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 StSimonsIslandGAGuy:


4,000 comments by midnight CaneWarning? Call over or under :)

When I got on here ten minutes ago there where only about 800 comments, now theres over 1000!
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I do not see 93L (Alex) being a threat to Florida at this time. As StormW indicated- it must become a major hurricane to shift to the right. I believe Texas & Louisianna are the targets at this time unless there is an unusual rapid intensification.
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Intensity in the Gulf, and the Caribbean is notoriously hard to forecast (Mainly due to the high heat content of the waters there) This could hit as a TD or a strong hurricane. Either is possible, but there's no point in getting all worked up until we see a trend one way or the other.
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Quoting StSimonsIslandGAGuy:


4,000 comments by midnight CaneWarning? Call over or under :)


Over unless Dr. M does a new update. What do you think?
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Quoting TerraNova:


Here ya go.
Tropical Atlantic: Reconnaissance (GE)


Thank you Sir!
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Quoting CaneWarning:
The blog is just moving too quickly.
1000+ comments posted in 3 and a half hours over an invest.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting gator23:

XTRP stands fo Extrapolation and its not really a model, just an extrapolation of all models.

Thats not right either. XTRAP is the current motion extrapolated into the future.
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1018. leo305
anyone have a live track of the Hurricane Hunters? If so please post it here
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting IKE:


It may have been you that said it earlier today...the NHC wasn't calling for Celia in the east-PAC to rev up so much.

NHC has stated intensity is hard to forecast.


NHC at 12Z has it up to 45kt before the Yucatan
Member Since: September 23, 2005 Posts: 15 Comments: 11341
Looking at the big picture really helps gives you an idea of how much spin 93L has now: Link
Member Since: July 30, 2007 Posts: 76 Comments: 4063
1013. Drakoen
Quoting TOMSEFLA:
anyone see a west wind in recon report?


They are still on the north side of the system
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anyone see a west wind in recon report?
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Quoting homelesswanderer:


What kind of model is the LBAR? I think thats the one that has been going strait to TX/LA on the statistical model. I cant tell for sure. Is that like the xtrp?


Hi Homeless...
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1009. leo305
Quoting extreme236:


It's not going to be heading WNW if it ramps up.


agreed, and its already ramping up based on vis satellite and this is DMIN, remember guys.. this thing is erupting at DMIN, imagine DMAX..
Member Since: April 17, 2010 Posts: 0 Comments: 1753
The blog is just moving too quickly.
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Quoting kmanislander:
Just came on. Has this been posted yet ?

Yup.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting StormW:


No, I didn't. Got to meet and talk shop though with Beven (NHC), Jamie Rhome, Phil Klotzback, Dr. Lyons, and Jim Cantore.


I was there also. I noticed someone that looked like you, but I never saw you in person before.
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Just came on. Has this been posted yet ?

Member Since: August 19, 2006 Posts: 0 Comments: 15948
Quoting hurricanejunky:


Wasn't it down to 1005mb earlier this morning?


That's not the max pressure. That pressure was well away from the center.

EDIT: The 1007 isn't the max pressure. The 1005 is.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
There are two key factors in 93L's transformation from an invest into a TC. One is how fast it spins up. Remember, there is still no spin to this system as of yet. The second is how long it takes to get to its crossover position on the YucPen. The faster it evolves into a spinning TC, then it will head more north, putting it over a smaller area of the YucPen to cross. A slower developing system will send it over the meaty area of the YukPen. It is supposed to be one or two days away from crossing the YukPen. These one or two days (not three?) will determine not only where 93L will go, but how big it will be, also.
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1000. gator23
Quoting homelesswanderer:


What kind of model is the LBAR? I think thats the one that has been going strait to TX/LA on the statistical model. I cant tell for sure. Is that like the xtrp?

XTRP stands fo Extrapolation and its not really a model, just an extrapolation of all models.
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999. IKE
12Z HWRF on 93L
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting btwntx08:
could become 70 mph imo and hit the yucatan then come out in the gom as a 50 mph heading wnw


It's not going to be heading WNW if it ramps up.
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Quoting StonedCrab:
Does anyone have a link for the kml file (Google Earth) for the Hurricane Hunter aircraft on its way in to 93L?


