Tropical Depression SEVENTEEN-E

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TROPICAL DEPRESSION SEVENTEEN-E DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP172008
800 AM PDT FRI OCT 24 2008
 
WIND SHEAR...ANALYZED AT 30-50 KT BY CIMSS AT THE UNIVERSITY OF
WISCONSIN...HAS TAKEN A TOLL ON THE SYSTEM IN THE LAST SEVERAL
HOURS.  THE MID-LEVEL MOISTURE AND VORTICITY ARE MOVING QUICKLY 
NORTHEAST...SPREADING MODERATE TO HEAVY RAINFALL INTO PORTIONS OF
SOUTHWESTERN MEXICO.  THE LOW-LEVEL CENTER HAS BECOME ELONGATED AND
DIFFICULT TO IDENTIFY...MAKING THE INITIAL MOTION ESTIMATE AN
UNCERTAIN 325/07.  DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB
HAVE DECREASED TO 25 KT...BUT I HAVE HELD THE INITIAL INTENSITY AT
30 KT...BASED ON A 1258 UTC QUIKSCAT PASS THAT SHOWS A FEW 
AMBIGUITIES WITH 25-30 KT WINDS EAST OF THE ESTIMATED CENTER
LOCATION.
 
IF THE LOW-LEVEL CENTER SURVIVES...THE FORECAST REASONING IS
UNCHANGED.  THE DEPRESSION WILL BE STEERED MORE TOWARD THE NORTHWEST
AND EVENTUALLY TOWARD THE WEST IN THE NEXT 48 HOURS SOUTH OF THE
LOW-LEVEL RIDGE OVER THE EASTERN PACIFIC.  THE CURRENT TRACK
FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS ADVISORY.
 
THE INTENSITY FORECAST FOLLOWS THE SHIPS MODEL...HOLDING THE
INTENSITY AT 30 KT THROUGH 12 HOURS...AND SHOWING GRADUAL WEAKENING
TO A REMNANT LOW AT 48 HOURS BEFORE DISSIPATION AT 72 HOURS.
HOWEVER...ADDITIONAL VISIBLE IMAGERY LATER TODAY MAY INDICATE THAT
THE CENTER HAS ALREADY DISSIPATED.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/1500Z 16.4N 106.7W    30 KT
 12HR VT     25/0000Z 17.2N 107.5W    25 KT
 24HR VT     25/1200Z 17.9N 108.3W    25 KT
 36HR VT     26/0000Z 18.3N 109.5W    25 KT
 48HR VT     26/1200Z 18.4N 110.8W    20 KT...REMNANT LOW
 72HR VT     27/1200Z...DISSIPATED
 
$$
FORECASTER BRENNAN/FRANKLIN
 
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