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| #906149 (Received by flhurricane at: 5:07 PM 07.Oct.2017) TCDAT1 Hurricane Nate Discussion Number 14 NWS National Hurricane Center Miami FL AL162017 400 PM CDT Sat Oct 07 2017 Nate is sending mixed signals on its organization this afternoon. On one side, the hurricane has a ragged central dense overcast with a good complex of outer bands in the northeastern semicircle, and there are hints of an eye trying to form. On the other side, the cloud tops near the center have warmed significantly during the past several hours, and there are signs that vertical shear is starting to affect the storm. In addition, the eye only has deep convection in the eastern semicircle in land-based radar data. The last reports from an Air Force Reserve Hurricane Hunter aircraft indicated that the central pressure was near 981 mb, with flight-level and SFMR winds supporting an intensity of 80 kt. A new aircraft is just starting its investigation of the hurricane. Between the developing shear and the imminent landfall, Nate is about out of time to strengthen. While not explicitly shown in the intensity forecast, there could still be some intensification to category 2 status in the next few hours. After landfall, Nate should weaken rapidly as it moves through the eastern United States. The cyclone is forecast to become a remnant low by 48 h, extratropical near the 72 hr point, and dissipate completely by 96 h. The initial motion is now 345/20. Nate is moving around the western end of a low- to mid-level ridge over Florida and the western Atlantic, and the cyclone is expected to enter the mid- latitude westerlies during the next 12-24 h. This should cause Nate to turn northward in the next several hours, then turn northeastward after 12-24 h. The new forecast track is similar in both direction and speed to the previous track and lies near the center of a tightly clustered set of guidance. KEY MESSAGES: 1. Nate is expected to bring life-threatening storm surge flooding near and well east of where the center makes landfall, and a storm surge warning is in effect from Grand Isle, Louisiana, to the Okaloosa/Walton county line in Florida. Maximum flooding of 7 to 11 feet above ground level is expected in portions of southeastern Louisiana and along the Mississippi coast. 2. Nate will bring hurricane conditions to portions of the northern Gulf Coast from Louisiana to Alabama, where a hurricane warning is in effect. The strongest winds are expected to occur primarily to the east of the track of the center. 3. Nate`s fast forward speed after landfall will bring tropical-storm-force winds well inland across portions of the southeastern U.S. Tropical storm watches and warnings are in effect for portions of southeastern Mississippi, much of Alabama, and western Georgia. 4. Nate will bring heavy rainfall of 3 to 6 inches with isolated totals of 10 inches east of the Mississippi River from the central Gulf Coast into the Deep South, eastern Tennessee Valley, and southern Appalachians through Monday, resulting in the potential for flash flooding in these areas. 5. Moisture from Nate interacting with a frontal zone will also bring 2 to 5 inches of rain with isolated totals of 7 inches across the Ohio Valley and central Appalachians Sunday and Monday, which will increase the risk for flash flooding across these locations. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 28.4N 89.1W 80 KT 90 MPH 12H 08/0600Z 30.8N 89.2W 75 KT 85 MPH...INLAND 24H 08/1800Z 34.1N 87.0W 45 KT 50 MPH...INLAND 36H 09/0600Z 37.9N 83.1W 30 KT 35 MPH...INLAND 48H 09/1800Z 41.1N 77.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 10/1800Z 46.0N 63.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 96H 11/1800Z...DISSIPATED $$ Forecaster Beven |
