Tropical Depression NINE-E

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TROPICAL DEPRESSION NINE-E DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092008
200 PM PDT WED AUG 06 2008
 
THE LOW PRESSURE SYSTEM WELL SOUTHWEST OF THE PACIFIC COAST OF
MEXICO HAS STEADILY BEEN GAINING ORGANIZATION TODAY...WITH A
GRADUAL INCREASE IN CONVECTIVE COVERAGE AND A WELL-DEFINED SURFACE
CIRCULATION EVIDENT IN VISIBLE SATELLITE IMAGERY.  DVORAK
CLASSIFICATIONS AT 18Z FROM BOTH TAFB AND SAB WERE T2.0...AND THE
SYSTEM IS DESIGNATED A TROPICAL DEPRESSION WITH ESTIMATED MAXIMUM
WINDS OF 30 KT.

AS IS USUALLY THE CASE FOR EASTERN PACIFIC TROPICAL CYCLONES...THE
FORWARD MOTION IS BEING DICTATED BY A SUBTROPICAL RIDGE OVER
MEXICO...AND THE INITIAL MOTION ESTIMATE IS 290/14.  WATER VAPOR
IMAGERY DEPICTS A MID- TO UPPER-LEVEL TROUGH JUST OFF THE COAST OF
CALIFORNIA.  AS A RESULT...THE FORWARD SPEED OF THE DEPRESSION IS
FORECAST TO SLOW DOWN A LITTLE DURING THE NEXT COUPLE OF DAYS AS IT
APPROACHES A WEAKNESS IN THE RIDGE.  BEYOND 48 HOURS...THE
DYNAMICAL MODELS FORECAST THE WEST COAST TROUGH TO LIFT OUT AND
ALLOW THE RIDGE TO BUILD WESTWARD A LITTLE OVER THE EASTERN
PACIFIC...KEEPING THE TROPICAL CYCLONE ON A GENERAL
WEST-NORTHWESTWARD HEADING.  ONCE THE CYCLONE REACHES COOLER WATERS
IN ABOUT THREE DAYS AND WEAKENS...IT SHOULD BECOME A MORE SHALLOW
SYSTEM AND TURN WESTWARD WITH THE LOW-LEVEL FLOW.  MODEL GUIDANCE
IS IN GOOD AGREEMENT ON THIS GENERAL SCENARIO...AND THE OFFICIAL
TRACK FORECAST IS JUST NORTH OF THE MODEL CONSENSUS.

THE DEPRESSION IS CURRENTLY OVER SEA-SURFACE TEMPERATURES OF ABOUT
28 CELSIUS...AND THAT WILL REMAIN THE CASE FOR ABOUT THE NEXT 24
HOURS ALONG THE FORECAST TRACK...FOLLOWED BY STEADILY COOLER
WATERS.  MODERATE EASTERLY WIND SHEAR IS CURRENTLY AFFECTING THE
CYCLONE...BUT MODELS FORECAST THE SHEAR TO WEAKEN A LITTLE AND
REMAIN WEAK THROUGHOUT THE FIVE-DAY FORECAST PERIOD.  AS A RESULT
OF THESE CONDITIONS...A FAIRLY TYPICAL RISE AND FALL IN THE
INTENSITY FOR AN EASTERN PACIFIC CYCLONE IS FORECAST.  THE OFFICIAL
FORECAST CALLS FOR A PEAK CLOSE TO HURRICANE INTENSITY IN A COUPLE
OF DAYS...FOLLOWED BY A RAPID DECLINE OVER COOL WATERS...IN GENERAL
AGREEMENT WITH BUT SLIGHTLY ABOVE THE SHIPS GUIDANCE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/2100Z 12.9N 111.8W    30 KT
 12HR VT     07/0600Z 13.6N 113.8W    40 KT
 24HR VT     07/1800Z 14.5N 116.1W    45 KT
 36HR VT     08/0600Z 15.2N 118.1W    55 KT
 48HR VT     08/1800Z 16.0N 120.2W    60 KT
 72HR VT     09/1800Z 17.5N 124.5W    50 KT
 96HR VT     10/1800Z 18.0N 128.5W    30 KT...REMNANT LOW
120HR VT     11/1800Z 18.0N 132.0W    20 KT...REMNANT LOW
 
$$
FORECASTER KNABB
 
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