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#902468 (Received by flhurricane at: 4:55 PM 10.Sep.2017) TCDAT1 Hurricane Irma Discussion Number 47 NWS National Hurricane Center Miami FL AL112017 500 PM EDT Sun Sep 10 2017 Irma made landfall a couple of hours ago near Marco Island, Florida with an estimated intensity of 100 kt. The eye just passed over Naples, and assuming some decay over land, the current intensity estimate is 95 kt. The interaction with the Florida Peninsula along with strong southwesterly shear should cause significant weakening, but Irma`s large and powerful circulation will likely maintain hurricane strength until Monday morning at the earliest. Irma should be well inland and weaken to a remnant low in 72 hours. The official intensity forecast is above the model consensus. Center fixes indicate a slightly west of due northward motion at about 350/12 kt. Global models indicate that Irma is embedded within a broader cyclonic mid-level gyre. The cyclone is expected to be steered around the eastern side of this gyre over the next few days. This will take the system inland over the southeastern United states within a day or so. The track guidance remains in good agreement, and the official forecast is close to the model consensus with a slight lean toward the ECMWF solution. This is very close to the previous NHC track. KEY MESSAGES: 1. Life-threatening wind and storm surge from Irma will continue in the Florida Keys and southwestern Florida and spread into central and northwestern Florida tonight and Monday. 2. There is imminent danger of life-threatening storm surge flooding along much of the Florida west coast, including the Florida Keys, where a Storm Surge Warning is in effect. The threat of catastrophic storm surge flooding is highest along the southwest coast of Florida, where 10 to 15 feet of inundation above ground level is expected. This is a life-threatening situation. 3. Irma will bring life-threatening wind impacts to much of Florida regardless of the exact track of the center. Wind hazards from Irma are also expected to spread northward through Georgia and into portions of Alabama, Tennessee, South Carolina, and North Carolina. 4. Irma is producing very heavy rain and inland flooding across much of Florida, which will quickly spread to the rest of the southeast United States. Intense rainfall rates of 2 to 4 inches 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 southeast Georgia, where average rainfall of 8 to 15 inches and isolated 20 inch amounts are expected. Significant river flooding is also possible beginning Monday and Tuesday in much of eastern and central Georgia, western South Carolina, and western North Carolina, where average rainfall of 3 to 8 inches and isolated 12 inch amounts are expected. Mountainous parts of these states will be especially vulnerable to flash flooding. Farther west, Irma is expected to produce average amounts of 2 to 5 inches in parts of Mississippi, Alabama and Tennessee, where isolated higher amounts and local flooding may occur. FORECAST POSITIONS AND MAX WINDS INIT 10/2100Z 26.2N 81.8W 95 KT 110 MPH...INLAND 12H 11/0600Z 28.0N 82.5W 75 KT 85 MPH...INLAND 24H 11/1800Z 30.7N 83.9W 55 KT 65 MPH...INLAND 36H 12/0600Z 33.1N 86.0W 35 KT 40 MPH...INLAND 48H 12/1800Z 34.5N 88.3W 30 KT 35 MPH...INLAND 72H 13/1800Z 36.5N 89.0W 25 KT 30 MPH...POST-TROP/INLAND 96H 14/1800Z 39.0N 86.5W 20 KT 25 MPH...POST-TROP/INLAND 120H 15/1800Z...DISSIPATED $$ Forecaster Pasch |