000 AXNT20 KNHC 012147 CCA TWDAT Tropical Weather Discussion...Corrected NWS National Hurricane Center Miami FL 105 PM EST Thu Mar 01 2018 Corrected Special Features Section 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. ...SPECIAL FEATURES... Atlantic Gale Warning: A strong cold front associated with a large and intense low pressure system that will reach the Mid- Atlantic coast this afternoon before it tracks southeastward over the waters north of the area through Fri night and begins to drift eastward on Sat will move across the northwestern waters of the discussion area Fri through Sat, followed by minimal gale force W to NW winds on Fri night north of about 29N between 65W-70W and north of about 26N between 45W-75W on Sat. These winds will be accompanied by large seas. Far E Atlantic Gale Warning: A tight pressure gradient existing between deep low pressure inland over far northern Portugal and higher pressure to its S and SW, and with the added feature of a surface trough that stretches from along the coast of the southwest portion of Western Sahara to near 20N22W is inducing gale force winds north of 29N and to the east of 24W. Ascat data from last night confirmed these winds. The OUTLOOK, for the 24 hours that follow the forecast that is valid until 02/1200 UTC, consists of: the persistence of a westerly near gale or gale in: IRVING, MADEIRA, and AGADIR. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends through the coastal sections of Liberia near 06N10W to 01N12W. The ITCZ continues from 01N12W, crossing the Equator along 13W, to 04S24W, to 03S36W. Scattered moderate isolated strong convection is within 120 nm S of the ITCZ axis between 27W-32W. Scattered moderate convection is within 90 nm S of the ITCZ axis between 34W-36W. ...DISCUSSION... GULF OF MEXICO... The cold front, that was over far eastern Texas this morning has moved off the coast to over the NW Gulf, and is along a position from just NE of Galveston to 27N96W and to just east of Brownsville and inland NE Mexico. A pre-frontal trough is analyzed from 28.5N95W to 26N96.5W. Isolated showers are along the trough, and mainly along the southern part of the front. Strong northerly winds will follow the front along the coast of Mexico until Fri evening. The front will stall from western Cuba to near Veracruz Mexico Fri night, then dissipate Sat. A ridge will build across the northern waters in the wake of the front. Otherwise, weak ridging across the central gulf is supporting light to gentle winds over the eastern Gulf with 2 to 4 ft seas, and moderate to fresh southerly flow over the western Gulf with 4 to 6 ft seas. The fresh southerly flow will diminish through this afternoon as the front progresses across the north-central and NW gulf waters. The ridge over the central waters will shift east-southeastward through this evening. CARIBBEAN SEA... Buoy and scatterometer satellite data indicate moderate trade winds across the region currently. This is due to weakening high pressure north of the area, with the exception of the waters near and along the coast of Colombia, where stronger trades of fresh intensity are highlighted in the latest available Ascat pass. Similar winds, NE-E in direction, are noted in the same Ascat pass to be along and within 60 nm south of the coast of Hispaniola. Divergence aloft related to an upper level trough that is positioned from the northern Leeward Islands to 12.5W74W and to just south of Panama is supporting a few trade wind showers from the Leeward Islands to the ABC Islands. Moderate to strong subsidence along the trough axis and to the west of the trough is maintaining fairly dry conditions over the remainder of the area, except for the water north of 15N between 66W-76W and to the south of 17N between 78W-83W where patches of scattered to broken moving westward with isolated showers are noted. A weak inverted trough in the easterlies, resembling a tropical wave, is approaching the Windward Islands and southern Leeward Islands are seen in satellite imagery. The 1354 UTC Ascat pass nicely captured the NE-SE wind shift across the trough axis. These winds are of the gentle to moderate range. This feature will bring scattered showers and possible isolated thunderstorms to those islands through possible early Fri afternoon. Scattered showers are already ahead of the trough over the far southeastern portion of the Caribbean. This activity will gradually spread westward through Fri. High pressure north of the area will support moderate to locally fresh trade winds across the basin, with strong winds pulsing at night off Colombia through Sat. Large NE swell will impact the tropical Atlantic waters through Sat, with an even more significant N swell event will propagate through NE Caribbean Passages beginning on Sun. ATLANTIC OCEAN... West of 60W, light to gentle winds persist across the region associated with weak ridging along 29N. A trough, the western extension extension of a central Atlantic stationary front, extends from 23N60W to 25N70W and to 25N75W. Multiple cyclonic swirls of broken to overcast low and mid-level clouds with isolated showers are observed within 150 nm north of the trough. Otherwise, no significant shower or thunderstorm activity is noted. The weak ridge along 29N will shift eastward ahead of a cold front that will move off the NE Florida coast late this afternoon or evening. The front will reach from Bermuda to SE Florida Fri afternoon, just ahead of a reinforcing front which will generate strong to gale force winds north of 27N east of 75W as a large and intense low pressure system begins to move off the Virginia coast this afternoon. The fronts will merge Sat and stall from 22N65W to the Windward Passage by Sun before dissipating Mon. A significant swell event and likely the largest of this winter season will accompany this system, affecting all waters E of Florida and the Bahamas by the end of this week. East of 60W, a cold front is analyzed from near 32N26W to 25N43W to 23N50W, where it transitions to a stationary front to 60W. Fresh northerly winds are noted north of the front. But the main weather impact continues to be large northerly swell dominating the entire region to the east of 60W. Altimeter data from early this morning and this afternoon revealed seas in the range of 10- 14 ft between 35W and 60W, and in excess of 20 ft east of 35W, mainly in the area of gales mentioned in the Special Features section. The swell will subside to 8 ft or less through Sun, just ahead of another significant swell event originating out of the north central Atlantic. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre