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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3279. KEEPEROFTHEGATE (Mod)
WUEST enjoy that lollipop
Member Since: July 15, 2006 Posts: 171 Comments: 53841
3278. islagal
In Isla Mujeres, just off of Cancun. What is the worst we should prepare for and when? Gracias!
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3277. centex
I'll wait on new model runs to take notice.
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Blog Update!

June 25, 2010 - 7:30 PM EDT - First Tropical Depression Develops -
Member Since: September 2, 2009 Posts: 130 Comments: 21193
3275. HadesGodWyvern (Mod)


orange is -90C, right?
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3274. KEEPEROFTHEGATE (Mod)
EMPTY SPACE CREATED
Member Since: July 15, 2006 Posts: 171 Comments: 53841
Quoting TropicalNonsense:


6PM 18Z GFS ENSEMBLE ....

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30 Hour GFDL

Stronger than the previous run.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Here was the 18z SHIPS RI section

Prob of RI for 25 kt RI threshold= 49% is 3.9 times the sample mean(12.6%)
Prob of RI for 30 kt RI threshold= 29% is 3.5 times the sample mean( 8.1%)
Prob of RI for 35 kt RI threshold= 19% is 3.9 times the sample mean( 4.8%)
Prob of RI for 40 kt RI threshold= 9% is 2.7 times the sample mean( 3.4%)

Member Since: Posts: Comments:
Quoting KoritheMan:
This is what people need to be focusing on:



Roughly equal chance of feeling tropical storm force winds from northeast Mexico to Grand Isle.



and takeing the oil with it
Member Since: May 21, 2006 Posts: 5091 Comments: 115125
Quoting GreenMe2225:
if someone else has asked this please forgive me as the blog is moving very fast and i may have missed the answer.

if the depression gets into the gulf with depression energy remaining what would stop it from becoming a hurricane?

Some shear, but mostly time. If it dallied about, it could.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
This is what people need to be focusing on:



Roughly equal chance of feeling tropical storm force winds from northeast Mexico to Grand Isle.
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3266. txjac
Kind of off topic but affects whats going on now ...at what point do they decide what to doing about the BP oil recovery process? How long does it take to move all the equipment out there? Does the storm have to get to a certain strenth or a specific distance in proximity to the leak before things are moved?

I'm hoping that Pat is on as he knows these kind of things

Thanks
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3265. HadesGodWyvern (Mod)
It was close to -90C for cloud top temperature
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Quoting weatherman12345:
this **** guy is ruining every post


Easy fix for that. If you can't, get the site to do it for you. IGNORE
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Quoting TexasHurricane:
ok, I'm confussed. The NOAA has a track of most likely somewhere in TX and our locals (channel 6) was just saying that the high should stick and it should make landfall somewhere in Mexico. Did I miss something??


That's why I choose to ignore all of them. Don't care who they are. Again, they have no business trying to forecast anything that far out in advance.
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Quoting extreme236:


Guess it's showing some of that RI. I don't see it getting that strong, but we'll see.
Remember that is not at the surface, so you take off another 10 or 20 mph.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting KoritheMan:
Does anybody know if the 18z models were fed recon data?
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Quoting weatherman12345:
this wuest guy is ruining every post


Everyone's ignored him and moved on. You should join the crowd :)
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Quoting TropicalNonsense:


6PM 18Z GFS ENSEMBLE ....



Rapid intensification is not out of the question..VERY hot sea surface temperatures between it and the Yucatan.
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3255. uplater
Quoting Hhunter:


30 Minutes Later. Major -80c tower.

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Quoting KaNaPaPiJoSa:
I think it's peculiar that the NHC will make the forecast a "split down the middle" of the model consensus. I think it will go east (fl panhandle), or go west (like browsville). However, I don't think it will go anywhere near the middle track of the consensus. My guess (which will probably change in 12 hours, I'm entitled to do that on occasion), will be Southern Mississippi to Pensacola.



it's a Percentage based system where all the MAJOR models are respected.

The only True HURRICANE FORECASTING MODELS are the
GFDL and HWRF which were designed to be storm specfic.

otherwise the ECMFW also has a decent reputaion for storm
tracks but the rest can usually be taken with a grain of salt frankly.
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Quoting Drakoen:
I agree with the NHC track considering how spread out the models are:


Until/IF it crosses the Yucatan picking it's track is like spinning a roulette wheel and the odds of getting it right are about the same..I'm sure all will pick a viable scenario and a couple will be close enough to be right..
So lets get everyones shipping address and a bunch of cocked crows and a couple of cookies or maybe twinkies...
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting MiamiHurricanes09:
HWRF 18z 30 hours - image as TD #1 makes landfall, seems to be a pretty significant system.





Guess it's showing some of that RI. I don't see it getting that strong, but we'll see.
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3020 TankHead93 "...very similar to the way Hurricane Wilma looked before she exploded."

