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Potential Tropical Cyclone Sixteen Forecast Discussion Number 5
2019-10-18 16:55:28| National Hurricane Center (Atlantic)
Issued at 1000 AM CDT Fri Oct 18 2019 000 WTNT41 KNHC 181455 TCDAT1 Potential Tropical Cyclone Sixteen Discussion Number 5 NWS National Hurricane Center Miami FL AL162019 1000 AM CDT Fri Oct 18 2019 The satellite presentation of the system features an area of very deep convection with cloud tops colder than -80C within the eastern part of a rather broad and elongated surface circulation seen in visible satellite imagery and data from an Air Force Reserve Hurricane Hunter aircraft. A NOAA Hurricane Hunter aircraft found flight-level winds as high as 72 kt and SFMR winds of 45-50 kt southeast of the ill-defined center, and based on these data the initial intensity is set to 50 kt. The NOAA aircraft also measured a pressure of around 1001 mb. While the cyclone has deepened, the circulation is still quite elongated and not well defined, so the system is maintained as a Potential Tropical Cyclone for now. The global models continue to indicate that the circulation will consolidate and the system will strengthen some during the next 12 hours or so, as the low-level circulation will be overtaken by an upper-level trough currently situated over southwest Louisiana. The system is still expected to become a tropical or subtropical storm later today, with the exact phase dependent on the timing of the circulation improving and the interaction with the upper trough. Once the system moves inland, it should become extratropical by 36 hours and slowly weaken once it moves offshore of the Carolinas by 72-96 hours before dissipating by day 5. The new NHC intensity forecast is adjusted upward from the previous one through 24 hours based on the initial intensity and allows for the possibility of at least some additional strengthening later today. The initial motion is a somewhat uncertain 055/19 given the lack of a well-defined center. The track model guidance remains in good agreement on the system moving quickly northeastward toward the northeastern Gulf Coast during the next 24 hours as it interacts with the upper trough. After moving inland, a northeastward motion is forecast to continue until after 48 hours, when an east- northeastward motion is expected, which will take the circulation offshore over the Atlantic by 72 hours. The new NHC track forecast is similar to, but a bit to the south of the previous one and is close to the various track consensus aids. Regardless of the exact evolution of the system, portions of the northeastern coast of the Gulf of Mexico will experience strong winds, locally heavy rains, and storm surge later today and Saturday. Similar impacts are expected across portions of the Atlantic coast of the southeastern United States Saturday and Sunday. Key Messages: 1. There is a danger of life-threatening storm surge inundation of up to 5 feet above ground level beginning later today along the Florida Gulf Coast from Indian Pass to Clearwater Beach, where a Storm Surge Warning is in effect. Residents in these areas should follow advice given by local officials. 2. Tropical storm force winds are likely later today and tonight along portions of the central and eastern Gulf Coast, where tropical storm warnings are in effect. Regardless of the exact track and intensity of the system, these winds will cover a large area, especially east of the center. 3. Isolated flash flooding is possible along the central and eastern Gulf Coast and the southeast United States coast through Saturday night. 4. Wind and coastal flooding hazards along the U.S. East Coast will be covered by non-tropical watches and warnings issued by local NWS offices, since the system is expected to lose any tropical characteristics after it moves inland along the Gulf Coast. FORECAST POSITIONS AND MAX WINDS INIT 18/1500Z 25.9N 90.0W 50 KT 60 MPH...POTENTIAL TROP CYCLONE 12H 19/0000Z 27.8N 88.0W 55 KT 65 MPH...TROPICAL STORM 24H 19/1200Z 29.9N 85.5W 50 KT 60 MPH 36H 20/0000Z 32.2N 82.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 48H 20/1200Z 34.4N 78.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 21/1200Z 37.0N 71.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 22/1200Z 37.0N 69.0W 25 KT 30 MPH...POST-TROP/EXTRATROP 120H 23/1200Z...DISSIPATED $$ Forecaster Brennan
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