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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1229. Levi32
Quoting StormW:


Well, don't forget Drak and Levi too..and 456 if he is back on...wonder where he's been BTW?


I really hope he's ok....don't like seeing him disappear like this. I hope he didn't get a serious illness or something.
Member Since: November 24, 2005 Posts: 635 Comments: 26698
Insofar as June climatology is concerned, this one is in the right place at the right time; as far as a potential threat to the US, the land interaction in the short term, and, sheer values in the longer term over the Gulf if a viable circulation can reform/or remain over water will make all the difference...We will not know the out come for several days as steering currents are weak at the moment and it appears to be a slow mover.....
Member Since: August 8, 2006 Posts: 0 Comments: 9377
I think at 5:00 or 6:00pm the NHC is going to issue a Special Tropical Disturbance advisory to upgrade this system to Tropical Depression 1.
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Quoting ezcColony:


No, that is not spinning. That is rapid intensification. Difference. Don't argue. It's not spinning yet.


I'm sorry, I respectfully disagree with you. There is LLC, full with convection, great outflow, spinning clouds on the visible. The storm is spinning and NOT going through RI, though I'm not ruling that out tonight.
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Quoting kmanislander:


Current motion is NW. This may shoot the Yucatan channel. The models will come right soon.
If it does we might have a much stronger system than what we are currently thinking, especially with those TCHP.
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1223. xcool
WHXX01 KWBC 251825
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1825 UTC FRI JUN 25 2010

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL932010) 20100625 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
100625 1800 100626 0600 100626 1800 100627 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 16.9N 82.9W 17.7N 84.9W 18.9N 86.9W 19.7N 88.6W
BAMD 16.9N 82.9W 17.4N 84.6W 18.2N 86.3W 19.0N 87.7W
BAMM 16.9N 82.9W 17.7N 84.7W 18.7N 86.4W 19.6N 87.9W
LBAR 16.9N 82.9W 17.5N 84.5W 18.4N 86.5W 19.4N 88.3W
SHIP 30KTS 39KTS 50KTS 58KTS
DSHP 30KTS 39KTS 50KTS 43KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
100627 1800 100628 1800 100629 1800 100630 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 20.6N 90.1W 22.4N 92.3W 23.1N 94.3W 23.3N 96.4W
BAMD 19.9N 88.9W 22.1N 90.2W 24.0N 90.9W 25.7N 91.4W
BAMM 20.7N 89.4W 22.9N 91.2W 24.4N 92.4W 25.5N 93.5W
LBAR 20.7N 89.8W 23.6N 92.2W 26.8N 93.3W 29.6N 91.9W
SHIP 65KTS 74KTS 76KTS 71KTS
DSHP 32KTS 41KTS 42KTS 38KTS

...INITIAL CONDITIONS...
LATCUR = 16.9N LONCUR = 82.9W DIRCUR = 305DEG SPDCUR = 5KT
LATM12 = 16.3N LONM12 = 82.1W DIRM12 = 300DEG SPDM12 = 5KT
LATM24 = 16.2N LONM24 = 81.0W
WNDCUR = 30KT RMAXWD = 100NM WNDM12 = 25KT
CENPRS = 1005MB OUTPRS = 1010MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

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Quoting LRandyB:


You are reading it right. At the area of min pressure, they encountered a very broad weak center with light and variable winds. Winds north of the center were easterly to northeasterly, winds sounth of the center look to be southeasterly. Typical open wave so far.

Dude, I'd have thought you were in the air right now...
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1221. Levi32
Quoting Drakoen:


Or the low is very small which is what it appears to be on visible imagery


That could be too, except that the WNW winds in Honduras earlier this morning suggested a larger circulation.
Member Since: November 24, 2005 Posts: 635 Comments: 26698
Quoting tennisgirl08:
question - which blob of convection is the center? the blob to the north?



Anyone? Just wondering...because if that is so, looks to be moving in a more NW fashion.
Member Since: July 17, 2008 Posts: 0 Comments: 1242
1219. Levi32
As of 18:25z recon is finding the northerly winds now.

