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Tropical Depression NINE-E


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TROPICAL DEPRESSION NINE-E DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092010
800 PM PDT SAT AUG 21 2010
 
SATELLITE IMAGERY INDICATES THAT THE DEPRESSION HAS BECOME A LITTLE
BETTER ORGANIZED DURING THE PAST FEW HOURS AS AN IRREGULAR CENTRAL
CONVECTIVE FEATURE HAS FORMED WITH SOME OUTER BANDING.  THE INITIAL
INTENSITY IS RAISED TO 30 KT IN AGREEMENT WITH A SATELLITE
INTENSITY ESTIMATE FROM TAFB.  THE DEPRESSION IS CURRENTLY IN A
LIGHT VERTICAL WIND SHEAR ENVIRONMENT FAIR TO GOOD CIRRUS OUTFLOW
IN ALL DIRECTIONS EXCEPT TO THE NORTH.

THE INITIAL INTENSITY IS A SOMEWHAT ERRATIC 270/3.  THE CYCLONE
REMAINS IN A WEAK STEERING FLOW ENVIRONMENT...AND IN THE SHORT-TERM
SOME ADDITIONAL ERRATIC MOTION MAY BE SUPERIMPOSED ON A WESTWARD
DRIFT.  AFTER 24 HOURS OR SO...A BUILDING LOW/MID-LEVEL RIDGE OVER
MEXICO SHOULD STEER THE SYSTEM SLOWLY TOWARD THE WEST AND
WEST-NORTHWEST.  THERE REMAINS SOME SPREAD IN THE GUIDANCE.  THE
GFS AND THE HWRF SHOW THE CYCLONE MOVING ONSHORE NEAR OR OVER THE
ISTHMUS OF TEHUANTEPEC...WHILE THE UKMET HAS A WEST-NORTHWESTWARD
TRACK ALONG OR CLOSE TO THE COAST OF MEXICO.  THE REMAINDER OF THE
GUIDANCE FORECASTS A MOTION PARALLEL TO...BUT OFFSHORE OF...THE
COAST OF MEXICO.  THE NEW FORECAST TRACK FOLLOWS THAT SCENARIO AND
IS SIMILAR TO...BUT SOMEWHAT FASTER THAN THE PREVIOUS FORECAST. 
THE FORECAST TRACK IS IN BEST OVERALL AGREEMENT WITH THE ECMWF.
 
VERTICAL WIND SHEAR AND SEA SURFACE TEMPERATURES CONDITIONS APPEAR
CONDUCIVE FOR DEVELOPMENT...AND THE SHIPS AND LGEM MODELS FORECAST
THE DEPRESSION TO BECOME A HURRICANE IN 48-60 HOURS.  THE SHIPS
RAPID INTENSIFICATION INDEX HAS A 85-90 PERCENT CHANCE OF 25 KT OF
INTENSIFICATION DURING THE NEXT 24 HOURS...AND A 40-45 PERCENT
CHANCE OF 40 KT OF INTENSIFICATION.  ON THE OTHER HAND...ANY MOTION
THAT BRINGS THE CENTER NEAR THE COAST OF MEXICO WOULD LIKELY
PREVENT RAPID INTENSIFICATION. ALSO...THE GFDL MODEL...WHICH KEEPS
THE CENTER OFFSHORE...DOES NOT FORECAST HURRICANE STRENGTH DURING
THE FORECAST PERIOD.  DUE TO THESE THINGS...THE INTENSITY FORECAST
DOES NOT CALL FOR RAPID INTENSIFICATION.  INSTEAD...IT WILL BE
SIMILAR TO...BUT A LITTLE BELOW...THE SHIPS/LGEM MODELS.  
 
TROPICAL STORM WARNINGS COULD BE REQUIRED FOR PORTIONS OF THE
PACIFIC COAST OF MEXICO ON SUNDAY IF THE DEPRESSION TRACKS CLOSE TO
LAND OR BECOMES LARGER THAN CURRENTLY FORECAST. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0300Z 13.8N  93.8W    30 KT
 12HR VT     22/1200Z 13.8N  94.5W    35 KT
 24HR VT     23/0000Z 13.8N  95.6W    45 KT
 36HR VT     23/1200Z 13.8N  96.6W    55 KT
 48HR VT     24/0000Z 13.9N  97.9W    60 KT
 72HR VT     25/0000Z 14.5N 100.0W    65 KT
 96HR VT     26/0000Z 15.5N 102.0W    65 KT
120HR VT     27/0000Z 17.0N 104.5W    65 KT
 
$$
FORECASTER BEVEN
 
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