000 AXNT20 KNHC 240005 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 804 PM EDT Sun Apr 23 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 2345 UTC. ...SPECIAL FEATURES... The pressure gradient between a center of low pressure in the SE CONUS merging with a 1007 mb center of low pressure moving across southern Florida, and a surface ridge moving to central Atlc waters will support the development of gale force winds in the SW N Atlc starting near 1200 UTC Monday. Gale conditions will cease on Tuesday morning as both the low and the high move N of the area. Seas in this region during this period will range between 8 to 12 ft. Please see the latest High Seas Forecast product under the WMO header FZNT02 KNHC and under the AWIPS header MIAHSFAT2 for further details. A cold front associated with the center of low pressure in the SE CONUS extends from the Florida Panhandle SW to near Tampico, Mexico. Strong high pressure behind this front anchored by a 1022 mb high over NE Mexico tightens the gradient over the W Gulf to support gale force winds N of the front to 25N W of 96W. Latest scatterometer data confirms the gale winds. Gale winds are forecast to diminish tonight as the center of high pressure dissipates, thus relaxing the pressure gradient in the region. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across the western Africa coast from 07N12W to 03N20W to 02N26W. The Intertropical Convergence Zone continues from 02N26W to 01N34W to the coast of Brazil near 02S43W. Scattered moderate convection and isolated tstms are from 05S to 07N between 12W and 40W. ...DISCUSSION... GULF OF MEXICO... A middle to upper level low over W Tennessee with associated trough extends S across the Gulf to a base over the NW Caribbean. The same supports a surface 1007 mb low N of Georgia from which a cold front extends S across the Florida Panhandle to the central Gulf near 25N90W to near Tampico, Mexico. There is not deep convection associated with the front due to very dry conditions at the surface and aloft as indicated by water vapor and CIRA LPW imagery. Gale force winds are behind the front W of 96W. See the special features section for further details. A surface low pressure is ahead of the front, over S Florida, however the convection associated with it has moved out of the Gulf already. Besides the area of gale winds, N moderate to fresh winds dominate W of the cold front while light to moderate winds are ahead of it. The front is forecast to move out of the basin early Tuesday morning. CARIBBEAN SEA... A middle level diffluent environment across the central Caribbean along with abundant low level moisture across most of the basin continue to support scattered heavy showers across Hispaniola and adjacent waters. Scattered to isolated showers extends W across the Windward Passage and E Cuba and E over the Mona Passage. A short-wave upper trough over central America along a middle diffluent environment in that region favor scattered showers within 120 nm off the coast of Nicaragua, Costa Rica and N Panama. Dry air aloft across the remainder basin support fair weather. Except for S of Hispaniola where fresh trade winds are present, light to moderate winds dominate elsewhere. Showers across the north-central Caribbean will continue through Tuesday, extending to Puerto Rico Monday and Tuesday. Otherwise, the tail of a cold front is forecast to move across the NW Caribbean waters Monday through Tuesday. ...HISPANIOLA... Abundant low level moisture across the northern Caribbean and a middle level diffluent wind environment support showers across Hispaniola and adjacent waters, including the Windward and the Mona Passage. Heavy showers will continue over tonight through Tuesday morning. ATLANTIC OCEAN... Except for the tail of a dissipating cold front over the north- central Atlc extending from 30N35W to 26N39W with isolated showers extending E to 27W, the remainder basin N of 16N is being dominated by surface ridging. W of the dissipating front, the ridge is anchored by a 1020 mb high near 28N63W, which is moving N of 30N over the next 24 hours. The E ridge is centered by a 1020 mb high near 30N19W, which is forecast to dissipate by Monday afternoon. Otherwise, a cold front is expected to enter the SW Atlc Monday night and gale force winds will develop between the front and the ridge to the east. See special features for further details of the gale. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos