000
WTPZ45 KNHC 070847
TCDEP5
 
TROPICAL STORM OLIVIA DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP152012
200 AM PDT SUN OCT 07 2012
 
WINDSAT AND SSMIS MICROWAVE DATA FROM SEVERAL HOURS AGO INDICATE
THAT OLIVIA HAS A TIGHT INNER CORE...AND RECENT INFRARED IMAGERY
SHOWS THAT THE CONVECTIVE BANDING HAS BECOME BROKEN AND SOMEWHAT
DISCONNECTED FROM THE INNER CIRCULATION.  NONETHELESS...DVORAK
INTENSITY ESTIMATES ARE T3.0 FROM TAFB AND T3.5 FROM SAB...AND A
CONSENSUS OF THESE NUMBERS SUGGESTS AN INTENSITY OF 50 KT.

OLIVIA IS MOVING OVER VERY WARM 29C WATER AND HAS RELATIVELY GOOD
UPPER-LEVEL OUTFLOW.  THE CYCLONE IS IN A LOW-SHEAR ENVIRONMENT...
WHICH IS EXPECTED TO CONTINUE FOR ANOTHER 36 HOURS OR SO BEFORE
DEEP-LAYER SOUTHWESTERLY SHEAR INCREASES.  THESE CONDITIONS SHOULD
ALLOW OLIVIA TO STRENGTHEN DURING THE NEXT DAY OR SO.  ALTHOUGH
ONLY THE FSU SUPERENSEMBLE AND HWRF MODELS SHOW OLIVIA REACHING
HURRICANE INTENSITY...THEIR SOLUTIONS SEEM REASONABLE SINCE STORMS
WITH COMPACT INNER CORES TEND TO STRENGTHEN MORE EASILY THAN THOSE
WITH BROADER CIRCULATIONS.  AFTER 36 HOURS...THE CYCLONE SHOULD
WEAKEN DUE TO THE INCREASING SHEAR...AND THE GLOBAL MODELS INDICATE
THAT THE CIRCULATION WILL LIKELY BECOME DECOUPLED.  THE NHC
INTENSITY FORECAST IS LARGELY AN UPDATE OF THE PREVIOUS ONE AND
LIES NEAR THE HIGHER END OF THE INTENSITY GUIDANCE.

THE STORM HAS TURNED WEST-NORTHWESTWARD WITH AN INITIAL MOTION OF
295/7 KT.  A MID-LEVEL ANTICYCLONE LOCATED OVER THE BAJA PENINSULA
IS EXPECTED TO BUILD SOUTHWARD DURING THE NEXT DAY OR SO...AND
BEING ON ITS WESTERN FLANK...OLIVIA SHOULD TURN NORTHWARD BY THIS
TIME TOMORROW.  THE TRACK GUIDANCE HAS SHIFTED SIGNIFICANTLY
NORTHEASTWARD FOR THE FIRST 48 HOURS...LED BY THE ECMWF AND GFS
WHICH SHOW THE MOST PRONOUNCED NORTHWARD MOTION.  THE NHC TRACK HAS
BEEN SHIFTED IN THAT DIRECTION...NOT GOING AS FAR AS THE ECMWF AND
GFS BUT ENDING UP NEAR THE FSU SUPERENSEMBLE AND MODEL CONSENSUS
TVCE.  AFTER 48 HOURS...THE STRONGER SHEAR SHOULD DECOUPLE THE
CIRCULATION...AND THE LOW-LEVEL PORTION IS FORECAST TO TURN
WESTWARD UNDER THE INFLUENCE OF THE TRADE WINDS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/0900Z 14.4N 120.9W   50 KT  60 MPH
 12H  07/1800Z 15.1N 121.6W   60 KT  70 MPH
 24H  08/0600Z 16.0N 121.8W   65 KT  75 MPH
 36H  08/1800Z 16.7N 121.9W   60 KT  70 MPH
 48H  09/0600Z 17.0N 122.3W   55 KT  65 MPH
 72H  10/0600Z 16.5N 123.5W   40 KT  45 MPH
 96H  11/0600Z 16.0N 125.5W   30 KT  35 MPH
120H  12/0600Z 15.5N 128.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER BERG