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 Hurricajun:
Who wants to take a shot at where TWC's Cantore ends up to catch this storm???


I'll take Corpus Christi for 500, Alex...
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Quoting MiamiHurricanes09:
TD1 is one impressive tropical depression.


This thing is MASSIVE
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Quoting Tazmanian:



what you think of a upgrade by 8pm ch are
Chances for Alex at 8PM are high, imo.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Recon is done ... do you think they will add an overnight mission?
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less than 12hrs this thing has gone from nothing to very symmetrical looking system,

ABOUT DAMN TIME!!
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Well, I promise that if he does come here to LA, I hope he comes down to Grand Isle. I'll go take his picture while he stands in the oily water.
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Quoting extreme236:
According to the vortex pass, 30kts at this advisory wasn't a bad call at all.


It was a good call. I still feel that it will strengthen more than they are saying for now. Maybe not by much.
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a track that makes you go hmmmmmmm. Definitely be keeping an eye on it.
Member Since: July 2, 2009 Posts: 0 Comments: 2811
NOT trying to be a wishcaster or an alarmist, but do any of the experts on this blog feel this has an opportunity to pull a "Wilma" on us? Just here to learn and observe. I ask this due to an eerily reminiscent outflow pattern and central structure before the big "boom" Wilma put on overnight, as well as the ridiculously high TCHP. TIA! ;)
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Quoting MiamiHurricanes09:
TD1 is one impressive tropical depression.




what you think of a upgrade by 8pm ch are
Member Since: May 21, 2006 Posts: 5091 Comments: 114756
Call me crazy, but I believe this will be a cane by tomorrow.
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Quoting Levi32:


They say in the discussion that it is very close to TS strength. It's a good forecast....no need to unload on them on the first advisory of the year.


I'm not unloading on them haha. I truly do respect the mets that work at the NHC, and do wish that maybe I could someday work there. (Of course I just started HS, things can change). I'm just saying what I truly believe, and I believe that it will not take 24 hours to strengthen 10 mph at the rate this thing is going. Serve me up some crow if I'm wrong! I meant no disrespect in my post.
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TD1 is one impressive tropical depression.

Member Since: September 2, 2009 Posts: 130 Comments: 21091
i take LA for $1000
Member Since: May 21, 2006 Posts: 5091 Comments: 114756
Cantore is going to NOLA or Biloxi. Seidel is going to the other that Cantore does not go to.
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2814. bappit
Quoting Hurricanes101:
Someone asked a few days ago if Darby would inhibit this system; very well could be the other way around lol

this thing is HUGE


Look at the clouds for 94L.
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2813. Ighuc
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Quoting Hurricajun:
Who wants to take a shot at where TWC's Cantore ends up to catch this storm???


I'll take Brownsville for $100
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Quoting Hhunter:
let me be the first to say sadly....before the major cable networks...

"oilcane 2010"

in seriousness. Bastardi believes this to be a western gulf storm or even mexico.


I heard it here first!
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I said yesterday and I'll say it again... Baton Rouge, LA to Brownsville, TX and boy oh boy oh boy was I right....
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Quoting Michfan:


ROFL. I hope you have a ready supply of it this year. Should be a part of every blogger's hurricane kit.


Stepping away from the keyboard now after two deep breaths. See you later.
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According to the vortex pass, 30kts at this advisory wasn't a bad call at all.
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2805. Michfan
Quoting kmanislander:
Will return when the xanax kicks in


ROFL. I hope you have a ready supply of it this year. Should be a part of every blogger's hurricane kit.
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Who wants to take a shot at where TWC's Cantore ends up to catch this storm???
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Quoting IKE:
102 hr. 18Z GFS....



That other GFS at 90 hours


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2802. Hhunter
let me be the first to say sadly....before the major cable networks...

"oilcane 2010"

in seriousness. Bastardi believes this to be a western gulf storm or even mexico.
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Quoting IKE:


NHC is not forecasting it to be one.

