Tropical Depression THIRTEEN-E

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TROPICAL DEPRESSION THIRTEEN-E DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT FRI SEP 10 2004
 
CONVECTION AROUND TROPICAL DEPRESSION THIRTEEN-E HAS DECREASED
SOMEWHAT OVER THE PAST SEVERAL HOURS...HOWEVER A BANDING FEATURE
HAS PERSISTED IN THE NW SEMICIRCLE. SATELLITE INTENSITY ESTIMATES
ARE 35 KT FROM TAFB...30 KT FROM SAB AND 25 KT FROM AFWA. THE
INITIAL INTENSITY OF 30 KT REPRESENTS AN AVERAGE OF THE INTENSITY
ESTIMATES FROM THE THREE AGENCIES. SHEAR ANALYSES FROM THE
UNIVERSITY OF WISCONSIN/CIMMS INDICATE 15-20 KT OF EASTERLY SHEAR IN
THE VICINITY OF THIRTEEN-E. 

THE INITIAL MOTION IS 280/10. THE DIFFERENCES IN INITIALIZATION OF
THE TROPICAL CYCLONE BY THE VARIOUS MODELS HAS ONCE AGAIN LED TO
DIFFERING SOLUTIONS. THE LATEST NOGAPS HAS A POOR INITIALIZATION OF
THE TROPICAL CYCLONE AND AS THE LONE OUTLIER IMMEDIATELY TURNS THE
SYSTEM NORTHWARD FOR 24 HOURS THEN RAPIDLY NORTHEASTWARD OVER
GUATEMALA AFTER THAT TIME. THIS SOLUTION WAS DISCOUNTED. THE
GFS...GFDL...LBAR...CONU CONSENSUS AS WELL AS THE BAMS MOVE THE
SYSTEM WEST-NORTHWESTWARD FOR THE NEXT 48-60 HOURS AT VARYING
SPEEDS THEN TURN THE SYSTEM NORTHWARD TOWARD THE COAST OF MEXICO.
ALL THE MODELS AGREE THAT THE RIDGE CURRENTLY TO THE NORTH OF
THIRTEEN-E WILL RETROGRADE AFTER 48 HOURS AND ALLOW HEIGHTS TO FALL
NORTH OF THE SYSTEM OVER MEXICO AND THEREBY INDUCING A MORE
NORTHWARD MOTION. THE OFFICIAL FORECAST IS SOUTH OF THE PREVIOUS
FOR THE FIRST 36-48 HOURS TAKING INTO ACCOUNT THE MORE WESTWARD
MOTION INITIALLY. AFTER 48 HOURS...THE FORECAST IS TO THE RIGHT OF
THE PREVIOUS WITH A SHARP DECREASE IN THE FORWARD SPEED TO
ACKNOWLEDGE THE POSSIBLE TURN TO THE NORTH BEING OFFERED BY MORE
MEMBERS OF THE MODEL SUITE. 

THE SYSTEM IS FORECAST TO REMAIN OVER 28-29C WATER THROUGH THE
FORECAST PERIOD WITH UPPER LEVEL SHEAR DECREASING WITH TIME. THE
INTENSITY FORECAST CALLS FOR INTENSIFICATION TO A HURRICANE IN 48
HOURS AND A LEVELLING OF THE INTENSITY TO 75 KNOTS AT DAYS 4 AND 5.
THIS IS IN GOOD AGREEMENT WITH SHIPS. THE GFDL IS MORE AGGRESSIVE
AND FORECASTS AN INTENSITY OF 90-95 KT BY 48 HOURS.
 
FORECASTER COBB/JARVINEN
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/0300Z 11.5N  95.8W    30 KT
 12HR VT     11/1200Z 11.8N  97.3W    40 KT
 24HR VT     12/0000Z 12.4N  99.2W    45 KT
 36HR VT     12/1200Z 12.8N 100.5W    55 KT
 48HR VT     13/0000Z 13.0N 101.5W    65 KT
 72HR VT     14/0000Z 13.5N 103.0W    70 KT
 96HR VT     15/0000Z 14.0N 104.0W    75 KT
120HR VT     16/0000Z 15.0N 105.0W    75 KT
 
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