honduras beat Swiss in the World Cup and will let you know how the weather is at 16.1N 86.9W at 4:30ET.


Okay, good luck!
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93L continues to get better organized convectively
Member Since: October 28, 2006 Posts: 57 Comments: 30084
im seeing 1009.7mb on google earth.. still pretty low w/o being near coc yet.
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Guys chill on the NHC page LOL. We're clicking F5 so much that its starting to overload the site!
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Quoting WPBHurricane05:


NHC will issue an update shortly.

Hurricane Hunters are currently investigating the system. If they find a closed circulation (tropical depression) they will issue a Vortex Data Message. Should one be issued, you'll see it posted about 10 times here (lol).


There been a closed Low for some time now.

So thats not accurate for sure.
Member Since: July 3, 2005 Posts: 423 Comments: 127803
Quoting bappit:


From the Doctor's blog today: "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."

So it has had a closed circulation for a while (since yesterday IMHO). The question is has it tightened up or not (see Archie Bell and the Drells).
Circulation today looks much more consolidated than yesterday on ASCAT, 850mb vorticity, and satellite imagery.
Member Since: September 2, 2009 Posts: 130 Comments: 21098
855. IKE
Quoting btwntx08:
both gfdl and hwrf are outlier at this point they seem that they cant make their minds up</em>


They've been consistent the entire time!

The CMC is the one that's flip-flopped at least a couple of times. How come you don't mention that?
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Well Ike - that doesn't look too good for you or me. Yikes!
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853. xcool
I'M WAIT FOR NEW Data FROM RECON
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Quoting Michaelkaii10:
Hey im new To This
Been Listing To the Barotmeter Bob Show So i mite kno people From it on This

what Time is the Next Update About 93L?


NHC will issue an update shortly.

Hurricane Hunters are currently investigating the system. If they find a closed circulation (tropical depression) they will issue a Vortex Data Message. Should one be issued, you'll see it posted about 10 times here (lol).
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GFDL still sticking on to that trough being strong enough to pull 93L NE towards Florida on this run. Other models just build the ridge back in and 93L continues in a WNW-NW direction the next couple of days.
Member Since: July 8, 2005 Posts: 259 Comments: 23855
im seeing 1009.7mb on google earth.. still pretty low w/o being near coc yet.
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Quoting StormW:
Back.


Am I the only one that whenever I see StormW check in I feel like yelling "Storm", kinda like they yelled "Norm" on Cheers?

Quick question...I know that 93L is forecast to go over the Yucatan or the Channel, but if it slid east a bit, what is the geography of western Cuba? As mountainous as the East? Thanks!
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Quoting JRRP:


All models now forecasting a La Nina, some making it strong.
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Quoting MiamiHurricanes09:
No, but ASCAT just did.


From the Doctor's blog today: "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."

So it has had a closed circulation for a while (since yesterday IMHO). The question is has it tightened up or not (see Archie Bell and the Drells).
Member Since: May 18, 2006 Posts: 10 Comments: 5995
846. IKE
GFS vol. 1 and the GFDL want no part of 93L heading to Texas/Mexico...also the HWRF.
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Quoting IKE:
12Z GFDL on 93L


Thanks Ike.....Right over my house......
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Quoting Patrap:
Hi,.Im Tony Hayward talking to you from Sweden where Im relaxing and Skiing with my Family.

We at BP have a Hurricane Response Plan Ready to Implement in case of a Hurricane or Tropical Storm Emergency.

Rest assured,..were going to make this right.


I was to meet with obama over the weekend to discuss but he had a tee time to make and then dancing with michelle
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Hey im new To This
Been Listing To the Barotmeter Bob Show So i mite kno people From it on This

what Time is the Next Update About 93L?
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Quoting xcool:
12z HWRF take to MS .GFLD TAKE TO FL


still think the models are being conservative
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840. JRRP
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839. IKE
12Z GFDL on 93L
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Floater - Rainbow Color Infrared Loop
Member Since: July 3, 2005 Posts: 423 Comments: 127803
they are reporting a 1007mb pressure that far away from the center? LOL
Member Since: April 17, 2010 Posts: 0 Comments: 1753
836. xcool
12z HWRF take to MS .GFLD TAKE TO FL
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Quoting Thundercloud01221991:
They are flying right in to the COC.
Member Since: September 2, 2009 Posts: 130 Comments: 21098
Quoting Chicklit:

Please keep in touch with us if you can.
I expect the floater to relocate north.


Going to watch Honduras beat Swiss in the World Cup and will let you know how the weather is at 16.1N 86.9W at 4:30ET.

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Quoting HurricaneSwirl:


Global Cloud link? How do I get there?


Link
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93L is getting it act together quick now. wow..
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EPAC TWO out, should see the ATL TWO shortly.
Member Since: July 8, 2005 Posts: 259 Comments: 23855

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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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