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Tropical Storm Eta Forecast Discussion Number 46
2020-11-11 22:44:07| National Hurricane Center (Atlantic)
Issued at 400 PM EST Wed Nov 11 2020 000 WTNT44 KNHC 112143 CCA TCDAT4 Tropical Storm Eta Discussion Number 46...Corrected NWS National Hurricane Center Miami FL AL292020 400 PM EST Wed Nov 11 2020 Corrected to show dissipated at 72H. Almost as quickly as Eta regained hurricane status, it then lost it shortly thereafter. Dry air entrainment eroded most of the significant convection around the center this afternoon until a slight resurgence recently developed. However, the overall convective pattern has changed little with the bulk of the convection located primarily northeast through southeast of the center. The last recon pass through Eta showed that the central pressure had increased to 990 mb. Recent Doppler velocities of around 70 kt between 5000-6000 ft east of the center supports surface winds of about 56-58 kt, so the 1800Z intensity of 60 kt will also be kept for the 21Z advisory intensity. The initial motion estimate is northward, or 010/10 kt. Eta is expected to move between north and north-northeastward tonight as the cyclone rounds the western periphery of a deep-layer ridge to the east. The new NHC model guidance remains in excellent agreement on Eta turning northeastward after 12 hours, with the cyclone making landfall along the western coast of the northern Florida peninsula in the region from Cedar Key to Crystal River. Eta is then expected to accelerate northeastward across northern Florida as a weakening tropical cyclone, and emerge over the western Atlantic by late Thursday morning or early afternoon. By 72 hours, if not sooner, Eta is forecast to merge with a frontal system off of the southeastern United States. The new official track forecast is similar to the previous advisory track, and lies close to a blend of the consensus models TVCN, NOAA-HCCA, and FSSE. Eta will be moving over progressively cooler waters during the next 12 hours, with SSTs decreasing to less than 25 deg C just before the cyclone makes landfall along the Florida coast. The cooler waters, in conjunction with continued dry air entrainment and increasing westerly vertical wind shear, should result in at least gradual weakening until landfall occurs, followed by more rapid weakening as Eta moves over the northern Florida peninsula. Although the official forecast calls for Eta to be a tropical storm as it nears the northeast coast of Florida, a Tropical Watch or Warning are not required at this time since any tropical-storm-force will likely be occurring over water and not inland or along the coast due to Eta's poor convective structure that is expected at that time. Eta is forecast to degenerate into a remnant low by 60 hours due to even stronger wind shear, and dissipate by 72 hours due to frontal interaction. Key Messages: 1. There is a danger of life-threatening storm surge along portions of the Florida Gulf Coast from Bonita Beach to Suwannee River, including Tampa Bay and Charlotte Harbor. Residents in this area should follow any advice given by local officials. 2. Tropical-storm-force winds are expected this evening and tonight along portions of the Florida Gulf Coast from Bonita Beach to Suwanee River, and are possible tonight and early Thursday from Suwannee River to Aucilla River. Interests elsewhere along the Florida Gulf Coast should monitor the progress of Eta. 3. Heavy rainfall from Eta will continue to spread northward across west and central Florida through Thursday. Additional flash and urban flooding will be possible in south Florida through Thursday, especially across previously inundated areas. Flash, urban, and isolated minor river flooding are expected across portions of west and north Florida through Thursday. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 27.3N 83.6W 60 KT 70 MPH 12H 12/0600Z 28.6N 83.1W 55 KT 65 MPH 24H 12/1800Z 30.4N 81.5W 35 KT 40 MPH...INLAND 36H 13/0600Z 32.0N 78.9W 30 KT 35 MPH...OVER WATER 48H 13/1800Z 33.8N 75.2W 25 KT 30 MPH 60H 14/0600Z 36.0N 69.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 14/1800Z...DISSIPATED $$ Forecaster Stewart
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