000 AXNT20 KNHC 170921 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Tue Nov 17 2020 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Hurricane Iota is centered near 13.7N 84.3W at 17/0900 UTC or 10 nm ENE of El Pia Nicaragua moving W at 8 kt. Estimated minimum central pressure is 950 mb. Maximum sustained wind speed is 90 kt with gusts to 110 kt. Iota is moving toward the west and this general motion is expected to continue during the next day or so. On the forecast track, Iota will move farther inland across northern Nicaragua today, and move across southern Honduras tonight and Wednesday. Additional rapid weakening is expected today into Wednesday, and Iota is forecast to dissipate over Central America by Wednesday night. Numerous moderate to strong convection is noted within 210 nm of the center of Iota. Scattered moderate and isolated strong convection is noted elsewhere within 360 nm in the N semicircle and 270 nm in the SW quadrant of Iota. Life-threatening flash flooding and river flooding is expected through Thursday across portions of Central America due to heavy rainfall from Iota. Flooding and mudslides across portions of Honduras, Nicaragua and Guatemala could be exacerbated by Hurricane Etas recent effects there, resulting in significant to potentially catastrophic impacts. Please refer to statements issued by your national meteorological service for more details on the rainfall and flooding threats. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT1.shtml and Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT1.shtml for more details. Gulf of Mexico Gale Warning: Strong autumn high pressure will build southward across the Gulf of Mexico behind a cold front that extends from near Fort Myers, Florida to the southern Bay of Campeche. The high pressure will create a very tight gradient between it and the front by this evening. This synoptic set-up is forecast to lead to strong northeast winds, with frequent gusts to gale force over the southeastern half of the Gulf waters, including the Straits of Florida and waters adjacent to the Yucatan Channel starting this evening, 18/0000 UTC through Wednesday night. Expect building seas 12 to 16 ft across this area with very hazardous conditions between the wind waves against the flow of the gulf stream through the Straits of Florida, and due to SE swell generated by Iota which will move through the Yucatan Channel. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. Caribbean Gale Warning: The same conditions that will occur in the southeastern half of the Gulf of Mexico will spread into the far NW Caribbean with gusts to gale force possible behind the cold front and N of 20N Wed and Wed night. The cold front will stall from eastern Cuba to the Gulf of Honduras early Thu. Large and hazardous seas are expected in the Gulf of Honduras and approach to the Yucatan Channel today through Wed night as fresh northerly wind waves behind the front mix with swells generated by Iota. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. Atlantic Gale Warning: The pressure gradient which will lead to frequent gusts to gale force over the southeastern Gulf of Mexico and far NW Caribbean Sea will also bring frequent gusts to the western Atlantic off the coast of South Florida and the Bahamas. These gusts will begin by Wednesday evening, 19/0000 UTC through Thu offshore of the Bahamas, and through Thu night from 22N-27N and E of 70W. Expect seas to build 8 to 11 ft, except up to 14 ft across the gulfstream approach to the Straits of Florida where conditions will be very hazardous. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. ...TROPICAL WAVES... The axis of a tropical wave is near 32W from the equator to 14N, moving westward at 10-15 kt. Scattered moderate convection is noted from 07N-09N between 29W-32W. The axis of a tropical wave is near 55W/56W from central Suriname to 18N, moving westward at 10-15 kt. Scattered moderate to isolated strong convection is noted from 07N-13N between 51W-56W. The axis of a tropical wave is near 67W/68W from near the Mona Passage to western Venezuela, moving westward at 5-10 kt. Scattered moderate and isolated strong convection is noted from 11N-14N between 66W-71W, with additional convection inland and across the ABC Islands. ...MONSOON TROUGH/ITCZ The monsoon trough axis extends from the coast of Africa near the border of Guinea and Sierra Leone to 08N18W. The ITCZ axis continues from 08N18W to 06N31W then continues west of a tropical wave near 06N33W to the coast of Brazil near 01N51W. Scattered moderate and isolated strong convection is along the ITCZ from the equator to 06N between 19W-40W, with similar convection from 04N-07N between 40W-53W. GULF OF MEXICO... See Special Feature section above for details on a Gale Warning in effect over the southeastern half of the Gulf of Mexico. Ahead of the cold front mentioned above, overnight scatterometer data showed mainly moderate NE-E flow. SE swell associated with Hurricane Iota, situated well SE-S of the basin, is already spreading through the Yucatan Channel. Conditions should improve across the basin by the end of the week into the weekend. Moderate to fresh E-SE flow will prevail by Sat night as the high pressure area that is building in behind the cold front shifts E-NE to over the Carolinas. Seas will have subsided to 4-7 ft across the basin by Sat night as well. CARIBBEAN SEA... Please see the Special Features section for information on Hurricane Iota and on a Gale Warning in effect over the NW Caribbean N of 20N. Outside the influence of Hurricane Iota, isolated to scattered moderate convection is moving across the northern islands of the Lesser Antilles. Showers are also noted across the rest of the Lesser Antilles. Moderate to locally fresh trade winds are noted in the central and eastern Caribbean. Seas range 3-6 ft outside the influence of Iota. A new area of low pressure could form in a couple of days over the central or southwestern Caribbean Sea. Environmental conditions are forecast to be conducive for some development, and a tropical depression could form by the end of the week while the system moves slowly westward or west-southwestward across the southwestern Caribbean Sea. Otherwise, moderate to locally fresh trades will prevail SE of the front in the NW Caribbean through the end of the week into the weekend. Conditions in the NW Caribbean will greatly improve this weekend as the front washes out. ATLANTIC OCEAN... See the Special Features section for details on a Gale Warning in effect over the SW N Atlantic. SE of the cold front discussed with the Gale Warning, another cold front is noted, this one in the central Atlantic from 32N32W to 28N49W then becomes stationary to 29N56W. No significant convection is associated with this front, with scattered showers possible within 45-75 nm either side of the front. Moderate to fresh NE winds are noted N of the front along with building seas of 8 ft in northerly swell. Two troughs are analyzed in the central Atlantic. The western trough is from 27N59W to 20N66W, and the eastern trough is from 24N33W to 17N40W. Showers are possible within 60 nm of these troughs. Moderate to fresh trades are noted across the waters E of 60W with seas of 5-8 ft in mixed swell. Other than the front and associated Gale Warning in the SW N Atlantic, no other significant features are expected across the basin through the next several days. $$ Lewitsky