493
WTPZ45 KNHC 150834
TCDEP5
TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152007
200 AM PDT MON OCT 15 2007
THE SATELLITE PRESENTATION OF THE TROPICAL CYCLONE IS ESSENTIALLY A
BLOB OF COLD CLOUD TOPS...WITH NO EVIDENCE OF BANDING FEATURES IN
THE DEEP CONVECTION. ALTHOUGH SOME OF THE VERY HIGH CIRRUS CLOUDS
ARE RADIATING OUTWARD SLIGHTLY OVER THE EASTERN PART OF THE
SYSTEM...MOST OF THE UPPER-LEVEL OUTFLOW IS CONFINED TO THE WESTERN
SEMICIRCLE. DVORAK INTENSITY ESTIMATES ARE AT MARGINAL TROPICAL
STORM STRENGTH BUT THE CURRENT INTENSITY ESTIMATE IS HIGHLY
DEPENDENT ON HOW CLOSE THE LOW-LEVEL CENTER IS TO THE EDGE OF THE
DEEP CONVECTION. SINCE THE CENTER POSITION CANNOT BE DETERMINED
WITH MUCH CERTAINTY ON THE INFRARED IMAGES...I AM RELUCTANT TO
UPGRADE THE SYSTEM TO A TROPICAL STORM AT THIS TIME.
LATEST FIXES FROM TAFB AND SAB ARE SUBSTANTIALLY TO THE WEST OF THE
PREVIOUS TRACK. FOR THE SAKE OF CONTINUITY...HOWEVER...THE TRACK
IS SHIFTED ONLY SLIGHTLY TO THE LEFT OF THE PREVIOUS ADVISORY.
INITIAL MOTION IS GUESSED TO BE 330/2. A VERY WEAK STEERING
PATTERN PREVAILS IN THE VICINITY OF THE TROPICAL CYCLONE. THERE IS
A BREAK IN THE SUBTROPICAL RIDGE TO THE NORTH OF THE DEPRESSION DUE
TO A MID-LEVEL TROUGH APPROACHING THE BAJA PENINSULA. AFTER THE
TROUGH PASSES TO THE EAST OF BAJA IN A COUPLE OF DAYS...SOME WEAK
RIDGING IS LIKELY TO BUILD TO THE NORTH OF THE TROPICAL CYCLONE.
DURING THE NEXT DAY OR SO...THE TROPICAL CYCLONE COULD DEVELOP SOME
EASTWARD COMPONENT OF MOTION AS IT IS PULLED PARTIALLY INTO A BROAD
LOW- TO MID-LEVEL CYCLONIC GYRE TO ITS EAST. HOWEVER A SLOW
NORTH-NORTHWESTWARD MOTION IS EXPECTED LATER IN THE FORECAST
PERIOD. THE OFFICIAL TRACK FORECAST IS IN BEST AGREEMENT WITH THE
GFDL MODEL SOLUTION.
MODERATE EASTERLY SHEAR IS CONTINUING TO AFFECT THE CYCLONE. GLOBAL
MODELS SUGGEST THAT THERE MAY BE SOME ABATEMENT OF THE SHEAR OVER
THE NEXT DAY OR TWO WHICH WOULD ALLOW FOR SOME STRENGTHENING. THE
OFFICIAL INTENSITY FORECAST IS THE SAME AS IN THE PREVIOUS ADVISORY
PACKAGE AND IS QUITE CLOSE TO THE INTENSITY MODEL CONSENSUS...ICON.
FORECAST POSITIONS AND MAX WINDS
INITIAL 15/0900Z 15.3N 108.9W 30 KT
12HR VT 15/1800Z 15.4N 109.0W 35 KT
24HR VT 16/0600Z 15.6N 108.9W 40 KT
36HR VT 16/1800Z 15.8N 108.8W 45 KT
48HR VT 17/0600Z 16.2N 109.0W 50 KT
72HR VT 18/0600Z 16.8N 109.3W 50 KT
96HR VT 19/0600Z 17.5N 110.0W 50 KT
120HR VT 20/0600Z 18.5N 111.0W 45 KT
FORECASTER PASCH
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