ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM BLANCA DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP032009 200 PM PDT MON JUL 06 2009 BLANCA HAS CHANGED LITTLE IN INTENSITY SINCE THIS MORNING. MICROWAVE FIXES DURING THE DAY HAVE BEEN CONSISTENTLY NORTH OF DVORAK POSITION ESTIMATES...INDICATING THAT THE VORTEX MAY NOT BE VERTICALLY ALIGNED. ADDITIONALLY...CLOUD TOP TEMPERATURES HAVE RECENTLY WARMED AND THE CONVECTIVE DISTRIBUTION HAS SHRUNK... POSSIBLY IN RESPONSE TO THE DIURNAL CONVECTIVE MINIMUM. IN SPITE OF THE MORE RAGGED APPEARANCE...THE CYCLONE CONTINUES TO DISPLAY WELL-DEFINED BANDING FEATURES IN VISIBLE SATELLITE IMAGERY...WITH THE CENTER EMBEDDED WITHIN A CENTRAL CONVECTIVE MASS. DVORAK T-NUMBERS FROM TAFB AND SAB ARE 2.5 AND 3.0...RESPECTIVELY...AND THE INITIAL INTENSITY REMAINS 40 KT FOR THIS ADVISORY. THERE IS NOW LESS DOUBT WITH REGARD TO THE INITIAL MOTION...WITH RECENT FIXES INDICATING 305/09. MODEL GUIDANCE SHOWS BLANCA ON THE EASTERN PERIPHERY OF A MID-LEVEL RIDGE THAT EXTENDS FROM THE SUBTROPICAL EAST PACIFIC EASTWARD TO THE NORTHERN BAJA CALIFORNIA PENINSULA . THIS FEATURE SHOULD REMAIN IN PLACE DURING THE NEXT FEW DAYS AND STEER BLANCA ON A GENERALLY WEST-NORTHWESTWARD COURSE OVER THE NEXT 12-24 HOURS...FOLLOWED BY A DECREASE IN FORWARD SPEED AND A FURTHER BENDING OF THE TRACK TO THE WEST ONCE BLANCA BEGINS TO WEAKEN. EVEN THOUGH THE ORGANIZATION OF BLANCA HAS NOT IMPROVED FURTHER...THE STORM IS STILL MOVING OVER 27-28C WATER IN A RELATIVELY LOW SHEAR ENVIRONMENT. HOWEVER...THE CYCLONE SHOULD REACH SUB-26C WATER JUST AFTER 12 HOURS...WITH A CONTINUED DECREASE IN SSTS ALONG THE FORECAST TRACK OF THE STORM. THIS...ALONG WITH THE FACT THAT EASTERLY SHEAR IS FORECAST TO INCREASE SLIGHTLY OVER THE NEXT 24 HOURS...SHOULD PRECLUDE ANY SIGNIFICANT STRENGTHENING. THEREAFTER...WITH THE RAPID DROP-OFF IN SSTS...BLANCA SHOULD BEGIN WEAKENING AND BECOME A REMNANT FLOW BETWEEN 72-96 HR. FORECAST POSITIONS AND MAX WINDS INITIAL 06/2100Z 18.0N 112.9W 40 KT 12HR VT 07/0600Z 18.7N 114.1W 50 KT 24HR VT 07/1800Z 19.4N 115.9W 50 KT 36HR VT 08/0600Z 19.9N 117.5W 45 KT 48HR VT 08/1800Z 20.2N 118.9W 35 KT 72HR VT 09/1800Z 20.5N 121.0W 25 KT 96HR VT 10/1800Z 20.5N 123.0W 20 KT...REMNANT LOW 120HR VT 11/1800Z...DISSIPATED $$ FORECASTER KIMBERLAIN/BROWN NNNN
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Page last modified: Thursday, 31-Dec-2009 12:09:16 UTC