000 AXNT20 KNHC 091803 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 203 PM EDT Mon Apr 9 2018 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 1700 UTC. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from Sierra Leone on the coast of west Africa near 08N12W to 05N15W to 02N20W. The ITCZ continues from 02N20W to 03S32W to the coast of Brazil near 01S47W. Scattered moderate and isolated strong convection is present from 01N to 06N between 15W and 18W and within an area bounded by 03S21W to 08S32W to 00N47W to 02N22W to 03S21W. ...DISCUSSION... GULF OF MEXICO... A frontal boundary undulates WSW from N of Tampa Florida near 28N83W to just SE of the Mouth of the Mississippi near 29N89W to 26N92W to the coast of Mexico near 24N98W. The front has shifted northward over the western Gulf and currently possesses no associated deep convection. Warm air overrunning the boundary is producing extensive cloudiness and patchy rain north of the front. Gentle to locally moderate winds generally prevail across the basin. The front will remain over the northern Gulf today. A secondary push of cold air will combine with low pressure along the frontal boundary over the NE Gulf to cause the front to begin heading SE as a cold front tonight through Tue night. The front is forecast to finally exit the SE Gulf by Wed night and begin to dissipate near the Straits of Florida by Thu night. CARIBBEAN SEA... Gentle to moderate trade winds prevail over the basin. A relatively dry weather pattern is currently in place and mid to upper-level ridging extends northwestward over the basin from South America with strong subsidence noted over the eastern Caribbean. Low pres systems moving E from the United states mainland over the western Atlc continue to weaken the ridge to the N of the Caribbean. As a result, trade-wind flow over the basin remains lighter than normal. Consequently, seas are running fairly low across the area. The highest seas of around 5-8 ft are occurring near the coast of Colombia where low pres over S America tightens the pres gradient. Only subtle changes in the weather pattern are expected during the next couple of days as the surface ridge to the north remains relatively weak. Seas will briefly build to around 10 ft near the coast of Colombia early on Tue as the ridge to the N builds slightly and low pres over S America deepens. The weaker pres gradient will become reestablished Wed and Thu. ATLANTIC OCEAN... A cold front enters the discussion area over the W Atlantic near 32N60W, curves SW to 26N69W and 27N75W, then continues as a stationary boundary to Cape Canaveral Florida near 28.5N81W. Cloudiness and patchy rain are generally seen N of the front and W of 71W. However, Scattered showers and isolated thunderstorms are concentrated E of Florida and Georgia between 29N and 31N between 75W and 78W. Elsewhere, a large 1035 mb high centered over the northeast Atlantic SW of the Azores near 35N30W dominates the remainder of the area. Fair weather along with moderate to fresh trade winds will prevail over the tropical Atlantic north of the ITCZ and west of 30W. The western portion of the W Atlantic front is forecast to lift back to the N as a warm front this afternoon or evening and link up with a developing low pressure system just off the South Carolina coast. The low will move E-NE Tue and drag a cold front across Florida. The cold front will then extend from 31N72W to South Florida by Wed morning, and dissipate across the Straits of Florida by Thu night. Both fronts will be preceded by fresh to strong SW winds and building seas. For additional information please visit http://www.hurricanes.gov/marine $$ McElroy