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| #42472 (Received by flhurricane at: 5:11 AM 28.Aug.2005) TCDAT2 HURRICANE KATRINA DISCUSSION NUMBER 21 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT SUN AUG 28 2005 KATRINA CONTINUES TO INTENSIFY AND GROW LARGER. AN AIR FORCE RECONNAISSANCE AIRCRAFT MOST RECENTLY MEASURED A MINIMUM CENTRAL PRESSURE OF 935 MB... AND THE WINDS HAVE RESPONDED SIGNIFICANTLY... WITH THE MAXIMUM FLIGHT LEVEL WIND OF 137 KT EARLIER THIS MORNING. THIS OBSERVATION ALONG WITH RECENT DVORAK INTENSITY ESTIMATES SUPPORT THE ADVISORY INTENSITY OF 125 KT. ADDITIONALLY...THE AIRCRAFT DATA AND SHIP OBSERVATIONS INDICATE THAT THE WIND FIELD CONTINUES TO EXPAND. THE INITIAL AND FORECAST WIND RADII HAVE AGAIN BEEN EXPANDED. ALTHOUGH THE NEW OFFICIAL FORECAST SHOWS NO FURTHER EXPANSION OF THE RADII BEFORE LANDFALL...THIS IS CERTAINLY POSSIBLE. DUE TO THE UNCERTAINTY IN BOTH THE TRACK AND SIZE FORECASTS...TROPICAL STORM WARNINGS HAVE BEEN EXTENDED BOTH EAST AND WEST ALONG THE NORTHERN GULF COAST. THE INTENSITY FORECAST ANTICIPATES THAT KATRINA COULD APPROACH CATEGORY FIVE STATUS PRIOR TO LANDFALL. THE SHIPS GUIDANCE ACTUALLY DOES FORECAST 140 KT AT 24 HOURS... BUT IT IS ALSO POSSIBLE THAT INTERNAL STRUCTURAL CHANGES COULD CAUSE FLUCTUATIONS IN THE INTENSITY... SO THE OFFICIAL FORECAST PEAKS AT 135 KT. WHILE THE DETAILS OF THE LANDFALL INTENSITY CANNOT BE NOT KNOWN AT THIS TIME... KATRINA WILL BE A VERY DANGEROUS HURRICANE AT LANDFALL. KATRINA IS MOVING ALONG THE PREVIOUS FORECAST TRACK... JUST A LITTLE FASTER NOW WITH AN INITIAL MOTION ESTIMATE OF 290/9. DYNAMICAL MODELS ARE IN TIGHT AGREEMENT ON THE TURN TO THE NORTH DURING THE NEXT 24-36 HOURS INTO A WEAKNESS IN THE RIDGE ASSOCIATED WITH A LARGE MIDLATITUDE LOW PRESSURE SYSTEM OVER THE NORTHERN UNITED STATES AND SOUTHERN CANADA. THE MODEL CONSENSUS TRACK HAS HARDLY MOVED SINCE THE LAST FORECAST CYCLE AND IS VERY CLOSE TO THE PREVIOUS OFFICIAL FORECAST...WHICH THE NEW FORECAST BASICALLY JUST UPDATES. THE SPREAD IN THE MODEL TRACKS ALONG THE NORTHERN GULF COAST IS AT MOST 90 MILES... SO CONFIDENCE IN THE OFFICIAL FORECAST IS RELATIVELY HIGH. HOWEVER...IT MUST BE EMPHASIZED THAT THE EXACT LANDFALL POINT CANNOT BE SPECIFIED AND THAT KATRINA IS A LARGE HURRICANE THAT WILL AFFECT A LARGE AREA... BOTH AT THE COAST AND WELL INLAND. PREPARATIONS SHOULD BE RUSHED TO COMPLETION THROUGHOUT THE WARNING AREAS. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 28/0900Z 25.4N 87.4W 125 KT 12HR VT 28/1800Z 26.3N 88.4W 130 KT 24HR VT 29/0600Z 28.0N 89.4W 135 KT 36HR VT 29/1800Z 30.0N 89.8W 125 KT 48HR VT 30/0600Z 32.3N 89.3W 65 KT...INLAND 72HR VT 31/0600Z 37.5N 86.0W 35 KT...INLAND 96HR VT 01/0600Z 42.0N 79.0W 30 KT...EXTRATROPICAL 120HR VT 02/0600Z 47.0N 70.0W 25 KT...EXTRATROPICAL |
