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ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM Hurricane Irma Discussion Number 40 NWS National Hurricane Center Miami FL AL112017 1100 PM EDT Fri Sep 08 2017 An Air Force Hurricane Hunter flight has found that Irma has re-intensified to category 5 strength. The plane measured a maximum flight-level wind of 154 kt and SFMR winds of 140-145 kt in the northwestern eyewall, so the initial intensity is raised to 140 kt. The hurricane is producing very deep convection in all quadrants around the eye, which the Air Force flight measured to be 35 n mi wide. Apparently the ridge to the north of Irma has been stronger than expected, and the initial motion remains westward, or 280/11 kt. The track guidance continues to insist on Irma turning west-northwestward soon, moving along the Cuban Keys adjacent to the north coast of Cuba during the next 24 hours. After that time, Irma is expected to turn sharply north-northwestward and accelerate after 48 hours, moving parallel to the west coast of Florida and then into Georgia. Mainly because Irma's eye has not deviated from its westward motion, the new NHC forecast track has again shifted slightly westward. Because of the hurricane's angle of approach to the west coast of Florida, it is extremely difficult to pinpoint exactly where the center might move onshore. If the eye continues to move over the Cuban Keys and does not move inland over the main island of Cuba, then Irma would likely not lose much intensity during the next day or so. As we've stated many times, fluctuations in intensity are likely during the next 36 hours due to possible and unpredictable eyewall replacement cycles. After 36 hours, there are some indications that vertical shear may increase over the hurricane, and a little more weakening is anticipated at that time. Because of the concerns in the track forecast noted above, Irma would be able to maintain a strong intensity for a longer period of time if the center stays off the west Florida coast. Regardless, Irma is still expected to be a dangerous hurricane as it approaches the Florida Keys and the west coast of Florida through 48 hours. KEY MESSAGES: 1. Irma will continue to bring life-threatening wind, storm surge, and rainfall hazards to portions of the Bahamas and the north coast of Cuba, especially over the adjacent Cuban Keys, through Saturday. 2. Irma is expected to make landfall in Florida as an extremely dangerous major hurricane, and will bring life-threatening wind impacts to much of the state regardless of the exact track of the center. 3. There is the danger of life-threatening storm surge inundation in portions of central and southern Florida, including the Florida Keys, during the next 36 hours, where a Storm Surge Warning is in effect. The threat of significant storm surge flooding along the southwest coast of Florida has increased, and 8 to 12 feet of inundation above ground level is possible in this area. This is a life-threatening situation. Everyone in these areas should take all actions to protect life and property from rising water and follow evacuation instructions from local officials. 4. Irma is expected to produce very heavy rain and inland flooding. Total rain accumulations of 8 to 15 inches, with isolated amounts of 20 inches are expected over the Florida Keys and much of the Florida peninsula through Tuesday night. Irma will likely bring periods of heavy rain to much of the Florida Panhandle, Georgia, South Carolina, and western North Carolina early next week, including some mountainous areas which are more prone to flash flooding. All areas seeing heavy rainfall from Irma will experience a risk of flooding and flash flooding. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 22.1N 77.7W 140 KT 160 MPH 12H 09/1200Z 22.6N 79.1W 140 KT 160 MPH 24H 10/0000Z 23.3N 80.6W 135 KT 155 MPH 36H 10/1200Z 24.5N 81.4W 130 KT 150 MPH 48H 11/0000Z 26.5N 81.9W 115 KT 130 MPH...INLAND 72H 12/0000Z 31.6N 83.8W 50 KT 60 MPH...INLAND 96H 13/0000Z 35.0N 87.0W 25 KT 30 MPH...INLAND 120H 14/0000Z 35.5N 87.5W 20 KT 25 MPH...POST-TROP/INLAND $$ Forecaster Berg NNNN