Tropical Storm PRISCILLA

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TROPICAL STORM PRISCILLA DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP162013
800 AM PDT MON OCT 14 2013
 
INFRARED AND MICROWAVE SATELLITE IMAGERY CONTINUE TO INDICATE THAT
THE LOW-LEVEL CENTER OF PRISCILLA IS LOCATED ON THE NORTHEASTERN
EDGE OF THE DEEP CONVECTION.  ALTHOUGH SUBJECTIVE DVORAK ESTIMATES
ARE BETWEEN 30-35 KT...THE EARLIER ASCAT DATA SHOWED WINDS BETWEEN
35-40 KT...AND THE MOST RECENT OBJECTIVE ADT ESTIMATE IS T2.9/43
KT. THE LATTER TWO ESTIMATES SUGGEST AN INITIAL INTENSITY OF 40 KT.
 
ENVIRONMENTAL CONDITIONS ARE CURRENTLY ONLY MARGINALLY CONDUCIVE FOR
ADDITIONAL STRENGTHENING DUE TO 20 KT OF EASTERLY SHEAR.  THE SHEAR
IS FORECAST TO RELAX IN ABOUT 12 HOURS OR SO...AND PRISCILLA SHOULD
REMAIN OVER WATER OF AT LEAST 26C THROUGH 48 HOURS.  AT THE SAME
TIME...HOWEVER...SIGNIFICANT STRENGTHENING COULD BE LIMITED BY
INGESTION OF DRIER AIR WHILE THE CYCLONE MOVES NORTHWARD.  BY DAY
3...INCREASING WEST-SOUTHWESTERLY SHEAR...COLDER WATER...AND MORE
STABLE AND DRIER AIR SHOULD ALL INDUCE QUICK WEAKENING.  THE
INTENSITY GUIDANCE FOR THIS FORECAST IS HIGHER THAN IN THE PREVIOUS
CYCLE...AND IN FACT THE GFDL AND HWRF MODELS BRING PRISCILLA NEAR
OR AT HURRICANE STRENGTH IN A COUPLE OF DAYS.  THE NHC INTENSITY
FORECAST IS A LITTLE HIGHER THAN THE PREVIOUS ONE AND IS CLOSE TO
THE SHIPS AND LGEM MODELS.
 
PRISCILLA HAS TURNED NORTHWARD ALONG THE WESTERN PERIPHERY OF A
MID-LEVEL ANTICYCLONE CENTERED OVER EASTERN MEXICO...AND ITS
INITIAL MOTION IS 010/9 KT.  THE STORM IS FORECAST TO CONTINUE
MOVING NORTHWARD DURING THE NEXT DAY OR SO UNTIL THE BREAK IN THE
RIDGE ALONG 120W FILLS IN AND FORCES PRISCILLA TO SLOW DOWN AND
TURN NORTHWESTWARD.  A SIGNIFICANT WESTWARD SHIFT IN THE TRACK
GUIDANCE OCCURRED ON THIS FORECAST CYCLE...WHICH REQUIRED A FAIRLY
SIZEABLE WESTWARD ADJUSTMENT OF THE OFFICIAL TRACK FORECAST AS
WELL.  IT SHOULD BE NOTED THAT THE UPDATED NHC FORECAST STILL LIES
EAST OF THE GFS...ECMWF...AND THE MULTI-MODEL CONSENSUS TVCE...SO
AN ADDITIONAL ADJUSTMENT MAY BE REQUIRED LATER TODAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/1500Z 15.2N 115.5W   40 KT  45 MPH
 12H  15/0000Z 16.2N 115.5W   45 KT  50 MPH
 24H  15/1200Z 17.3N 116.1W   50 KT  60 MPH
 36H  16/0000Z 18.2N 117.1W   50 KT  60 MPH
 48H  16/1200Z 19.0N 118.2W   50 KT  60 MPH
 72H  17/1200Z 20.5N 119.5W   40 KT  45 MPH
 96H  18/1200Z 21.0N 120.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  19/1200Z 20.5N 121.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER BERG
 
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