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Tropical Storm Eta Forecast Discussion Number 2
2020-11-01 03:47:56| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT Sat Oct 31 2020 000 WTNT44 KNHC 010247 TCDAT4 Tropical Storm Eta Discussion Number 2 NWS National Hurricane Center Miami FL AL292020 1100 PM EDT Sat Oct 31 2020 Satellite imagery indicates that shower activity associated with the cyclone continues to become better organized, with a convective band wrapping about halfway around the center. Satellite intensity estimates from TAFB and SAB have increased to 35 kt, and the CIMSS satellite consensus is near 40 kt. Based on these data, the depression is upgraded to Tropical Storm Eta, the twenty-eighth named storm of the 2020 season. This ties the record for storms set in the 2005 season and is the first time the name Eta has been used in the Atlantic basin. The initial motion is 275/13. A low- to mid-level ridge axis that extends from the subtropical Atlantic southwestward to Cuba and the Bahamas is currently the main steering influence, and the model guidance is in good agreement that this feature should cause the storm to move westward for the next 24-36 h. Between 36-72 h, a building low- to mid-level ridge over the Gulf of Mexico should cause Eta to turn west-southwestward as it approaches the coasts of Nicaragua and Honduras. Beyond that time, there remains significant spread in the models, with the GFS showing a slow motion toward the northwest near the coast of Honduras while the ECMWF/UKMET show a continued west-southwestward motion into the Pacific. Given the spread, the NHC official track forecast shows a slow motion on days 3 through 5, and brings the cyclone's center slowly across portions of Nicaragua and Honduras. The new forecast track is close to the multi-model consensus, and the 72-120 h part remains low confidence. Eta is over warm water and is in environment of light vertical wind shear. These conditions are expected to continue until the system nears the coast of Central America on 60-72 h. Thus, steady to possibly rapid strengthening is expected, with the storm forecast to reach hurricane strength between 36-48 h. The intensity guidance has trended stronger since the last advisory, and this part of the new intensity forecast is now a little below the intensity consensus. After 72 h, the intensity forecast is tied to whether or not the cyclone's center moves inland over Central America, and the current forecast is based on the forecast track that takes the center well inland. Key Messages: 1. The depression is expected to strengthen to a hurricane early next week as it approaches the coast of Central America late Monday and Monday night, and there is a risk of storm surge, hurricane-force winds, and heavy rainfall for portions of Nicaragua and Honduras where Hurricane Watches have been issued. Hurricane warnings could be needed for portions of those areas on Sunday. 2. Through Thursday evening, heavy rainfall from Eta may lead to flash flooding and river flooding across portions of Jamaica, the Cayman Islands, and Central America, which could lead to landslides in areas of higher terrain. Flooding is also possible near the southern coast of Hispaniola, depending upon the track of the storm. FORECAST POSITIONS AND MAX WINDS INIT 01/0300Z 15.0N 74.2W 35 KT 40 MPH 12H 01/1200Z 15.1N 76.4W 40 KT 45 MPH 24H 02/0000Z 15.3N 78.8W 50 KT 60 MPH 36H 02/1200Z 15.2N 80.8W 60 KT 70 MPH 48H 03/0000Z 14.7N 82.1W 70 KT 80 MPH 60H 03/1200Z 14.2N 82.8W 80 KT 90 MPH 72H 04/0000Z 13.7N 83.7W 70 KT 80 MPH...INLAND 96H 05/0000Z 14.0N 85.5W 35 KT 40 MPH...INLAND 120H 06/0000Z 14.5N 87.0W 25 KT 30 MPH...INLAND $$ Forecaster Beven
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