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| #202093 (Received by flhurricane at: 5:08 PM 20.Jul.2008) TCDAT4 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 $$ FORECASTER KNABB |
