614
WTPZ45 KNHC 152039
TCDEP5
TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152007
200 PM PDT MON OCT 15 2007
DEEP CONVECTION HAS DECREASED DURING THE PAST FEW HOURS...EXPOSING
THE LOW-LEVEL CIRCULATION THAT IS NOT EXCEPTIONALLY WELL-DEFINED.
A QUIKSCAT OVERPASS AT AROUND 1330Z PROVIDED SEEMINGLY RELIABLE
WIND RETRIEVALS OF 25-30 KT...WITH HIGHER VALUES IN THE WESTERN
SEMICIRCLE THAT WERE LIKELY INFLATED BY THE CONVECTION AT THE TIME.
THE ADVISORY INTENSITY IS MAINTAINED AT 30 KT BASED ON THE QUIKSCAT
DATA. THE EASTERLY SHEAR IS FORECAST BY THE DYNAMICAL MODELS TO
PERSIST AT ROUGHLY ITS CURRENT MAGNITUDE THROUGHOUT THE NEXT FIVE
DAYS...SO SIGNIFICANT STRENGTHENING APPEARS UNLIKELY. MOST OF THE
OBJECTIVE INTENSITY MODELS FORECAST A LITTLE STRENGTHENING. THE
OFFICIAL FORECAST DOES TOO...BUT LEANS TOWARD THE WEAKER SOLUTIONS
GIVEN HOW MUCH THE SYSTEM IS CURRENTLY STRUGGLING IN THE SHEARED
ENVIRONMENT.
THE CENTER OF THE DEPRESSION HAS BEEN ESSENTIALLY STATIONARY DURING
THE PAST 12-18 HOURS. STEERING CURRENTS ARE OBVIOUSLY WEAK...AND
MOST OF THE DYNAMICAL MODELS FORECAST LITTLE CHANGE IN THE
SURROUNDING SYNOPTIC PATTERN FOR THE NEXT SEVERAL DAYS. THERE IS A
WEAK AND NARROW MID-LEVEL RIDGE TO THE NORTH OF THE TROPICAL
CYCLONE...BUT THE SYSTEM IS NOT DEEP ENOUGH TO RESPOND...AND THERE
ARE NO LOW-LEVEL STEERING MECHANISMS IN PLAY. THE MODEL GUIDANCE
TRACKS GO IN ALL KINDS OF DIRECTIONS. SOME OF THEM...INCLUDING THE
GFS...FORECAST NO SIGNIFICANT NET MOTION THROUGH THE ENTIRE
FORECAST PERIOD...WHICH SUPPORTS THE OFFICIAL FORECAST OF A NEARLY
STATIONARY CYCLONE FOR THE NEXT FIVE DAYS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 15/2100Z 15.1N 108.7W 30 KT
12HR VT 16/0600Z 15.1N 108.7W 35 KT
24HR VT 16/1800Z 15.1N 108.7W 35 KT
36HR VT 17/0600Z 15.1N 108.7W 35 KT
48HR VT 17/1800Z 15.1N 108.7W 35 KT
72HR VT 18/1800Z 15.0N 108.5W 35 KT
96HR VT 19/1800Z 15.0N 108.5W 35 KT
120HR VT 20/1800Z 15.0N 108.5W 35 KT
FORECASTER KNABB
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