Tropical Depression FIFTEEN-E

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TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP152007
800 PM PDT SUN OCT 14 2007
 
SATELLITE IMAGERY INDICATES THAT THE AREA OF LOW PRESSURE SOUTHWEST
OF MANZANILLO MEXICO HAS FINALLY ACQUIRED SUFFICIENT ORGANIZATION
TO BE CLASSIFIED A TROPICAL DEPRESSION.  AN IMPRESSIVE AREA OF DEEP
CONVECTION HAS PERSISTED JUST WEST OF THE CENTER FOR 6 TO 12
HOURS...AND THIS PATTERN HAS YIELDED DVORAK CLASSIFICATIONS OF 2.0
FROM TAFB AND SAB.  THE INITIAL INTENSITY IS SET AT 30 KT BASED ON
THIS DATA.  THE DEPRESSION IS CURRENTLY EXPERIENCING SOME MODERATE
EASTERLY SHEAR BUT GLOBAL MODELS INDICATE THAT THE SHEAR COULD
RELAX A LITTLE OVER THE NEXT DAY OR TWO ALLOWING SOME OPPORTUNITY
FOR STRENGTHENING.  THE SHEAR IS EXPECTED TO STRENGTHEN AGAIN IN
2-3 DAYS AND THIS SHOULD RESULT IN ARRESTED DEVELOPMENT OR EVEN
WEAKENING.  THE OFFICIAL FORECAST SHOWS THE CYCLONE REACHING A PEAK
INTENSITY OF 50 KT AND IS IN BEST AGREEMENT WITH THE SHIPS MODEL.
 
THE DEPRESSION IS LOCATED WITHIN A WEAK STEERING ENVIRONMENT AND THE
INITIAL MOTION IS THOUGHT TO BE A SLOW NORTHWARD DRIFT AT 360/2.
THE EVENTUAL TRACK IS STRONGLY DEPENDENT ON THE STRENGTH AND DEPTH
OF THE CYCLONE.  A WEAKER AND SHALLOWER CYCLONE WOULD TEND TO MOVE
EASTWARD OR NORTHEASTWARD WITHIN THE LARGE-SCALE CYCLONIC GYRE THAT
CURRENTLY EXISTS OFF THE COAST OF MEXICO.  CONVERSELY...A STRONGER
AND DEEPER CYCLONE WOULD TEND TO MOVE WESTWARD...ALBEIT
SLOWLY...UNDER THE INFLUENCE OF A WEAK MID-LEVEL RIDGE THAT LIES
ALONG 22N LATITUDE.  SINCE THE OVERALL ENVIRONMENT DOES NOT APPEAR
TO BE OPTIMAL FOR STRENGTHENING...A VERY SLOW NORTHEASTWARD MOTION
IS SHOWN THROUGH 48 HOURS FOLLOWED BY A TURN TOWARD THE NORTHWEST
AS THE RIDGE TO THE NORTH STRENGTHENS.  GIVEN THE UNCERTAINTY...THE
OFFICIAL FORECAST IS CLOSEST TO THE DYNAMICAL MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/0300Z 15.0N 108.5W    30 KT
 12HR VT     15/1200Z 15.2N 108.5W    35 KT
 24HR VT     16/0000Z 15.4N 108.3W    40 KT
 36HR VT     16/1200Z 15.5N 108.0W    45 KT
 48HR VT     17/0000Z 15.7N 107.8W    50 KT
 72HR VT     18/0000Z 16.5N 107.5W    50 KT
 96HR VT     19/0000Z 17.5N 108.0W    50 KT
120HR VT     20/0000Z 18.0N 109.0W    45 KT
 
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FORECASTER RHOME
 
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