SPECIAL UPDATE…TROPICAL DISTURBANCE INVEST 98L COULD BE APPROACHING TROPICAL STORM STATUS…FORECAST SYNOPSIS…JULY 23, 2013…ISSUED 11:20 P.M. EDT…PHFC

Good evening.  Post would have been up sooner, except PC problems…talk about SLOW!

As of the 10:40 P.M. EDT Tropical Weather Outlook from the NHC, probabilities of Tropical Disturbance INVEST 98L becoming a tropical cyclone during the next 48 hours has increased to HIGH (70%).

NHC GRAPHICAL TROPICAL WEATHER OUTLOOK

Current satellite imagery, and satellite loop images indicate 98L has become slightly better organized over the past 6 hours, with a slight increase of convection near the center.  Satellite imagery also indicates this system may be trying to develop a small CDO, as what appears to be a semi ring near the center.

INVEST 98L FLOATER SATELLITE LOOP IMAGERY

The disturbance is moving to the WNW, and I expect this motion to continue for the next 48-60 hours, before the subtropical ridge becomes more oriented east to west, and nudges westward each day as presented int he current run of the forecast steering layers maps.

Based on analysis of current and forecast steering layers maps, I am concurring with the dynamic model guidance, and still prefer a rack with a blend of the TVCC, TVCN, and AEMI track guidance.  Track thereafter or past 72 hours can change quickly.  However, on the last two frames of the forecast steering maps loop, the subtropical ridge is shown elongating and pushing it’s nose slightly further west with each frame.

00Z DYNAMIC MODEL GUIDANCE
00zatcfearlyinvest1best.98L

Current wind shear depicts a semi upper level anticyclone at the moment, however winds are light enough to allow further intensification of this disturbance.  In fact, as of the typing of this synopsis, the NHC increased the probability for development to 70%, and will be reflected in the graphical TWO.

NHC had indicated the presence of some wind shear after tomorrow, along with cooler sst’s, which would inhibit further organization.  However, based on model guidance shifting further south, it will hit cooler sst’s, however the disturbance may be over these cooler temps shorter than anticipated earlier.

In regards to wind shear, I’m scratching my head trying to figure this one out.  The 18Z run of the GFS Zonal Shear forecast does indicate a weakening of the upper level anticyclone, but brings it back about 12 hours after it diminishes.  Based on analysis of the zonal shear forecast, and future forecast track, it appears 98L will be in semi conducive, to conducive upper pattern over the next 5 days, with little to no zonal shear, and redevelopment of the upper level anticyclone.  This has been consistent in the 3 consecutive runs today.  Based on these factors, I am calling for a possible halt to intensification after tomorrow, for a brief period, and believe, should forecast conditions hold true, a re-intensification of this system after 48 hours.

GFS ZONAL SHEAR MAPS

Based on information contained in the TWO, this system may become a tropical depression, or even a tropical storm by morning, if the current convective trend continues.

I will have another update in the a.m.

Have a great night!

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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3 Responses to SPECIAL UPDATE…TROPICAL DISTURBANCE INVEST 98L COULD BE APPROACHING TROPICAL STORM STATUS…FORECAST SYNOPSIS…JULY 23, 2013…ISSUED 11:20 P.M. EDT…PHFC

  1. originallt says:

    Thanks Storm, sounds complicated–glad YOU are trying to figure it out! But it does appear that in 5-6 days we might have a problem on our hands, somewhere in the SE or even Florida.

  2. stefanie says:

    Thanks Storm. I’m so sleepy but you made that very easy to understand. Have a good night. 🙂

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