Tropical Depression SIX-E

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TROPICAL DEPRESSION SIX-E DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062012
200 AM PDT THU JUL 12 2012
 
THE AREA OF LOW PRESSURE LOCATED ABOUT 400 NMI SOUTH-SOUTHWEST OF
MANZANILLO MEXICO HAS ACQUIRED ENOUGH ORGANIZED CONVECTION THIS
MORNING TO BE CLASSIFIED AS A TROPICAL DEPRESSION. A SERIES OF
MICROWAVE PASSES OVER THE PAST SEVERAL HOURS...ESPECIALLY A 0430
UTC AMSU OVERPASS...INDICATED THE INNER CORE CIRCULATION HAS BECOME
BETTER DEFINED. THE INITIAL INTENSITY OF 30 KT IS BASED ON A BLEND
OF DVORAK SATELLITE INTENSITY ESTIMATES OF T2.0/30 KT FROM TAFB AND
T2.5/35 KT FROM SAB.

THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 290/06 KT. THE CYCLONE
HAS BEEN WOBBLING ABOUT A MEAN WEST-NORTHWESTWARD MOTION OVER THE
PAST 12 HOURS...WHICH IS LIKELY DUE TO THE ASYMMETRY IN THE CENTRAL
DEEP CONVECTION CAUSED BY NORTHEASTERLY MID- TO UPPER-LEVEL
VERTICAL WIND SHEAR. HOWEVER...MOST OF THE NHC MODEL GUIDANCE IS IN
GOOD AGREEMENT ON THE CYCLONE MOVING WEST-NORTHWESTWARD FOR THE
NEXT 3 DAYS AS IT MOVES AROUND THE SOUTHERN PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL HIGH SITUATED OVER MEXICO. AFTER THAT...
HOWEVER...A WEAKNESS IS FORECAST TO DEVELOP IN THE RIDGE AXIS OVER
BAJA CALIFORNIA AS A SHORTWAVE TROUGH OFF THE U.S. WEST COAST DIGS
SOUTHEASTWARD TOWARD SOUTHERN CALIFORNIA BY DAYS 4 AND 5. THIS
SHOULD RESULT IN THE CYCLONE TURNING MORE TOWARD THE NORTHWEST AND
BE ACCOMPANIED BY A DECREASE IN FORWARD SPEED. THE OFFICIAL TRACK
IS CLOSE TO A BLEND OF THE GFS AND ECMWF MODELS.

VERTICAL SHEAR IS MARGINAL FOR STEADY DEVELOPMENT TO OCCUR FOR THE
NEXT 72 HOURS. AFTER THAT...THE CYCLONE WILL BE MOVING OVER MUCH
COOLER WATERS...WHICH SHOULD INDUCE STEADY WEAKENING DESPITE THE
CYCLONE MOVING INTO A LOW VERTICAL SHEAR ENVIRONMENT BY 96 HOURS.
THE OFFICIAL INTENSITY FORECAST IS CLOSE TO THE SHIPS INTENSITY
MODEL.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/0900Z 13.6N 106.4W   30 KT  35 MPH
 12H  12/1800Z 13.9N 107.3W   35 KT  40 MPH
 24H  13/0600Z 14.5N 108.5W   45 KT  50 MPH
 36H  13/1800Z 15.3N 110.0W   50 KT  60 MPH
 48H  14/0600Z 16.0N 111.5W   55 KT  65 MPH
 72H  15/0600Z 16.7N 114.3W   65 KT  75 MPH
 96H  16/0600Z 18.0N 116.5W   55 KT  65 MPH
120H  17/0600Z 20.7N 118.5W   30 KT  35 MPH
 
$$
FORECASTER STEWART
 
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