Tropical Storm OLIVIA

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TROPICAL STORM OLIVIA DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP152012
200 PM PDT SAT OCT 06 2012
 
THE CYCLONE HAS BECOME BETTER ORGANIZED DURING THE LAST SEVERAL
HOURS. A CONVECTIVE CLOUD BAND HAS GAINED CURVATURE OVER THE
NORTHWEST QUADRANT OF THE CIRCULATION AND A CENTRAL DENSE OVERCAST
HAS PERSISTED. DVORAK CLASSIFICATIONS HAVE INCREASED TO T3.0/45 KT
FROM SAB...T2.5/35 KT FROM TAFB...AND T2.4/34 KT FROM UW-CIMSS.
BASED ON THESE CLASSIFICATIONS...THE INITIAL WIND SPEED ESTIMATE IS
40 KT...AND THE DEPRESSION IS UPGRADED TO TROPICAL STORM OLIVIA.
 
OLIVIA HAS A COUPLE OF DAYS TO STRENGTHEN AS THE SHEAR IS EXPECTED
TO REMAIN FAIRLY LOW AND THE CYCLONE SHOULD BE OVER WATERS AROUND
28C DURING THAT TIME. AFTER 48 HOURS...SOUTHWESTERLY SHEAR IS
ANTICIPATED TO INCREASE...AND VERTICAL CROSS SECTIONS FROM THE GFS
AND ECMWF MODELS SHOW THE VORTEX BECOMING SHALLOWER WITH DEEP-LAYER
DRY AIR IMPINGING ON THE SYSTEM. THE NHC FORECAST IS ADJUSTED
UPWARD FROM THE PREVIOUS ONE...AND CLOSELY FOLLOWS THE CONSENSUS
AIDS. REMNANT LOW STATUS IS PREDICTED TO OCCUR AROUND DAY 5...A
LITTLE LATER THAN IN THE OLD FORECAST.
 
THE TROPICAL STORM IS MOVING WESTWARD AT ABOUT 10 KT TO THE SOUTH OF
A MID-LEVEL RIDGE THAT IS CENTERED JUST TO THE WEST OF BAJA
CALIFORNIA. THE RIDGE IS EXPECTED TO WEAKEN AS A DEEP-LAYER LOW
CURRENTLY LOCATED A FEW HUNDRED MILES WEST OF NORTHERN CALIFORNIA
MOVES SOUTHEASTWARD. THIS PATTERN EVOLUTION SHOULD CAUSE OLIVIA TO
TURN WEST-NORTHWESTWARD AND THEN NORTHWESTWARD WITH A DECREASE IN
FORWARD SPEED DURING THE NEXT TWO DAYS. BY TUESDAY...THE WEAKENING
SYSTEM IS EXPECTED TO TURN BACK TO THE WEST OR POSSIBLY EVEN
SOUTHWEST AS IT BECOMES VERTICALLY SHALLOW AND IS STEERED BY THE
LOW-LEVEL TRADES.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  06/2100Z 13.9N 119.6W   40 KT  45 MPH
 12H  07/0600Z 14.4N 120.7W   45 KT  50 MPH
 24H  07/1800Z 15.2N 121.8W   50 KT  60 MPH
 36H  08/0600Z 15.8N 122.3W   55 KT  65 MPH
 48H  08/1800Z 16.1N 122.6W   55 KT  65 MPH
 72H  09/1800Z 16.1N 123.5W   45 KT  50 MPH
 96H  10/1800Z 15.8N 125.0W   35 KT  40 MPH
120H  11/1800Z 15.5N 126.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER CANGIALOSI
 
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