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Hurricane Sally Forecast Discussion Number 13
2020-09-14 18:31:30| National Hurricane Center (Atlantic)
Issued at 1130 AM CDT Mon Sep 14 2020 000 WTNT44 KNHC 141631 TCDAT4 Hurricane Sally Special Discussion Number 13 NWS National Hurricane Center Miami FL AL192020 1130 AM CDT Mon Sep 14 2020 A NOAA Hurricane Hunter aircraft investigating Sally recently measured peak flight-level winds of 88 kt at 700 mb and SFMR winds of 78 kt north of the center, and an Air Force reconnaissance aircraft just measured 79 kt flight-level winds at 700 mb. These data indicate that Sally has rapidly strengthened into a hurricane with an intensity of around 80 kt. In addition, data from the KEVX WSR-88D show an eye forming at around 16,000 ft altitude. This special advisory has been issued to increase the initial and forecast intensity. Additional adjustments to the intensity forecast could be required this afternoon. Only a slight adjustment was made to the 12-h track forecast position based on the more northward and eastward initial position. KEY MESSAGES: 1. It is too early to determine where Sally's center will move onshore given the uncertainty in the timing and location of Sally's northward turn near the central Gulf Coast. Users should not focus on the details of the official forecast track, since NHC's average forecast error at 48 hours is around 80 miles, and dangerous storm surge, rainfall, and wind hazards will extend well away from the center. 2. An extremely dangerous and life-threatening storm surge is expected for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from Port Fourchon, Louisiana, to the Alabama/Florida border, where a Storm Surge Warning is in effect. Residents in these areas should follow any advice given by local officials. 3. Hurricane conditions are expected tonight within the Hurricane Warning area in southeastern Louisiana and are expected by late Tuesday within the Hurricane Warning area along the Mississippi and Alabama coastline. Tropical storm conditions are likely to begin later today and this evening in these areas and preparations should be rushed to completion. 4. Life-threatening flash flooding is likely, as well as widespread minor to isolated major flooding, on area rivers along and just inland of the Central Gulf Coast. Significant flash and urban flooding, as well as widespread minor to moderate river flooding is likely across Mississippi and Alabama through the middle of the week. Flooding impacts are expected to spread farther across the Southeast through the week. Sally could continue to produce flash flooding across the Florida peninsula and prolong existing minor river flooding across west-central Florida through today. FORECAST POSITIONS AND MAX WINDS INIT 14/1630Z 28.7N 87.0W 80 KT 90 MPH 12H 15/0000Z 28.8N 87.8W 85 KT 100 MPH 24H 15/1200Z 29.2N 88.8W 90 KT 105 MPH 36H 16/0000Z 29.8N 89.1W 90 KT 105 MPH 48H 16/1200Z 30.8N 88.7W 65 KT 75 MPH...INLAND 60H 17/0000Z 31.8N 87.7W 30 KT 35 MPH...INLAND 72H 17/1200Z 32.6N 86.5W 25 KT 30 MPH...INLAND 96H 18/1200Z 33.1N 84.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 19/1200Z...DISSIPATED $$ Forecaster Brown
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Category:Transportation and Logistics