000
WTPZ43 KNHC 062029
TCDEP3
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