TROPICAL DISTURBANCE INVEST 93L EVENING FORECAST SYNOPSIS…ISSUED JUL. 31, 2014…6:25 P.M. EDT…WEST CENTRAL FLORIDA HURRICANE AND SEVERE WEATHER FORECAST CENTER

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Good day everyone!

Tropical Disturbance INVEST 93L is now moving toward the WNW.  Based on the 18Z ATCF FTP data, the following was available on INVEST 93L

LOCATED: LAT. 11.5N…LONG. 53.0W
MOVEMENT: W 15 – 17 MPH
MAX SUSTAINED WIND: 35 MPH
PRESSURE: 1008 MB / 29.77 IN.

Analysis of satellite loop imagery indicates convection has diminished greatly during the course of the day, and the LLC can be seen a almost a totally naked swirl of Stratocumulus clouds, indicating a stable environment at the moment.  The disturbance has attained this state from both northerly shear today, as well as ingestion of dry air.  The combination of these two conditions has allowed for the LLC to separate from the convection.  Water vapor imagery clearly shows dry air wrapping into the system from the north and west., as well as the presence of outflow boundaries noted in visible and RGB satellite loop imagery.

CATL AND INVEST 93L FLOATER SATELLITE LOOP IMAGERY

WATER VAPOR LOOP IMAGERY

RAMSDIS FLOATER

INVEST 93L will be entering an area where wind shear increases to around 30 kts.

CIMSS WIND SHEAR MAP

The NHC in Miami has the probability of this disturbance becoming a Tropical Cyclone during the next 48 hours through 5 days at HIGH (70%).  The recent Special Tropical Weather Outlook issued by the NHC at 4:15 P.M. EDT indicates Reconnaissance aircraft have found sustained winds of 40  – 45 mph in the northern portion of the circulation.


STWO:

000 ABNT20
KNHC 312013 TWOAT
SPECIAL TROPICAL WEATHER OUTLOOK NWS
NATIONAL HURRICANE CENTER MIAMI FL
415 PM EDT THU JUL 31 2014

For the North Atlantic…Caribbean Sea and the Gulf of Mexico: A Hurricane Hunter aircraft has continued to investigate the low pressure system located about 500 miles east of the Windward Islands. Observations from the aircraft indicate that this system is producing winds of up to 40 to 45 mph in the northern portion of the circulation.

Showers and thunderstorms could redevelop over the low tonight or Friday, which could result in tropical cyclone formation. Regardless of development, winds of gale force are likely to spread across portions of the Lesser Antilles beginning early Friday. Interests in the Lesser Antilles should continue to monitor the progress of this disturbance as it moves west-northwestward near 20 mph, and watches or warnings may be required for some of these islands later tonight or Friday.

* Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…70 percent.

$$ Forecaster Pasch

Based on my analysis of the current and forecast wind shear products, and water vapor loop imagery, the only way I see this now becoming a Tropical Depression is as stated in the outlook.  I do believe however, this may have a better chance of becoming an open wave over the next 48 hours, if it cannot regain any convection.  Based on my current forecast track thinking, I do not foresee this coming to fruition as far as regeneration of convection.  Water Vapor loop imagery not only indicates dry air, but an upper level low is noted to the NW of this system, which will continue to drag drier, cooler air into the system as it continues on its current path.  I really do believe with the interaction of drier air, and land interaction within the next 72 hours, as well as upper level winds being forecast to be marginal at best at this time, that INVEST 93L may not survive for too long.  Also noted was the lack of any significant vorticity at the 5000 mb level.

Analysis of current and forecast steering layers products in the shallow layer of 700 – 850 mb indicates INVEST 93L should continue to head toward the WNW during the next 48 – 60 hours, prior to turning more toward the NW as the system heads into a weakness in the subtropical ridge.  Given the orientation of the ridge, model guidance has shifted to the left, slightly, which is in agreement of the shallow layer steering forecast.  Based on this analysis, what may be left of the LLC could pass within 120 nm of the Miami and West Palm Beach FL. vicinity.  Given this, I prefer the TVCC / TVCN Dynamic Model Track Guidance.

CURRENT STEERING LAYER MEAN

18Z DYNAMIC MODEL TRACK GUIDANCE
93L DYNAMIC

As stated by the NHC, residents within the Lesser Antilles, as well as the Greater Antilles and Bahamas should monitor this system in case ANY significant changes occur.

I will have another full update in the a.m.

Have a blessed evening!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST / SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER
OFFICIAL SKYWARN SPOTTER (ADVANCED)

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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10 Responses to TROPICAL DISTURBANCE INVEST 93L EVENING FORECAST SYNOPSIS…ISSUED JUL. 31, 2014…6:25 P.M. EDT…WEST CENTRAL FLORIDA HURRICANE AND SEVERE WEATHER FORECAST CENTER

  1. originallt says:

    Wow, we do have Bertha. Maybe the NHC jumped the gun a bit on this one. Lets see if it survives.—45mph winds now.

  2. 7s1b4SW says:

    Thanks Storm for your analysis! Thanks for sticking your neck out!! I, for one, would place a lei around it , ALOHA !! , but there are those who would “chop it off.” Their loss!

    BeachBum

  3. Monty says:

    Whoa…looks like NHC is sticking to their guns. Other than Gale Force winds…which I guess is criteria for TS formation…can’t really make out an organized system. I’m no expert by any means but I’m agreeing with the guy that…in my opinion…has outguessed the NHC. I’m sticking with your synopsis but please advise if I should send anything out to the gang. Thanks Senior Chief!!

  4. Monty says:

    Thanks Storm. What a difference a day makes. It looked much more impressive yesterday. Hmmm…the NHC must have misplaced the address to your blog!!

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