ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM Hurricane Irma Discussion Number 49 NWS National Hurricane Center Miami FL AL112017 500 AM EDT Mon Sep 11 2017 Irma is continuing to weaken as it moves across the western Florida peninsula, with the eye dissipating and weakening banding near the center. There are no recent observations of hurricane-force winds near the center, but based on the premise that such winds still exist over the Gulf of Mexico west of the center the initial intensity is reduced to 65 kt. It should be noted that near- hurricane force winds are occurring in a band well northeast of the center with sustained winds of 60 kt reported in the Jacksonville area. The cyclone should continue to weaken as it moves through the southeastern United States, becoming a tropical storm later today, a tropical depression by 36 h, and a remnant low by 48 h. The large-scale models forecast Irma to dissipate completely by 72 h, so the 72 h point has been removed from the forecast. The initial motion is 340/16. The cyclone is expected to move around the eastern side of a mid-level disturbance currently located along the U.S. Gulf Coast, which should cause a north-northwestward to northwestward motion until dissipation. The forecast track takes the center across the eastern Florida Panhandle, southwestern Georgia, eastern and northern Alabama, and eventually into western Tennessee. KEY MESSAGES: 1. There is the danger of life-threatening storm surge flooding along portions of the coasts of Florida, Georgia and South Carolina, where a Storm Surge Warning remains in effect. 2. Irma will continue to bring life-threatening wind impacts to much of central and north Florida, with hurricane-force winds near the center. Also, Irma is a large hurricane, and hurricane-force wind gusts and sustained tropical-storm force winds extend far from the center. Wind hazards from Irma will continue to spread northward through Georgia and into portions of Alabama, Tennessee, South Carolina, and North Carolina. 3. Irma continues to produce very heavy rain and inland flooding across much of the northern peninsula and eastern panhandle of Florida and southern Georgia, which is quickly spreading to the rest of the southeast United States. Intense rainfall rates of 2 inches or more per hour is leading to flash flooding and rapid rises on creeks, streams, and rivers. Significant river flooding is likely over the next five days in the Florida peninsula and southern Georgia, where average rainfall totals of 8 to 15 inches are expected. Significant river flooding is possible beginning Monday and Tuesday in much of central Georgia and southern South Carolina where average rainfall of 3 to 6 inches and isolated 10 inch amounts are expected. Portions of these states within the southern Appalachians will be especially vulnerable to flash flooding. Farther north and west, Irma is expected to produce average amounts of 2 to 4 inches in parts of Mississippi, Alabama, and Tennessee, northern South Carolina and western North Carolina, where isolated higher amounts and local flooding may occur. FORECAST POSITIONS AND MAX WINDS INIT 11/0900Z 28.9N 82.6W 65 KT 75 MPH...INLAND 12H 11/1800Z 30.8N 83.7W 55 KT 65 MPH...INLAND 24H 12/0600Z 33.0N 85.7W 35 KT 40 MPH...INLAND 36H 12/1800Z 34.5N 87.8W 25 KT 30 MPH...INLAND 48H 13/0600Z 35.5N 89.0W 20 KT 25 MPH...POST-TROP/INLAND 72H 14/0600Z...DISSIPATED $$ Forecaster Beven NNNN