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Tropical Storm DEBBY (Text)

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TROPICAL STORM DEBBY DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042012
400 AM CDT SUN JUN 24 2012
 
THE CLOUD PATTERN OF THE TROPICAL STORM HAS NOT BECOME SIGNIFICANTLY
BETTER ORGANIZED OVER THE PAST FEW HOURS.  DEBBY HAS BEEN PRODUCING
VERY COLD-TOPPED DEEP CONVECTION BUT THESE THUNDERSTORMS...AND
LIKELY THE STRONGEST WINDS...ARE OCCURRING SOME 100 TO 150 MILES
NORTHEAST OF THE LOW-LEVEL CENTER.  THE CURRENT INTENSITY IS KEPT
AT 45 KT...WHICH IS IN AGREEMENT WITH DATA FROM AN ASCAT PASS
SEVERAL HOURS AGO.  NO CHANGE IS MADE TO THE PREVIOUS INTENSITY
FORECAST...HOWEVER THIS FORECAST IS BASED ON THE PREMISE THAT THE
VERTICAL SHEAR WILL DECREASE OVER THE NEXT FEW DAYS AND THE GLOBAL
MODELS ARE NOT UNANIMOUS ON THIS.  THE OFFICIAL WIND SPEED FORECAST
IS CLOSEST TO THE MOST RECENT HWRF GUIDANCE...AND IT SHOULD BE
NOTED THAT WE HAVE LIMITED SKILL IN PREDICTING TROPICAL CYCLONE
INTENSITY CHANGE. 

WITH INFRARED IMAGERY THE CENTER...ALTHOUGH PARTIALLY EXPOSED...HAS
BECOME A LITTLE MORE DIFFICULT TO LOCATE AND THE FIXES FROM TAFB
AND SAB ARE ABOUT 50 MILES APART.  MY BEST ESTIMATE OF INITIAL
MOTION IS SLOWLY NORTHWARD...OR 360/3.  THE TRACK FORECAST FOR THIS
STORM IS EXTREMELY CHALLENGING.  THE SYNOPTIC REASONING IN PREVIOUS
ADVISORIES WAS BASED ON A MID-LEVEL RIDGE BUILDING TO THE NORTH OF
THE TROPICAL CYCLONE...WHICH WOULD CAUSE DEBBY TO MOVE TOWARD THE
NORTHWEST GULF OF MEXICO COAST IN SEVERAL DAYS.  THAT TRACK
SCENARIO WAS SUPPORTED BY THE ECMWF MODEL...WHICH HAS BEEN THE
BEST-PERFORMING GUIDANCE OVER THE PAST FEW YEARS.  HOWEVER...THE
0000 RUN OF THAT MODEL HAS SHIFTED SUBSTANTIALLY TO THE NORTH AND
EAST OF THE PREVIOUS RUNS.  THE U.K. MET. OFFICE MODEL HAS ALSO
SHIFTED SIGNIFICANTLY TO THE RIGHT.  IN FACT...ONLY THE HWRF MODEL
IS CLOSE TO THE PREVIOUS OFFICIAL FORECASTS...AND EVEN IT IS TO THE
NORTH OF THEM.  THEREFORE AN UNUSUALLY LARGE RIGHTWARD ADJUSTMENT
TO THE NHC FORECAST IS REQUIRED...AND ADDITIONAL SHIFTS TO THE
NORTH AND EAST MAY BE NECESSARY IN SUBSEQUENT ADVISORY PACKAGES.

NEEDLESS TO SAY...THIS IS A LOW CONFIDENCE FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0900Z 27.3N  87.3W   45 KT  50 MPH
 12H  24/1800Z 27.5N  87.4W   50 KT  60 MPH
 24H  25/0600Z 27.9N  87.8W   50 KT  60 MPH
 36H  25/1800Z 28.2N  88.4W   55 KT  65 MPH
 48H  26/0600Z 28.3N  89.0W   60 KT  70 MPH
 72H  27/0600Z 28.5N  90.5W   65 KT  75 MPH
 96H  28/0600Z 28.5N  92.0W   70 KT  80 MPH
120H  29/0600Z 28.5N  93.5W   70 KT  80 MPH
 
$$
FORECASTER PASCH
 
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