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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2979. centex
Notice where maintaining convection at sunset?
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TD 1 will get rip a part in the gulf by shear
Member Since: May 21, 2006 Posts: 5091 Comments: 115455
2977. Drakoen
Something about the way this system look is just too ominous...
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Is it my eyes... or am I seeing a reformation of the center at around 17N between 83.5 and 84W?
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2975. Drakoen
Black on AVN:

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65 mph certainly not out of the question, the NHC itself stated many times in the past few years that intensity predictions are always problematic. Look at Celia for example, it was at first expected to only peak at 75 mph.. it became a 160 mph Category 5 Hurricane. With the amount of TCHP in the Caribbean nothing is certain.
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2973. xcool
GFS DID POOR JOB ON OLD 93L
Member Since: September 26, 2009 Posts: 2 Comments: 15684
I think the trough will have some affect on this system especially if it gets stronger down the road....I can clearly see a hook into Central or Northern Texas or god forbid i say it Louisiana...
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Quoting Tazmanian:
heh the gulf has 50kt of shear in it


That area of shear is moving northwest, and future Alex is expected to move west of the main shear, and GFS's shear model expect the shear to clear out when the storm moves in plus there's a strong anticclone over TD 1.
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2970. bappit
Quoting Patrap:












I don't think the surface circulation extends out that far, but I know the upper circulation does.
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2969. HadesGodWyvern (Mod)
It takes them awhile to see T2.5 on their radar satellites.
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2967. JLPR2
Celia seems to be shrinking away

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2966. HadesGodWyvern (Mod)
kuppen

nah that is not the NHC. That would be the IMD.
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Are we seeing Explosive development?
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Quoting Patrap:


I think I noted earlier,.. todays Low Sun Angle will be impressive by Dusk


We are starting to see some of that now. The last few visible shots should look great.

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2963. ATL
Quoting futuremet:
This can't be right. The GFS has it stalling for days in the Bay of Campeche.

The NHC track reflects that somewhat. Needless to say not good for people in the Gulf...
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2962. Patrap


A hurricane's "hot towers" can increase its intensity by adding power to boost the storm's heat engine. For the first time, research meteorologists have run complex simulations of these phenomena using a very fine temporal resolution. They have combined this new simulation data with satellite observations to study the innerworking of the "hot towers" in never-before-seen detail.
Member Since: July 3, 2005 Posts: 428 Comments: 129902
2961. xcool
cat 1 hmmm
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2960. Michfan
Here comes the CDO and the hot towers.
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Apparently,BP needs 120 hour lead time before gale force winds begin.Isn't it apparent,that if TD1 misses the Yucatan the will have to leave,within the next 24 hours?
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2958. Patrap
Quoting kmanislander:


My point is that it is intensifying at the start of the evening which will only aid in further development. Even hurricanes are affected by daily cycles.


I think I noted earlier,.. todays Low Sun Angle will be impressive by Dusk
Member Since: July 3, 2005 Posts: 428 Comments: 129902
This can't be right. The GFS has it stalling for days in the Bay of Campeche.
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Quoting Drakoen:


Yup. I think this could approach or become a minimal hurricane before hitting the Yucatan Peninsula.
I agree.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2955. 1965
Quoting louisianaboy444:
TD One is showing all the signs of RI..Central Dense Overcast....Great outflow and banding features...as Drak showed -80C cloud tops shooting up into the Tropopause


You can put this old timer in the RI camp. I say cane by morning.
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Quoting kmanislander:


My point is that it is intensifying at the start of the evening which will only aid in further development. Even hurricanes are affected by daily cycles.
Yeah just slightly but not a lot. But I understand your reasoning.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting AstroHurricane001:
GFS sends a packet of energy from the storm out of the Gulf and explodes it in the Gulf Stream within seven days.


how much?
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You know how the Hurricane Center is. This wont be classified a TS til tmrw afternoon
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Member Since: June 9, 2007 Posts: 4 Comments: 15950
Quoting DocBen:
Is 94L close enough to TD1 to effect its path? (The Fuyaka effect (mis-spelled I am sure))


