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Tropical Storm Iota Forecast Discussion Number 3
2020-11-14 03:40:31| National Hurricane Center (Atlantic)
Issued at 1000 PM EST Fri Nov 13 2020 000 WTNT41 KNHC 140240 TCDAT1 Tropical Storm Iota Discussion Number 3 NWS National Hurricane Center Miami FL AL312020 1000 PM EST Fri Nov 13 2020 Satellite images show that Iota has changed little during the past several hours. Deep convection is organized in fragmented bands around the center, except in the northwestern quadrant where there is a dry slot. All of the satellite intensity estimates are around 35 kt, and therefore, the initial intensity is held at that value. Iota has been drifting to the south-southwest during the past several hours, however, the steering currents are expected to become more pronounced soon. A strong and sprawling mid-level ridge currently centered over the Gulf of Mexico will shift eastward and build to the north of the tropical cyclone. Since this ridging is expected to remain well established to the north of Iota during the next several days, a general westward motion is expected through the forecast period. The NHC track forecast takes the core of Iota to the Nicaragua and Honduras coasts in about 3 days. However, conditions are expected to deteriorate along that part of the coast before the center arrives. The latest models are in fairly good agreement, except for the HWRF which is a northern outlier, and the NHC track forecast lies near the middle of the guidance envelope. This forecast is a little slower than the previous one. An upper-level trough to the west of Iota is expected to move west and dissipate on Saturday. This should leave the storm in favorable conditions of 29-30 C waters, and in an air mass of low wind shear and high moisture this weekend and early next week. These conditions support steady to possibly rapid intensification until Iota makes landfall. The main question is how strong will Iota become before it crosses the coast. The SHIPS Rapid Intensification Index shows a 55 percent chance of Iota strengthening 65 kt or more before it makes landfall, which is about 11 times the climatological mean. The NHC intensity forecast is an update of the previous one, and shows Iota strengthening to a major hurricane in about 60 hours. Key Messages: 1. Iota is expected to strengthen and be a major hurricane when it approaches the coast of Central America. There is a risk of dangerous wind, storm surge, and rainfall impacts across portions of Nicaragua and Honduras beginning Monday. Hurricane Watches will likely be issued for a portion of this area on Saturday. 2. Through Wednesday, heavy rainfall from Tropical Storm Iota will likely lead to life-threatening flash flooding and river flooding across portions of northern Colombia and Central America. Flooding and mudslides in Honduras and Nicaragua could be exacerbated by Hurricane Eta's recent effects there. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 13.6N 74.2W 35 KT 40 MPH 12H 14/1200Z 13.5N 74.9W 45 KT 50 MPH 24H 15/0000Z 13.7N 76.0W 55 KT 65 MPH 36H 15/1200Z 14.0N 77.6W 70 KT 80 MPH 48H 16/0000Z 14.3N 79.5W 85 KT 100 MPH 60H 16/1200Z 14.5N 81.2W 100 KT 115 MPH 72H 17/0000Z 14.7N 82.7W 105 KT 120 MPH 96H 18/0000Z 14.8N 85.4W 50 KT 60 MPH...INLAND 120H 19/0000Z 14.3N 88.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Cangialosi
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