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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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
Member Since: Posts: Comments:
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?

80% is a 4out of 5 chance which is basically a certainty at this point.
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Nice to see Dr. Avila on this one at the moment....His first post of the season.
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Folks there is a 90-100% chance we will upgrade this to a TD by 5pm.. just looking for winds of 35kt or more for this to be instantly upgraded to a TS. Lowest pressure so far is 1005mbs
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Does anyone have a link for the kml file (Google Earth) for the Hurricane Hunter aircraft on its way in to 93L?
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974. IKE
Quoting MiamiHurricanes09:
Me too. Nothing is stopping it, and I mean nothing.


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.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Humberto, Gustav, and Ida all went from Disturbance to Hurricane in 24 hours. Its actually becoming common now.
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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?
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Quoting IKE:
IS FORECAST
TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST AND REACH THE YUCATAN
PENINSULA IN A DAY OR TWO.


If it takes 2 days and conditions are ideal, I could see it reaching a cane.


Exactly
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Quoting MrsOsa:


I still think we're missing each other. Or maybe I'm just being stupid, lol. I AM talking about private insurance companies prior to Katrina. So in your words, private companies would drop you or sky rocket your rates after a major loss. This is exactly what I'm saying.

This is not the case NOW as we are all mostly under the federal program (though written through private) and they can't do that. But I was talking about homeowners being dropped right after they made ONE major claim after Katrina. Which personally I think is BS.


You kept talking about flood insurance, so I assumed that was what you were referring to.

My bad.
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Quoting Jeff9641:


Could close in on hurricane strength tomorrow IF it stays over water. COC looks to be moving WNW or NW right now.


It's got a long way to go.
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93l 80%


94l 20%
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Quoting Fl30258713:
No problem with NHC web site for me.


I don't even go to it.. I know within seconds of anything changing on it... 15 people will cut and paste it here :)
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its going west. won't it make landfall soon?
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962. xcool
GAME ON NOW.
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Quoting StSimonsIslandGAGuy:
From disturbance to hurricane in 24 hours would be extremely rare.


If conditions are ideal it can and has happened.
Member Since: July 30, 2007 Posts: 76 Comments: 4063
Quoting StSimonsIslandGAGuy:
From disturbance to hurricane in 24 hours would be extremely rare.


I know, but Wilma went from disturbance to Cat 5 in like 36 hours.
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just loaded for me. Up to 80 now
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Quoting IKE:
IS FORECAST
TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST AND REACH THE YUCATAN
PENINSULA IN A DAY OR TWO.


If it takes 2 days and conditions are ideal, I could see it reaching a cane.
Me too. Nothing is stopping it, and I mean nothing.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting cg2916:
Wow, I just realized, this blog is so powerful, we can crash a government site over a fricken invest!

Me tinks you have a inflated view of the wunderground clout.

But its kinda flattering to think that.

The NHC server is way larger that the WU one in San Fran, so I doubt the hits from folks just blogging or lurking here are crashing their server.
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Two mentions in the the TWO the "season" is here
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Quoting StormChaser81:
We didnt crash the NHC site, its working just fine from my computer, we dont have that much power.


That's exactly right.....Could be the Chinese launching a cyber-attack....
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Ok, now 1000 people are gonna post the TWO.
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80%
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93L= 80%
94L = 20%
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NHC says a TD might form at any time.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
948. IKE
IS FORECAST
TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST AND REACH THE YUCATAN
PENINSULA IN A DAY OR TWO.


If it takes 2 days and conditions are ideal, I could see it reaching a cane.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
947. xcool
DAM 80
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ABNT20 KNHC 251750
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT FRI JUN 25 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT THE LOW
PRESSURE AREA BETWEEN THE NORTHERN COAST OF HONDURAS AND GRAND
CAYMAN HAS BECOME BETTER ORGANIZED TODAY. AN AIR FORCE
RECONNAISSANCE PLANE IS CURRENTLY APPROACHING THE SYSTEM TO
DETERMINE IF A TROPICAL DEPRESSION HAS FORMED. REGARDLESS...
UPPER-LEVEL WINDS ARE BECOMING MORE CONDUCIVE FOR DEVELOPMENT AND A
TROPICAL DEPRESSION WILL LIKELY FORM AT ANY TIME LATER TODAY OR
SATURDAY. THERE IS A HIGH CHANCE...80 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THIS
SYSTEM...ACCOMPANIED BY HEAVY RAINS AND GUSTY WINDS...IS FORECAST
TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST AND REACH THE YUCATAN
PENINSULA IN A DAY OR TWO.
ALL INTERESTS IN THE NORTHWESTERN
CARIBBEAN SEA AND YUCATAN SHOULD MONITOR THE PROGRESS OF THIS
SYSTEM.

