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TROPICAL STORM DEAN DISCUSSION NUMBER   8
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT MON AUG 27 2001
 
DEAN HAS CONTINUED TO BECOME BETTER ORGANIZED AND IS STILL TRYING TO 
CLOSE OFF AN EYE.  THE INITIAL INTENSITY OF 60 KT IS BASED ON DVORAK 
SATELLITE INTENSITY ESTIMATES OF 55 KT...T3.5... FROM TAFB...AND 45 
KT...T3.0...FROM BOTH SAB AND AFWA.  HOWEVER...THE INTENSITY WAS 
INCREASED SLIGHTLY OVER THE SATELLITE ESTIMATES BASED ON THE 
APPEARANCE OF AN INTERMITTENT TIGHT BANDED EYE FEATURE.
 
INITIAL MOTION ESTIMATE IS 035/20.  EXCELLENT AGREEMENT IN THE 
NHC MODEL GUIDANCE CONTINUES WITH DEAN FORECAST TO MOVE 
NORTHEASTWARD THROUGHOUT THE PERIOD. THE ONLY DIFFERENCES ARE IN THE 
FORWARD SPEED.  THE CURRENT MOTION IS LEFT OF THE PREVIOUS FORECAST 
TRACK...WHICH IS MAINLY DUE TO THE NEGATIVELY-TILTED SHORTWAVE 
TROUGH UNDERCUTTING DEAN AND LIFTING IT MORE POLEWARD.  HOWEVER... 
12Z UPPER-AIR DATA AND SATELLITE ANIMATION INDICATE THAT A STRONG 
SOUTHWESTERLY UPPER-LEVEL JET LIES ACROSS THE NORTHEAST U.S. AND 
SOUTHEAST CANADA...WHICH SHOULD ACT TO TURN DEAN BACK TO THE RIGHT 
OF ITS CURRENT MOTION BY 12 HOURS.  THE OFFICIAL TRACK IS CLOSE TO 
THE UKMET-AVN-GFDL CONSENSUS.
 
DEAN HAS LIKELY PEAKED IN INTENSITY...ALTHOUGH I CAN NOT RULE OUT A 
POSSIBLE EYE APPEARING AND DEAN BECOMING A HURRICANE IN THE NEXT 6 
HOURS.  HOWEVER...TIME IS RAPIDLY RUNNING OUT FOR DEAN TO INTENSIFY 
SINCE THE CYCLONE WILL BE OVER 22C SST WATER IN ABOUT 12 HOURS. BY 
24 HOURS...DEAN IS EXPECTED TO UNDERGO EXTRATROPICAL TRANSITION AS 
IT MERGES WITH OR IS ABSORBED BY AN APPROACHING MID-LATITUDE LOW 
PRESSURE SYSTEM.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     27/2100Z 41.3N  58.6W    60 KTS
12HR VT     28/0600Z 43.5N  56.0W    60 KTS...BECOMING EXTRATROPICAL
24HR VT     28/1800Z 45.7N  51.7W    55 KTS...EXTRATROPICAL
36HR VT     29/0600Z 47.4N  46.9W    50 KTS...EXTRATROPICAL
48HR VT     29/1800Z 50.1N  42.9W    40 KTS...EXTRATROPICAL
72HR VT     30/1800Z 54.0N  36.5W    35 KTS...EXTRATROPICAL
 
 
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