LOL, No, not even. Btw, it's Fujiwara

http://en.wikipedia.org/wiki/Fujiwhara_effect
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2949. Drakoen
Quoting louisianaboy444:
TD One is showing all the signs of RI..Central Dense Overcast....Great outflow and banding features...as Drak showed -80C cloud tops shooting up into the Tropopause


Yup. I think this could approach or become a minimal hurricane before hitting the Yucatan Peninsula.
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2948. Patrap
Quoting nrtiwlnvragn:


I will go against consensus, I don't think the RECON data will have much affect on the models. The SFMR and Tail Doppler Radar data don't go into the models, and position and strength are not that much different than before the RECON mission. They did not even get to do an X pattern to get the shape of the windfield. If this has been a Gulfstream IV mission I would expect more affect on the models.


Most well said..

Eggcellent
Member Since: July 3, 2005 Posts: 428 Comments: 129902
2947. bappit
Quoting Drakoen:
-80C tops:


Looking awesome.
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Quoting MiamiHurricanes09:
TD1 is already strong enough to not be greatly affected by the diurnal cycles.


My point is that it is intensifying at the start of the evening which will only aid in further development. Even hurricanes are affected by daily cycles.
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Quoting ElConando:


They do affect them a tad bit.
Yeah just a little bit, but not as much as if it were a weak tropical wave.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2944. Levi32
Quoting reedzone:


Look Levi! A typhoon is forming in the Western Caribbean!! :P LOL


Yes, very like a typhoon or an Indian Ocean monsoon depression. That is what has made this so intriguing to watch.
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Member Since: June 9, 2007 Posts: 4 Comments: 15950
Quoting MiamiHurricanes09:
TD1 is already strong enough to not be greatly affected by the diurnal cycles.


Thats because their is so much Heat and potential energy in the area that the air is constantly buoyant
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Quoting Stormchaser2007:
Going out on a limb, but I think TD1 could ramp up to about 65 mph before its landfall tomorrow.



If it was half the size I wouldn't be surprised if it became a minimal cat 1.
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Quoting StormW:
I'll have a special update late tonight.


Thanks, Storm. As always, your forecasts are most appreciated.
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2938. Drakoen
Quoting kmanislander:


Right near the center and night about to fall.


Yep through diabatic evaporational cooling
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Quoting Levi32:


Impressive stuff....that's what happens when that much heat finally gets bundled. It took 93L 5 days to accomplish this, and now it's going to take off until land stops it.


Look Levi! A typhoon is forming in the Western Caribbean!! :P LOL
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Going out on a limb, but I think TD1 could ramp up to about 65 mph before its landfall tomorrow.

Member Since: June 9, 2007 Posts: 4 Comments: 15950
GFS sends a packet of energy from the storm out of the Gulf and explodes it in the Gulf Stream within seven days.
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heh the gulf has 50kt of shear in it
Member Since: May 21, 2006 Posts: 5091 Comments: 115455
Looking more and more likely that we will have a TS at 8 PM.
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Quoting Drakoen:
We are going to have to wait till the 00z models to get models with proper initialization and intensity


I will go against consensus, I don't think the RECON data will have much affect on the models. The SFMR and Tail Doppler Radar data don't go into the models, and position and strength are not that much different than before the RECON mission. They did not even get to do an X pattern to get the shape of the windfield. If this has been a Gulfstream IV mission I would expect more affect on the models.
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2931. Patrap

Quoting MiamiHurricanes09:
Huh? You mean that the anticyclone aloft is causing the banding? Don't get how the anticyclone develops banding.









Member Since: July 3, 2005 Posts: 428 Comments: 129902
Quoting MiamiHurricanes09:
TD1 is already strong enough to not be greatly affected by the diurnal cycles.


They do affect them a tad bit.
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2755 TankHead93 "...do any of the experts on this blog feel this has an opportunity to pull a "Wilma" on us?"

I doubt that any expert would, and I doubt that any serious amateur would either. While not fitting into either category, I did watch what-would-become-Wilma from when it was first declared an Invest to when it died.
And 93L has borne no resemblance to Wilma at any time during its cyclogenesis ...sheesh... Wilma hit Cozumel as a Cat.5 just before landfall on the Yucatan.
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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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