Tropical Depression THIRTEEN-E
ZCZC MIATCDEP3 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION THIRTEEN-E DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
200 AM PDT SAT SEP 22 2012
CONVENTIONAL SATELLITE IMAGERY AND MICROWAVE DATA INDICATE THAT THE
CLOUD PATTERN IS GRADUALLY BECOMING BETTER ORGANIZED. THE
CONVECTION IS RAGGED NEAR THE CENTER...BUT THERE ARE BANDING
FEATURES DEVELOPING IN ALL QUADRANTS. THE OUTFLOW IS FAIR
INDICATING THAT THE SHEAR IS LOW. IN FACT...SHIPS MODEL MAINTAINS
VERY LOW SHEAR THROUGH 5 DAYS. THE INITIAL INTENSITY IS KEPT AT 30
KNOTS BASED ON THE AVERAGE OF DVORAK T-NUMBERS. DUE TO THE LOW
SHEAR ENVIRONMENT AND THE WARM OCEAN...STRENGTHENING IS FORECAST.
BY THE END OF THE FORECAST PERIOD...THE CIRCULATION WILL BE NEARING
COOL WATERS AND A GRADUAL WEAKENING SHOULD THEN BEGIN.
THE INITIAL MOTION IS A LITTLE BIT UNCERTAIN SINCE THE CENTER IS
STILL IN FORMATIVE STAGE. THE BEST ESTIMATE IS 280 DEGREES AT 6
KNOTS. THE DEPRESSION IS SOUTH OF A SUBTROPICAL RIDGE CENTERED
ACROSS NORTHERN MEXICO AND THE SOUTHWESTERN UNITED STATES. THE FLOW
AROUND THE RIDGE WILL STEER THE CYCLONE ON A GENERAL WEST-NORTHWEST
TO NORTHWEST TRACK FOR THE NEXT 3 DAYS. AFTER THAT...AN EASTWARD
MOVING SHORTWAVE WILL ERODE THE RIDGE...AND THE CYCLONE SHOULD TURN
MORE THE NORTH WITH A DECREASE IN FORWARD SPEED. THE NHC FORECAST
HAS BEEN SHIFTED A LITTLE BIT TO THE NORTH AND EAST FROM THE
PREVIOUS ONE. THIS IS BASED ON THE FACT THAT BOTH THE GFS AND THE
ECMWF GLOBAL MODELS...AND THE HWRF/GFDL PAIR...TURN THE CYCLONE
NORTHWARD AHEAD OF THE APPROACHING TROUGH. THE BULK OF THE
DYNAMICAL MODELS RECURVE THE CYCLONE EAST OF 118 DEGREES WEST.
FORECAST POSITIONS AND MAX WINDS
INIT 22/0900Z 13.7N 107.5W 30 KT 35 MPH
12H 22/1800Z 14.0N 108.4W 40 KT 45 MPH
24H 23/0600Z 14.5N 109.7W 50 KT 60 MPH
36H 23/1800Z 15.5N 111.0W 60 KT 70 MPH
48H 24/0600Z 16.3N 112.5W 70 KT 80 MPH
72H 25/0600Z 18.0N 115.5W 75 KT 85 MPH
96H 26/0600Z 19.5N 117.0W 65 KT 75 MPH
120H 27/0600Z 21.0N 118.0W 50 KT 60 MPH
$$
FORECASTER AVILA
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