And in all honestly NHC is a lot better at all this than us. We can sometimes spot things before post it and sometimes give explanations why something may or may not happen. And we are REALLY good a speculating what might happen which they are not allowed to do. But they have all the data, modeling software, expertise to do the best job the majority of the time. Every now and then you can catch them leaving early on a Friday afternoon though.....
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I said yesterday and I'll say it again... Baton Rouge, LA to Brownsville, TX and boy oh boy oh boy was I right....
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Will return when the xanax kicks in
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Quoting Tazmanian:
am going to be a wishcaster and say TD 1 is exploding
You are not being a wishcaster. If you look at satellite animation TD1 is literally exploding.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
2797. tkeith
Bloggers...pace yourselves :)
Member Since: November 1, 2004 Posts: 25 Comments: 8923
Quoting bappit:


She mommed us yesterday.


Yep, watch out or I'll do it again... :)
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2795. KEEPEROFTHEGATE (Mod)
your fast grasshopper
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2794. Levi32
Low elongated north to south...would explain the uncertainty with its movement today.
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Quoting swfla:
Why does the tropical page on WU show TD1 off the coast of Africa?


It shows it below that little "panhandle" of africa lol.

The reason for this is that 0 degrees N/S and 0 degrees E/W is the default position. This happens for a moment to a lot of new atlantic systems.
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2792. Michfan
Quoting HurricaneSwirl:


Look at the last part. Honestly, at this rate, who thinks it's gonna take 12 hours to get named Alex when data right now supports Alex is already here? And 24 hours to strengthen 10 mph? At this rate it'll 1/8 of that time.


NHC always plays it conservatively. Their history shows that. Were in a state where tropical cyclones over the past few years have done things that no one has ever seen before when it comes to intensification. I wouldn't expect them to jump on that bandwagon just yet.
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Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting TerraNova:

LOL that was quick
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2788. bappit
Quoting txag91met:

1002.9 is a tropical storm in my book...regardless of the wind field, the wind field will respond quickly to the pressure.


It's the pressure gradient. Pressures are generally low in the area so the gradient is not as steep as one might think.
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Quoting connie1976:
Is it me or does there seem to be a lot of big waves coming off of Africa? Is this normal in June?
Definatly NOT!
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TD1 really beginning to intensify, wouldn't be surprised to see a moderate strength TS at 8PM. Notice the banding and the convection expanding.

Member Since: September 2, 2009 Posts: 130 Comments: 21091
2785. KEEPEROFTHEGATE (Mod)


972

URNT12 KNHC 252158

VORTEX DATA MESSAGE AL932010

A. 25/21:38:50Z

B. 16 deg 29 min N

083 deg 34 min W

C. NA

D. 26 kt

E. 120 deg 15 nm

F. 227 deg 22 kt

G. 125 deg 19 nm

H. EXTRAP 1004 mb

I. 24 C / 296 m

J. 22 C / 297 m

K. 18 C / NA

L. NA

M. NA

N. 13 / 1

O. 0.02 / 15 nm

P. AF302 01AAA INVEST OB 16

MAX FL WIND 35 KT NE QUAD 19:51:20Z

SLP EXTRAP FROM BELOW 1500 FT

BROAD LOW ESTIMATED DIAMETER 20NM E-W / 40NM N-S

;


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2784. Levi32
000
URNT12 KNHC 252158
VORTEX DATA MESSAGE AL932010
A. 25/21:38:50Z
B. 16 deg 29 min N
083 deg 34 min W
C. NA
D. 26 kt
E. 120 deg 15 nm
F. 227 deg 22 kt
G. 125 deg 19 nm
H. EXTRAP 1004 mb
I. 24 C / 296 m
J. 22 C / 297 m
K. 18 C / NA
L. NA
M. NA
N. 13 / 1
O. 0.02 / 15 nm
P. AF302 01AAA INVEST OB 16
MAX FL WIND 35 KT NE QUAD 19:51:20Z
SLP EXTRAP FROM BELOW 1500 FT
BROAD LOW ESTIMATED DIAMETER 20NM E-W / 40NM N-S
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Member Since: July 2, 2009 Posts: 0 Comments: 2811
TD1 track

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WOW...cue the multitudes of reposting the NOAA/NHC track chart
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2779. Levi32
Quoting HurricaneSwirl:


Look at the last part. Honestly, at this rate, who thinks it's gonna take 12 hours to get named Alex when data right now supports Alex is already here? And 24 hours to strengthen 10 mph? At this rate it'll 1/8 of that time.


They say in the discussion that it is very close to TS strength. It's a good forecast....no need to unload on them on the first advisory of the year.
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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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