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Tropical Depression THIRTEEN-E

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TROPICAL DEPRESSION THIRTEEN-E DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132006
200 PM PDT WED SEP 13 2006
 
SATELLITE AND RADAR IMAGERY SHOWS THAT THE AREA OF DISTURBED WEATHER
SOUTH OF ACAPULCO MEXICO HAS GOTTEN BETTER ORGANIZED TODAY.
BANDING FEATURES ARE BECOMING MORE DEFINED ESPECIALLY NORTH OF THE
CENTER AND RADAR FROM ACAPULCO SHOWS A BROAD ROTATION WITHIN THESE
BANDS.  DVORAK CLASSIFICATIONS FROM TAFB/SAB ARE 30 KT... AND THIS
IS THE INITIALLY INTENSITY.  SHIP V2HZ REPORTED WINDS OF 33 KT...
BUT THIS IS NOT CONSIDERED REPRESENTATIVE OF THE CIRCULATION AS A
WHOLE.  HOWEVER IT DOES SUGGEST THAT THE SYSTEM HAS A RELATIVELY
LARGE WIND FIELD... AND REQUIRES THE ISSUANCE OF TROPICAL STORM
WARNINGS FOR SOUTHWEST MEXICO.
 
WATERS OFFSHORE OF MEXICO ARE QUITE WARM... AND... COMBINED WITH
LIGHT SHEAR FORECAST... INTENSIFICATION COULD BE RAPID.  SHIPS
SUGGESTS THERE IS ABOUT A 60 PERCENT CHANCE OF A 25 KT OR MORE
MAXIMUM WIND INCREASE IN THE NEXT 24 HOURS.  ON THE OTHER HAND...
THE GFDL HAS A MUCH SLOWER STRENGTHENING RATE... WHICH SEEMS A
LITTLE SUSPECT GIVEN THE ENVIRONMENTAL CONDITIONS.  THE INTENSITY
FORECAST IS A LITTLE LOWER THAN SHIPS... IN DEFERENCE TO THE GFDL.
 
THE BEST ESTIMATE OF INITIAL MOTION IS A RATHER UNCERTAIN 305/10.
MIDDLE-LEVEL RIDGING OVER MEXICO SHOULD CONTINUE TO PUSH THE
DEPRESSION TO THE NORTHWEST OR WEST-NORTHWEST FOR THE NEXT SEVERAL
DAYS.  THE OFFICIAL FORECAST IS A LITTLE FASTER THAN MOST GUIDANCE
IN THE SHORT-TERM ACCOUNTING FOR THE INITIAL MOTION. THE FORECAST
BEYOND 72 HOURS DEPENDS ON THE STRENGTH OF THE RIDGE TO THE NORTH
AND A MID-LEVEL TROUGH DIPPING INTO THE SOUTHWEST UNITED STATES.
THE UKMET SEEMS TO MOVE THE SYSTEM MUCH TOO FAR TO THE NORTH GIVEN
THE RIDGING OVER MEXICO WHILE THE GFS IS SEEMINGLY UNAFFECTED BY
THE TROUGH.  THE OFFICIAL FORECAST LEANS TO THE RIGHT OF THE
GUIDANCE... AND IS JUST A LITTLE NORTH OF THE GFS ENSEMBLE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/2100Z 16.0N 101.5W    30 KT
 12HR VT     14/0600Z 16.8N 102.8W    40 KT
 24HR VT     14/1800Z 17.6N 104.5W    50 KT
 36HR VT     15/0600Z 18.3N 106.0W    60 KT
 48HR VT     15/1800Z 18.9N 107.3W    70 KT
 72HR VT     16/1800Z 20.0N 109.5W    75 KT
 96HR VT     17/1800Z 21.5N 112.5W    70 KT
120HR VT     18/1800Z 23.5N 114.5W    65 KT
 
$$
FORECASTER BLAKE/BEVEN
 
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