A LARGE BUT DISORGANIZED AREA OF CLOUDINESS AND SHOWERS CENTERED
JUST EAST OF THE NORTHERN LEEWARD ISLANDS IS ASSOCIATED WITH A
TROPICAL WAVE INTERACTING WITH AN UPPER-LEVEL TROUGH. THIS SYSTEM
HAS THE POTENTIAL FOR SLOW DEVELOPMENT AS IT MOVES TOWARD THE
NORTHWEST AT 10 TO 15 MPH. THERE IS A LOW CHANCE...20 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA/ROBERTS


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No problem with NHC web site for me.
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Quoting Drakoen:


The system is 48 hours from the Yuctan Peninsula and it has acquired a well defined circulation with evident upper level outflow. I give it a 30% chance of becomming a hurricane.


Interesting. Thanks Drak.
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80%
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Up to 80 and 20 now.
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What's this all mean?? I just copied it off the flight info from google earth
:
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 25th day of the month at 17:29Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 302)
Mission Purpose: Investigate first suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 05

Mandatory Data...

Observation Time: Friday, 17:29Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 18.2N 84.1W
Location: 271 miles (436 km) to the SE (139°) from Cancún, Quintana Roo, México.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 300 meters
Flight Level Wind: From 70° at 14 knots (From the ENE at ~ 16.1 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 25°C
Flight Level Dew Point: 24°C
Weather (within 30 nautical miles): Broken clouds (5/8 to 7/8 cloud coverage)
Mean Sea Level Pressure (MSLP): 1008 mb (extrapolated)

Optional Data...

Estimated Surface Wind: From 100° at 115 knots (From the E at ~ 132.2 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 15 knots (~ 17.3mph)
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I was spot on.. 80% and 20%.
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I swear it was out for a minute, 5 people rfeported it.
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80%
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SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT THE LOW
PRESSURE AREA BETWEEN THE NORTHERN COAST OF HONDURAS AND GRAND
CAYMAN HAS BECOME BETTER ORGANIZED TODAY. AN AIR FORCE
RECONNAISSANCE PLANE IS CURRENTLY APPROACHING THE SYSTEM TO
DETERMINE IF A TROPICAL DEPRESSION HAS FORMED. REGARDLESS...
UPPER-LEVEL WINDS ARE BECOMING MORE CONDUCIVE FOR DEVELOPMENT AND A
TROPICAL DEPRESSION WILL LIKELY FORM AT ANY TIME LATER TODAY OR
SATURDAY. THERE IS A HIGH CHANCE...80 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THIS
SYSTEM...ACCOMPANIED BY HEAVY RAINS AND GUSTY WINDS...IS FORECAST
TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST AND REACH THE YUCATAN
PENINSULA IN A DAY OR TWO. ALL INTERESTS IN THE NORTHWESTERN
CARIBBEAN SEA AND YUCATAN SHOULD MONITOR THE PROGRESS OF THIS
SYSTEM.
Member Since: Posts: Comments:
000
ABNT20 KNHC 251750
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT FRI JUN 25 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT THE LOW
PRESSURE AREA BETWEEN THE NORTHERN COAST OF HONDURAS AND GRAND
CAYMAN HAS BECOME BETTER ORGANIZED TODAY. AN AIR FORCE
RECONNAISSANCE PLANE IS CURRENTLY APPROACHING THE SYSTEM TO
DETERMINE IF A TROPICAL DEPRESSION HAS FORMED. REGARDLESS...
UPPER-LEVEL WINDS ARE BECOMING MORE CONDUCIVE FOR DEVELOPMENT AND A
TROPICAL DEPRESSION WILL LIKELY FORM AT ANY TIME LATER TODAY OR
SATURDAY. THERE IS A HIGH CHANCE...80 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THIS
SYSTEM...ACCOMPANIED BY HEAVY RAINS AND GUSTY WINDS...IS FORECAST
TO MOVE SLOWLY TOWARD THE WEST-NORTHWEST AND REACH THE YUCATAN
PENINSULA IN A DAY OR TWO. ALL INTERESTS IN THE NORTHWESTERN
CARIBBEAN SEA AND YUCATAN SHOULD MONITOR THE PROGRESS OF THIS
SYSTEM.

A LARGE BUT DISORGANIZED AREA OF CLOUDINESS AND SHOWERS CENTERED
JUST EAST OF THE NORTHERN LEEWARD ISLANDS IS ASSOCIATED WITH A
TROPICAL WAVE INTERACTING WITH AN UPPER-LEVEL TROUGH. THIS SYSTEM
HAS THE POTENTIAL FOR SLOW DEVELOPMENT AS IT MOVES TOWARD THE
NORTHWEST AT 10 TO 15 MPH. THERE IS A LOW CHANCE...20 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA/ROBERTS

Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting StSimonsIslandGAGuy:




Naw, it will be interesting to see the cone of Terror. 93L looking better than yesterday, but the storms are still not well organized. But that 1006 mb pressure is quite low for a disturbance. The pressure drop is the biggest change I see.
93L looking organized on satellite imagery, more so than yesterday.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Wow, Wunderground, get ready for a lawsuit, LOL.
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Quoting cg2916:
It crashed again!

Having the same problem.
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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.