000
WTPZ43 KNHC 180233
TCDEP3
TROPICAL STORM BLAS DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP032010
800 PM PDT THU JUN 17 2010
 
BLAS HAS CHANGED LITTLE IN ORGANIZATION OVER THE LAST SEVERAL HOURS
WITH BANDING FEATURES CONFINED TO THE WESTERN SEMICIRCLE OF THE
STORM...ALTHOUGH THERE HAS BEEN A RECENT BURST OF DEEP CONVECTION
NEAR THE CENTER.  THE INITIAL INTENSITY IS HELD AT 40 KT...
CONSISTENT WITH A BLEND OF THE TAFB AND SAB DVORAK INTENSITY
ESTIMATES.  ONLY A LITTLE STRENGTHENING OF BLAS IS FORECAST IN THE
SHORT-TERM AS MODERATE EASTERLY SHEAR IS EXPECTED TO CONTINUE TO
IMPACT THE SYSTEM DURING THE NEXT 24 HOURS. BEYOND THAT TIME...THE
CYCLONE IS EXPECTED TO MOVE OVER COOLER SEA SURFACE TEMPERATURES
AND INTO A MORE STABLE ENVIRONMENT...WHICH SHOULD CAUSE WEAKENING. 
THE OFFICIAL INTENSITY FORECAST IS UNCHANGED FROM THE PREVIOUS ONE
AND REMAINS IN GOOD AGREEMENT WITH THE INTENSITY MODEL CONSENSUS.
 
BLAS APPEARS TO HAVE INCREASED SLIGHTLY IN FORWARD SPEED...BASED ON
GEOSTATIONARY SATELLITE FIXES AND VERY HELPFUL AMSR-E AND TRMM
PASSES...AND THE INITIAL MOTION ESTIMATE IS 300/4.  GLOBAL MODELS
SHOW MID-LEVEL RIDGING OVER MEXICO BUILDING WESTWARD OVER THE NEXT
COUPLE OF DAYS...WHICH SHOULD ALLOW BLAS TO CONTINUE MOVING
WEST-NORTHWESTWARD DURING THE NEXT 48 HOURS OR SO.   A TURN TOWARD
THE WEST IS FORECAST LATER IN THE PERIOD AS BLAS BECOMES A SHALLOW
SYSTEM AND IS STEERED MAINLY BY THE LOW-LEVEL FLOW.  THE NEW NHC
TRACK FORECAST IS NUDGED ONLY SLIGHTLY TO THE NORTH...TRENDING
TOWARD THE VARIABLE TRACK MODEL CONSENSUS...TVCN.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0300Z 15.5N 106.4W    40 KT
 12HR VT     18/1200Z 15.8N 106.9W    45 KT
 24HR VT     19/0000Z 16.0N 107.7W    45 KT
 36HR VT     19/1200Z 16.3N 108.7W    40 KT
 48HR VT     20/0000Z 16.7N 109.9W    40 KT
 72HR VT     21/0000Z 17.0N 113.0W    35 KT
 96HR VT     22/0000Z 17.0N 116.0W    25 KT
120HR VT     23/0000Z 16.5N 120.5W    20 KT...POST-TROP/REMNT LOW
 
$$
FORECASTER CANGIALOSI/PASCH