ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM Hurricane Irma Discussion Number 39 NWS National Hurricane Center Miami FL AL112017 500 PM EDT Fri Sep 08 2017 Latest data from an Air Force Hurricane Hunter plane a few hours ago indicate that Irma's intensity continues to fluctuate, and the winds are estimated at 135 kt. The last minimum central pressure was 925 mb. Another reconnaissance plane will check Irma soon. The environment is favorable for Irma to maintain its category 4 status, and only unpredictable eyewall replacement cycles could result in intensity fluctuations during the next 48 hours. The interaction of the hurricane's circulation with Cuba will probably not result in any relevant change in intensity. In summary, the NHC forecast brings Irma near south Florida as a category 4 hurricane. After landfall, interaction with land and an increase in wind shear should induce gradual weakening. Satellite images and radar fixes from Cuba indicate that Irma has slowed down and is now moving toward the west or 280 degrees at about 10 kt. The hurricane should continue on this track for the next 12 hours to 24 hours, and this track will bring the core of Irma very close to the north coast of Cuba. After that time, Irma should reach the southwestern edge of the subtropical high and begin to move toward the northwest and north-northwest toward the Florida peninsula. The precise moment of this turn is still uncertain, and that is why NHC emphasizes that nobody should focus on the exact track of the center. This afternoon's NHC forecast was again adjusted a little bit westward following the trend of the ECMWF model and both the HFIP corrected consensus and the FSU Superensemble. In fact, these 3 aids continued to be tightly packed. 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 southern Florida and 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. The highest amounts are expected over the eastern Florida peninsula and upper Florida Keys. Irma will likely bring periods of heavy rain to much of 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 08/2100Z 22.1N 76.5W 135 KT 155 MPH 12H 09/0600Z 22.4N 78.2W 135 KT 155 MPH 24H 09/1800Z 23.0N 79.9W 135 KT 155 MPH 36H 10/0600Z 24.1N 81.0W 140 KT 160 MPH 48H 10/1800Z 25.7N 81.5W 125 KT 145 MPH 72H 11/1800Z 30.6N 83.0W 50 KT 60 MPH...INLAND 96H 12/1800Z 35.0N 85.9W 25 KT 30 MPH...INLAND 120H 13/1800Z 35.6N 87.0W 20 KT 25 MPH...POST-TROP/INLAND $$ Forecaster Avila NNNN