000 AXNT20 KNHC 291800 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 100 PM EST Fri Dec 29 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 1745 UTC. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 05N09W to 05N16W to 04N20W. The Intertropical Convergence Zone axis extends from 04N20W to 04N30W to 01N40W to 04N50W. Scattered moderate convection is from 01N-08N between 30W-48W. ...DISCUSSION... GULF OF MEXICO... Zonal westerly flow aloft prevails over the northern half Gulf where strong high pressure starts to build. Just south of the ridge, a stationary front extends from 26N81W to 27N86W to 26N90W to a 1023 mb low near 25N95W. The stationary front continues S-SW from the low to near Veracruz, Mexico. A tighter pressure gradient between the ridge and the frontal boundary support fresh to locally strong NE winds in the NW basin, extending to near 87W. Light to moderate northerlies are elsewhere N of the front. GOES-16 water imagery show very dry air in the middle and lower levels, which is allowing only for isolated showers within 60 nm either side of the front. Across the northern Gulf, upper level tropical moisture from the EPAC supports broken to overcast clouds. The front will weaken and is forecast to dissipate by Saturday morning leaving a remnant surface trough in the SW Gulf. Otherwise, surface ridging will influence the eastern Gulf and Florida peninsula through Sunday night. Thereafter, the next strong cold front is expected to emerge off the Texas and Louisiana coasts Sunday evening. CARIBBEAN SEA... Middle to upper level ridging persists over the Caribbean basin with water vapor imagery indicating mostly dry and stable conditions aloft. Moderate to fresh trades dominate the Caribbean waters, however strong high pressure building over the Gulf of Mexico will increase slightly the pressure gradient in the SW basin, leading to fresh to strong winds in that region starting Saturday morning and continuing through Sunday. Otherwise, patches of shallow moisture continue to move across Hispaniola and Puerto Rico supporting isolated to scattered showers. Similar shower activity is occurring over the Gulf of Honduras and off the Yucatan Peninsula and Belize associated with a surface trough in that region. Low pressure off the coast of Colombia and west of Colombia over Pacific waters support scattered showers S of 15N W of 68W. This convection is expected to continue moving westward across interior portions of Central America. Little change is expected during through Tuesday. ...HISPANIOLA... Mostly dry and stable conditions are aloft, however, patches of shallow moisture embedded in the trade wind flow continue to support scattered to isolated showers over the Dominican Republic. Similar weather is forecast to persist through Saturday as low level moisture continue to advect from the east. ATLANTIC OCEAN... A broad middle to upper level trough covering the eastern CONUS and the NW Atlc waters supports a 1018 mb low over the SW N Atlc waters near 29N77W. A cold front extends from the low SW to the SE tip of Florida with isolated showers affecting the northern Bahamas. A warm front extends E-SE of the low to 30N73W to 28N68W where it transitions to a stationary front that continues to 27N60W. A cold front continues from that last point location to 30N51W. Scattered showers are N of the low between the low center and 67W. Otherwise, isolated showers are within 75 nm either side of the frontal boundary. Two pre-frontal trough are generating scattered to isolated showers S of 26N between 52W and 77W. Otherwise, the remainder of central and eastern Atlc is under the influence of a surface ridge anchored by a 1030 mb high centered SE of the Azores near 34N16W. A middle level low noted between 30W and 40W and diffluent flow east of this feature support scattered showers N of 14N E of 35W. The cold front will move across the SW N Atlc waters through Sunday. A new cold front will enter this region on Monday evening. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos