Tropical Storm DARBY

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TROPICAL STORM DARBY DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT TUE JUL 27 2004
 
SATELLITE IMAGES INDICATE THAT THE CLOUD PATTERN ASSOCIATED WITH
DARBY IS GRADUALLY IMPROVING. THERE IS A WELL DEFINED CONVECTIVE
CURVED BAND TO THE WEST AND DEEP CONVECTION NEAR THE CENTER. THE
UPPER-LEVEL OUTFLOW IS WELL ESTABLISHED AND IT IS MOST PRONOUNCED
ON THE WESTERN SEMICIRCLE. DVORAK T-NUMBERS FROM TAFB AND SAB
SUGGEST THAT THE WINDS ARE ALREADY 55 KNOTS. DARBY IS EXPECTED TO
BE OVER WARM WATERS AND LOW SHEAR FOR THE NEXT 2 TO 3 DAYS.
THEREFORE...THE CHANCES OF BECOMING A HURRICANE AND THEN FURTHER
STRENGTHENING ARE HIGH. THIS IS CONSISTENT WITH SHIPS AND GFDL
MODELS.
 
DARBY IS MOVING 290 DEGREES AT 12 KNOTS AROUND THE PERIPHERY OF A
SUBTROPICAL RIDGE WHICH HAS A WEAKNESS TO ITS WEST. THIS PATTERN IS
FORECAST TO GRADUALLY MOVE WESTWARD AS INDICATED BY MOST OF THE
GLOBAL MODELS. THIS WOULD ALLOW DARBY TO MOVE WEST OR 
WEST-NORTHWESTWARD DURING THE NEXT 3 TO 5 DAYS. THE OFFICIAL
FORECAST IS A LITTLE BIT TO THE SOUTH OF THE MODEL CONSENSUS AS IN
PREVIOUS FORECASTS. I WAS TEMPTED TO SHIFT THE OFFICIAL FORECAST
NORTHWARD TO BE IN AGREEMENT WITH THE CONSENSUS BUT I RATHER WAIT
FOR TODAYS EVOLUTION OF THE CYCLONE TO MAKE A CHANGE IN THE
FORECAST.
 
FORECASTER AVILA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/1500Z 13.4N 118.7W    55 KT
 12HR VT     28/0000Z 14.0N 120.5W    65 KT
 24HR VT     28/1200Z 14.7N 123.0W    75 KT
 36HR VT     29/0000Z 15.3N 125.5W    85 KT
 48HR VT     29/1200Z 16.0N 127.5W    85 KT
 72HR VT     30/1200Z 16.5N 131.0W    75 KT
 96HR VT     31/1200Z 17.0N 135.5W    65 KT
120HR VT     01/1200Z 17.0N 139.5W    65 KT
 
 
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