000
URNT15 KNHC 251825
AF302 01AAA INVEST HDOB 23 20100625
181530 1610N 08315W 9772 00257 0063 +241 +180 129007 008 999 999 03
181600 1610N 08316W 9770 00258 0063 +243 +180 127007 007 999 999 03
181630 1610N 08318W 9772 00258 0062 +248 +180 105006 006 999 999 03
181700 1610N 08320W 9772 00257 0062 +247 +180 085006 007 999 999 03
181730 1610N 08322W 9770 00259 0062 +248 +180 069008 009 999 999 03
181800 1610N 08323W 9771 00258 0062 +245 +180 083007 008 999 999 03
181830 1610N 08325W 9770 00259 0063 +244 +180 055005 006 999 999 03
181900 1610N 08327W 9772 00257 0062 +247 +180 031006 006 999 999 03
181930 1610N 08328W 9772 00256 0062 +250 +180 027006 007 999 999 03
182000 1611N 08330W 9766 00261 0061 +248 +180 040004 006 999 999 03
182030 1612N 08330W 9781 00248 0062 +248 +180 360009 011 999 999 03
182100 1613N 08331W 9771 00257 0061 +254 +180 355011 011 999 999 03
182130 1615N 08332W 9772 00257 0061 +255 +180 357011 011 999 999 03
182200 1616N 08333W 9771 00257 0061 +254 +180 357010 010 999 999 03
182230 1617N 08333W 9772 00257 0061 +255 +180 351009 010 999 999 03
182300 1618N 08332W 9769 00259 0060 +255 +180 350009 009 999 999 03
182330 1620N 08331W 9771 00257 0060 +255 +180 351008 008 999 999 03
182400 1621N 08331W 9772 00256 0060 +255 +180 350008 008 999 999 03
182430 1622N 08330W 9772 00256 0060 +253 +180 354008 008 999 999 03
182500 1623N 08329W 9772 00255 0059 +255 +180 353007 008 999 999 03
$$
Member Since: November 24, 2005 Posts: 635 Comments: 26698
1218. Drakoen
Quoting Levi32:
Recon obs south of the center showing easterly winds....perhaps weakly closed but not very well.


Or the low is very small which is what it appears to be on visible imagery
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The enigmas of 93L. West or East? Mild or Beast?

Member Since: June 16, 2010 Posts: 0 Comments: 28
Quoting MiamiHurricanes09:
25/1745 UTC 16.9N 83.3W T1.0/1.0 93L


Current motion is NW. This may shoot the Yucatan channel. The models will come right soon.
Member Since: August 19, 2006 Posts: 0 Comments: 15948
Dvorak stays at T1.0, I disagree with it greatly.
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Quoting MiamiHurricanes09:
25/1745 UTC 16.9N 83.3W T1.0/1.0 93L


thats surprising...
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1211. Levi32
Recon obs south of the center showing easterly winds....perhaps weakly closed but not very well.
Member Since: November 24, 2005 Posts: 635 Comments: 26698
1210. Patrap
93L NASA Viewer
Member Since: July 3, 2005 Posts: 427 Comments: 129439
1209. LRandyB
Quoting bwi:
16.833N 83.117W at 1005.4mb lowest on that pass if I'm reading it right.


You are reading it right. At the area of min pressure, they encountered a very broad weak center with light and variable winds. Winds north of the center were easterly to northeasterly, winds sounth of the center look to be southeasterly. Typical open wave so far.
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25/1745 UTC 16.9N 83.3W T1.0/1.0 93L
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Quoting Jeff9641:


I am not calling landfalls! GEESH! The fact is it can't be ignore about the GFS showing a strong trough on every run since Wednesday. I would pay attention to things right now as the 8pm track maybe interesting.


When you say FL/TX what do you think 50/50 is calling landfall areas anyway you want to look at it. I'm not bashing you, I'm bashing the information that your portraying. Remember its the internet where all just information sharing (data packets).

I'm not here to say who's right or wrong. But pointing to places out is not a good way to portray information about the general direction of the storm.
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AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26512
1205. GBguy88
Quoting Jeff9641:


I am not calling landfalls! GEESH! The fact is it can't be ignore about the GFS showing a strong trough on every run since Wednesday. I would pay attention to things right now as the 8pm track maybe interesting.


