000 AXNT20 KNHC 272322 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Thu Oct 28 2021 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Gulf of Mexico Gale Warning: Strong to gale force winds will follow a strong cold front that as of 21Z extends from southwestern Louisiana to 26N95W and to inland northeastern Mexico. The front will quickly move across the basin through Thu night. A Gale Warning is in effect for post-frontal gale-force winds of 30-40 kt for the north-central and NE Gulf waters beginning late tonight into early Thu and continuing through Fri morning. Prior to that time, strong to near- gale force northwest winds will follow in behind the front along with seas to 9 ft. Seas will build to near 20 ft in the wake of the front over the northern Gulf. Mariners are urged to exercise caution as a rather robust squall line denoted by scattered moderate to strong convection is racing out ahead of the front. This activity is occurring north of 27N between 90W- 92W and from 26N to 27N between 92W-94W. Some of this activity may be reaching severe limits. It is capable of producing strong gusty winds, heavy rain and reduced visibility. Please, see the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for further details. ...TROPICAL WAVES... The axis of an eastern Atlantic tropical wave extends from 20N31W to 14N34W and to 04N33W. It is moving westward at about 10-15 kt. Isolated showers and thunderstorms are east of the wave to 30W from 10N to 13N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends off the southern coast of Senegal near 14N17W to 08N30W and to 06N40W. The ITCZ axis extends from 07N40W to 07N50W and to the northeast Venezuelan coast near 08N59W. Scattered moderate convection is within 300 nm south of the trough between 20W-29W, within 120 nm north of the trough between 20W-25W and within 120 nm south of the trough between 36W-38W. GULF OF MEXICO... A Gale Warning related to a western Gulf cold front is presently in effect for the north-central and NE Gulf areas. Please see the Special Features section for more information on this marine event. As stated earlier, as of 2100 UTC a strong cold front extends from southwestern Louisiana to 26N95W and to inland northeastern Mexico. A potent squall line extends from south-central Louisiana to 28N93W and to 26N95W. Both buoy and oil platform observations reveal that fresh to strong southerly winds are present over the NW Gulf as well as over the western part of the central Gulf. A recent observation from ship with caller ID "KAWM" near 27N91W indicates 30 kt winds. Strong wind gusts, heavy rain and reduced visibility can be expected as the squall line races eastward across the northern Gulf waters through late Thu. Oil platform station "KGHB" located near 28N92W recently reported northwest 35 kt winds as convection with the squall line passed over it. Elsewhere, a warm front extends from southeastern Louisiana to 27N86W, where it transitions to a stationary front to Fort Myers, Florida. Aside from convection with the aforementioned squall line, isolated showers are near the stationary front between 84W- 86W and east of the warm front to 88W north of 29N. The remainder of the Gulf is under fairly tranquil weather conditions. Outside of the winds being influenced by the strong cold front and squall line over the NW Gulf, light to gentle southerly winds are east of 86W, while moderate to fresh southerly winds are west of 86W. Seas of 3-6 ft are west of 90W and 1-3 ft are east of 90W. For the forecast, the previously mentioned strong cold front will quickly move across the rest of the basin through Thu night preceded by a squall line that is accompanied by scattered strong to possibly severe scattered showers and thunderstorms. Fresh to strong S winds will continue ahead of the front, with strong to gale force winds expected over the north-central and NE Gulf from starting late tonight into Thu and continuing through early Fri. CARIBBEAN SEA... The interaction of a weak surface trough in the central Caribbean Sea and a weak 1010 mb low pressure along the eastern segment of the eastern Pacific monsoon trough is resulting in an area of showers and isolated thunderstorms from the northwestern coast of Colombia to 12N and between 76W and 81W. The rest of the basin is under the influence of a dry air mass as inferred from the subsidence as depicted in water vapor imagery. This is allowing for fairly tranquil weather conditions to exist. Latest ASCAT data indicates mainly fresh trades south of 15N and east of 78W. Fresh trades are also over a portion of the Gulf of Honduras per latest ASCAT data, while gentle to moderate trades are present elsewhere over the basin. Seas are generally in the 2-4 ft range, except for slighter higher seas of 4-6 ft north of 15N and east of 80W. For the forecast, a weak ridge over the northern Caribbean Sea will support mainly fresh trades across the south-central Caribbean, including the Gulf of Venezuela through early Thu. Gentle to moderate southeast to south winds will continue over the northwestern Caribbean through Thu night ahead of a cold front that is forecast to reach western Cuba and the northwestern Caribbean. The front will extend from western Cuba to the Gulf of Honduras by midday Fri, and from central Cuba to the northeastern part of Honduras on Sat, then stall on Sun from eastern Cuba to near Cabo Gracias a Dios, Nicaragua while dissipating. ATLANTIC OCEAN... A cold front extends from the strong extratropical cyclone located off New England to near 31N65W and southwestward to 27N72W, where it becomes a stationary front to across the northwestern Bahamas and to South Florida. A pre-frontal trough extends from near 31N62W to just north of the southeastern Bahamas. Scattered moderate to isolated strong convection is within 120 nm east of the trough north of 27N, while scattered moderate convection is within 30 nm of the cold front. Isolated showers and thunderstorms are along the stationary front. Afternoon ASCAT data passes reveal fresh to strong cyclonic winds north of 25N and between 57W and 75W. Seas of 7-10 ft due to a northwest to north swell mixed with a southeast to south swell are occurring N of 27N and between 57W-77W. Farther east, a weak trough is analyzed from 31N43W to 24N47W.s are found in the central Atlantic, but no significant convection is associated with this feature. The central and eastern tropical Atlantic are dominated by broad high pressure anchored by two 1021 mb high pressure centers: one between the Azores and Madeira Islands and the other one near 31N32W. This area of broad high pressure is supporting fairly tranquil weather over this part of the area. The associated gradient between the high pressure and lower pressures to the south is allowing for moderate to locally fresh trades to exist south of about 16N and east of about 60W. Seas in the range of 4-7 ft are elsewhere over the basin. The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. High volcanic ash concentration is in the vicinity of the volcano. Light volcanic ash concentration is elsewhere. Volcanic ash is drifting southwestward. Marine and aviation interests should monitor this ongoing situation by reading the Volcanic Ash Advisory issued by Meteo- France, at http://vaac.meteo.fr/volcanoes/la- palma/. For the forecast west of 65W, the cold front will stall tonight. The entire frontal boundary will gradually dissipating into Thu North of 25N and east of 75W, fresh to strong west winds follow this boundary, along with seas of 8-10 ft. The next cold front from will move across the northwestern forecast waters Thu night through Fri night, then stall from near 31N68W to eastern Cuba and over the weekend. Fresh to strong winds and building seas are expected on either side of this front. $$ Aguirre