ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM HURRICANE DANIEL DISCUSSION NUMBER 27 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP052006 800 AM PDT SUN JUL 23 2006 DANIEL REMAINS AN IMPRESSIVE CATEGORY FOUR HURRICANE IN SATELLITE IMAGERY. DESPITE MOVING OVER SLIGHTLY COOLER WATERS....CLOUDS TOPS HAVE COOLED ONCE AGAIN AND THE EYE HAS BECOME MORE DISTINCT. A BLEND OF SUBJECTIVE SATELLITE INTENSITY ESTIMATES YIELDS AN AVERAGE OF 115 KT...WHILE UW-CIMSS THREE-HOURLY AVERAGE RAW ADT ESTIMATES ARE T6.3 ABOUT 122 KT. THEREFORE...THE INITIAL INTENSITY REMAINS 115 KT. EVEN THOUGH THE HURRICANE HAS BEEN FORECAST TO SOON SLOW DOWN... DANIEL CONTINUES TO MOVE STEADILY WEST-NORTHWESTWARD AND THE INITIAL MOTION IS ESTIMATED AT 285/12. THE CYCLONE CONTINUES TO BE STEERED BY A STRONG MID-TO-UPPER LEVEL RIDGE TO ITS NORTH...WHICH MOST OF THE MODELS HAVE BEEN FORECASTING TO WEAKEN. UNCERTAINTIES IN THE FORECAST TRACK AFTER 72 HOURS EXIST AS A RESULT OF A RATHER LARGE SPREAD IN THE DYNAMICAL MODEL TRACKS. BOTH THE GFDL AND GFS SIGNIFICANTLY BREAK DOWN THE RIDGE IN THE NEXT 24-48 HOURS. HOWEVER...BOTH MODELS HAVE VASTLY DIFFERENT SOLUTIONS. THE GFS SLOWS THE SPEED OF DANIEL TO 5 KT IN 24 HOURS AND THEN 2 KT OR LESS BETWEEN 36 AND 96 HOURS...WHILE THE GFDL TURNS DANIEL NORTHWARD JUST WEST OF 140W. IN CONTRAST...THE UKMET AND NOGAPS KEEPS A FAIRLY STRONG RIDGE THROUGHOUT THE ENTIRE FORECAST PERIOD WHICH KEEPS DANIEL ON A STEADY WEST-NORTHWESTWARD TRACK. SINCE IT DOES NOT APPEAR THAT THE RIDGE WILL WEAKEN AS MUCH AS THE GFS/GFDL SOLUTIONS THE OFFICIAL FORECAST TRACK WILL MAINTAIN A GENERALLY WEST-NORTHWESTWARD MOTION...ALTHOUGH A BIT SLOWER THAN THE CURRENT SPEED. THE OFFICIAL FORECAST IS SLOWER THAN THE UKMET BUT IS CLOSE TO THE NOGAPS AND GFDL/UKMET/NOGAPS MODEL CONSENSUS. DANIEL IS EXPECTED TO REMAIN OVER 25C SSTS FOR THE NEXT 48 HOURS... AND THEN MOVE OVER ONLY SLIGHTLY COOLER WATER. VERTICAL SHEAR IS FORECAST BY THE GFS-BASED SHIPS MODEL TO REMAIN LOW THROUGH 96 HOURS AND THEN INCREASE TO 15-20 KT FROM THE SOUTH-SOUTHWEST. AS A RESULT...THE SHIPS MODEL WEAKENS DANIEL SIGNIFICANTLY AT DAYS 4 AND 5. HOWEVER...THE LARGE SAMPLING RADIUS USED BY THE SHIPS MODEL APPEARS TO BE RESULTING IN AN OVERESTIMATE OF THE SHEAR SINCE BOTH IT AND THE OTHER GLOBAL MODELS INDICATE DANIEL IS FORECAST TO MOVE INTO A LIGHT WIND REGIME THAT IS EXPECTED TO EXIST BETWEEN SEVERAL SMALL UPPER LEVEL LOWS AROUND THE HAWAIIAN ISLANDS. LOWER SHEAR CONDITIONS COMBINED WITH SSTS NEAR 25C MAY RESULT IN DANIEL NOT WEAKENING AS MUCH AS CURRENTLY INDICATED IN THE OFFICIAL FORECAST AND BY THE SHIPS MODEL. FORECAST POSITIONS AND MAX WINDS INITIAL 23/1500Z 14.9N 135.7W 115 KT 12HR VT 24/0000Z 15.4N 137.3W 105 KT 24HR VT 24/1200Z 15.9N 139.1W 95 KT 36HR VT 25/0000Z 16.3N 140.4W 85 KT 48HR VT 25/1200Z 16.8N 141.8W 75 KT 72HR VT 26/1200Z 17.8N 144.0W 65 KT 96HR VT 27/1200Z 19.0N 147.5W 55 KT 120HR VT 28/1200Z 20.0N 152.5W 45 KT $$ FORECASTER BROWN/STEWART NNNN
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Page last modified: Monday, 11-Sep-2006 11:28:40 UTC