In relation to the oil spill, it doesn't really matter where a storm makes landfall. If you get a storm in the Gulf, it doesn't even have to be a monster to generate enough wave action to move a substantial amount of oil. It won't have to pass over the spill.
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Wind Direction (WDIR): SE ( 130 deg true )
Wind Speed (WSPD): 25.3 kts
Wind Gust (GST): 31.1 kts
Wave Height (WVHT): 7.2 ft
Dominant Wave Period (DPD): 6 sec
Average Period (APD): 4.8 sec
Atmospheric Pressure (PRES): 29.76 in
Pressure Tendency (PTDY): -0.01 in ( Falling )
Air Temperature (ATMP): 84.2 °F
Water Temperature (WTMP): 84.2 °F
Dew Point (DEWP): 76.8 °F
Heat Index (HEAT): 93.9 °F
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Quoting btwntx08:

hey matt is actually san angelo :)
Sorry. I knew it was San something and I knew it was in TX...couldn't remember what it was though. Thanks rob!
Member Since: July 14, 2009 Posts: 51 Comments: 1731
1201. Drakoen
Quoting Tropicaddict:


What's that mean Drak??


Cumulonimbus cloud tops shooting up into the tropopause
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1200. scott39
I compare 93Ls developement like a mother giving birth in a broom closet
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Kman, Working on it. Sitting here in my cubical. LOL. Off all next week, planning a trip to Sea World (17yrs of wedded bliss to be celebrated) hoping this thing goes poof.
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Hey Wunderground Blog!

Looks like 93L has finally gotten its act together.

Now that we have a more developed system, I think there are many surprises in store for us in the coming days.
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1197. Levi32
Quoting Hurricanes101:


maybe the center is further west than we thought?


No you can see north winds clearly on visible satellite imagery. The center is easily discernible. They should find it eventually.

High-resolution rapid-scan visible loop of 93L
Member Since: November 24, 2005 Posts: 635 Comments: 26698
As I am a not even a professional wish-caster like so many on this august forum, no one wants 93L to explode into a cat 5 and level Tampa as much as I do. I just don't see any meteorological reason to think it has a better chance than a random asteroid of landing near Florida right now. I defer to serious folk like StormW for my informed opinions on this thing. :)
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AL, 93, 2010062518, , BEST, 0, 169N, 829W, 30, 1005, LO,
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Quoting Jeff9641:


I am not calling landfalls! GEESH! The fact is it can't be ignore about the GFS showing a strong trough on every run since Wednesday. I would pay attention to things right now as the 8pm track maybe interesting.


Also keep in mind the GFS is notorious for overdoing the strength of troughs
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93L looks great this afternoon. It will likely be upgraded to TD status at 18z or 0z.
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question - which blob of convection is the center? the blob to the north?

Member Since: July 17, 2008 Posts: 0 Comments: 1242
NHC 80% chance
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1005.6mb
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Quoting StormW:


Doesn't have to be a hurricane to have a CDO.
Usually it is with a weak to moderate strength TS when a system acquires a CDO.
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Hello Tropical Depression # 1...

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Quoting Levi32:


Yeah....WNW winds out of Honduras almost has to mean a closed low. I'm seeing a lot of southerlies in the vicinity of the center though on the latest recon obs.


maybe the center is further west than we thought?
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Quoting Levi32:


Yeah....WNW winds out of Honduras almost has to mean a closed low. I'm seeing a lot of southerlies in the vicinity of the center though on the latest recon obs.
Indeed.
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1183. brla61
Stays weak, moves west...sounds like a plan to me.
By the way, hello everyone! I'm a newbie. back to lurking..
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Quoting reedzone:


That's not spinning up?? Sorry, I disagree, 93L (TD1) is indeed spinning up today.


No, that is not spinning. That is rapid intensification. Difference. Don't argue. It's not spinning yet.
Member Since: June 16, 2010 Posts: 0 Comments: 28
Quoting charlottefl:
Hey Matt, how's it going?


Whats up man?

been pretty busy lately, how you been?
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1179. Drakoen
We have to wait until the HH get into the right front quadrant of the system to find out what the winds are in this system.
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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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