000 AXNT20 KNHC 201640 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1140 AM EST Wed Dec 20 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 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...ITCZ/MONSOON TROUGH... The monsoon trough enters the Atlantic Ocean from 08N13W to 03N23W. The ITCZ extends from 03N23W to northeast Brazil near 01N50W. Scattered moderate convection is present from 00N-05N between 22W-35W. ...DISCUSSION... ...GULF OF MEXICO... A cold front extends from the central Louisiana coast southwestward to the US-Mexico border and is producing scattered moderate convection. This front is expected to stall this afternoon and retreat toward the northeast Gulf coast while weakening tonight. Elsewhere, surface ridging associated with a 1022 mb high east of the Florida peninsula near 27N73W dominates the basin and gentle to moderate anticyclonic flow is present throughout the remainder of the Gulf. These winds will relax to light to gentle on Friday. Another cold front will reach the northwest Gulf late Friday or early Saturday, and move over the western Gulf on Saturday. Fresh southerly return flow is expected across the western Gulf ahead of the front. Fresh to strong northerly winds and building seas will follow the front this weekend. ...CARIBBEAN SEA... Broad upper-level anticyclonic flow and upper- to mid-level dry air are acting to suppress deep convection, and only low-topped showers are present throughout the Caribbean. Scatterometer data indicates that strong to near gale winds are present over the southwest Caribbean from 10N-13N between 73W-78W. Moderate to fresh easterly flow is present over the eastern and northwestern portions of the basin, east of 68W, and north of 16N, west of 81W. Fresh to strong east-northeasterly flow is present through the remainder of the basin. Little change is expected in the upper- to mid-level pattern through Friday and these conditions will persist through that time. ...HISPANIOLA... As previously discussed, broad mid to upper-level anticyclonic wind flow and dry upper- to mid-level air dominate the entire Caribbean Sea supporting mostly stable conditions. However, low- topped trade wind showers will continue to affect the island from time to time for the next couple of days. ...ATLANTIC OCEAN... A mid-to upper-layer trough associated with a dissipating stationary front extending from 32N37W to 28N43W is supporting isolated moderate convection from 24N-32N between 36W-47W. A cold front follows, from 32N56W to 28N66W, and is associated with only scattered low-topped showers. The cold front will continue moving eastward today and early tomorrow before dissipating within the next 36 hr. East of the two fronts, the subtropical high dominates the northern east Atlantic. An upper-level trough is supporting scattered weak convection in an area bounded from 10N- 17N between 18W-30W. To the west, a 1022 mb surface high centered near 27N73W is the prominent feature over the western Atlantic. An eastward moving cold front associated with a surface low will emerge from the southeast U.S. coast by tomorrow morning and spread through the northwest portion of the basin for the next several days. For additional information please visit http://www.hurricanes.gov/marine $$ ZELINSKY