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| #42542 (Received by flhurricane at: 10:55 AM 28.Aug.2005) TCDAT2 HURRICANE KATRINA DISCUSSION NUMBER 23 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT SUN AUG 28 2005 THE AIR FORCE HURRICANE HUNTERS JUST MEASURED A 166 KT FLIGHT LEVEL WIND IN THE NORTHEAST EYEWALL...WHICH REQUIRES AN ADDITIONAL UPWARD ADJUSTMENT OF THE CURRENT INTENSITY TO 150 KT. A DROP IN THE EYE GAVE A CENTRAL PRESSURE OF 907 MB. KATRINA IS COMPARABLE IN INTENSITY TO HURRICANE CAMILLE OF 1969...ONLY LARGER. GPS DROPSONDE DATA FROM THE NOAA G-IV MISSION EARLIER TODAY SHOWED KATRINA'S INTENSE CYCLONIC CIRCULATION EXTENDING THROUGH THE 200 MB LEVEL...WITH THE FLOW SPIRALING ANTICYLONICALLY OUTWARD IN A WELL-DEVELOPED UPPER-LEVEL OUTFLOW PATTERN BEYOND A COUPLE HUNDRED N MI FROM THE CENTER. FLUCTUATIONS IN STRENGTH...DUE TO INTERNAL STRUCTURAL CHANGES...ARE LIKELY PRIOR TO LANDFALL. HURRICANES RARELY SUSTAIN SUCH EXTREME WINDS FOR MUCH TIME. HOWEVER WE SEE NO OBVIOUS LARGE-SCALE EFFECTS TO CAUSE A SUBSTANTIAL WEAKENING THE SYSTEM...AND IT IS EXPECTED THAT THE HURRICANE WILL BE OF CATEGORY 4 OR 5 INTENSITY WHEN IT REACHES THE COAST. THERE IS NO CHANGE TO THE TRACK FORECAST. KATRINA SHOULD GRADUALLY TURN TOWARD THE NORTH...INTO A WEAKNESS IN THE SUBTROPICAL RIDGE ASSOCIATED WITH A LARGE MID-LATITUDE CYCLONE OVER THE NORTHERN UNITED STATES AND SOUTHERN CANADA. THE OFFICIAL FORECAST TRACK IS ABOUT IN THE MIDDLE OF THE DYNAMICAL GUIDANCE MODELS...WHICH ARE RATHER TIGHTLY CLUSTERED. RECALLING THAT THE AVERAGE NHC 24-HOUR TRACK FORECAST ERROR IS ABOUT 80 N MI...THE ACTUAL LANDFALL POINT COULD STILL BE ANYWHERE FROM SOUTHEASTERN LOUISIANA TO THE MISSISSIPPI COAST. ALSO...WE MUST CONTINUE TO STRESS THAT THE HURRICANE IS NOT JUST A POINT ON THE MAP...BECAUSE DESTRUCTIVE WINDS...TORRENTIAL RAINS...STORM SURGE...AND DANGEROUS WAVES EXTEND WELL AWAY FROM THE EYE. IT IS IMPOSSIBLE TO SPECIFY WHICH COUNTY OR PARISH WILL EXPERIENCE THE WORST WEATHER. THIS ADVISORY SHOWS AN ADDITIONAL EXPANSION OF THE WIND FIELD OVER THE EASTERN SEMICIRCLE BASED ON AIRCRAFT AND SURFACE OBSERVATIONS. HURRICANE FORCE WINDS ARE FORECAST TO SPREAD AT LEAST 150 N MI INLAND ALONG THE PATH OF KATRINA. CONSULT INLAND WARNINGS ISSUED BY NATIONAL WEATHER SERVICE FORECAST OFFICES. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 28/1500Z 26.0N 88.1W 150 KT 12HR VT 29/0000Z 27.2N 88.9W 145 KT 24HR VT 29/1200Z 29.1N 89.6W 140 KT 36HR VT 30/0000Z 31.4N 89.5W 85 KT...INLAND 48HR VT 30/1200Z 34.5N 88.5W 45 KT...INLAND 72HR VT 31/1200Z 40.0N 84.0W 30 KT...INLAND 96HR VT 01/1200Z 45.0N 77.0W 25 KT...EXTRATROPICAL 120HR VT 02/1200Z 52.0N 69.0W 25 KT...EXTRATROPICAL |
