000
WTPZ43 KNHC 191437
TCDEP3
TROPICAL STORM BLAS DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP032010
800 AM PDT SAT JUN 19 2010
 
EARLY MORNING VISIBLE SATELLITE IMAGERY SUGGESTS THAT THE CENTER OF
BLAS IS LOCATED JUST TO THE EAST-NORTHEAST OF THE DEEPEST
CONVECTION.  THIS IS CONSISTENT WITH THE MORE EASTERLY SHEAR
ANALYZED OVER THE CYCLONE BY UW-CIMSS.  WITH THE CENTER EMBEDDED
CLOSER TO THE CONVECTION...DVORAK INTENSITY ESTIMATES HAVE
INCREASED TO 55 KT FROM TAFB AND SAB...AND THAT IS THE INITIAL
INTENSITY FOR THIS ADVISORY.  

WITH A LACK OF MICROWAVE IMAGERY OVER THE PAST SEVERAL HOURS THE
INITIAL MOTION ESTIMATE IS A RATHER UNCERTAIN 280/06.  WHILE THE
INITIAL POSITION IS A LITTLE SOUTH OF THE PREVIOUS FORECAST...THE
OVERALL TRACK FORECAST REASONING REMAINS UNCHANGED.  BLAS WILL
CONTINUE MOVING GENERALLY WESTWARD TO THE SOUTH OF A DEEP-LAYER
RIDGE OVER THE EASTERN PACIFIC FOR THE NEXT COUPLE OF DAYS WITH A
SLIGHT INCREASE IN FORWARD SPEED. BY 72 HOURS AND BEYOND...A MOTION
SOUTH OF DUE WEST IS EXPECTED AS THE WEAKENING CYCLONE IS
INCREASINGLY STEERED BY THE LOW-LEVEL FLOW.  THE NEW TRACK FORECAST
IS ADJUSTED SOUTHWARD FROM THE PREVIOUS PACKAGE DUE TO THE MORE
SOUTHERLY INITIAL POSITION...BUT LIES CLOSE TO THE MIDDLE OF THE
GUIDANCE ENVELOPE. 

THE INTENSITY FORECAST HAS BEEN ADJUSTED UPWARD TO ACCOUNT FOR THE
OBSERVED INTENSITY TRENDS...AND SHOWS A PEAK AT 12 HOURS IN
AGREEMENT WITH THE SHIPS...LGEM...HWRF...AND GFDL.  WHILE NONE OF
THE GUIDANCE SHOWS BLAS REACHING HURRICANE INTENSITY...THERE IS
ABOUT A 30 PERCENT CHANCE THAT BLAS COULD BECOME A HURRICANE IN THE
NEXT 24 HOURS ACCORDING TO PROBABILISTIC GUIDANCE BASED ON
PREVIOUS NHC FORECAST ERRORS.  SLOW WEAKENING IS FORECAST TO BEGIN
BY 24 HOURS AS BLAS MOVES OVER COOLER WATERS AND INTO A LESS
FAVORABLE THERMODYNAMIC ENVIRONMENT.  THE OFFICIAL FORECAST IS CLOSE
TO THE LGEM GUIDANCE AND IS A LITTLE HIGHER THAN THE PREVIOUS
PACKAGE.  BLAS SHOULD BECOME A REMNANT LOW IN 4 OR 5 DAYS. 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/1500Z 16.3N 109.7W    55 KT
 12HR VT     20/0000Z 16.5N 111.0W    60 KT
 24HR VT     20/1200Z 16.7N 112.8W    55 KT
 36HR VT     21/0000Z 16.9N 114.8W    50 KT
 48HR VT     21/1200Z 17.0N 116.8W    45 KT
 72HR VT     22/1200Z 16.5N 120.5W    35 KT
 96HR VT     23/1200Z 16.0N 124.5W    25 KT
120HR VT     24/1200Z 15.5N 128.0W    20 KT...POST-TROP/REMNT LOW
 
$$
FORECASTER BRENNAN