Tropical Depression FIFTEEN-E

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TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP152007
800 PM PDT MON OCT 15 2007
 
CONVECTION REMAINS LIMITED AND DISORGANIZED WITH THE DEPRESSION. 
THERE IS A SINGLE RAGGED BAND ABOUT 120 NMI TO THE NORTHWEST OF THE
CENTER...WITH SMALL AND BRIEF CONVECTIVE BURSTS CLOSER TO THE
CENTER.  DVORAK CLASSIFICATIONS ARE UNCHANGED SINCE 18Z...AND THE
ADVISORY INTENSITY WILL REMAIN 30 KT.  

WITH MULTIPLE CLOUD SWIRLS ROTATING AROUND A MEAN CENTER...THE
MOTION IS HARD TO GAUGE...BUT OVER THE PAST 12-18 HOURS IT APPEARS
THAT THE MEAN CENTER HAS DRIFTED TO THE SOUTH-SOUTHWEST. STEERING
CURRENTS REMAIN WEAK...AND ARE CHARACTERIZED BY A LARGE CYCLONIC
GYRE AT LOW LEVELS AND MODERATE EASTERLY FLOW AT THE UPPER-LEVELS.
THERE IS CURRENTLY LITTLE NET FLOW ACROSS THE CYCLONE IN THE MIDDLE
TROPOSPHERE...ALTHOUGH THE GLOBAL MODELS SUGGEST THAT THE
SUBTROPICAL RIDGE SHOULD BUILD IN TO THE NORTH OF THE SYSTEM OVER
THE NEXT FEW DAYS. GIVEN THE EASTERLY SHEAR...THE TRACK OF THE
DEPRESSION WILL DEPEND IN LARGE PART ON HOW MUCH DEEP CONVECTION
THE SYSTEM CAN MAINTAIN NEAR ITS CENTER. ALTHOUGH THE OBJECTIVE
GUIDANCE MODELS ARE SPREAD IN ALL DIRECTIONS...A COMMON THEME IS A
CONTINUATION OF A CYCLONIC LOOP...ENDING WITH SOME NET WESTWARD
MOTION AS THE RIDGE BUILDS IN. THE OFFICIAL FORECAST...WHICH IS IN
BEST AGREEMENT WITH THE GFS...ALSO SHOWS A SMALL LOOP...BUT WITH
LITTLE NET DISPLACEMENT OVER THE FIVE DAY PERIOD.  IT SHOULD BE
NOTED THAT THE UKMET AND ECMWF MODELS BRING THE DEPRESSION VERY
CLOSE TO THE MEXICAN COAST IN ABOUT FIVE DAYS.

THE DEPRESSION REMAINS UNDER MODERATE EASTERLY SHEAR...AND IS NOT
FAR FROM THE STABLE STRATO-CUMULUS FIELD TO THE WEST AND NORTH. 
THERE IS SOME DISAGREEMENT AMONG THE GLOBAL MODELS ABOUT HOW THE
UPPER EASTERLIES ARE GOING TO EVOLVE OVER THE NEXT FEW DAYS...WITH
THE GFS MAINTAINING THE SHEAR...WHILE THE ECMWF AND UKMET LESSEN IT
SOMEWHAT.  BOTH THE HWRF AND GFDL BRING THE CYCLONE TO NEAR 50
KT...WHILE THE SHIPS GUIDANCE CALLS FOR A MINIMAL TROPICAL STORM. 
THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND
FOLLOWS THE GFS/SHIPS SCENARIO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0300Z 14.7N 109.0W    30 KT
 12HR VT     16/1200Z 14.7N 109.0W    30 KT
 24HR VT     17/0000Z 14.5N 108.5W    35 KT
 36HR VT     17/1200Z 14.8N 108.2W    35 KT
 48HR VT     18/0000Z 14.9N 108.5W    35 KT
 72HR VT     19/0000Z 15.2N 109.0W    35 KT
 96HR VT     20/0000Z 15.5N 109.5W    35 KT
120HR VT     21/0000Z 15.5N 110.0W    35 KT
 
$$
FORECASTER FRANKLIN
 
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