Tropical Depression EIGHTEEN-E

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TROPICAL DEPRESSION EIGHTEEN-E DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP182013
200 AM PDT SAT NOV 02 2013
 
THE DEPRESSION REMAINS POORLY ORGANIZED...WITH LIMITED CONVECTION
NEAR THE PRESUMED CENTER AND A CIRCULATION THAT SCATTEROMETER DATA
INDICATE IS STRETCHED NORTH TO SOUTH. THE MOST RECENT ASCAT PASS
MISSED THE WESTERN AND STRONGER SEMICIRCLE...AND THE DVORAK
CLASSIFICATIONS FROM TAFB AND SAB REMAIN BELOW STORM STRENGTH...SO
THE INITIAL INTENSITY IS UNCHANGED. A MICROWAVE PASS AT 0441Z
SUGGESTS THAT THE CENTER IS LOCATED PERHAPS ABOUT 50 NMI TO THE
EAST OF THE MORE SOUTHERN MAIN CONVECTIVE CLUSTER...WHICH YIELDS AN
INITIAL MOTION ESTIMATE OF 320/4.

THE TRACK GUIDANCE IS IN GENERAL AGREEMENT THAT A MID-LEVEL RIDGE
EXTENDING WESTWARD FROM CENTRAL MEXICO WILL NUDGE THE CYCLONE
NORTHWESTWARD FOR THE NEXT DAY OR SO...AND THAT A LARGE APPROACHING
DEEP-LAYER TROUGH WILL ACCELERATE AND RECURVE THE SYSTEM AFTER THAT. 
THE GUIDANCE IS FASTER ON THIS CYCLE...THE GFS PARTICULARLY
SO...AND THE OFFICIAL FORECAST IS CONSIDERABLY FASTER THAN THE
PREVIOUS FORECAST.  EVEN WITH THIS ADJUSTMENT THE OFFICIAL FORECAST
IS SLOWER THAN THE TVCE CONSENSUS...BUT IS CLOSE TO THE NEW ECMWF.

DEVELOPMENT HAS BEEN HINDERED BY EASTERLY WIND SHEAR AND...
POSSIBLY...THE SPRAWLING AND RELATIVELY ILL-DEFINED CIRCULATION.
THE SHEAR WILL LESSEN BRIEFLY AS IT SWITCHES FROM EASTERLY TO
SOUTHWESTERLY IN 24-36 HOURS...AND SO THE OFFICIAL FORECAST
CONTINUES TO CALL FOR THE SYSTEM TO REACH STORM STRENGTH.
HOWEVER...ONLY THE HWRF MAKES THE SYSTEM A STORM AND THEN ONLY
BARELY.  STRONG UPPER-LEVEL SOUTHWESTERLY SHEAR IS EXPECTED TO
INDUCE WEAKENING ON THE APPROACH TO BAJA AND MAINLAND MEXICO...AND
BOTH THE GFS AND ECMWF SHOW THE SURFACE CENTER LOSING DEFINITION
BEFORE LANDFALL.  THE OFFICIAL FORECAST GENEROUSLY INCLUDES A 72-HR
FORECAST POINT TO ALLOW THE FORECAST TO REACH THE COAST...BUT IT IS
UNLIKELY THAT THE SYSTEM WILL STILL EXIST IN THREE DAYS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0900Z 17.2N 108.7W   30 KT  35 MPH
 12H  02/1800Z 17.7N 109.5W   30 KT  35 MPH
 24H  03/0600Z 18.8N 110.3W   35 KT  40 MPH
 36H  03/1800Z 20.6N 110.0W   35 KT  40 MPH
 48H  04/0600Z 23.1N 108.8W   30 KT  35 MPH
 72H  05/0600Z 27.5N 105.5W   15 KT  15 MPH...POST-TROP/REMNT LOW
 96H  06/0600Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 
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