000 AXNT20 KNHC 220102 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 902 PM EDT Sat Oct 21 2017 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 1800 UTC surface analysis and satellite imagery through 2315 UTC. ...SPECIAL FEATURES... A cold front will be over the W Gulf of Mexico Monday evening from 30N86W to 25N88W to 22N91W. Gale force winds will be S of 20N W of 95W with NW winds 30-35 kt, and seas 8-12 ft. ...TROPICAL WAVES... A tropical wave is in the central Atlantic with axis extending from 21N48W to 10N50W, moving W at 20 kt. The wave is embedded in moderate moisture as seen on SSMI Imagery. There are distinct surface and 700 mb troughs. Scattered showers are within 120 nm of the wave axis S of 15N. A tropical wave is in the western Caribbean with axis extending from 21N81W to 09N81W, moving W at 15 kt. The wave is embedded in abundant moisture as seen on SSMI Imagery. There is a well defined surface trough, and a broad 700 mb trough. Clusters of scattered moderate to isolated strong convection is from 13N-21N between 77W-88W. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 08N13W to 07N20W. The Intertropical Convergence Zone axis extends from 07N20W to 07N40W to 09N61W. Scattered moderate convection is from 07N-11N between 34W-41W. ...DISCUSSION... GULF OF MEXICO... A 1028 mb high is centered off the coast of New Jersey near 39N74W producing surface ridging over the N Gulf of Mexico. Widely scattered moderate convection is over the Yucatan Peninsula, the Yucatan Channel, W Cuba, and the Straits of Florida, all moving N from the Caribbean Sea. In addition, radar imagery shows scattered showers are over the E Gulf and Florida. In the upper levels, an upper level trough is over Texas and the W Gulf with axis along 100W. Upper level diffluence E of the axis is enhancing the showers over the E Gulf of Mexico. An upper level ridge is over the E Gulf with axis along 79W. Abundant upper level moisture is over the E Gulf. Expect a cold front to enter the NW Gulf Sunday night, and a tropical wave to move across the SE Gulf waters Sunday night. Gale force winds are forecast to develop behind the cold front Monday. CARIBBEAN SEA... A tropical wave is over the W Caribbean. See above. In addition, the eastern extent of the E Pacific monsoon trough is over Costa Rica and Panama producing scattered moderate to isolated strong convection S of 11N. In the upper levels, a large upper level high is centered over the NW Caribbean near 17N80W with abundant upper level moisture. Scattered moderate convection is over most of Cuba. Further E, very strong subsidence is over the E Caribbean E of 72W, to include Puerto Rico and the Virgin Islands. The Saharan Airmass Layer Imagery also shows a plume of dry air and dust over the E Caribbean E of 67W decreasing air quality and reducing visibility. Expect the tropical wave to move W with convection. Also expect continued fair weather over Puerto Rico and the Leeward Islands for the next 24 hours. ...HISPANIOLA... Presently fair weather is over Hispaniola. Expect within the next 24 hours for the plume of dry air and dust to advect over the island. ATLANTIC OCEAN... A dissipating stationary front is over the W Atlantic from 31N54W to 24N67W. Scattered showers are within 120 nm of the front. A 1032 mb high is centered over the E Atlantic near 40N18W producing surface ridging to the E Atlantic. Of note in the upper levels, an upper level low is over the W Atlantic near 29N66W. Upper level diffluence E of the low enhancing the showers over the W Atlantic front. Another upper level low is centered over the central Atlantic near 23N43W producing scattered showers within 600 nm E of the center due to upper level diffluence. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa