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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1529. Patrap
The Overall Mean Center has been west of the Comma Shaped Clouds a lot believed was the Coc.

Its a Large Circ and its still trying to build a Warm column,

Its making progress, but slowly as forecasted.

Floater - Visible Loop
Member Since: July 3, 2005 Posts: 430 Comments: 130818
Looks like an eye is trying to form. About 75 NW of Puert Lampira Honduras. More than a little ragged. It also seems to be doing a little jog here and there. Still feel that it will follow the path of the tropical wave that preceded it by a few days.
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Water temp to the northeast of the center is not as warm as you would expect in this area of the caribbean. 84 degrees which is not conducive for rapid intensifying.

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Look at those cloud tops.

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Quoting CosmicEvents:
I don't know about our TD(or not TD)....but you can certainly feel the energy being knocked off the blog. Maybe if everybody exhales towards the west we can get something going here sooner than later.


yea pretty amazing
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Quoting MiamiHurricanes09:
Yes.


At this point I'd say no. Were close enough to the advisory time.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1521. Drakoen
Quoting CosmicEvents:
I don't know about our TD(or not TD)....but you can certainly feel the energy being knocked off the blog. Maybe if everybody exhales towards the west we can get something going here sooner than later.


LOL
Member Since: October 28, 2006 Posts: 57 Comments: 31550
I don't know about our TD(or not TD)....but you can certainly feel the energy being knocked off the blog. Maybe if everybody exhales towards the west we can get something going here sooner than later.
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Quoting Baltimorebirds:
If they do find a depression will they issue a special advisory or no??
Yes.
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1518. cg2916
Quoting Levi32:


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


2 1/2 to 3 more hours.
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2PM Models are out for 93L
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1513. Levi32
Quoting Grothar:


Are you sure about that?


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
Member Since: November 24, 2005 Posts: 635 Comments: 26717
The HH are looking 90 nautical miles to the east of the center fix per the last ASCAT pass ... they are looking where the center *appears* to be, but not at the coords at the top of the "map" of the 14:15Z pass (17N, 84.7W). What do you think, Skyepony?

Mebbe the calcs on the ASCAT pass were messed up somehow, but if you zoom in on that 17N, 84.7W area you can see where that spot might work.
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Quoting Grothar:


Are you sure about that?
Yes I am.
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1510. Grothar
Quoting MiamiHurricanes09:
Another 3 hours, until 6 PM EDT.


Are you sure about that?
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I fix the cap lock Problem
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Quoting ezcColony:


TD @ 5, okay. TS @ 8, no way. It won't spin up that fast. Tomorrow, perhaps and then it better hurry and get big fast because it has to move north to avoid going where StormW has it visiting.


Your forgetting the SST's and TCHP levels out in that area...It could easily spin up very rapidly.
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1505. JDSmith
Time: 19:04:30Z
Coordinates: 17.9167N 82.1W
Acft. Static Air Press: 977.4 mb (~ 28.86 inHg)
Acft. Geopotential Hgt: 265 meters (~ 869 feet)
Extrap. Sfc. Press: 1007.6 mb (~ 29.75 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 130° at 27 knots (From the SE at ~ 31.0 mph)
Air Temp: 22.8°C (~ 73.0°F)
Dew Pt: 18.0°C (~ 64.4°F)
Peak (10s) Flt. Lvl. Wind: 28 knots (~ 32.2 mph)
SFMR Peak (10s) Sfc. Wind: 27 knots (~ 31.0 mph)
SFMR Rain Rate: 1 mm/hr (~ 0.04 in/hr)
(*) Denotes suspect data


I take back my prior statement.
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1504. cg2916
It is open to the south, IMO, the south side should be reporting W winds, winds are SSE there.
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1502. Grothar
Looks more WNW than West on this image. It could be responding to a little weakness to its North.

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Quoting Hurricanes101:
94L could very well pose a threat to Bermuda by Tuesday or Wednesday

so put away your trouts, cuz 94L may not be a fish


Really? I thought everyone said it was going to be a fishy.
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Quoting extreme236:
HH will be in there for a couple more hours to collect data. It's just a wait and see right now.
Another 3 hours, until 6 PM EDT.
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1499. IKE
Quoting YourCommonSense:


Is your microwave retro?


LOL.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1498. JLPR2
Quoting Baltimorebirds:
I don't either but the models say it will move into a area of light shear and then develope.


ah, well then, if low shear appears then we could have something
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19:01:30Z
17.817N 82.217W
32 knots
(~ 36.8 mph)
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Quoting Drakoen:
Certainly find those strong winds in that NE quadrant
does it look like we have a TD from recon or still no west winds i have been on and off
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HH will be in there for a couple more hours to collect data. It's just a wait and see right now.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting Hurricanes101:


oh no they will be there for several more hours I think


Scheduled untill 6:00 PM EDT
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1491. IKE
I was going to ask....where's the center fix, but since it isn't closed...forget that question.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting wunderkidcayman:
HEY GUYS THE HURRICANE HUNTER ARE NOT HEADING NORTH NOW AND THEY HAVE FOUND 35 MPH WIND SOMEONE WITH GOOGLE EARTH LOOKING ON RECON PLEASE POST


May I recommend an important software update for your system? Link.
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1489. Patrap
Now Interviewing

WWL News Radio NOLA and Live Dr. Jeff Masters interview
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1488. twooks
Jeff masters is on wwl NOW
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Doc is on the radio show now, he just got on.
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Quoting Levi32:


It won't become exposed if there is no wind shear. A WNW track into the Bay of Campeche is still on the table....a lot of things are still on the table, but I don't see it going quite that far south. That is just my opinion of course.
I think it will stay south...my opinion of course.
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1485. Patrap
WWWL News Radio NOLA and Live Dr. Jeff Masters interview momentarily
Member Since: July 3, 2005 Posts: 430 Comments: 130818
1484. JDSmith
Quoting wunderkidcayman:
HEY GUYS THE HURRICANE HUNTER ARE NOT HEADING NORTH NOW AND THEY HAVE FOUND 35 MPH WIND SOMEONE WITH GOOGLE EARTH LOOKING ON RECON PLEASE POST



Time: 18:54:30Z
Coordinates: 17.6167N 82.5167W
Acft. Static Air Press: 977.3 mb (~ 28.86 inHg)
Acft. Geopotential Hgt: 262 meters (~ 860 feet)
Extrap. Sfc. Press: 1006.9 mb (~ 29.73 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 143° at 30 knots (From the SE at ~ 34.5 mph)
Air Temp: 23.5°C (~ 74.3°F)
Dew Pt: 18.0°C (~ 64.4°F)
Peak (10s) Flt. Lvl. Wind: 32 knots (~ 36.8 mph)
SFMR Peak (10s) Sfc. Wind: 19 knots (~ 21.8 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
(*) Denotes suspect data


It's at flight level though. Surface winds still around 20-25
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1483. Drakoen
Certainly find those strong winds in that NE quadrant
Member Since: October 28, 2006 Posts: 57 Comments: 31550
1482. Patrap
I need some earplugs apparently.

I need to add them to the Suits helmet..
Member Since: July 3, 2005 Posts: 430 Comments: 130818
94L could very well pose a threat to Bermuda by Tuesday or Wednesday

so put away your trouts, cuz 94L may not be a fish
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1480. xcool
the more organized 93L head to n
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1479. JLPR2
Quoting Baltimorebirds:
Yeah I know.I was talking about this system yesterday.The models do eventually develope this into a tropical storm.


I dont see how it will be able to do that, there's a wall of shear right in front of it
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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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