Tropical Storm ROSA

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TROPICAL STORM ROSA DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP172012
200 AM PDT FRI NOV 02 2012
 
BASED ON AN ASCAT PASS FROM 0533 UTC...ROSA IS ONLY PRODUCING
TROPICAL-STORM-FORCE WINDS IN ITS NORTHERN SEMICIRCLE AND HAS
MAXIMUM WINDS AROUND 40 KT.  WATER VAPOR IMAGERY SUGGESTS THAT
STRONG UPPER-LEVEL WESTERLY WINDS ARE CUTTING INTO THE CYCLONE
BELOW THE CIRRUS LAYER...AND THE DEEP-LAYER SHEAR IS ESTIMATED TO
BE ABOUT 20 KT.  WESTERLY TO SOUTHWESTERLY SHEAR WILL ONLY INCREASE
FROM THIS POINT FORWARD AS AN UPPER-LEVEL TROUGH AMPLIFIES WEST OF
THE BAJA PENINSULA...AND ROSA IS FORECAST TO CONTINUE GRADUALLY
WEAKENING.  THERE IS STRONG AGREEMENT AMONG THE INTENSITY AND
GLOBAL MODELS THAT ROSA WILL BECOME A REMNANT LOW IN ABOUT 48 HOURS
AND THEN DISSIPATE BY DAY 5.

ROSA HAS BEEN MEANDERING LATELY...BUT THE ASCAT CENTER FIX SUGGESTS
THAT THE LONGER-TERM MOTION IS A SOUTHWESTWARD DRIFT.  A WEAK
LOW-LEVEL RIDGE ALONG 21N SHOULD NUDGE ROSA SOUTHWESTWARD AND
WESTWARD DURING THE NEXT COUPLE OF DAYS.  THE RIDGE IS FORECAST TO
BREAK DOWN BY DAY 3 AS THE PREVIOUSLY MENTIONED TROUGH DEEPENS WEST
OF THE BAJA PENINSULA...AND ROSA SHOULD RESPOND BY GRADUALLY
TURNING NORTHWESTWARD WITH SOME ACCELERATION.  THE SPREAD AMONG THE
TRACK MODELS HAS CONTINUED TO DECREASE...ALTHOUGH THE ENTIRE
GUIDANCE ENVELOPE HAS SHIFTED GENERALLY SOUTHWESTWARD ON THIS
CYCLE.  THE UPDATED NHC FORECAST HAS ALSO BEEN SHIFTED
SOUTHWESTWARD AND LIES VERY CLOSE TO THE GFS MODEL AND THE
MULTI-MODEL CONSENSUS TVCE. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0900Z 13.3N 118.5W   40 KT  45 MPH
 12H  02/1800Z 13.1N 118.6W   35 KT  40 MPH
 24H  03/0600Z 13.0N 118.9W   35 KT  40 MPH
 36H  03/1800Z 13.0N 119.2W   30 KT  35 MPH
 48H  04/0600Z 13.2N 119.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  05/0600Z 14.0N 120.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  06/0600Z 15.5N 121.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  07/0600Z...DISSIPATED
 
$$
FORECASTER BERG
 
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