Tropical Depression FIVE-E

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TROPICAL DEPRESSION FIVE-E DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052008
800 PM PDT SAT JUL 05 2008
 
SATELLITE IMAGERY AND EARLIER ASCAT DATA SUGGEST THAT TROPICAL
DEPRESSION FIVE-E HAS A STRUCTURE SIMILAR TO THE MONSOON CYCLONES
OF THE WESTERN NORTH PACIFIC AND NORTH INDIAN OCEANS.  THE
SCATTEROMETER DATA SHOWED AN AREA OF 20-25 KT WINDS ABOUT 70-80 N
MI FROM THE CENTER OF THE CYCLONE...AND A SECOND LARGE AREA OF
20-25 KT WESTERLY WINDS WELL TO THE SOUTH AND SOUTHWEST OF THE
CENTER.  THE DEPRESSION IS PRODUCING WIDESPREAD STRONG...BUT
DISORGANIZED...CONVECTION.  SATELLITE INTENSITY ESTIMATES FROM TAFB
AND SAB REMAIN 25 KT...SO THAT REMAINS THE INITIAL INTENSITY.

THE CENTER IS HARD TO PINPOINT...AND THE INITIAL MOTION IS A RATHER
UNCERTAIN 315/6.  THE DEPRESSION IS ON THE SOUTHWEST SIDE OF A WEAK
LOW/MID-LEVEL RIDGE AND STRONG UPPER-LEVEL RIDGE...WHICH THE
LARGE-SCALE MODELS FORECAST TO PERSIST THROUGH THE FORECAST PERIOD. 
THE TRACK GUIDANCE SHOWS A SIGNIFICANT SPREAD...WITH THE GFS...
UKMET...HWRF...AND NOGAPS FORECASTING THE SYSTEM TO MAKE LANDFALL
ON THE MEXICAN COAST NEAR OR WEST OF ACAPULCO...WHILE THE GFDL...
ECMWF...AND CANADIAN MODELS FORECAST A WEST-NORTHWESTWARD MOTION
NEAR THE COAST.  THE FORECAST TRACK CALLS FOR A SLOW NORTHWESTWARD
MOTION FOR THE FIRST 24-48 HR...FOLLOWED BY A WEST-NORTHWESTWARD
MOTION.  THE NEW FORECAST TRACK IS SIMILAR TO THE OLD TRACK AFTER
SOME ADJUSTMENT FOR THE INITIAL POSITION...AND LIES BETWEEN THE
GFDL AND THE ECMWF.   IT SHOULD BE NOTED JUST ABOUT ANY MOTION TO
THE RIGHT OF THE TRACK WOULD BRING THE CENTER ONTO THE MEXICAN
COAST.  THERE IS ALSO A CHANCE OF SOME ERRATIC MOTION DURING THE
FIRST 24 HR AS THE SYSTEM CONSOLIDATES.
 
UPPER-LEVEL EASTERLY FLOW ON THE SOUTH SIDE OF THE RIDGE IS
PRODUCING 20-25 KT OF VERTICAL WIND SHEAR OVER THE CENTER...AND THE
LARGE-SCALE MODELS FORECAST THIS CONDITION TO PERSIST FOR AT LEAST
72 HR.  THIS COMBINED WITH THE SPRAWLING NATURE OF THE SYSTEM
SUGGESTS THAT INTENSIFICATION SHOULD BE SLOW...IF IT OCCURS AT ALL.  
THE ONLY GUIDANCE CALLING FOR SIGNIFICANT STRENGTHENING IS THE
SHIPS MODEL...WHICH CALLS FOR A PEAK INTENSITY OF 53 KT IN 60 HR. 
GIVEN THE SIMILARITY OF THE SYSTEM TO A MONSOON CYCLONE...WHICH CAN
INTENSIFY IN THIS TYPE OF ENVIRONMENT...THE INTENSITY FORECAST
CALLS FOR MODEST STRENGTHENING AS A COMPROMISE BETWEEN THE SHIPS
AND LGEM MODELS.  AN ALTERNATIVE SCENARIO IS THAT THE CYCLONE WILL
DISSIPATE IF IT MAKES LANDFALL OVER THE MOUNTAINS OF SOUTHWESTERN
MEXICO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/0300Z 14.5N 100.0W    25 KT
 12HR VT     06/1200Z 15.0N 100.3W    30 KT
 24HR VT     07/0000Z 15.7N 100.8W    35 KT
 36HR VT     07/1200Z 16.4N 101.4W    40 KT
 48HR VT     08/0000Z 17.0N 102.2W    40 KT
 72HR VT     09/0000Z 18.0N 104.0W    40 KT
 96HR VT     10/0000Z 19.0N 106.0W    45 KT
120HR VT     11/0000Z 20.5N 109.5W    45 KT
 
$$
FORECASTER BEVEN
 
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