000 WTPZ43 KNHC 070235 TCDEP3 TROPICAL STORM BLANCA DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP032009 800 PM PDT MON JUL 06 2009 ALTHOUGH THE COVERAGE AND INTENSITY OF THE DEEP CONVECTION NEAR THE CORE OF BLANCA HAS DIMINISHED SOMEWHAT OVER THE PAST FEW HOURS...THE OVERALL CLOUD PATTERN APPEARS TO BE A LITTLE MORE ORGANIZED WITH SLIGHTLY BETTER-DEFINED CURVED BANDING FEATURES. THE CURRENT INTENSITY ESTIMATE IS INCREASED TO 45 KT FOR THIS ADVISORY IN AGREEMENT WITH THE LATEST DVORAK SATELLITE ESTIMATES FROM TAFB AND SAB. THE SYSTEM IS IN AN ENVIRONMENT OF MODEST EASTERLY SHEAR AND CIRRUS MOTIONS SHOW FAIRLY STRONG UPPER-LEVEL OUTFLOW EXCEPT OVER THE NORTHEAST QUADRANT OF THE STORM. BLANCA COULD STRENGTHEN A LITTLE MORE...BUT ITS WINDOW OF OPPORTUNITY FOR INTENSIFICATION IS CLOSING QUICKLY AS THE CYCLONE SHOULD BEGIN TO TRAVERSE SSTS COOLER THAN 26 DEGREES C IN 12 HOURS OR SO. THUS THE OFFICIAL FORECAST SHOWS A WEAKENING TREND COMMENCING BY 24 HOURS... AND THE SYSTEM BEING REDUCED TO A REMNANT LOW IN 96 HOURS. THIS IS IN GOOD AGREEMENT WITH THE SHIPS GUIDANCE. HOWEVER GIVEN THE COOLER WATERS...AND A POSSIBLY MORE STABLE THAN EXPECTED AIR MASS...BLANCA'S DEMISE COULD OCCUR SOONER THAN INDICATED HERE. BASED ON A BLEND OF FIXES FROM GEOSTATIONARY AND MICROWAVE IMAGERY...THE INITIAL MOTION IS ESTIMATED TO BE 295/9. THERE IS LITTLE CHANGE TO THE TRACK FORECAST OR THE REASONING BEHIND IT. A WEAKENING MID-LEVEL SUBTROPICAL RIDGE TO THE NORTH OF BLANCA SHOULD PRODUCE A CONTINUED WEST-NORTHWESTWARD TRACK WITH A GRADUALLY DECREASING FORWARD SPEED OVER THE NEXT FEW DAYS. ONCE BLANCA BECOMES A VERY WEAK CYCLONE...A GENERALLY WESTWARD MOTION IS LIKELY. THE OFFICIAL TRACK FORECAST IS FAIRLY CLOSE TO THE DYNAMICAL MODEL CONSENSUS AND NOT TOO DISSIMILAR TO THE PREVIOUS NHC TRACK. FORECAST POSITIONS AND MAX WINDS INITIAL 07/0300Z 18.2N 113.8W 45 KT 12HR VT 07/1200Z 18.8N 115.1W 50 KT 24HR VT 08/0000Z 19.5N 116.9W 50 KT 36HR VT 08/1200Z 20.0N 118.4W 45 KT 48HR VT 09/0000Z 20.4N 119.8W 35 KT 72HR VT 10/0000Z 20.8N 122.0W 25 KT 96HR VT 11/0000Z 21.0N 124.0W 20 KT...REMNANT LOW 120HR VT 12/0000Z...DISSIPATED $$ FORECASTER PASCH