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 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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Member Since: July 3, 2005 Posts: 428 Comments: 129903
AL, 94, 2010062512, , BEST, 0, 178N, 578W, 25, 1013, DB
Member Since: August 2, 2007 Posts: 19 Comments: 19234
94L already?
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Quoting CaneWarning:
Wow StormW, so you think the Big Bend area of FL is possible with 93L?


If that does happen, then it could affect Ocala, my favorite city!
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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.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
70. IKE
NAM appears a little stronger on the trough this run. That trough and the strength of 93L are key.

Add the path it takes across the Yucatan.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Get ready for the real kick-off for the Atlantic! 93L almost a TD....now 94L....

11:00 am National Hurricane Center Update
**GRAPHICS UPDATE



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Quoting Stormchaser2007:
We have 94L

invest_al942010.invest

178N, 578W


Wow. Is that for the Leeward Islands wave?
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Hurricane Hunter recon has departed from Biloxi, MS and is now outbound to Invest 93L.
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Im a liking the scenario of Lili in 02 and Isadore 02.

Member Since: July 3, 2005 Posts: 428 Comments: 129903
64. IKE
Quoting CaneWarning:


Wouldn't landfall in the Big Bend area be favorable? It seems to me that would push the oil out to sea and away from the coast.


Still have to go by the spill area if it started NW...then N....and then NNE or NE.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting Stormchaser2007:
We have 94L

invest_al942010.invest

178N, 578W
wow.
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We have 94L

invest_al942010.invest

178N, 578W
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Thanks DRM.
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Quoting CaneWarning:


Wouldn't landfall in the Big Bend area be favorable? It seems to me that would push the oil out to sea and away from the coast.
And it would push it ashore along the fl west coast.... not good.
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They are wheels up out of Keesler.
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58. IKE
NAM has shifted back east slightly on the 12Z run...


12Z NAM @ 78 hours...



at 84 hours.....

Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting DookiePBC:
Sorry for what I'm sure is a really easy question, but after having no rain for days here in SE Florida, our rain chances are going way up this weekend. Is this in any way due to moisture from 93L? Can its influence really be that big?
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.
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Quoting IKE:


The most important things about 93L...at this point....

(1)Flooding rains.
(2)Is the oil-volcano involved?
(3)Oil impacting land along the gulf coast?


Wouldn't landfall in the Big Bend area be favorable? It seems to me that would push the oil out to sea and away from the coast.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Sorry for what I'm sure is a really easy question, but after having no rain for days here in SE Florida, our rain chances are going way up this weekend. Is this in any way due to moisture from 93L? Can its influence really be that big?
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Wow StormW, so you think the Big Bend area of FL is possible with 93L?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
49. IKE
Quoting CaneWarning:
I'm not getting too worked up about 93L. As Dr. Masters stated, there's only a 10% chance of this ever being a hurricane. I think Tampa could handle a tropical storm.


The most important things about 93L...at this point....

(1)Flooding rains.
(2)Is the oil-volcano involved?
(3)Oil impacting land along the gulf coast?
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Recon link
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thanks StormW...
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I'm not getting too worked up about 93L. As Dr. Masters stated, there's only a 10% chance of this ever being a hurricane. I think Tampa could handle a tropical storm.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Thanks Dr.......Still at DEFCON Five.....
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Where are the hurricane hunters leaving out from?
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Quoting Chucktown:


Recon doesn't go off until 2 today.

No, they leave at 14:30 UTC, which was 17 minutes ago.

000
NOUS42 KNHC 241445
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT THU 24 JUNE 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 25/1100Z TO 26/1100Z JUNE 2010
TCPOD NUMBER.....10-024

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (WESTERN CARIBBEAN)
FLIGHT ONE - TEAL 70
A. 25/1800Z
B. AFXXX 01AAA INVEST
C. 25/1430Z
D. 17.5N 83.0W
E. 25/1730Z TO 25/2200Z
F. SFC TO 10,000 FT

FLIGHT TWO - TEAL 71
A. 26/0600Z
B. AFXXX 0201A CYCLONE
C. 26/0200Z
D. 18.0N 84.5W
E. 26/0500Z TO 26/0900Z
F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK: BEGIN 6-HRLY FIXES
AT 26/1800Z IF SYSTEM DEVELOPS.
3. REMARKS: TASKING FOR 24/1800Z AND 25/0600Z
CANCELED BY NHC AT 24/1135Z.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
JWP
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Thanks, Doc!
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Great Blog Dr. Masters..Key words: strength of trough and strength of the storm..we may have a player on our hands..I dont see this as just a TS, this will become a hurricane..too many favorable conditions exist for this to only explode to TS status
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Quoting MiamiHurricanes09:
Recon hasn't left yet.


yea I didnt think they had, probably will leave between 11 and 12 EDT
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting hurricanefiend85:
I remember there is a way to have a nearly live look at the hurricane hunters readings in Google Earth. I can't remember if it was a separate add-on or if it was a feature already embedded. Anyone know what I am talking about?


Recon doesn't go off until 2 today.
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Quoting Hurricanes101:
anyone have a good link for recon data

I have the one from tropical atlantic, but it is not reporting as of yet

Do they have a newer version of their site?
Recon hasn't left yet.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting ajcamsmom2:
Praying for extremely high shear over the GOM....
Yeah. That will blow off all the convection and will bring more rain to c fl
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Information About Low (Invest 93L)

Storm information valid as of: Friday, June 25, 2010 12:00 Z
Coordinates: 16.5N 82.5W
Location: 207 miles (333 km) to the SSW (201°) from George Town, Cayman Islands (GBR)
Pressure (MSLP): 1005 mb (29.68 inHg | 1005 hPa)
Sustained wind speed (1 min. avg.): 30 knots (35 mph | 15 m/s)
Member Since: September 2, 2009 Posts: 130 Comments: 21194
anyone have a good link for recon data

I have the one from tropical atlantic, but it is not reporting as of yet

Do they have a newer version of their site?
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Thx 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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