Tropical Depression TWELVE-E

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TROPICAL DEPRESSION TWELVE-E DISCUSSION NUMBER   1...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122009
200 PM PDT MON AUG 24 2009
 
CORRECTED AWIPS BIN NUMBER

DEEP CONVECTION ASSOCIATED WITH THE BROAD AREA OF LOW PRESSURE
LOCATED SOUTHWEST OF CABO SAN LUCAS HAS BECOME BETTER ORGANIZED
TODAY. A CURVED BAND FEATURE HAS BECOME MORE DEFINED OVER THE
WESTERN SEMICIRCLE OF THE CIRCULATION AND DVORAK T-NUMBERS HAVE
INCREASED. ALTHOUGH MICROWAVE IMAGES HAVE NOT BEEN DEPICTING A
WELL-ORGANIZED LOW-LEVEL CIRCULATION...ANIMATION OF VISIBLE IMAGERY
SUGGESTS THAT THE CIRCULATION IS NOW BECOMING BETTER ESTABLISHED.
THEREFORE THE SYSTEM IS BEING UPGRADED TO A TROPICAL DEPRESSION AT
THIS TIME. UPPER-LEVEL WINDS ARE BECOMING MORE CONDUCIVE FOR
STRENGTHENING AND UPPER-LEVEL OUTFLOW IS BECOMING ESTABLISHED OVER
THE SYSTEM. THE INTENSITY FORECAST IS FAIRLY CLOSE TO THE SHIPS
GUIDANCE AND SHOWS STRENGTHENING FOR THE NEXT 36 HOURS. BY 48
HOURS...THE TROPICAL CYCLONE WILL BE MOVING OVER SUB-26 DEG C SST
...SO THE OFFICIAL FORECAST SHOWS A WEAKENING TREND COMMENCING
AROUND THAT TIME. LATE IN THE FORECAST PERIOD THE SYSTEM SHOULD BE
OVER SIGNIFICANTLY COOLER WATERS...SO IT IS FORECAST TO DEGENERATE
INTO A REMNANT LOW BY 96 HOURS.
 
THE CENTER IS STILL NOT THAT WELL-DEFINED AND THE INITIAL MOTION
ESTIMATE IS A SOMEWHAT UNCERTAIN 285/9. THE GLOBAL MODELS FORECAST
A MID-LEVEL SUBTROPICAL RIDGE EXTENDING FROM THE WESTERN U.S.
WESTWARD TO NEAR 125-130 W OVER THE NEXT SEVERAL DAYS. THE TRACK
MODELS SHOW THE TROPICAL CYCLONE TURNING NORTHWESTWARD IN A COUPLE
OF DAYS AS IT NEARS THE WESTERN PERIPHERY OF THE RIDGE. THE
OFFICIAL FORECAST FOLLOWS THIS GENERAL SCENARIO. A MORE WESTWARD
MOTION IS INDICATED BY DAY 5 AS THE SYSTEM IS EXPECTED TO BE
REDUCED TO A WEAK AND SHALLOW REMNANT DISTURBANCE.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/2100Z 16.3N 117.2W    30 KT
 12HR VT     25/0600Z 16.7N 118.6W    40 KT
 24HR VT     25/1800Z 17.4N 120.4W    50 KT
 36HR VT     26/0600Z 18.4N 122.0W    55 KT
 48HR VT     26/1800Z 19.7N 123.6W    50 KT
 72HR VT     27/1800Z 22.8N 126.8W    40 KT
 96HR VT     28/1800Z 26.0N 130.0W    30 KT...REMNANT LOW
120HR VT     29/1800Z 27.5N 133.5W    20 KT...REMNANT LOW
 
$$
FORECASTER PASCH
 
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