TROPICAL DISTURBANCE INVEST 92L / TROPICAL LOW INVEST 93L EVENING FORECAST SYNOPSIS…AUG. 14, 2013…ISSUED 7:30 P.M. EDT…PHFC

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Good evening everyone!

Tropical Disturbance INVEST 92L continues to consolidate and become better organized.  The NHC in Miami has now increased the probability of this becoming a tropical cyclone over the next 48 hours to 60% (HIGH), and to 70% during the next 120 hours.

GRAPHICAL TROPICAL WEATHER OUTLOOK

Based on my analysis of the current run of the GFS Wind Shear and Zonal Shear forecast, and current satellite loop imagery, I believe INVEST 92L may become a Tropical Depression late tonight, or by tomorrow morning.  My reasoning for this is, the shear forecast is indicating upper level winds to become more conducive over the next 6 hours, where the upper level anticyclone should be over the disturbance.  The CIMSS site is down right now due to hardware failure, but the last run of the GFS Global Model indicates the upper level anticyclone to be displaced as of earlier this afternoon.  However, shear values are indicated to be below 15 knots, and based on satellite loop imagery, there is an established outflow pattern over the system mainly in the north and east portions.  One other factor in this, before the system crosses onto the Yucatan Peninsula, it will be traversing some pretty high TCHP values, which should aid in intensification.  In terms of a hurricane, TCHP values of >60 kJ / cm-2 will allow for sustaining a hurricane, and allow for rapid intensification in a hurricane.  In fact, a little more research implies the TCHP value may be lower as far as aiding in intensification, as provided by the RAMSDIS site, referencing a value of 50+ kJ / cm-2.

INVEST 92L SATELLITE LOOP IMAGERY / WATL SATELLITE LOOP IMAGERY

GFS SHEAR VALUES
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GFS WIND SHEAR / ZONAL SHEAR FORECAST

TCHP MAP

Based on these parameters, I believe again we should see a Tropical Depression sooner than later.  Once the system reaches the southern GOMEX, upper level winds are forecast to become less conducive for development, even marginal at best.

Based on the current steering layers map, 92L should continue to move toward the WNW through tonight and tomorrow morning, with a turn more toward the NW afterwards, as it gets ready to cross the Yucatan Peninsula, based on the current run of the forecast steering layers maps from the PSU e-WALL site, valid for 00Z this evening.

CURRENT STEERING LAYER MEAN

Based on this, and current satellite motion, I agree with the 18Z Dynamic Model guidance, preferring the TVCC / TVCN suite.  Given the shear forecast and steering parameters, I still prefer the track and strength as shown by the FIM Experimental Model, and based on this at the moment, look for the center to make landfall anywhere from south of Houma, LA, to the MS/AL border, save any center relocation’s.  However, this will be an east weighted storm, in that the strongest winds and precipitation should occur to the east where the center comes ashore.  Based on the FIM model, it projects a weaker Tropical Storm, of 40 – 45 mph at landfall.  A weaker system makes sense at the moment, given the forecast shear pattern.

INVEST 92L DYNAMIC MODEL GUIDANCE
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FIM MODEL 

FIM TOTAL RAINFALL 144 HOURS

Residents from the central Louisiana coast, to the W. Florida Panhandle should monitor the progress of this system closely for any significant changes to forecast parameters, especially once it enters the GOMEX.

I will continue to monitor this system and have another update in the a.m.

Tropical low INVEST 93L has become better organized throughout the day, and the NHC in Miami has increased the probability of this system becoming a tropical cyclone during the next 48 hours to 70 percent.  Based on the projected upper level wind pattern, I have to concur at this time.  Based on satellite loop imagery, the rate of organization is very good, and I cannot rule out 93L becoming a Tropical Depression by tomorrow sometime.

INVEST 93L SATELLITE LOOP IMAGERY

Based on Dynamic Model track guidance, and steering forecast maps, 93L should move more toward the WNW to NW in about 24-36 hours, and then bend back toward the west.  I prefer the track in the 18Z Dynamic Guidance of the TVCC / TVCN.  This track will in fact bring the system over some slightly cooler sst’s, and possibly into some drier air.  However, based on the current shear forecast, an upper level anticyclone is forecast to remain established over the system as it travels west later in the period.  It could be possible that further development in a few days, if it occurs, could allow for more moisture to be out out around the system.  So, right now for 93L, we are going to have to play intensity by ear.

INVEST 93L DYNAMIC MODEL GUIDANCE
18zatcfearlyinvest1best.gif.93L

I will continue monitoring 93L for any significant changes during the next 48-72 hours, and will have another update in the a.m.

Have a blessed evening!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced)
CoCoRaHS OBSERVER

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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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6 Responses to TROPICAL DISTURBANCE INVEST 92L / TROPICAL LOW INVEST 93L EVENING FORECAST SYNOPSIS…AUG. 14, 2013…ISSUED 7:30 P.M. EDT…PHFC

  1. Karen says:

    Thanks Storm. Please continue to keep us updated.

  2. Monty says:

    Thanks Storm. We…..August 20th isn’t too far away. Nice call my friend!! It’s looking like a majority of the guidance puts 92L in or around MSY…not good for Dellamom. Any chance 93L could threaten the Eastern Seaboard…CHS in particular? Thanks always Senior Chief for your continued dedication!!

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