000 AXNT20 KNHC 041206 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 706 AM EST Sun Mar 4 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 0600 UTC surface analysis and satellite imagery through 1100 UTC. ...SPECIAL FEATURES... Atlantic Gale Warning: Cold front extends from near 32N48W to 22N60W to the eastern Dominican Republic near 19N70W. A very tight pressure gradient between the front and intense low pressure well north of the discussion area continues to maintain W to NW 30 to 40 kt winds north of 26N and west of the front to 72W along with large seas in the 18 to 31 ft range. Gale-force SW to W winds are also N of 29N within 90 nm east of the front with accompanying seas in the 17 to 20 ft range. The cold front will be weakening as it reaches a position from near 32N44W to 25N51W to near 18N60W tonight. A second round of even more vigorous gales between 35 kt and 45 kt with seas of 18 to 32 ft can be expected Mon night and Tue morning N of 27N between 52W and 67W as tight low pressure develops within a trough rotates around the south side of the parent low over the Western Atlantic. Gale conditions will persist through Mon while shifting eastward to the central Atlantic. Please refer to the Atlantic High Seas Forecast under the AWIPS header MIAHSFAT2 and under the WMO header FZNT02 KNHC for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends through the coastal sections of Sierra Leone near 09N13W to 04N17W to 02N21W. The ITCZ continues from 02N21W to 00N30W then along the Equator to the coast of Brazil near 00N46W to end near 01S51W. There is no significant convection currently associated with these features. ...DISCUSSION... GULF OF MEXICO... A strong and elongated ridge extends from the Ohio Valley over the central Gulf to the Yucatan Peninsula and adjacent waters. The ridge provides moderate NE to E winds over the eastern half of the basin and E to SE moderate flow across the western Gulf. GOES-16 animated water vapor imagery shows strong upper-level ridging over the Gulf. Very dry air present in the lower and middle levels is supporting mainly clear skies. The surface ridge will slide eastward through Monday night, thus allowing for the next cold front to move into the NW Gulf early Tuesday morning. A secondary surge of cold air will push the front and across the rest of basin by Thu morning. CARIBBEAN SEA... The tail of a cold front associated with the intense low pressure system over the NW Atlc extends across Hispaniola and the Windward Passage to end just SW of the Yucatan Channel near 20N85W. No significant convection accompanies this weakening boundary. Aside from shallow moisture associated with the front, deep layer dry air is over most of the basin, which supports mostly clear skies and fair weather conditions. The exception is the SE Caribbean where a small area of convergent low-level flow is supporting the continuation of cloudiness as well as scattered to isolated showers over the southern Windward Island and NE Venezuela. Large NE swell will impact the tropical Atlantic Ocean waters through mid week as the low pressure system lingers over NW Atlc waters and secondary low pres develops on the S side of the system. This will produce a large N to NE swell, that will penetrate the NE Caribbean Sea Passages today into next week reaching the A-B-C Islands and coast of Venezuela. Otherwise, the low pressure center will drag the cold front into the northeast Caribbean tonight while it gradually dissipates through early next week. ATLANTIC OCEAN... Please read the SPECIAL FEATURES section for more details about the ongoing gale event over the western and central Atlantic. A cold front associated with an intense low pressure system over the NW Atlc, enters the area of discussion near 32N48W and continues SW to 22N60W to NE Hispaniola. Aside from scattered showers and isolated thunderstorms along and up to 120 nm ahead of the front N of 26N, strong to gale force winds continue to persist behind this front. These conditions are forecast to continue through Tuesday as the front moves E towards the central Atlantic. The largest swell event thus far this winter is already in progress and will accompany this system as it progresses, affecting all waters E of Florida and the Bahamas through early next week. Another strong cold front is forecast to impact the waters E of Florida Wednesday. Gales will be possible along the front N of 30N as it emerges from the Georgia and Florida coasts. Over the eastern Atlantic Ocean, a cold front stretches from the coast of NW Africa near 22N17W to 20N21W where it continues as a nearly stationary front to 19N40W. No significant convection is present near the front. For additional information please visit http://www.hurricanes.gov/marine $$ McElroy