Tropical Depression PRISCILLA
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TROPICAL DEPRESSION PRISCILLA DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP162013
800 PM PDT TUE OCT 15 2013
A SMALL AREA OF DEEP CONVECTION PERSISTS TO THE WEST AND NORTHWEST
OF THE CENTER OF PRISCILLA. THE OVERALL CONVECTIVE ORGANIZATION HAS
NOT CHANGED MUCH IN THE PAST FEW HOURS...AND THE INITIAL INTENSITY
REMAINS 30 KT IN AGREEMENT WITH THE LATEST DVORAK FINAL-T NUMBERS
FROM TAFB AND SAB. PRISCILLA WILL BE MOVING OVER PROGRESSIVELY
COOLER WATERS IN A DRY ATMOSPHERIC ENVIRONMENT DURING THE NEXT
COUPLE OF DAYS. THESE FACTORS...IN COMBINATION WITH AN INCREASE IN
SHEAR SHOULD RESULT IN PRISCILLA BECOMING A REMNANT LOW BY 36 HOURS
AND DISSIPATING AFTER 72 HOURS.
BASED ON A 2315Z AMSU PASS...THE CENTER OF PRISCILLA WAS LOCATED A
LITTLE TO THE SOUTH OF PREVIOUS ESTIMATES...AND THE INITIAL MOTION
ESTIMATE IS 290/06. PRISCILLA SHOULD CONTINUE MOVING GENERALLY
WEST-NORTHWESTWARD FOR THE NEXT 24 TO 36 HOURS DUE TO A MID-LEVEL
RIDGE CENTERED WELL TO THE EAST OF THE CYCLONE. AS PRISCILLA
BECOMES A SHALLOW REMNANT LOW...A TURN TOWARD THE WEST AND THEN
TOWARD THE WEST-SOUTHWEST IS EXPECTED AS THE LOW-LEVEL TRADE WIND
FLOW BECOMES THE DOMINANT STEERING MECHANISM. MUCH OF THE TRACK
GUIDANCE HAS SHIFTED TO THE LEFT...OR SOUTH...OF THE PREVIOUS
OFFICIAL FORECAST...AND THE GUIDANCE HAS ALSO TRENDED FASTER AFTER
24 HOURS. THE NEW NHC TRACK HAS BEEN ADJUSTED FOLLOWING THOSE
TRENDS AND IS CLOSE TO THE LATEST ECMWF FORECAST...BUT SLOWER THAN
THE GFS.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0300Z 17.7N 117.9W 30 KT 35 MPH
12H 16/1200Z 18.1N 119.0W 30 KT 35 MPH
24H 17/0000Z 18.6N 120.3W 25 KT 30 MPH
36H 17/1200Z 19.0N 121.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 18/0000Z 18.8N 122.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 19/0000Z 18.0N 124.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 20/0000Z...DISSIPATED
$$
FORECASTER BRENNAN
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