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TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   2
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT WED AUG 09 2000
 
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE
A CENTRAL PRESSURE OF 1010 MB AND 39 KT FLIGHT LEVEL WINDS 7 NM
NORTHWEST OF THE CENTER.  THIS SHOWS THAT DESPITE THE LACK OF
PERSISTENT CONVECTION THE DEPRESSION HAS CHANGED LITTLE IN STRUCTURE
SINCE YESTERDAY.  THE MAXIMUM WINDS REMAIN AT 30 KT FOR THIS
ADVISORY.
 
THE INITIAL MOTION IS 270/4.  THE DEPRESSION REMAINS IN A WEAK
STEERING ENVIRONMENT CAUSED BY THE SUBTROPICAL RIDGE AND A LARGER
TROPICAL WAVE TO THE EAST.  THIS IS FORECAST TO CONTINUE FOR THE
NEXT 24 HR OR SO.  AFTER THAT...A STRONG MID/UPPER LEVEL TROUGH AND
ASSOCIATED SURFACE FRONT WILL INTENSIFY OVER THE EASTERN U.S. 
LARGE-SCALE MODELS SUGGEST THE LOW LEVEL FLOW SHOULD BECOME WEST TO
SOUTHWEST BY 36-48 HR...WHICH SHOULD STEER THE CYCLONE OUT TO SEA. 
NHC TRACK GUIDANCE AGREES WITH THIS SCENARIO...AGAIN WITH SOME
DISAGREEMENTS ON DETAILS.  THE OFFICIAL FORECAST FOLLOWS THIS
SCENARIO AND IS SHIFTED A LITTLE NORTH OF THE PREVIOUS PACKAGE.

THE DEPRESSION CONTINUES TO PRODUCE SMALL PUFFS OF CONVECTION WHICH
ARE SHEARED AWAY BY UPPER LEVEL EASTERLY FLOW.  NO INTENSIFICATION
IS FORECAST UNTIL THE SYSTEM SHOWS IT CAN DEVELOP PERSISTENT
CONVECTION.  THIS MIGHT HAPPEN WHEN THE SHEAR LETS UP IN 24 HR OR
SO...WHICH IS HINTED AT BY THE LARGE-SCALE MODELS.
 
WITH THE SMALL SIZE AND SLOW MOTION...THE DEPRESSION IS CURRENTLY A
THREAT PRIMARILY TO MARINE INTERESTS.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     09/2100Z 27.9N  78.1W    30 KTS
12HR VT     10/0600Z 27.9N  78.5W    30 KTS
24HR VT     10/1800Z 28.2N  79.1W    30 KTS
36HR VT     11/0600Z 28.8N  79.5W    30 KTS
48HR VT     11/1800Z 29.5N  79.0W    30 KTS
72HR VT     12/1800Z 31.0N  76.5W    30 KTS
 
 
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