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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1829. Levi32
The empty places where convection has been lacking within 93L's circulation are gradually filling in with new thunderstorms as time goes on.

Member Since: November 24, 2005 Posts: 635 Comments: 26681
1828. Drakoen
When Dolly opened back up her circulation after being classfied she had TS force winds
Member Since: October 28, 2006 Posts: 57 Comments: 30602
if i get # 2000 some one has too by me a new X BOX 360 lol
Member Since: May 21, 2006 Posts: 5091 Comments: 115347
Quoting CaneWarning:
I wonder if they may call this TS Alex at 5.
If recon finds west winds it will likely be upgraded to TS status.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Afternoon..Just heard Dr. Masters on WWL Radio in New Orleans. Great Job! Enjoyed the program and it's nice to put a voice with a face.
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Quoting Levi32:


That's just estimation by looking at satellite loops. I don't see it going due NW but it is moving north of west. We will know more about the exact movement if the recon gets us a solid center fix which we can use as a relative position later.


Oh okay. I was afraid there was more concrete evidence. But you're right.. satellite images are indicating a break from yesterday's pattern, revealing a northward push. I live in south florida and am keeping an eye on the thing. Thanks for hte comment!
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Quoting Levi32:


Lol yeah....remember in 2008 I think we had one of these in the central Caribbean with 45-knot winds but couldn't get named because it wasn't closed. I don't remember if it ever got named or not.


Dolly?
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Quoting tennisgirl08:


5pm - TD
11pm - TS Alex

Also, I think this is looking more and more like a northern gulf coast hit, unfortunately.


Like how far north? just curious...
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Taz, you completely destroyed any respect I, and I'm sure others, had for you during the last few weeks - you are nothing more then a troll at this point.

*poof*
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Quoting Drakoen:
If this isn't a tropical storm is is a very powerful wave lol...
Lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Levi32:


Lol yeah....remember in 2008 I think we had one of these in the central Caribbean with 45-knot winds but couldn't get named because it wasn't closed. I don't remember if it ever got named or not.


Are you thinking of Dolly?
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I expect w/confidence that we'll have TS alex when I come home from work tonight at 11pm,play nice,see you all then!!!
Member Since: October 5, 2007 Posts: 20 Comments: 4970
this thing is going right too Alex
Member Since: May 21, 2006 Posts: 5091 Comments: 115347
1816. Levi32
Quoting Drakoen:
If this isn't a tropical storm is is a very powerful wave lol...


Lol yeah....remember in 2008 I think we had one of these in the central Caribbean with 45-knot winds but couldn't get named because it wasn't closed. I don't remember if it ever developed or not.
Member Since: November 24, 2005 Posts: 635 Comments: 26681
1815. OneDay
1783 and 1792

Of course not, just remember that wind speed coming out of a thunderstorm is only one piece (and one of the most highly suspect pieces) of the puzzle. 93l is closer than it was yesterday, but it is no TS.
Member Since: July 13, 2005 Posts: 35 Comments: 931
I wonder if they may call this TS Alex at 5.
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Quoting MississippiWx:
1945UTC vis of 93L from RAMMB: Alex, anyone?

Link
Looks like Alex to me.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Hurricanes101:


I say 5am because they will wait for recon to go back out and verify the low is closed


5pm - TD
11pm - TS Alex

Also, I think this is looking more and more like a northern gulf coast hit, unfortunately.
Member Since: July 17, 2008 Posts: 0 Comments: 1242
Nice wind observations there.
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Quoting CybrTeddy:
Looking more and more organized each frame..
Link


And since it's in DMIN, or at least entering it, we know this isn't just a disturbance anymore, or at least won't be for long.
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1809. Drakoen
If this isn't a tropical storm is is a very powerful wave lol...
Member Since: October 28, 2006 Posts: 57 Comments: 30602
1945UTC vis of 93L from RAMMB: Alex, anyone?

Link
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1807. Levi32
Quoting cg2916:


Are they in the system?


They are a bit far away from the center with those winds but yes they are definitely in the system.

Member Since: November 24, 2005 Posts: 635 Comments: 26681
Quoting GreenMe2225:
CLOSE THAT LOW! CLOSE THAT LOW!


lol
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I know NOTHING about weather....but I am fascinated by it...don't slam me too bad for this observation...but it looks like the "out flow" on the southern side is really starting to wrap around...am I totally off on that?? lol!
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Quoting Patrap:
Shucks..

I look mo Impressive in the IR than Viz easily.



I heard that about you...LOL
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting GreenMe2225:
CLOSE THAT LOW! CLOSE THAT LOW!

LOL LOL LOL :o)

Taco :o)
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Quoting HaboobsRsweet:

When I went for a tour there they said they did...looks like they may have changed it up just a bit. Sometimes land changes things. Getting some interesting wind speeds now.
TS force.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting cg2916:


You copied him! :o Shun! *scrapes finger perpendicularly over other finger*

Copied who?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting CaneWarning:
Taz, spay that troll for us please.




i ran out you need too buy some lol
Member Since: May 21, 2006 Posts: 5091 Comments: 115347
1799. Levi32
Quoting 92Andrew:
I have a question, and hopefully bloggers aren't too busy to answer. So... how do we know the storm is moving NW ? I've read a few comments on this thing by the upper echelon of bloggers who say its moving NW. How do we know?


That's just estimation by looking at satellite loops. I don't see it going due NW but it is moving north of west. We will know more about the exact movement if the recon gets us a solid center fix which we can use as a relative position later.
Member Since: November 24, 2005 Posts: 635 Comments: 26681
1798. scott39
Quoting Tazmanian:
TS today cat 5 may be by sunday


94L today cat 5 by monday
Lay off the caffine Taz!LOL
Member Since: June 13, 2009 Posts: 0 Comments: 6881
Taz, spay that troll for us please.
Member Since: Posts: Comments:
Looking more and more organized each frame..
Link
Member Since: July 8, 2005 Posts: 259 Comments: 24457
1795. cg2916
Quoting Levi32:
Time: 19:51:30Z
Coordinates: 17.2833N 81.25W
Acft. Static Air Press: 979.1 mb (~ 28.91 inHg)
Acft. Geopotential Hgt: 250 meters (~ 820 feet)
Extrap. Sfc. Press: 1007.7 mb (~ 29.76 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 157° at 34 knots (From the SSE at ~ 39.1 mph)
Air Temp: 20.7°C (~ 69.3°F)
Dew Pt: 18.0°C (~ 64.4°F)
Peak (10s) Flt. Lvl. Wind: 35 knots (~ 40.2 mph)
SFMR Peak (10s) Sfc. Wind: 41 knots (~ 47.1 mph)
SFMR Rain Rate: 11 mm/hr (~ 0.43 in/hr)


Are they in the system?
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Quoting scott39:
Whats going on with 92L?


Last I heard him and Mr TUTT didn't get along.
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Getting in some tropical storm force winds from the eastern side. If the Hurricane Hunters find a closed surface low, then this will become Tropical Storm Alex.
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Quoting weatherwatcher12:

Does your everyday thunderstorm have a closed or almost closed low and persistent convection?


and cover an area of several hundred miles?
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Quoting btwntx08:
1759:good bye poof u go



LOL LOL LOL
Member Since: May 21, 2006 Posts: 5091 Comments: 115347
CLOSE THAT LOW! CLOSE THAT LOW!

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1789. Levi32
It should be noted that the reading of 47mph was within a strong thunderstorm cell, and is likely a local max, and will probably not be considered the max winds of the system. Max winds appear to be near 35 knots (40mph).
Member Since: November 24, 2005 Posts: 635 Comments: 26681
As long as it gets away from the coast, 93L is going to get another convection injection shortly.

Only thing hindering it right now is it's proximity to land with a steep gradient and high elevations.
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Quoting TropicalNonsense:



I agree totally Levi32. The Anticyclone will help 93L survive better than expected even
once it makes landfall negating much of the usual downgrade/discoupling effects.

If by chance 93L can keep it's center just offshore for awhile we could be looking at a
Rapid Intensification Cycle perhaps even here shortly.

Also the models should be getting a better handle on 93L most likely in the next runs
as 93L's center becomes more pronounced which is likely to stir this blog up when the
new tracks come out.

This is gonna be an exciting next few days! I hope everyone is paying attention and ready.
Yes indeed when the new Models come out this "Blog" will go "Nuts" thats for sure....

Taco :o)
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Quoting Tazmanian:



that would make it a strong TS


No.. still a weak TS. Strong TS is like 60 mph.
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Quoting MiamiHurricanes09:
The only flight pattern I know of is the X over the COC, didn't know that the flight had a specific pattern.

When I went for a tour there they said they did...looks like they may have changed it up just a bit. Sometimes land changes things. Getting some interesting wind speeds now.
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Quoting OneDay:
We had a thunderstorm at my house the other day with 41 mph winds...I wonder if that should have been classified TS Alex?

Does your everyday thunderstorm have a closed or almost closed low and persistent convection?
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1782. scott39
Quoting Tazmanian:



that would make it a strong TS
strong????
Member Since: June 13, 2009 Posts: 0 Comments: 6881
1781. cg2916
Quoting MiamiHurricanes09:
Close the low and we have TS Alex.


You copied him! :o Shun! *scrapes finger perpendicularly over other finger*

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Quoting TexasHurricane:


glad I could make you laugh. :)


Lol. Yeah thanks. :) We're all gonna need our sense of humor this year.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
1759:good bye poof u go
Member Since: July 13, 2008 Posts: 6 Comments: 10796

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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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