Here ya go.
Tropical Atlantic: Reconnaissance (GE)
Member Since: July 30, 2007 Posts: 76 Comments: 4063
Quoting DookiePBC:


Am I the only one that whenever I see StormW check in I feel like yelling "Storm", kinda like they yelled "Norm" on Cheers?

Quick question...I know that 93L is forecast to go over the Yucatan or the Channel, but if it slid east a bit, what is the geography of western Cuba? As mountainous as the East? Thanks!

no
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Quoting gator23:

80% is a 4out of 5 chance which is basically a certainty at this point.


I know. Im just said that because it really looks good now on satellite.
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Quoting Jeff9641:


We have some good mets in Orlando did you meet Tom Terry or Tony M?

I must respectfully disagree with you here, I really dont like Orlando mets.
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Quoting CybrTeddy:
Humberto, Gustav, and Ida all went from Disturbance to Hurricane in 24 hours. Its actually becoming common now.


yep, like I said a couple of hours back, it's not unlikely, but a possibility, as the CDO and the waters and conditions are there for this to just explode into a hurricane within 12-24 hours.. major hurricane? That I can't say, but hurricane for sure
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting MiamiHurricanes09:
NHC says a TD might form at any time.


Basically NHCspeak for "its probably already a TD, but we like updating stuff at 5 pm, makes it easier for us"
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990. xcool
93L OVER HOT HOT SST OMG
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Quoting StormW:


The only way I'm buying that hard right, is if it is a major hurricane.

The GFDL, GFDN, and HWRF are not good for long range track...period.


What kind of model is the LBAR? I think thats the one that has been going strait to TX/LA on the statistical model. I cant tell for sure. Is that like the xtrp?
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Quoting Patrap:
Shucks I never keep a NHC tab open,

Cuz soon as sumthing new pops up.,

We get the UPS delivery here really fast


Ditto, Pat.
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Quoting Jeff9641:


We have some good mets in Orlando did you meet Tom Terry or Tony M?


Tom Terry is on vacation.
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Quoting raggpr:
Up to 80% chance of a cyclone next 48 hours, I will say it is 90% chance even more. If the hurricane hunters find a TD we will need to wait until 5 pm to be declare as so?


They may issue a special outlook, but yeah otherwise 5 pm.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
Quoting IKE:


It may have been you that said it earlier today...the NHC wasn't calling for Celia in the east-PAC to rev up so much.

NHC has stated intensity is hard to forecast.
Indeed.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Hello all from coastal TX. First time back on for the 2010 season. New computer and can't find the link for an animated rainbow loop google earth overlay for the carib/gom. Any assistance would be great. Thanks
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Quoting CybrTeddy:
1007 mb, 25 mph winds now. Getting close.


Wasn't it down to 1005mb earlier this morning?
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Quoting raggpr:
Up to 80% chance of a cyclone next 48 hours, I will say it is 90% chance even more. If the hurricane hunters find a TD we will need to wait until 5 pm to be declare as so?

They could issue a special advisory.
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If we get a vortex message from the HH we will likely have TD1 at 5pm
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Time: 17:45:00Z
Coordinates: 17.6N 83.2833W
Acft. Static Air Press: 977.0 mb (~ 28.85 inHg)
Acft. Geopotential Hgt: 272 meters (~ 892 feet)
Extrap. Sfc. Press: 1007.6 mb (~ 29.75 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 89° at 16 knots (From the E at ~ 18.4 mph)
Air Temp: 24.1°C (~ 75.4°F)
Dew Pt: 24.1°C (~ 75.4°F)
Peak (10s) Flt. Lvl. Wind: 17 knots (~ 19.5 mph)
SFMR Peak (10s) Sfc. Wind: 21 knots* (~ 24.1 mph*)
SFMR Rain Rate: 0 mm/hr* (~ 0 in/hr*)
(*) Denotes suspect data
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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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