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Tropical Storm Eta Forecast Discussion Number 43
2020-11-11 03:54:53| National Hurricane Center (Atlantic)
Issued at 1000 PM EST Tue Nov 10 2020 000 WTNT44 KNHC 110254 TCDAT4 Tropical Storm Eta Discussion Number 43 NWS National Hurricane Center Miami FL AL292020 1000 PM EST Tue Nov 10 2020 Eta has been maintaining a large cluster of deep convection over the northeastern portion of its circulation this evening. NWS Doppler radar data from Key West is showing a well-defined mid-level circulation in that area, but NOAA reconnaissance aircraft data so far still indicates that the low-level center is located near the southwestern portion of the convective mass. However, it is possible that the center will re-form closer to the mid-level center overnight. The plane has measured peak 850-mb flight-level winds of 67 kt, and SFMR winds of 52 kt. Based on these data the initial intensity has been raised to 55 kt. Eta's initial motion is a somewhat uncertain 015/8 kt. There has once again been a significant eastward shift in the 18Z dynamical model guidance, with the GFS, HWRF, and UKMET models all showing a faster north-northeastward motion toward the Florida west coast. As a result, the NHC forecast has again been shifted eastward and lies near the TVCA multi-model consensus through 36 h. After that time, the NHC track is slower and west of the bulk of the consensus aids as the ECMWF still shows Eta weakening and lingering near the Florida Big Bend. While the new track has been shifted significantly eastward after 36 h or so, some continuity with the previous forecast is maintained with a slower northward motion between the two model camps. While there is increasing confidence in the faster north-northeastward motion in the short-term, there is still considerable uncertainty by 48 hours and beyond, and further adjustments to the track forecast could be required overnight. Some additional strengthening is likely overnight and Wednesday while Eta remains over warm water and within an area of low-to-moderate vertical wind shear. If the center re-forms closer to the deep convection, Eta could re-gain hurricane status within the next 12-24 hours. After that time, increasing southwesterly shear and cooler SSTs are likely to result in some weakening. The updated NHC intensity forecast is close to the SHIPS and HCCA model guidance. Given the eastward shift in the track and the expected faster motion of Eta, a Tropical Storm Warning and Storm Surge Watch are being issued for a portion of the west coast of Florida. Additional warnings could be required early Wednesday. Key Messages: 1. Life-threatening storm surge is possible Thursday along portions of the Florida Gulf Coast from Bonita Beach to Steinhatchee 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 by late Wednesday along portions of the Florida Gulf Coast from Bonita Beach to Suwanee River, and are possible Thursday from Suwannee River to Aucilla River. Interests elsewhere along the Florida Gulf Coast should monitor the progress of Eta, as additional watches and warnings may be needed overnight. 3. Heavy rainfall from Eta will continue across western Cuba and south Florida through tonight, and spread northward across portions of west Florida, the eastern Florida Panhandle, and north Florida Wednesday through Friday. Additional flash and urban flooding is possible in south Florida tonight, especially across previously inundated areas, and eventually across portions of west Florida, the eastern Florida Panhandle, and north Florida Wednesday through Friday. FORECAST POSITIONS AND MAX WINDS INIT 11/0300Z 23.8N 84.5W 55 KT 65 MPH 12H 11/1200Z 25.0N 84.3W 60 KT 70 MPH 24H 12/0000Z 26.5N 84.0W 60 KT 70 MPH 36H 12/1200Z 27.7N 83.7W 55 KT 65 MPH 48H 13/0000Z 28.8N 83.1W 45 KT 50 MPH 60H 13/1200Z 29.7N 82.5W 35 KT 40 MPH...INLAND 72H 14/0000Z 30.3N 82.3W 30 KT 35 MPH...INLAND 96H 15/0000Z 30.8N 82.3W 30 KT 35 MPH...INLAND 120H 16/0000Z...DISSIPATED $$ Forecaster Brown
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