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TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER   4
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT WED JUL 10 2002
 
TROPICAL DEPRESSION FOUR-E HAS BEEN LITTLE MORE THAN A LOW-CLOUD
SWIRL FOR THE LAST 6-9 HOURS...LACKING THE REQUISITE ORGANIZED DEEP
CONVECTION OF A TROPICAL CYCLONE.  IT IS ALSO QUESTIONABLE WHETHER
THERE IS A CLOSED SURFACE CIRCULATION...AND A RECENT QUIKSCAT PASS
OFFERED SCANT EVIDENCE OF SUCH.  WHILE THERE IS A TEMPTATION TO
DISCONTINUE ADVISORIES ON THIS SYSTEM...I AM RELUCTANT TO DO SO ON
NIGHTTIME IMAGERY...AND THERE IS AN ADDITIONAL COMPLICATION AS
DISCUSSED BELOW.

DURING THE PAST TWELVE HOURS WHAT PASSES FOR A CENTER RACED AHEAD OF 
THE DEEP CONVECTION...WHICH HAS SINCE DISSIPATED.  A SECOND AREA OF 
CONVECTION AND CYCLONIC TURNING...DISTINCT FROM TD FOUR-E...IS 
CENTERED ABOUT 175 NM TO ITS SOUTH.  THE AVN SUGGESTS THAT THESE TWO 
SYSTEMS WILL COALESCE OVER THE NEXT COUPLE OF DAYS AND DEVELOP INTO 
A SIGNIFICANT CYCLONE AS THE CURRENT NORTHWESTERLY SHEAR LESSENS AND 
THE OVERALL SYSTEM MOVES UNDER UPPER ANTICYLONIC FLOW.  IF THIS 
OCCURS...IT IS NOT CLEAR WHETHER THE CURRENT DEPRESSION WILL HAVE 
CONTINUITY WITH THE ULTIMATE CYCLONE...OR WHETHER FOUR-E WILL 
DISSIPATE AND A NEW CYCLONE DEVELOP.  WHILE I SUSPECT THE LATTER 
WILL OCCUR...I HAVE CHOSEN NOT TO FORECAST DISSIPATION SO THAT THE 
OFFICIAL FORECAST BETTER CONVEYS THE POTENTIAL FOR A SIGNIFICANT 
SYSTEM IN TWO OR THREE DAYS TIME.

A STRONG MID-LEVEL RIDGE TO THE NORTH OF THE CYCLONE WILL PROVIDE A 
BASIC EASTERLY STEERING CURRENT FOR THE NEXT TWO TO THREE DAYS.  THE 
AVN...WHICH HAS BEEN HARD TO BEAT THIS YEAR...IS SOUTH OF AND FASTER 
THAN MOST OF THE OTHER TRACK GUIDANCE.  THE CURRENT FORECAST IS 
FASTER THAN THE PRECEDING ONE...ESPECIALLY IN THE FIRST 24 
HOURS...AND IS ALSO SHIFTED TO THE SOUTH.
 
FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     10/0900Z 13.0N 105.8W    25 KTS
12HR VT     10/1800Z 13.4N 107.8W    25 KTS
24HR VT     11/0600Z 13.5N 110.5W    30 KTS
36HR VT     11/1800Z 13.8N 113.0W    40 KTS
48HR VT     12/0600Z 14.5N 115.0W    50 KTS
72HR VT     13/0600Z 15.5N 117.5W    70 KTS
 
 
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