000 AXNT20 KNHC 121756 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1256 PM EST Mon Feb 12 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 1730 UTC. ...SPECIAL FEATURES... Caribbean Sea Gale Warning: A tight surface pressure gradient between the strong surface ridge over the north Atlantic Ocean and lower pressure over northwestern South America will continue to support gale-force winds off the coast of Colombia. These conditions are expected continue through late this week. Please read the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...MONSOON TROUGH/ITCZ... The Monsoon Trough axis enters the Atlantic through the coast of Liberia, Africa near 05N09W and continues to 01N18W where latest scatterometer data indicates the ITCZ begins and dips below the Equator at 20W. It resumes southwestward to the coast of Brazil near 05S36W. Scattered moderate convection is within 150 nm S of the axis between 09W-14W, and within 90 nm S of the axis between 14W-18W. ...DISCUSSION... GULF OF MEXICO... As of 21Z, a cold front extends from near the Destin/Santa Rosa area southwestward to 27N91W to 22N95W to inland the coast Mexico just S of Veracruz. A pre-frontal trough is along a position from 27N90W to 23N96W to inland the coast of Mexico near Coatzacoalcos. Another trough is ahead of the front along a position from 29N84W to 27N88W. A 1027 mb high center is analyzed over eastern Mexico near Ciudad Mante. Associated strong ridging is surging southward across eastern Mexico and over the NW Gulf behind the cold front. The pressure gradient between the ridge and the front is producing fresh to near gale-force northerly winds over the western gulf waters. The minimal gale force winds that were earlier observed near the coast of Tampico diminished to strong winds as of 15Z. Moist southerly winds advecting northward over the gulf from the Caribbean in combination with a mid to upper shortwave trough sliding eastward across the western Florida panhandle and far NE Gulf continues to result in scattered moderate isolated strong convection over the northern gulf waters along and to the E of both the cold front and trough, roughly N of about 26N and between 84W-86W. Latest satellite lightning data reveals frequent strikes primarily in the southern and central sections of this area of convection. This activity may be attended by strong gusty winds as quickly moves eastward. Elsewhere, isolated showers are along and within 90 nm E of the pre-frontal trough. The scattered moderate isolated strong convective activity is forecast to move E of the Gulf of Mexico late tonight as the mid/upper trough slides to E of NE Florida. Strong high pressure over the north Atlc continue to extends SW across the eastern half of the Gulf allowing for light to moderate E to SE winds ahead of the front. Fresh easterly winds are over the Straits of Florida. The cold front is forecast to become stationary this afternoon from northern Florida to the central Bay of Campeche while it weakens. The frontal remnants are expected to lift back N as a warm front on Tue. The fresh to near gale-force winds over the western waters will significantly diminish tonight and through Tue. Seas associated with these winds subside tonight into Tue as a ridge develops over the southeastern United States. This pattern will support fresh east winds by mid week. CARIBBEAN SEA... Please refer to the SPECIAL FEATURES section above for details about the gale-force winds expected near the coast of Colombia. The GOES-16 low to mid-level water vapor imagery continues to suggest generally dry and stable atmospheric conditions continue across the basin. Latest GOES-16 visible imagery depicts patches of shallow moisture, in the form of broken to scattered low clouds, advecting westward over much of the basin, including portions of Hispaniola. Brief passing isolated showers are with these clouds. A strong ridge N of the area anchored by a 1038 mb high center over the N central Atlantic extends southward across the northern half of the Caribbean, with the associated pressure gradient supporting the continuation of fresh to strong trade winds across the eastern and central basin as indicated by latest scatterometer data. Seas are in the range of 12 to 18 ft near the Colombia coast and 8 to 12 ft elsewhere. Fresh to near gale-force are also occurring through the Atlc passages and will continue through mid week. Otherwise, little change is expected through mid-week. ATLANTIC OCEAN... Broad surface high pressure over the area is associated with a 1038 mb high center over the N central Atlantic at 35N48W moving to the SW. The ridge is supporting fresh to strong E-NE winds over most of the basin, except over NW forecast waters N of 24N where E-SE winds are mainly moderate. An area of scattered showers and isolated thunderstorms is noted over the tropical Atlantic waters from 14N to 21N and between 45W and 60W in association with broad mid to upper troughing that stretches from a cyclonic circulation just SW of the Canary Islands to 23N40W to 21N52W and as a shear axis from there to the northern Caribbean Sea. The scattered shower and thunderstorm activity should move across the Leeward Islands tonight through Tue night. A cold front is forecast to move off the northeast Florida coast by Tue morning. Scattered showers and thunderstorms are expected to form out ahead of the front and impact the NW waters tonight into Tue as a mid/upper level trough translates eastward from the NE Gulf to NE Florida and the far NW waters. The front then will stall before dissipating Thu morning. The next cold front is forecast to enter the NW forecast waters by early Saturday morning. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre