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 bwt1982:


Definetly not a TS so if I have to pick one..... TD



have you even been following
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Quoting PanhandleChuck:


Why not a bull?



even better
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I am hearing Alex from NHC is this true? winds at 40 mph.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
2326. bwt1982
Quoting Tazmanian:
new poll


A TD

or B TS


Definetly not a TS so if I have to pick one..... TD
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well once it goes over the yucatan it will sure disrupt the coc and it will weaken it ..it wont move into the boc until monday then we will see what happens...it looks to me right now it will go over the yucatan at 18.0 and 87.0 it should then take a whole day to get bac in the boc...doesnt look good at all for any rapid development if this takes place...new data shows it will definitely be torn up over the yucatan...a texas rain maker..
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Quoting MiamiHurricanes09:
LMAO! Why you happy?



not sure this 93L been a pain in the butt too track from day one
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Quoting Drakoen:
Just awaiting the vortex message now
Me too.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
if it werent for land interaction, 93, i mean alex would prolly intensify perty quick
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41.0 knots (~ 47.1 mph)
Tropical Storm
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Quoting Orcasystems:


I try to stick with remarks based on some sort of evidence... makes it harder for the casters to ping off you :)



Well... the pressures are supportive of a weak TS (1004 mb)

Erin, of 2007 had minimum pressures of 1003 mb.

-Snowlover123
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Quoting Tazmanian:
YAY am happy has a cow


Why not a bull?
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expect the vortex message shortly
Member Since: July 13, 2008 Posts: 6 Comments: 10796
Quoting 10Speed:
So ....

1. Do they take the chance and name 93L even though it might end up not qualifying for a name by the time the night's out?

2. Do they name it simply because of it's proximity to land?

3. Do they refrain from naming it because of the oil promoted media frenzy that's going transpire as soon as they name it?

4. Do they do their job and follow their own rules regarding naming?


somewhere between #3 and #4...LOL!
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We are going to reach 3000 posts once it gets classified.
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2315. Patrap
Breaking News

Wu members declare their Allegiance to 93L Upgrade to TD.

Film at 6

Member Since: July 3, 2005 Posts: 426 Comments: 129090
Quoting MiamiHurricanes09:
I wonder how many people are going to post the renumber? Lol.


Poll time!

A. 5 or less
B. 10-15
C. 15-20
D. 20-25
E. 25+
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2313. Drakoen
Just awaiting the vortex message now
Member Since: October 28, 2006 Posts: 57 Comments: 30614
Quoting Tazmanian:
YAY am happy has a cow
LMAO! Why you happy?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
THIS BLOG IS LIGHTING UP LOL.
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I think there calling it Alex.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
Quoting cchsweatherman:
For the first time this entire mission, we have some real solid westerly winds recorded by the Hurricane Hunters. Given several tropical storm force winds measured and now a closed low based upon the given data presented, this should become Tropical Storm Alex.
Agreed!
Member Since: September 2, 2009 Posts: 130 Comments: 21194
"I can feel it coming in the air tonight...Oh lord..."
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YAY am happy has a cow
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Quoting Snowlover123:


That could very easily be a weak TS, but I won't say anything...

-Snowlover123


I try to stick with remarks based on some sort of evidence... makes it harder for the casters to ping off you :)

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Quoting Levi32:
This is a tropical depression and possibly a storm.


Levi
thanks for those posts of the recon...
and of course the good info you and some of the others are giving us here this afternoon!


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Quoting homegirl:
I said it about 5 mins ago...on my blog, Hello Alex.


Hi Alex! Just don't do too much damage okay?

-Snowlover123
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For the first time this entire mission, we have some real solid westerly winds recorded by the Hurricane Hunters. Given several tropical storm force winds measured and now a closed low based upon the given data presented, this should become Tropical Storm Alex.
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2302. centex
Special Statement now seems imminent.
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Quoting Levi32:
This is a tropical depression and possibly a storm.
Yes sir.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2300. Skyepony (Mod)
It looks closed and to be a TS.
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http://www.nhc.noaa.gov/gtwo/gtwo_atl_sub.shtml?area2#contents
94L up to 20%
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Quoting smmcdavid:


Thanks.... me too. :)

We all have our "off days".


As do I :).
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Quoting Levi32:


23kt flight-level 41kt SFMR.


Read it wrong and kept editing my post between the two numbers rofl.
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2296. bwi
SFMR measured 41kts. From W.
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I wonder how many people are going to post the renumber? Lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Alex?
Member Since: November 4, 2009 Posts: 0 Comments: 6577
I said it about 5 mins ago...on my blog, Hello Alex.
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Quoting seflagamma:



rofl....you are really being a funny man today!


Thank you...LOL

This is the material folks...sometimes it's good and sometimes it bombs...I don't make it up, I just report it
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2291. Patrap
Floater - Visible Loop
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2290. Drakoen
Quoting Levi32:
This is a tropical depression and possibly a storm.


Yup
Member Since: October 28, 2006 Posts: 57 Comments: 30614
2289. 900MB
Quoting StormW:


Well, I feel it may interact too much with land...go here, look at the clouds ahead of it to the west, and north...which way they goin?

RGB LOOP


Thanks for the visual. Looks like you are spot on and we may luck out this time! However, I think we are 60-70mph before we hit land and I still think how much land is an open question with an absence of steering currents. We'll see, but I'll always go with your humble opinion over MHO.
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2288. Levi32
Quoting Jeff9641:


Is it further N or is it in the same location hard to tell.


It is hard to tell yes....it may have reformed slightly to the south and tightened up under the heaviest convection. The first pass suggested it was farther north at the time.
Member Since: November 24, 2005 Posts: 635 Comments: 26684
Quoting Stormchaser2007:
41 knot SFMR
47 mph SFMR west winds.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Tazmanian:
new poll


A TD

or B TS
TS.
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Time: 21:02:00Z
Coordinates: 16.1167N 84.W
Acft. Static Air Press: 978.1 mb (~ 28.88 inHg)
Acft. Geopotential Hgt: 241 meters (~ 791 feet)
Extrap. Sfc. Press: 1005.8 mb (~ 29.70 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 267° at 22 knots (From the W at ~ 25.3 mph)
Air Temp: 21.0°C (~ 69.8°F)
Dew Pt: 18.0°C (~ 64.4°F)
Peak (10s) Flt. Lvl. Wind: 24 knots (~ 27.6 mph)
SFMR Peak (10s) Sfc. Wind: 38 knots (~ 43.7 mph)
SFMR Rain Rate: 15 mm/hr (~ 0.59 in/hr)
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Quoting Levi32:
I have no doubt it's closed now.



Wow, I almost died of old age waiting for them to find that lol. Maybe looking at a renumber soon.
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Quoting Orcasystems:


I think that last 1004.3 could come out as a Vortex message ... its very close.


That could very easily be a weak TS, but I won't say anything...

-Snowlover123
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Quoting KEEPEROFTHEGATE:
smmcdavid:
i would like to say iam sorry for yesterday


Thanks.... me too. :)

We all have our "off days".
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From 323° at 18 knots
(From the NW at ~ 20.7 mph)
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2280. leo305
Quoting Jeff9641:


Is it further N or is it in the same location hard to tell.


I think it(the center) is further north of that.. on vis the area they found the strong west winds, is were a strong developing feeder band has developed
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2279. Relix
Fellas, I am sure we have our first TS of the season. Cheers. Now let's watch this guy, it wants to be an evil system =(
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.