Tropical Depression EIGHT

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TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082006
1100 PM EDT TUE SEP 12 2006

THE DEPRESSION IS RATHER DISORGANIZED TONIGHT AND CONSISTS OF A
BROAD AREA OF LOW PRESSURE WITH MULTIPLE LOW-LEVEL SWIRLS. AN
AVERAGE POSITION OF THE LARGER CIRCULATION GYRE IS USED FOR THE
HIGHLY UNCERTAIN INITIAL POSITION. THIS POSITION IS NUDGED
SOUTHWARD A LITTLE BIT FROM THE PREVIOUS ADVISORY... IN AGREEMENT
WITH AN EARLIER QUIKSCAT PASS SUGGESTING THAT THE CENTER WAS SOUTH
OF 12N. CONVECTION NEAR THE MIDDLE OF THE DEPRESSION IS SCANT...
THOUGH THERE IS A SOMEWHAT CURVED BAND TO THE SOUTHEAST OF THE
CENTER AND HEAVY CLUSTERS OF THUNDERSTORMS RACING WESTWARD AWAY
FROM THE CIRCULATION. THE INITIAL INTENSITY IS BEING HELD AT 30 KT
AND IS SUPPORTED BY BELIEVABLE 25-30 KT WIND VECTORS FROM QUIKSCAT. 

ALTHOUGH THE DEPRESSION IS OVER WARM WATER AND EXPERIENCING
RELATIVELY LOW VERTICAL WIND SHEAR... IT WILL PROBABLY TAKE SOME
TIME FOR THE LARGE SYSTEM TO CONSOLIDATE.  THE INTENSITY FORECAST
IS LOWERED FROM THE PREVIOUS PACKAGE AND IS MUCH LOWER THAN
SHIPS... WHICH SEEMS TO BE MUCH TOO FAST IN MAKING THE DEPRESSION
ALMOST A HURRICANE IN 36 HOURS.  THE GFDL HAS A SEEMINGLY MORE
REALISTIC DEPICTION OF THE FUTURE INTENSITY CHANGE... SLOW AT FIRST
THEN MORE RAPID IN THE EXTENDED PERIOD... AND IS USED AS THE
PRIMARY GUIDANCE FOR THE INTENSITY FORECAST.  

THE BEST ESTIMATE OF INITIAL MOTION IS 270/14. A STRENGTHENING
MIDDLE-LEVEL RIDGE NORTH OF THE CYCLONE SHOULD KEEP THE CYCLONE ON
THIS GENERAL TRACK WITH AN INCREASE IN FORWARD SPEED OVER THE NEXT
COUPLE OF DAYS.   BEYOND 48 HOURS... THE RIDGE WEAKENS OVER THE
CENTRAL ATLANTIC... ALLOWING THE DEPRESSION TO START MOVING MORE TO
THE NORTHWEST. MODELS ARE GENERALLY SHOWING MORE OF A WEAKNESS IN
THE SUBTROPICAL RIDGE THAN EARLIER TODAY AND... CONSEQUENTLY... THE
OFFICIAL FORECAST IS SHIFTED NORTHWARD AT DAYS 3-5.  THE FORECAST
IS STILL ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE... AND CLOSE TO
THE GFDL.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/0300Z 11.8N  25.3W    30 KT
 12HR VT     13/1200Z 12.1N  27.8W    35 KT
 24HR VT     14/0000Z 12.4N  31.3W    40 KT
 36HR VT     14/1200Z 12.9N  34.8W    45 KT
 48HR VT     15/0000Z 13.8N  38.0W    50 KT
 72HR VT     16/0000Z 16.3N  43.0W    60 KT
 96HR VT     17/0000Z 19.0N  47.0W    75 KT
120HR VT     18/0000Z 21.5N  50.0W    90 KT
 
$$
FORECASTER BLAKE/AVILA
 
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