000
WTPZ43 KNHC 072032
TCDEP3
TROPICAL STORM BLANCA DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP032009
200 PM PDT TUE JUL 07 2009
 
CLOUD TOP TEMPERATURES HAVE WARMED CONSIDERABLY AND THE OVERALL
CONVECTIVE ORGANIZATION HAS DETERIORATED RAPIDLY DURING THE PAST
FEW HOURS. LATEST DVORAK T-NUMBERS ARE DOWN TO 2.0 FROM BOTH TAFB
AND SAB.  BASED UPON THESE ESTIMATES...THE INITIAL INTENSITY IS
LOWERED TO 35 KT.

BLANCA IS NEARING THE 24C SST ISOTHERM AS IT MOVES ACROSS A
STRONG GRADIENT OF SST. MOREOVER...THE CYCLONE HAS ALREADY
BEGUN TO INGEST INCREASINGLY MORE STABLE BOUNDARY LAYER AIR AND
ENCOUNTER A MODEST AMOUNT OF EASTERLY SHEAR.  THESE FACTORS FAVOR A
CONTINUED STEADY DECLINE IN INTENSITY.  THE OFFICIAL INTENSITY
FORECAST IS IN CLOSE ACCORDANCE WITH THE LATEST SHIPS MODEL
GUIDANCE.  BLANCA IS FORECAST TO BECOME A REMNANT LOW WITHIN 36
HOURS...BUT GIVEN CURRENT TRENDS THIS EVENT COULD OCCUR SOONER.
 
RECENT VISIBLE SATELLITE FIXES YIELD AN INITIAL MOTION OF 305/10...A
LITTLE TO THE RIGHT OF THE PREVIOUSLY ESTIMATED MOTION.  THE TRACK
REASONING WITH REGARD TO BLANCA HAS NOT CHANGED.  THE CYCLONE
REMAINS ON THE SOUTHWEST SIDE OF A WEAKENING LOW- TO MID-LEVEL
SUBTROPICAL RIDGE...WHICH SHOULD FAVOR A WEST-NORTHWEST TO
NORTHWEST TRACK WITH A GRADUAL DECREASE IN FORWARD SPEED PRIOR TO
DISSIPATION.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      07/2100Z 19.7N 116.5W    35 KT
 12HR VT     08/0600Z 20.3N 117.6W    30 KT
 24HR VT     08/1800Z 21.0N 119.0W    25 KT
 36HR VT     09/0600Z 21.8N 120.3W    20 KT...REMNANT LOW
 48HR VT     09/1800Z 22.5N 121.5W    20 KT...REMNANT LOW
 72HR VT     10/1800Z...DISSIPATED
 
$$
FORECASTER KIMBERLAIN/AVILA