000
WTPZ45 KNHC 070234
TCDEP5
 
TROPICAL STORM OLIVIA DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP152012
800 PM PDT SAT OCT 06 2012

OLIVIA IS STRENGTHENING THIS EVENING.  THE CLOUD PATTERN SHOWS A LOT
OF CURVATURE WITH MANY BANDING FEATURES AND PERHAPS A DEVELOPING
CENTRAL DENSE OVERCAST.  SUBJECTIVE DVORAK ESTIMATES FROM TAFB AND
SAB ARE BOTH 45 KT...SO THAT VALUE WILL BE THE INITIAL WIND SPEED. 
THERE DOES NOT SEEM TO BE MUCH IN THE LARGE-SCALE ENVIRONMENT
TO PREVENT FURTHER INTENSIFICATION OF OLIVIA FOR THE NEXT DAY OR
TWO WITH LIGHT SHEAR AND WARM WATER PRESENT.  AFTER THAT TIME...AN
INCREASE IN SOUTHWESTERLY SHEAR SHOULD CAUSE THE CYCLONE TO START A
WEAKENING TREND...WHICH COULD BE AIDED BY PLENTIFUL DRY AIR ALOFT. 
THE OFFICIAL FORECAST IS CONSERVATIVELY RAISED FROM THE PREVIOUS ONE
IN THE FIRST 48 H AND NOW SHOWS OLIVIA BECOMING A HURRICANE...NOT
TOO FAR FROM THE LATEST INTENSITY CONSENSUS AND LGEM MODELS.  IT
WOULD NOT BE TOO SURPRISING...GIVEN THE CONDUCIVE ENVIRONMENT...IF
THE HIGHER PEAK INTENSITIES OF THE FSU SUPERENSEMBLE AND HWRF
MODELS ENDED UP CLOSER TO REALITY. 

THE TROPICAL STORM IS MOVING SLIGHTLY NORTH OF WEST AT ABOUT 9 KT
BENEATH A LARGE FLAT RIDGE OVER THE EASTERN PACIFIC.  THE RIDGE
SHOULD WEAKEN AND SLIDE EASTWARD OVER THE NEXT DAY OR SO DUE TO A
STRONG LOW DIVING DOWN THE WEST COAST OF THE UNITED STATES.  THIS
PATTERN CHANGE WILL LIKELY STEER OLIVIA MORE TO THE WEST-NORTHWEST
AND NORTHWEST AT A SLOWER FORWARD SPEED DURING THE NEXT COUPLE OF
DAYS.  BY TUESDAY...THE CYCLONE IS EXPECTED TO DECOUPLE FROM THE
MID-LEVEL STEERING AND BECOME SHALLOWER...WHICH WOULD CAUSE OLIVIA
TO TURN TO THE WEST OR WEST-SOUTHWEST IN THE LONGER RANGE.  THE
FORECAST MODELS ARE IN REASONABLE AGREEMENT ON THIS SCENARIO...WITH
THE BIGGEST DISCREPANCY BEING HOW LONG THE NORTHWESTWARD TRACK
CONTINUES.  SINCE OLIVIA IS EXPECTED TO BE A LITTLE STRONGER THAN
LAST TIME...THE NEW NHC FORECAST SHOWS THE CYCLONE GAINING A BIT
MORE LATITUDE IN A COUPLE OF DAYS...BUT STILL ENDS UP ALONG THE
PREVIOUS FORECAST TRACK BY DAYS 4 AND 5.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/0300Z 14.0N 120.5W   45 KT  50 MPH
 12H  07/1200Z 14.6N 121.6W   55 KT  65 MPH
 24H  08/0000Z 15.4N 122.4W   60 KT  70 MPH
 36H  08/1200Z 16.0N 122.7W   65 KT  75 MPH
 48H  09/0000Z 16.3N 122.9W   60 KT  70 MPH
 72H  10/0000Z 16.0N 124.0W   45 KT  50 MPH
 96H  11/0000Z 15.5N 125.5W   35 KT  40 MPH
120H  12/0000Z 15.0N 127.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER BLAKE