Tropical Storm BLANCA

ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM BLANCA DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT THU JUN 19 2003

DEEP CONVECTION DIMINISHED CONSIDERABLY OVER THE PAST SEVERAL HOURS
ALTHOUGH SOME CELLS ARE NOW RE-DEVELOPING NEAR THE CENTER.  A
QUIKSCAT PASS FROM SEVERAL HOURS AGO SHOWED NO WIND SPEEDS HIGHER
THAN 35 KT.  ALTHOUGH BLANCA WAS NEAR THE EDGE OF THE SWATH...WHERE
THE WIND DATA ARE SOMEWHAT LESS RELIABLE...THESE OBSERVATIONS
SUGGESTS THAT THE STORM HAS WEAKENED.  DVORAK INTENSITY ESTIMATES
ARE PROBLEMATIC WHEN A SYSTEM HAS SO LITTLE DEEP CONVECTION...BUT
HIGHEST CURRENT INTENSITY ESTIMATES FROM TAFB...SAB...AND AFWA ARE
45 KT.  THE WEAKENING WAS LIKELY DUE TO A COMBINATION OF PERSISTENT
VERTICAL SHEAR AND A COOLING OF THE SEA SURFACE BENEATH THIS
SLOW-MOVING SYSTEM.  GLOBAL MODEL 200 MB WIND FORECASTS INDICATE
THAT SOUTHEASTERLY SHEAR OVER THE TROPICAL CYCLONE WILL INCREASE
OVER THE NEXT FEW DAYS. IN VIEW OF THIS...AND BLANCA'S RECENT
WEAKENING TREND...THE OFFICIAL INTENSITY FORECAST HAS BEEN ADJUSTED
DOWNWARD FROM THE PREVIOUS FEW ADVISORIES. INDEED...UNLESS THE
TROPICAL CYCLONE MAKES A MAJOR COMEBACK SOON...BLANCA MAY MEET ITS
DEMISE SOONER THAN INDICATED HERE.

THE CENTER IS DIFFICULT TO LOCATE BUT SHORTWAVE IR IMAGERY...WHICH
PICKS UP SOME OF THE LOW CLOUD LINES...SUGGESTS THAT IT IS IN
ABOUT THE SAME PLACE AS IT WAS SEVERAL HOURS AGO.  BLANCA REMAINS
SITUATED NEAR A WEAKNESS IN THE SUBTROPICAL RIDGE AND MODEL
GUIDANCE SUGGESTS ONLY WEAK EASTERLY STEERING CURRENTS FOR THE NEXT
SEVERAL DAYS.  THE OFFICIAL TRACK FORECAST IS VERY SIMILAR TO THAT
FROM THE PREVIOUS ADVISORY.
 
FORECASTER PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0900Z 16.5N 104.6W    45 KT
 12HR VT     19/1800Z 16.5N 105.2W    45 KT
 24HR VT     20/0600Z 16.5N 105.9W    45 KT
 36HR VT     20/1800Z 16.5N 106.5W    45 KT
 48HR VT     21/0600Z 16.5N 107.1W    40 KT
 72HR VT     22/0600Z 16.5N 108.5W    35 KT
 96HR VT     23/0600Z 16.5N 110.0W    30 KT
120HR VT     24/0600Z 16.5N 112.0W    20 KT...REMNANT LOW
 
NNNN