TROPICAL WEATHER FORECAST SYNOPSIS…DISTURBANCE CENTRAL CARIBBEAN / POSSIBLE CATL STORM…AUG. 13, 2013, ISSUED 12:15 P.M. EDT…PHFC

Good day everyone!

An area of disturbed weather in conjuncture with a tropical wave, a broad surface low, and the Monsoon trof continues in the central Caribbean Sea this morning.  Albeit coverage has decreased somewhat with this area, shower and thunderstorm activity has become more concentrated over the past few hours.  The NHC still holds a 10% (LOW) probability of this disturbance becoming a Tropical Cyclone during the next 48 hours, and a 30% (MEDIUM) chance in 120 hours.  Satellite loop imagery seems to indicate shower activity becoming more concentrated, as well as the broad low possibly trying to reform under the convective area to its north.

NHC GRAPHICAL TROPICAL WEATHER OUTLOOK

WATL SATELLITE LOOP IMAGERY

The 06Z run of the NCEP/EMC SREF model indicates a 40% chance of development in this area during the next 48 hours.  The Multi Model and NCEP Ensemble models indicate a 40% chance of a development north of Panama from 120 hours, out…however, this would have to be a separate entity, as our current disturbance is further north, and continues to move just north of due west.

NCEP SREF SOLUTION

Analysis of the current wind shear map from CIMSS indicates a shift to more favorable conditions has not taken place at the moment.

CURRENT WIND SHEAR

The 06Z run of the GFS Wind Shear and Zonal Shear forecast still calls for upper level winds to become more conducive for development in the next 24 hours with an upper level anticyclone becoming established in the western Caribbean.  The ULL in the GOMEX has given way to another ULL which is currently west of the Florida Keys area.  As this ULL continues to move west, conditions in the western Caribbean should improve, with a reduction in wind shear, and aid in ventilating the western Caribbean as it does so.

06Z GFS WIND SHEAR / ZONAL SHEAR FORECAST 30 HOURS

WATL WATER VAPOR LOOP IMAGERY SHOWING ULL

Based on all that is concurring at the moment, I am still calling for slow development of this disturbance over the next 72 hours, however this may not take place until the extreme western Caribbean, near the Yucatan Channel / Peninsula.  This reduces the probability of a hurricane since the disturbance has not developed, prior to entering the extreme TCHP values in the western Caribbean.  The three models mentioned yesterday have come into a little better agreement on strength if this develops, with the GFS being the weaker of the three in showing a Tropical Depression affecting the Gulf coast region in about 4 – 5 days or so, the CMC a strong Tropical Storm, and the FIM Experimental model indicating a moderate Tropical Storm.

TCHP MAPS

As far as possible forecast tracks, SHOULD this develop, and develop further south than I am planning, a motion more toward the west would be in order, to which this could cross the Yucatan Peninsula, and eventually anywhere from south TX into Mexico with minimal development.  However, based on the premise a LLC develops under the current convection, the current run of the forecast steering layers maps indicates more of a track of 285-290 degrees in about 18-24 hours, as a break in the ridge is forecast to begin in the GOMEX.  This may be enough to “tug” the disturbance slightly further north, and allow for a more pronounced WNW track in about 30 hours.  At around 42 hours from now, the steering forecast calls for a more NW flow, and would allow for the disturbance to enter the GOMEX, and eventually curving toward the NE.  Out of the 3 models, I still prefer the FIM model solution, showing the “center” making landfall near Mobile Bay AL.  Based on the wind field however, TS force winds, if indeed we have a tropical storm, will be to the right of the center, close to the Fort Walton Beach, FL. area.

FIM EXPERIMENTAL MODEL SOLUTION

Elsewhere, I will be closely monitoring the area of disturbed weather that is exiting the African coast for signs of development in a few days.  At the moment, there are some parameters supporting development of this feature:  The NCEP/EMC Multi Model and NCEP Ensemble indicate a high probability of development in the EATL in 120 hours.  The current 500 mb anomaly departure forecast indicates a cyclone in the CATL in about 144 hours.  This would coincide with the disturbance just off the African coast.  This disturbance will also be traversing a narrow corridor of fairly conducive upper level winds.

EATL SATELLITE IMAGE AND EUMETSAT SATELLITE LOOP

NCEP MULTI MODEL AND ENSEMBLE FORECAST

500 MB ANOMALY MEAN DEPARTURE 144 HOURS

I will continue to monitor this area for any significant changes over the next 96 hours.

Based on the current forecast for the upward motion pulse of the MJO, and ensemble forecast for the NAO, I am still sticking with the 21st and after for an upswing in tropical activity over the MDR.  The majority of the Dynamic Models of the MJO Multivariate Index indicate the MJO to arrive in Octants 8 and/or 1 by the third week of this month.  The ECMWF has even come around to the GFS and UKMET forecast solution.

ECMWF MJO INDEX FORECAST

The NCEP ensemble forecast for the NAO appears to be coming inline with the ECMWF ensemble forecast for the NAO to head toward neutral or a weak negative signal. IF this comes to fruition, along with the MJO forecast, I do believe we will see an increase of activity within the time mentioned.

NAO FORECAST

00zecmwfensnao
Tropical Storm formation is not expected within the next 48 hours.

Have a blessed day!

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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7 Responses to TROPICAL WEATHER FORECAST SYNOPSIS…DISTURBANCE CENTRAL CARIBBEAN / POSSIBLE CATL STORM…AUG. 13, 2013, ISSUED 12:15 P.M. EDT…PHFC

  1. Monty says:

    Thanks Storm. I’ll warn the gang along the GOMEX…looks like you have another one exiting Africa…here comes August 20th…just like you said!!

  2. Mike Doll says:

    Thanks Storm, The local TV met is saying anything that me develope will get ripped apart by high wind sheer. so no worries for us in the Mobile area. Not sure what he is seeing but !!!!!!
    Mike

  3. TexasHurricane says:

    Thanks Storm….Guess TX is out of luck with rain on this one.

  4. stefanie says:

    Thanks Storm. 🙂

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