000
WTPZ45 KNHC 072033
TCDEP5
 
TROPICAL STORM OLIVIA DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP152012
200 PM PDT SUN OCT 07 2012
 
SATELLITE IMAGES SUGGEST THAT OLIVIA HAS BECOME SLIGHTLY BETTER
ORGANIZED THAN IT WAS EARLIER TODAY...WITH THE CENTRAL DENSE
OVERCAST FEATURE NOW A LITTLE LARGER AND CLOUD TOPS COLDER NEAR THE
CENTER. DESPITE THE SOMEWHAT IMPROVED STRUCTURE...A BLEND OF THE
LATEST DVORAK CLASSIFICATIONS FROM TAFB...SAB...AND UW-CIMSS
SUPPORT HOLDING THE INITIAL WIND SPEED AT 50 KT.
 
OLIVIA COULD STRENGTHEN SOME DURING THE NEXT 24 HOURS AS
SOUTHWESTERLY SHEAR IS EXPECTED TO REMAIN RELATIVELY LOW. AFTER
THAT TIME...HOWEVER...THE SHEAR SHOULD INCREASE SIGNIFICANTLY AND
THE SEA SURFACE TEMPERATURES DECREASE ALONG THE EXPECTED TRACK.
VERTICAL CROSS SECTIONS FROM THE GFS AND ECMWF MODELS SHOW OLIVIA
BEGINNING TO TILT NORTHEASTWARD WITH HEIGHT IN ABOUT 36-48 HOURS...
AND BECOME COMPLETELY DECOUPLED IN 48-72 HOURS. THE NHC INTENSITY
FORECAST IS AGAIN LOWERED SLIGHTLY FROM THE PREVIOUS ONE...BUT
REMAINS AT THE HIGH END OF THE MODEL GUIDANCE. OLIVIA IS EXPECTED TO
BECOME A REMNANT LOW BY DAY 4 AND DISSIPATE BY DAY 5.
 
GEOSTATIONARY SATELLITE AND MICROWAVE DATA INDICATE THAT THE CENTER
OF OLIVIA HAS EITHER JUMPED OR REFORMED TO THE NORTH DURING THE
PAST FEW HOURS. A HIGHLY UNCERTAIN INITIAL MOTION ESTIMATE IS
340/5. DESPITE THE CENTER RELOCATION...THE OVERALL TRACK FORECAST
REASONING IS UNCHANGED. A MID-LEVEL RIDGE LOCATED OVER NORTHWESTERN
MEXICO IS EXPECTED TO SHIFT SOUTHEASTWARD AS A DEEP-LAYER LOW MOVES
TOWARD SOUTHERN CALIFORNIA. THIS STEERING FLOW SHOULD CAUSE OLIVIA
TO MOVE GENERALLY NORTHWARD THROUGH MONDAY. BY MONDAY NIGHT...
HOWEVER...MOST OF THE MODELS SHOW THE SHALLOW CYCLONE TURNING
WESTWARD OR SOUTHWESTWARD WITHIN THE LOW-LEVEL TRADE WINDS. THE NHC
TRACK FORECAST HAS BEEN ADJUSTED TO THE RIGHT...MAINLY BECAUSE OF
THE ADJUSTED INITIAL POSITION....AND LIES CLOSE TO THE CONSENSUS
AIDS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/2100Z 15.5N 120.8W   50 KT  60 MPH
 12H  08/0600Z 16.2N 120.9W   55 KT  65 MPH
 24H  08/1800Z 16.9N 120.9W   55 KT  65 MPH
 36H  09/0600Z 17.2N 121.2W   50 KT  60 MPH
 48H  09/1800Z 17.2N 121.8W   40 KT  45 MPH
 72H  10/1800Z 17.0N 123.3W   30 KT  35 MPH
 96H  11/1800Z 16.3N 125.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  12/1800Z...DISSIPATED
 
$$
FORECASTER CANGIALOSI