Only after ya drop industrial quantities of acid upon a stomach full of magic mushrooms, peyote, and loco weed... of course by then, FredFlintstone could be mistaken for HurricaneWilma.
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It's offical. TD 1 on NHC
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3249. bappit
Quoting Chicklit:


Hiya.
Looks like TD1 is about to get fix with the anticyclone.

PGSuggested


Just look how those stream lines of the upper winds perfectly match the bands of rain around TD01. Beautiful.
Member Since: May 18, 2006 Posts: 10 Comments: 6031
3248. Drakoen
Quoting atmoaggie:

Broad...

(the system, not you, Ike)


LOL
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3247. 7544
so does so fla get any rain from td1
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3245. amd
Quoting HellaGoose:
When is the next HH recon scheduled for TD!?


it is leaving Mississippi at 10 p.m. edt, and will arrive at TD1/Alex sometime between 1 and 2 a.m. edt
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Does anybody know if the 18z models were fed recon data?
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HWRF 18z 30 hours - image as TD #1 makes landfall, seems to be a pretty significant system.



Member Since: September 2, 2009 Posts: 130 Comments: 21193
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3240. GetReal


New convective burst erupting directly over the LLC.... First stage for the formation of the CDO.....
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3239. IKE
Quoting atmoaggie:

Broad...

(the system, not you, Ike)


LOL.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
3237. IKE
Quoting centex:
This late June trough which picks up a Mid Yucatan weakened system due noth is highly suspect.


I don't think it's going to happen.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Hope the soil is not saturated in the Yucatan. Looks like they're going to get quite a bit of rain.
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Quoting Clearwater1:
Just google "wilma hurricane track" But why?


Wikipedia has a complete collection of recent Atlantic storm tracks.

Quoting Claudette1234:


Looks organized and dangerous TD01. Uhmm IR is too strong so heavy rain.


Is that an eye, dry pocket, or hot tower collapse zone at the coast of Honduras?

Quoting Tazmanian:



wind shear is vary high in the gulf its RIP


Brickwallcasting? Sorry, 92L slid right underneath a wall of shear.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting IKE:


You're correct....GFS vol. 2 does show a SW GOM system...but look where the moisture is pooling at....

at 120 hours....




Broad...

(the system, not you, Ike)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting Stormchaser2007:
Pretty close to CA still. If this was heading N instead of NW/WNW, this would be a pretty potent storm.



my thought is
Central America is a potential double edged sword, it helped get the low together with the energy and moisture that just a couple days ago was some distance to its east and now i think it is far enough north of Honduras to not have negative impact from interaction with Central America at moment, but depending on interaction with Yucatan the future of the storm rest. If it stalls or spends a lot of time over yucatan it could disintegrate to something like about where the storm is right now, which has plenty of potential to develop into strong tropical storm or weak cane, but due to size that could be a lot of water stirred up and a storm surge that will push oil and dispersant into all sorts of places along the coast. oilcane, or tropical oil, it will still be known as "Dirty" Alex for years to come.
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3232. hamla
if this td1 slows down in the gom all bets are off.2 or 3 days stewing in 85++ soup in the gom /b o camp.will only make things worse since now that i live 4.5 miles from gom things cud get real bad cause most storms have a thing for moving to the ne after they start to groow in intenisity been here since 1961 and have learned that you have no control over muther nature she can be bioht when she wants and all the modles cant perdict wats gonna happen
lets all wait till mon/tues and then we can all put our 2 cents in all off the disscussions.
lets just hope for a best case outcome but dont let ur guard down

have a great night to all

gonna play slots at the silver slipper
c ya
rick
n1rg
hamla
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Quoting KoritheMan:


Nope.

I wouldn't say that , anything is possible storms don't always follow computer models and yes if this becomes strong enough it will in my opinion move more northward , not really buying a NE movement before exiting the Caribbean, but never say never!
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Quoting nrtiwlnvragn:



GFDL didn't


HOUR:108.0 LONG: -91.95 LAT: 27.85 MIN PRESS (hPa): 978.82 MAX SURF WIND (KNOTS): 72.75
HOUR:114.0 LONG: -92.03 LAT: 28.70 MIN PRESS (hPa): 968.67 MAX SURF WIND (KNOTS): 85.37
HOUR:120.0 LONG: -91.94 LAT: 29.30 MIN PRESS (hPa): 966.58 MAX SURF WIND (KNOTS): 83.31
HOUR:126.0 LONG: -91.37 LAT: 29.95 MIN PRESS (hPa): 970.80 MAX SURF WIND (KNOTS): 68.99
Not liking those coordinates, the strength either.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
3229. centex
This late June trough which picks up a Mid Yucatan weakened system due noth is highly suspect.
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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.