Tropical Storm DOLLY

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TROPICAL STORM DOLLY DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042008
1100 AM EDT MON JUL 21 2008
 
THERE IS LITTLE DOUBT NOW THAT DOLLY HAS A CLOSED SURFACE
CIRCULATION...WHICH HAS BECOME EVIDENT IN VISIBLE SATELLITE IMAGERY
OVER THE GULF OF MEXICO JUST OFF THE NORTHERN COAST OF THE YUCATAN
PENINSULA.  A NOAA RECONNAISSANCE AIRCRAFT RECENTLY CONFIRMED THE
EXISTENCE OF THE CLOSED CIRCULATION IN THE LOW-LEVEL WIND
FIELD...AND FOUND THAT MAXIMUM WINDS REMAIN ABOUT 45 KT.  THE DEEP
CONVECTION IS NOW STARTING TO WRAP AROUND THE WESTERN SIDE OF THE
CIRCULATION...AND OUTFLOW CONTINUES TO EXPAND IN ALL QUADRANTS.  A
LARGE UPPER-LEVEL ANTICYCLONE COVERS MOST OF THE GULF OF
MEXICO...SO THE ATMOSPHERIC ENVIRONMENT APPEARS QUITE CONDUCIVE FOR
STRENGTHENING...AND THE SEA-SURFACE TEMPERATURES ALONG THE
ENTIRE OVER-WATER FORECAST TRACK ARE QUITE WARM.  IN ABOUT 18-24
HOURS...DOLLY IS EXPECTED TO PASS OVER SSTS GREATER THAN 29
CELSIUS...AND A RELATIVE MAXIMUM IN OCEAN HEAT CONTENT...AN AREA
WITH A SOMEWHAT DEEPER RESERVOIR OF WARM WATER BENEATH THE SURFACE. 
AS A RESULT OF THESE CONDITIONS...STRENGTHENING APPEARS
LIKELY...BUT GIVEN THE CURRENT SPRAWLING NATURE OF THE
CIRCULATION...THE RATE OF INTENSIFICATION IS DIFFICULT TO
FORECAST...SINCE IT IS UNCERTAIN HOW LONG IT WILL TAKE FOR A TRUE
INNER CORE TO DEVELOP.  THE NEW OFFICIAL FORECAST LEANS TOWARD THE
HIGHER END OF THE INTENSITY GUIDANCE...CLOSE TO THE GFDL
SOLUTION...IN CALLING FOR A SLIGHTLY HIGHER PEAK INTENSITY THAN THE
PREVIOUS ADVISORY.  SINCE THE EXACT TIMING AND LOCATION OF LANDFALL
ARE UNCERTAIN...THE FORECAST WEAKENING BETWEEN 48 AND 72 HOURS ONLY
RESULTS FROM THE 72-HOUR POINT BEING INLAND...AND A STRENGTHENING
TREND IS FORECAST UP TO THE TIME OF FINAL LANDFALL.

DOLLY IS STILL MOVING RATHER QUICKLY...300/16...TO THE SOUTH OF A
MID-LEVEL RIDGE OVER THE SOUTHEASTERN UNITED STATES.  ALL OF THE
DYNAMICAL MODELS FORECAST THIS RIDGE TO GRADUALLY WEAKEN DURING THE
NEXT FEW DAYS...RESULTING IN TRACK GUIDANCE SHOWING A SIGNIFICANT
SLOWING OF THE FORWARD MOTION AS THE CYCLONE PROCEEDS INTO THE
WESTERN GULF.  MOST OF THE GUIDANCE HAS SHIFTED A LITTLE
NORTHWARD OVER THE WESTERN GULF...AND SO HAS THE OFFICIAL
FORECAST...WHICH REMAINS DOWN THE MIDDLE OF THE GUIDANCE ENVELOPE. 
THERE ARE VERY RELIABLE MODELS ON BOTH SIDES OF THE OFFICIAL
TRACK...SO IT IS IMPORTANT NOT TO FOCUS ON THE EXACT LOCATION OF
LANDFALL IMPLIED BY THE OFFICIAL TRACK.

THE NEW FORECAST REQUIRES THE ISSUANCE OF HURRICANE AND TROPICAL
STORM WATCHES FOR THE COAST OF THE WESTERN GULF OF MEXICO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/1500Z 22.1N  89.5W    45 KT
 12HR VT     22/0000Z 23.0N  91.6W    55 KT
 24HR VT     22/1200Z 24.2N  93.8W    60 KT
 36HR VT     23/0000Z 25.1N  95.2W    70 KT
 48HR VT     23/1200Z 25.9N  96.4W    80 KT
 72HR VT     24/1200Z 26.5N  98.5W    50 KT...INLAND
 96HR VT     25/1200Z 27.0N 100.5W    30 KT...INLAND
120HR VT     26/1200Z...DISSIPATED
 
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FORECASTER KNABB
 
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