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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93L would need to deepen significantly for it to be in the steering levels for a hard right turn. Right now, the flow does not support that. Is it possible? Sure. But it is gonna have to put on a helluva show tonight for a EGOMEX solution to pan out.
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Quoting CaneWarning:


Do you think it will become a hurricane? Dr. M gave it only a 10% chance.


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.
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We didnt crash the NHC site, its working just fine from my computer, we dont have that much power.
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a load of feeder bands are forming around Alex, and the CDO continued to grow and develop over the center...
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Agreed Storm. Way too early. The models always indicate the turn right it seems but it rarely pans out.
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The NHC just called me. They want me to ask all of you to stop hitting F5.
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It crashed again!
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So they get the data and put into the new runs of the models. The question is when will those runs come out? Everything is speculative with all estimates so far, the first run with real data will be very interesting...
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Quoting weatherwatcher12:
NHC site still works for me.
I just checked in to see the SSD satellite images, but I just saw a blank page. Anyways, why is everyone F5ing the NHC site, we all know it is still going to be red.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting StormW:


Not going east...gonna be over the Peninsula.


Hi Storm,

How do you think this track is going to go once in the GOM?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
93L Floater - Rainbow Color Infrared Loop
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Wow, I just realized, this blog is so powerful, we can crash a government site over a fricken invest!
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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.


I sure hope you are right but Orlando mets are saying the samething as well. I hope this goes west because he looks like he is going to blow hard.
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Quoting weatherwatcher12:
NHC site still works for me.

It worked for me too, but was very slow
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This is the only place I know that people can manage to crash a government site.
Member Since: July 8, 2005 Posts: 259 Comments: 24468
Quoting Jeff9641:
For people that don't by the sharp right turn might want to look at the GFDL and HWRF which both have the best track record with tropical systems. An upper low is progged to dive SE from the Great Lakes early next week and enhance a trough in the eastern us. A Stronger system will feel this and swing N then NE as Doc mentioned. Doc hit it right on.


I have been watching models for years. The right hook is always projected early on. the last 7 years or so it never pans out and the lows rarely have any effect on the storm. That has been my experience. way to early. It could stall while developing. You just never know.
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Quoting Drakoen:
If 93L becomes a hurricane in the Caribbean it will most likely affect the central or eastern GOM.


Do you think it will become a hurricane? Dr. M gave it only a 10% chance.
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AOI
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NHC site still works for me.
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Quoting cg2916:
We must have a lot of people on if we crashed the NHC site over an INVEST!


Huh? I can still access their website...
Member Since: August 30, 2008 Posts: 8 Comments: 2835
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.

exactly
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Quoting Drakoen:
Great Loop to monitor the system you can see the well defined center
nice view...thanks
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If 93L becomes a hurricane in the Caribbean it will most likely affect the central or eastern GOM.
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Quoting StormW:


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


Panhandle is very feasable. I think Doc was right infact local mets in Orlando said the samething Doc said. Weak west Strong more east in track. This why we all have to watch this.
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Shoot, I'm surprised we don't break the recon obs with our F5 clicking..
Member Since: July 8, 2005 Posts: 259 Comments: 24468
It's back now, but wow, guys!

NEW RULE: only hit F5 once every 30 seconds.
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Quoting CaneWarning:
CMC goes right over Patrap.

read post 822
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...SPECIAL FEATURE...

A WEST CENTRAL CARIBBEAN SEA TROPICAL WAVE IS ALONG 82W...
DRIFTING WESTWARD. A 1006 MB LOW PRESSURE CENTER IS ALONG THE
WAVE NEAR 17N. STRONG SHOWERS AND THUNDERSTORMS ARE FROM 13N
TO 17N BETWEEN 81W AND 83W/84W...AT LEAST REACHING THE EASTERN
COASTS OF HONDURAS AND NICARAGUA. OTHER STRONG SHOWERS AND
THUNDERSTORMS ARE OVER THE WATERS IN THE NORTHWESTERN CORNER...
TO THE SOUTH OF 19N BETWEEN 85W AND THE YUCATAN PENINSULA AND
BELIZE. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS ARE TO THE NORTH OF 19N BETWEEN 79W AND THE
NORTHEASTERN THE NORTHEASTERN YUCATAN PENINSULA. THE SURFACE
LOW PRESSURE CENTER IS SHOWING SIGNS OF ORGANIZATION. THE
SURFACE PRESSURES ARE FALLING. UPPER-LEVEL WINDS GRADUALLY
ARE BECOMING MORE CONDUCIVE FOR DEVELOPMENT. IT IS LIKELY
THAT THIS SYSTEM MAY BECOME A TROPICAL DEPRESSION BEFORE IT
REACHES THE YUCATAN PENINSULA DURING THE NEXT FEW DAYS.
THE CHANCE OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS IS HIGH. AN AIR FORCE RECONNAISSANCE PLANE
IS SCHEDULED TO INVESTIGATE THIS AREA OF WEATHER LATER TODAY.

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We must have a lot of people on if we crashed the NHC site over an INVEST!
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Agreed.
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It will be interesting to see the cone of error.
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894. Gorty
93l is looking much more like a cyclone.
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Great Loop to monitor the system you can see the well defined center
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Quoting IKE:
12Z GFDL on 93L


That would make us some oil stew in the worst way...
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Who would DDoS the NHC site?
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Quoting StormW:


Not going east...gonna be over the Peninsula.


You should clarify which Peninsula... I know you mean the Yucatan, but somebody is going to see that and get excited. LOL
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889. ATL
All the F5F5F5F5F5F5ing you guys are doing is crashing the site, lol...
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We've just crashed the NHC site with our obsessive 'F5' clicking. Usually that only happens with Category 4 or 5 hurricanes.
Member Since: July 8, 2005 Posts: 259 Comments: 24468
Quoting StormW:


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


Agreed StormW
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Quoting cg2916:
Dang it guys, we crashed the NHC site, LOL, first time if I recall correctly.
LOL!!
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885. xcool
WAIT for Recon Data people .
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Quoting Patrap:
Shucks I never keep a NHC open,

Cuz soon as sumthing new pops up.

We get the UPS delivery here really fast
LMAO!
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Dang it guys, we crashed the NHC site, LOL, first time if I recall correctly.
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Quoting IKE:


LOL...sorry.


That's OK; I'll skip mowing the grass this weekend....... :)
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Quoting CybrTeddy:
GFDL still sticking on to that trough being strong enough to pull 93L NE towards Florida on this run. Other models just build the ridge back in and 93L continues in a WNW-NW direction the next couple of days.
that is interesting most moldels say trough wont be storng enough except for those two
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Quoting Jeff9641:
For people that don't by the sharp right turn might want to look at the GFDL and HWRF which both have the best track record with tropical systems. An upper low is progged to dive SE from the Great Lakes early next week and enhance a trough in the eastern us. A Stronger system will feel this and swing N then NE as Doc mentioned. Doc hit it right on.


Their still models and its a little while out still, it will change.
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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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