000 AXNT20 KNHC 170955 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 555 AM EDT Mon Apr 17 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 0600 UTC surface analysis and satellite imagery through 0945 UTC. ...SPECIAL FEATURES... Strong high pressure over the SW N Atlantic tightens the gradient behind a cold front extending from 30N40W to 21N47W to 19N58W, thus supporting gale force winds N of 28.5N between 43W and 54W with seas from 22 to 30 ft. Winds are forecast to diminish below gale tonight. Please refer to the high seas forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the E tropical Atlc near 06N11W and continues to 03N16W to 02N24W. The Intertropical Convergence Zone continues from 02N24W to 0N40W to 0N50W. Scattered moderate convection and isolated tstms are from 2S to 4N W of 32W. ...DISCUSSION... ...THE GULF OF MEXICO... Broad surface high pressure anchored by a 1025 mb high over SW N Atlc waters extends a ridge axis SW across the Florida peninsula and Gulf of Mexico. This is supporting gentle to moderate easterly-southeasterly flow across the basin according to latest surface and scatterometer data, except in the E Bay of Campeche where a surface trough supports NE fresh winds. Water vapor imagery show an upper level short-wave trough in the NW basin, which is supporting cloudiness and scattered to isolated showers W of 90W. Cira LPW imagery show shallow moisture in the SE basin being advected from the Caribbean and the SW N Atlc that is supporting cloudiness and possible isolated showers in that region. No major changes are expected through Wed. CARIBBEAN SEA... The pressure gradient between strong high pressure over SW N Atlantic waters and lower pressure over northern Colombia supports fresh to strong winds from 10.5N to 16N between 64W and 79W. Fresh to strong winds funnel across the Windward Passage this morning due to the high pressure N of the area. The area of high pressure is forecast to weaken tonight, thus acting to reduce the winds and seas. Water Vapor and CIRA LPW imagery continue to show very stable conditions over the NW Caribbean while SW winds aloft advects moisture from South America and the EPAC to the eastern basin. All this moisture is supporting showers E of 76W, including southern Puerto Rico, the Virgin Islands and Hispaniola. Shower activity for this region and Hispaniola is expected to continue through Tuesday. An upper level trough across Central America along with abundant low level moisture in the SW Caribbean support scattered heavy showers and isolated tstms over Costa Rica and Nicaragua adjacent waters W of 80W. Model guidance indicate that convection in this region will prevail through tonight. ...HISPANIOLA... Trailing moisture associated with the passage of a former cold front N of the Island and tropical Atlc moisture moving across the Caribbean support cloudiness across the Island as well as isolated showers. Model guidance indicate the continuation of these showers through Tue. ATLANTIC OCEAN... A cold front extends from a 987 mb center of low pressure N of the area near 33N46W and continues to 30N38W to 20N43W to 18N59W. A tight pressure gradient between high pressure in the SW N Atlc and the cold front supports gale force winds N of 28.5N. See the special features section for further details. Low pressure and a relaxed pressure gradient is in the E Atlc along with fair weather being supported by low to middle level dry air. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos