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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828. Gorty
Wow, the latest CMC is brutal with 93l although it is at 850mb.
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Quoting WPBHurricane05:


Right click the recon layer on the side (probably in places or layers) and click Get Info (or Properties if you run a Windows). Click the altitude box and slide the slider over to the right some. Eventually it should be higher than the clouds, just gotta play with it.


Nevermind...doesn't work like that. ;)
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825. unf97
Quoting CybrTeddy:


I live on the Gulf Coast, I know people who are being affected.. I've prayed every night for this oil to just go away.. the last thing we need is a Hurricane in the Gulf. Yet words can't stop it, only nature and God can. Its just been our tough luck that the BP oil spill happened on the verge of a possibly very active hurricane season in the Gulf of Mexico. Its not fair this is happening, peoples lives are being ruined already.. people know that on here.. I've not seen any wishcasting except from the newer bloggers who don't really understand the situation.


Well stated CybrTeddy. I pray daily for the many people on the Gulf Coast who have been or are currently being affected by this oil spill disaster in the GOM. It is devastating, and my heart goes out to everyone in that region. No one wants any tropical cyclone to come in and make things even worse to people along the Gulf Coast. We are only simply on this blog to observe and learn about the complexities of forecasting tropical weather. We have no control over how, when and where these tropical cyclones will eventually play out.

My heart and prayers go out to everyone to the the Gulf Region, and to other areas that have been impacted by natural disasters, i.e. The Earthquake in Haiti earlier this year, tornado victims etc...

I'm fairly confident that people on this blog are sensitive beings to what is going on.
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Quoting cg2916:
Are the HH finding a closed LLC yet?
Not yet, but ASCAT just did.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
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.

Hi I am here with Tony. Rest assured he is very sorry!
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Quoting IKE:


if it goes down the middle of that track it stays over land.


12Z CMC
That's a hurricane hitting southern Texas right there.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Hurricanes101:


In a few days maybe, right now it is interacting with the TUTT, but that TUTT is splitting in half and once 94L gets north of it, it will have favorable conditions and could develop



ok
Member Since: May 21, 2006 Posts: 5091 Comments: 114712
Quoting HaboobsRsweet:
latest I have is 1715z ob...anyone else have something newer? Seems mine hasnt updated for a bit.
1725 here
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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.


LOL. Too funny. PS. "I want my life back"
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93L looking less like a taranchula and more like a snail.GoesEastLoop
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The HH folks might have their hands full as another ball of convection is starting to fire to the North of the convection we have been looking at most of the morning......What we really need is a good fix on a COC so upcoming model runs can take another stab at it I think......
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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 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."
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Quoting Tazmanian:
94L looks good at this time may be come TD 2


In a few days maybe, right now it is interacting with the TUTT, but that TUTT is splitting in half and once 94L gets north of it, it will have favorable conditions and could develop
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Recon near the surface - 912 feet. Current location is:

17:25:00Z - 18.400N 84.317W

Still northwest of the 12z coordinates.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Are the HH finding a closed LLC yet?
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nevermind...closed and reopened and it refreshed finally.
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Quoting Orcasystems:


Use the Global Cloud link, it is capable of being transparent.


Global Cloud link? How do I get there?
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808. JRRP
CMC
Link
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Quoting TerraNova:


Ive been away for a while, is recon already there or are they on their way?


Yup. Probably around the center within the next hour.
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1007 mb, 25 mph winds now. Getting close.
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Quoting Grothar:


Woops, wrong image bet you still will never guess, atmo:



Gee, given that the image is hosted at www.heidelberg.edu , well...
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Quoting Patrap:
Floater - Visible Loop


Why are the last 6 frames blank??
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latest I have is 1715z ob...anyone else have something newer? Seems mine hasnt updated for a bit.
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802. IKE
Quoting StormW:


if it goes down the middle of that track it stays over land.


12Z CMC
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Quoting Tazmanian:
whats the news on 94L


According to Fox News its in the Gulf, and if it gets too 73MPH it COULD be a hurricane.

http://www.foxnews.com/scitech/2010/06/25/hurricane-season-building-gulf/?test=latestnews

lol
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its not going too hit Belize
Member Since: May 21, 2006 Posts: 5091 Comments: 114712
Quoting HurricaneSwirl:


Repost.


Right click the recon layer on the side (probably in places or layers) and click Get Info (or Properties if you run a Windows). Click the altitude box and slide the slider over to the right some. Eventually it should be higher than the clouds, just gotta play with it.
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94L looks good at this time may be come TD 2
Member Since: May 21, 2006 Posts: 5091 Comments: 114712
Wake up in the morning feeling like 93L
(Hey, what up Invest?)
Put my glasses on, Im on the GFS - Im gonna hit this Run(Lets go)
Before I log on, brush my teeth with a bottle of Capri Sun
Cause when I post for the night, I aim to be Number one

Im talking - mjo on our, toes, Blows
Trying on all our GOES,GOES
Post's blowing up our phones, phones
Drop-toping, playing our favorite cds
Pulling up to the Blog-sies
Trying to get a little bit tipsy..
Member Since: July 3, 2005 Posts: 420 Comments: 127543
Quoting Skyepony:
Fresh ASCAT


That's WAY west of what they were projecting for a center for the HH flight and pretty much throws the OFCL track forecast into a cocked hat.

It's also a lot south of what was projected for tomorrow's flight, so Bastardi's Belize hit is looking quite a bit more likely.
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1007.9 mb reported:

17:09:30Z 19.333N 84.900W 589.5 mb
(~ 17.41 inHg) 4,564 meters
(~ 14,974 feet) 1007.2 mb
(~ 29.74 inHg)
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Well, let's hope 93L doesn't pull any funny business, ramp up on steroids and move NE.
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Quoting HurricaneSwirl:


Repost.


Use the Global Cloud link, it is capable of being transparent.
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It could possibly be Alex right now.
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Quoting WPBHurricane05:
Just gotta wait for that first Vortex data message.


Ive been away for a while, is recon already there or are they on their way?
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Quoting Stormchaser2007:
Das a purty TS...

Agreed.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
786. sigh
Quoting Grothar:


Woops, wrong image bet you still will never guess, atmo:




Yeah, I'm going to go out on a limb here and guess that's Heidelberg University.
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Quoting Orcasystems:


Nope, but they did tell me how to turn them off so I could post them :)


Yup, the logos and branding you can't use legally, but the NOAA and NHC products are all public domain data. WU is probably the largest mashup (aka scraper) site of public domain data on earth.
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Das a purty TS...

Member Since: June 9, 2007 Posts: 4 Comments: 15776
Quoting nash28:
That would be too funny Pat if it weren't disturbingly true.


a lil Tony Phun is good fer a Friday afternoon
Member Since: July 3, 2005 Posts: 420 Comments: 127543
Quoting HurricaneSwirl:
Hey guys can someone answer my new question about Google Earth? How can I set the clouds BEHIND the recon data? I can't see the darn bobs because the clouds are covering it. How do I change up what goes behind what and what covers what?


Repost.
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Quoting stillwaiting:
i'm thinking a td1 upgrade at 2pm.....
NHC is going to wait for Recon to investigate before making any official calls.
Member Since: September 2, 2009 Posts: 130 Comments: 21091

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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.