Tropical Storm DOLLY

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TROPICAL STORM DOLLY DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042008
500 PM EDT SUN JUL 20 2008
 
DOLLY APPEARS TO BE SLOWLY ORGANIZING OVER THE VERY WARM WATERS OF
THE NORTHWESTERN CARIBBEAN...ALTHOUGH DATA FROM THE AIR FORCE
RECONNAISSANCE AIRCRAFT INDICATE THE LOW-LEVEL CIRCULATION IS NOT
QUITE AS WELL-DEFINED AS IT WAS THIS MORNING. DEEP CONVECTION HAS
BEEN PERSISTENT THROUGHOUT THE DAY...AND SFMR AND FLIGHT-LEVEL
WINDS SUPPORT MAINTAINING THE INTENSITY AT 40 KT. UPPER-LEVEL
OUTFLOW IS GRADUALLY EXPANDING...EVEN TO THE WEST...AS WATER VAPOR
IMAGERY SHOWS THAT THE UPPER-LEVEL LOW JUST WEST OF DOLLY IS HEADED
RAPIDLY SOUTHWESTWARD AND IS WEAKENING. DOLLY IS NOT EXPECTED TO
STRENGTHEN MUCH...IF AT ALL...AS IT CROSSES THE YUCATAN PENINSULA
EARLY TOMORROW. ONCE IT EMERGES OVER THE SOUTHERN GULF...
HOWEVER...IT WILL BE SITUATED BENEATH A LARGE UPPER-LEVEL
ANTICYCLONE AND OVER SEA-SURFACE TEMPERATURES OF AT LEAST 28
CELSIUS. GIVEN THESE CONDITIONS...AND ASSUMING THE CYCLONE REMAINS
INTACT AND VERTICALLY ALIGNED AFTER ITS PASSAGE OVER YUCATAN...
STRENGTHENING OVER THE GULF APPEARS TO BE THE MOST LIKELY SCENARIO.
ALL OF THE PRIMARY OBJECTIVE INTENSITY MODELS FORECAST THAT TO
HAPPEN...AND ALL FORECAST DOLLY TO ATTAIN HURRICANE STATUS OVER THE
WESTERN GULF. THE NEW OFFICIAL INTENSITY FORECAST FOLLOWS THAT
GUIDANCE...BUT IT IS IMPORTANT TO REMEMBER THAT LONG-RANGE
INTENSITY FORECASTS HAVE A SIGNIFICANT AMOUNT OF UNCERTAINTY.

EVEN WITH THE AIRCRAFT DATA...THE INITIAL MOTION HAS BEEN A LITTLE
DIFFICULT TO GAUGE...BUT IT IS ESTIMATED TO BE 305/12.  THE MODELS
FORECAST A SOMEWHAT FASTER FORWARD MOTION DURING THE NEXT 24-36
HOURS...BUT THE OFFICIAL FORECAST LAGS A LITTLE BEHIND THE
CONSENSUS DURING THAT PERIOD...GIVEN THE SLOWER INITIAL MOTION AND
THAT THERE IS NO STRONG INDICATION FROM THE MODEL FIELDS THAT DOLLY
SHOULD ACCELERATE MUCH.  THE MID-LEVEL RIDGE ALONG THE GULF COAST
IS FORECAST BY ALL OF THE MODELS TO GRADUALLY WEAKEN AFTER DOLLY
REACHES THE GULF...SO THEY ALL FORECAST A DECREASE IN FORWARD
MOTION STARTING IN A COUPLE OF DAYS.  THE TRACK MODEL SPREAD IS NOT
ALL THAT LARGE THROUGH 72 HOURS...AND THE CONSENSUS HAS NOT MOVED
MUCH SINCE THIS MORNING...SO THE NEW OFFICIAL TRACK IS VERY SIMILAR
TO THE PREVIOUS ONE...JUST PERHAPS A LITTLE FASTER AT THE END.  IT
IS FAR TOO EARLY TO DETERMINE EXACTLY WHERE DOLLY WILL MAKE FINAL
LANDFALL.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/2100Z 18.9N  85.0W    40 KT
 12HR VT     21/0600Z 20.1N  86.9W    45 KT
 24HR VT     21/1800Z 21.6N  89.8W    45 KT
 36HR VT     22/0600Z 22.9N  92.4W    50 KT
 48HR VT     22/1800Z 23.8N  94.1W    55 KT
 72HR VT     23/1800Z 25.0N  96.5W    65 KT
 96HR VT     24/1800Z 26.0N  99.0W    35 KT...INLAND
120HR VT     25/1800Z 27.0N 101.5W    25 KT...INLAND
 
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FORECASTER KNABB
 
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