Tropical Depression SEVEN-E

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TROPICAL DEPRESSION SEVEN-E DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072012
200 AM PDT TUE AUG 07 2012
 
THE LOW PRESSURE SYSTEM LOCATED WELL SOUTHWEST OF THE MEXICAN COAST
HAS CONTINUED TO GAIN CONVECTIVE ORGANIZATION OVER THE PAST FEW
HOURS.  ALTHOUGH THE AREA OF SHOWERS AND THUNDERSTORMS IS SOMEWHAT
SMALL...TAFB AND SAB WERE ABLE TO PROVIDE DVORAK ESTIMATES OF T2.0.
THE LOW IS THEREFORE BEING UPGRADED TO A 30-KT DEPRESSION AT THIS
TIME.
 
THE INITIAL MOTION IS ESTIMATED TO BE 295/10 KT.  THE DEPRESSION IS
BEING STEERED WEST-NORTHWESTWARD BY A MID-LEVEL RIDGE OF HIGH
PRESSURE THAT IS ANCHORED OVER THE SOUTHWESTERN UNITED STATES AND
EXTENDS SOUTHWESTWARD TO THE HAWAIIAN ISLANDS.  THE RIDGE IS
EXPECTED TO HOLD FIRM IN THE VICINITY OF THE CYCLONE DURING THE
5-DAY FORECAST PERIOD.  HOWEVER...THE GLOBAL MODELS SUGGEST THAT
BROAD LOW-LEVEL CYCLONIC FLOW WILL DEVELOP NEAR THE MEXICAN COAST
ON DAYS 3 THROUGH 5 AND POTENTIALLY SLOW THE WESTWARD MOTION OF THE
CYCLONE.  THE NHC FORECAST INDICATES A STEADY WEST-NORTHWESTWARD
MOVEMENT DURING THE FIRST 2 DAYS OR SO...FOLLOWED BY A DECELERATING
WESTWARD MOTION THEREAFTER.  CONFIDENCE IN THIS TRACK FORECAST IS
HIGH GIVEN THE LESS-THAN-NORMAL SPREAD IN THE TRACK GUIDANCE.
 
THE DEPRESSION IS OVER WATER OF ABOUT 29C AND IN AN ENVIRONMENT OF
LIGHT SHEAR.  A LARGE UPPER-LEVEL LOW LOCATED SOUTHWEST OF THE BAJA
PENINSULA IS MOVING STEADILY WESTWARD...WHICH IS ALLOWING THE
UPPER-LEVEL OUTFLOW OVER THE DEPRESSION TO EXPAND WESTWARD. 
ENVIRONMENTAL CONDITIONS SHOULD ALLOW FOR STRENGTHENING OVER THE
NEXT 3 DAYS OR SO...AND THE OFFICIAL FORECAST IS AT THE HIGHER END
OF THE INTENSITY GUIDANCE.  BY DAYS 4 AND 5...THE CYCLONE WILL BE
LOCATED IN A MORE MARGINAL THERMODYNAMIC ENVIRONMENT...AND THE
CIRCULATION COULD BECOME DECOUPLED WHEN THE LOW-LEVEL CENTER IS
TUGGED BACK TO THE EAST.  WEAKENING IS THEREFORE EXPECTED AT THE
LATTER STAGES OF THE FORECAST.


FORECAST POSITIONS AND MAX WINDS
 
INIT  07/0900Z 14.3N 111.7W   30 KT  35 MPH
 12H  07/1800Z 14.9N 113.0W   35 KT  40 MPH
 24H  08/0600Z 15.7N 114.9W   45 KT  50 MPH
 36H  08/1800Z 16.5N 116.7W   50 KT  60 MPH
 48H  09/0600Z 17.0N 118.5W   55 KT  65 MPH
 72H  10/0600Z 17.0N 120.5W   60 KT  70 MPH
 96H  11/0600Z 17.0N 121.5W   55 KT  65 MPH
120H  12/0600Z 17.0N 121.5W   45 KT  50 MPH
 
$$
FORECASTER BERG
 
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