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Tropical Storm Iota Forecast Discussion Number 4
2020-11-14 09:39:28| National Hurricane Center (Atlantic)
Issued at 400 AM EST Sat Nov 14 2020 000 WTNT41 KNHC 140839 TCDAT1 Tropical Storm Iota Discussion Number 4 NWS National Hurricane Center Miami FL AL312020 400 AM EST Sat Nov 14 2020 Satellite imagery and scatterometer data received since the last advisory indicate that Iota is a bit disorganized. The deep convection is currently not concentrated near the center, and the scatterometer wind data showed an elongated circulation with a trough extending west-southwestward from the center. The scatterometer data also showed maximum winds of 30-35 kt in the northeastern quadrant, and based on this, the initial intensity is held at 35 kt. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Iota at around 18Z. Iota continues to move south of west with the initial motion of 245/4 kt. A mid-level ridge over the Gulf of Mexico should build eastward to the north of Iota during the next day or two, and this feature should cause the cyclone to move westward at a somewhat faster forward speed through 72 h. This motion is expected to bring the center near or over the coasts of Nicaragua or Honduras near the 72-h point. After that time, a west-southwestward motion is forecast, with the center of the cyclone moving across portions of Central America. The new forecast track is similar to, but slightly slower than, the previous forecast, and it lies in the center of the guidance envelope near the various consensus models. Iota is currently experiencing light westerly wind shear produced by an upper-level trough to the west. The shear should subside over the next 12-24 h as the trough moves westward and dissipates, leaving the cyclone in more favorable upper-level winds and over sea surface temperatures near 29C. Thus, conditions appear conducive for steady to rapid intensification once the storm becomes well enough organized internally to take advantage of the favorable environment. The new intensity forecast is similar to the previous one, and calls for rapid intensification to major hurricane intensity, with a peak intensity of near 105 kt as the system makes landfall in Central America. It should be noted that the HWRF and HMON forecast the center to go north of the official forecast track and keep it over water north of Honduras. As a result, they forecast a stronger cyclone than indciated by the official forecast. 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 later today. 2. Through Wednesday, heavy rainfall from 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 Etas recent effects there, resulting in significant impacts. FORECAST POSITIONS AND MAX WINDS INIT 14/0900Z 13.5N 74.8W 35 KT 40 MPH 12H 14/1800Z 13.6N 75.4W 45 KT 50 MPH 24H 15/0600Z 13.9N 76.8W 55 KT 65 MPH 36H 15/1800Z 14.3N 78.6W 70 KT 80 MPH 48H 16/0600Z 14.5N 80.4W 85 KT 100 MPH 60H 16/1800Z 14.8N 82.0W 100 KT 115 MPH 72H 17/0600Z 14.9N 83.3W 105 KT 120 MPH...INLAND 96H 18/0600Z 14.5N 86.0W 50 KT 60 MPH...INLAND 120H 19/0600Z 14.0N 89.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Beven
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