TROPICAL DISTURBANCE INVEST 98L…FAR EASTERN ATLANTIC FORECAST SYNOPSIS SPECIAL UPDATE…JULY 22, 2013…ISSUED 9:30 P.M. EDT…PHFC

Good evening everyone!

The area of disturbed weather in his morning’s forecast has been officially designated as INVEST 98L.

As of the 8:00 P.M. EDT Tropical Weather Outlook (TWO) from the NHC, the probability of INVEST 98L becoming a Tropical Cyclone during the next 48 hours has been increased, since this afternoon, to MEDIUM (30%).

NHC GRAPHICAL TROPICAL WEATHER OUTLOOK

Satellite loop imagery throughout the day, and the most recent satellite still from RAMSDIS, indicate the disturbance has become much better organized over the past 3-4 hours, and a Tropical Depression could be forming.  The most recent images from RAMSDIS indicate a much better consolidation of convection and overcast clouds, with possible inflow bands being noted on the southern periphery of the disturbance.

EUMETSAT SATELLITE LOOP IMAGE

RAMSDIS LATEST SATELLITE IMAGE

The recent update of the near real time wind shear map from CIMSS indicates a textbook upper level anticyclone over the disturbance, which has been present pretty much most of the day near 12.0N…21.0W.  Upper divergence and Lower convergence are not really that impressive at the moment, however based on the latest satellite imagery, this may improve over the next few hours.

CIMSS WIND SHEAR PRODUCT

Current steering suggests suggests more of a westerly component at the moment, however a WNW track should ensue within the next 18-24 hours.  Based on analysis of the current steering layers forecast maps from PSU e-WALL, I expect a more WNW motion sometime tomorrow, through the next 60-72 hours, before a more north of due west track may take place.  At day 6 in the steering forecast, models have this just near the northern portion of the Leeward Islands.  However, be advised about making any determination as to where it may be by then, as two important factors will be in play…How strong does it become by day 5, and does steering change drastically by then.  This track is to be taken as a preliminary estimate, based on CURRENT analysis of forecast parameters mentioned.

CURRENT LAYER MEAN STEERING

18Z DYNAMIC MODEL GUIDANCE
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As far as strength…I’ve seen a couple of folks questioning the forecast from the NHC in the TWO.  Based on what I am seeing in the shear forecast, I have to concur.  The current run of the GFS Zonal Shear forecast does indicate some decent westerly zonal shear near the northern Leeward Islands in about 5-6 days.  Until that time, upper level winds appear to remain marginal to favorable for further development of this disturbance as it will traverse an area that is shown to have little to zero zonal shear present.

GFS ZONAL SHEAR MAP VARIOUS TIMES

Based on this, I wouldn’t rue out just yet, that we may see a Tropical Storm within the next 48-72 hours, SHOULD THE CONTINUED TREND IN ORGANIZATION continue.

I will continue to monitor this disturbance, and will try to have an earlier update in the a.m.

Have a blessed evening!

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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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5 Responses to TROPICAL DISTURBANCE INVEST 98L…FAR EASTERN ATLANTIC FORECAST SYNOPSIS SPECIAL UPDATE…JULY 22, 2013…ISSUED 9:30 P.M. EDT…PHFC

  1. originallt says:

    Thanks Storm. A few days ago you said by Tuesday or so we might see something starting to form, so you got this one really close!

  2. Karen says:

    Thank you for the update!

  3. Monty says:

    Thanks Storm…forgetting Model guidance for now…following your lead.

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