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 Drakoen:
Anybody can claim to be a meteorologist here

Very true...you would hope people are honest but we know that is not true for all.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
Quoting Chicklit:
wowie zowie baby...



Definitely looks to be getting it's act together. Is it a TD yet?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Good job, Patrap!
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Pat - Gave them lots to talk about. I bet Dr. M was happy to get an educated question that he could sink his teeth into!
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Quoting Drakoen:
Anybody can claim to be a meteorologist here
quite true i am not but its a hobby that i have alot of intrest in and a learning process.
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1622. Patrap

John "Spud" McConnell hosts WWL’s "Talk Gumbo"


weekdays from 1pm to 4pm on WWL-AM-FM & WWL.com. Spud was born and raised in Bayou country and holds a Master’s degree in acting. His career has taken him to Hollywood for three seasons on ABC’s "Roseanne" Show and to a successful run Off-Broadway in the one-man show, "The Kingfish."
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It's Patrap on WWL asking Dr. M a question! Awesome, Pat. You sound great and it's an excellent question!
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1620. IKE
Quoting Drakoen:
Anybody can claim to be a meteorologist here


If he's lying that's wrong. I don't feel he is.
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hopefully recon finds west winds with the next pass if not looks like no upgrade till tomorrow may even go strait through to TS Alex
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1618. 900MB
Quoting Levi32:


SSTs are just fine. They are rarely hotter than 30C (86F) down there. What matters is the depth of the warmth, which is insane right now. The heat content is more than past the accepted threshold for rapid intensification.



If this gets a tad more organized, I can't help but wonder if it may drift towards those warmer ssts off the coast. It will be a good test of my "path of least resistance" theory.
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1616. IKE
Patrap on WWL with the world famous Dr. Masters.

I see the NW movement on SHIPS....INITIAL HEADING/SPEED (DEG/KT):305/ 5
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wowie zowie baby...

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Quoting DestinJeff:
Link

SWFL Water Mgt models ... can't get image to work. The XTRP of current movement raises cooncern for a North Central GOM solution


It defaults to https:
Change the URL to http: and it works. I had that problem earlier today. Hope it helps!
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1613. Levi32
Quoting Clearwater1:


Anyone know what the water temps were when Wilma did her rapid formation. Curious. Thnks


Algorithm for calculating this was different back then so it's hard to properly compare. The actual SSTs on the surface were about the same as they are now.

Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting Hurricanes101:


unless the "L" on google earth is in the wrong location
It could be.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1611. Drakoen
Anybody can claim to be a meteorologist here
Member Since: October 28, 2006 Posts: 57 Comments: 30825
I would say barring the unexpected 11 pm may be the time of TD or maybe Alex.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
1609. ATL
Quoting CosmicEvents:
PATRAP!!!

Yep. Confusing the hell out of the radio host ;)
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1608. twooks
Heard pat on WWL :P
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Quoting MiamiHurricanes09:
Agreed.


unless the "L" on google earth is in the wrong location
Member Since: March 10, 2010 Posts: 1 Comments: 7874
PATRAP!!!
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Uh... west winds anyone?



Look off northern Honduras.
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Quoting HaboobsRsweet:


Just look at the wind pattern on Google Earth. They show signs of wrapping around as if they fly on the east side of center. They are flying at only 925mbs as well. That is a decent sign there is a center and in the low levels. Just have to wait for them go go right back through that point and we will know for sure. I think everyone thinks the center is too far east of where it really is.
Agreed.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1602. IKE
Quoting btwntx08:
scottsvb doesnt know nothing he doesnt know what really going on


He's a met. Are you? I'm not.
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Quoting extreme236:
Patience is a virtue.


Its also an ability many lack lol
Member Since: March 10, 2010 Posts: 1 Comments: 7874
1600. Levi32
Recon is currently nearing completion of a pass into the NE quad, and will be turning back around towards the core of the storm soon.

Member Since: November 24, 2005 Posts: 635 Comments: 26700
Does anyone have a link where you can see historical SST's? Thanks
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Quoting TampaWeatherBuff:


Personally I think 93L needs to be replaced with a wave that understands proper protocol. We simply can't allow this kind of insubordination to go as an example to future invests. ;)


hahahahahahaha.....agreed!!!!
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1597. xcool
weather456 miss out
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting MiamiHurricanes09:
You just made a lot of people happy. LOL, watch the blog's spirit come back.


Just look at the wind pattern on Google Earth. They show signs of wrapping around as if they fly on the east side of center. They are flying at only 925mbs as well. That is a decent sign there is a center and in the low levels. Just have to wait for them go go right back through that point and we will know for sure. I think everyone thinks the center is too far east of where it really is.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
Patience is a virtue.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
93L is moving wnw at this moment. it was briefly moving nw. so these nw jogs should become more frequent
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Quoting Levi32:


SSTs are just fine. They are rarely hotter than 30C (86F) down there. What matters is the depth of the warmth, which is insane right now. The heat content is more than past the accepted threshold for rapid intensification.



Anyone know what the water temps were when Wilma did her rapid formation. Curious. Thnks
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Quoting Levi32:
CIMSS 18z maps show vorticity "advection" towards the northwest during the last 3 hours.

Wouldn't be surprised to see it go through the Yucatan channel and not over the Yucatan itself if it continues current northwestward motion.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting P451:
12 Hours of Celia, WV Imagery, notice it has begun to dry out some. I thought it was tagged to weaken in the face of shear today? I guess I got mixed up on what I had read.

12HR WV Imagery, Ending 245PM ET:



Nice to have you back with your long loops.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
1590. KEEPEROFTHEGATE (Mod)
INV/93/L
MARK
16.1N/84.3W
Member Since: July 15, 2006 Posts: 178 Comments: 56059
1587. Drakoen
Quoting HaboobsRsweet:
Looking closer at it I think they may have missed the center and there may be a low level low. Might find that west wind when it comes back to the other side of their first track.


I was wondering about that too...
Member Since: October 28, 2006 Posts: 57 Comments: 30825
1585. dearmas
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 25th day of the month at 19:26Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 302)
Mission Purpose: Investigate first suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 09

Mandatory Data...

Observation Time: Friday, 19:24Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 18.4N 81.3W
Location: 63 miles (101 km) to the S (175°) from George Town, Cayman Islands (GBR).
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 300 meters
Flight Level Wind: From 140° at 24 knots (From the SE at ~ 27.6 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 24°C
Flight Level Dew Point: Not available, probably because the dew point hygrometer was not working.
Weather (within 30 nautical miles): Thunderstorm(s)
Mean Sea Level Pressure (MSLP): 1008 mb (extrapolated)

Optional Data...

Estimated Surface Wind: From 150° at 25 knots (From the SSE at ~ 28.7 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 31 knots (~ 35.7mph)
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1583. xcool
ECMWF
I have to throw it out the car
Member Since: September 26, 2009 Posts: 2 Comments: 15684
1582. Levi32
CIMSS 18z maps show vorticity "advection" towards the northwest during the last 3 hours.

Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting Levi32:


SSTs are just fine. They are rarely hotter than 30C (86F) down there. What matters is the depth of the warmth, which is insane right now. The heat content is more than past the accepted threshold for rapid intensification.



The center looks like it will miss the insanely hot stuff I hope nothing touches that. Anything with a low would become an auto TD if shear and dry air is low enough.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
In about 150 miles 93L will have to get its forward speed going because it will enter deeper waters in the Caribbean. There is warm water on the surface, but at depth its a different story. It wont take much to upwell cooler waters and inhibit strengthening.

If it was later in the year I would know for sure the warm waters are at depth too. but its still early.
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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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