000 AXNT20 KNHC 171729 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1229 PM EST Sat Feb 17 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 1700 UTC. ...SPECIAL FEATURES... Caribbean Sea Gale Warning: A tight surface pressure gradient, that exists between surface high pressure in the western Atlantic Ocean, and lower surface pressure in northern sections of South America, should continue to support winds pulsing to minimal gale-force near the coast of Colombia through Sunday. The resultant wave heights with the gale-force winds are forecast to range from 10 feet to 15 feet. Please read the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the southern coastal sections of Liberia near 05N08W, to the Equator along 18W. The ITCZ continues from the Equator along 18W, to 02S28W, to 04S33W, and to the coast of Brazil near 04S38W. Precipitation: scattered to numerous strong rainshowers are from 04N southward between the Prime Meridian and 01W. widely scattered moderate to isolated strong from 01N to 03N between 08W and 11W. isolated moderate to locally strong rainshowers are elsewhere from 10N southward. Upper level SW wind flow is to the SE of the line that passes through 24N16W 21N40W, to 16N50W and to 14N63W in the Caribbean Sea. ...DISCUSSION... GULF OF MEXICO... A surface ridge extends from an Atlantic Ocean 1026 mb high pressure center that is near 27N66W, to central Florida, to 26N90W in the Gulf of Mexico, to 21N98W in interior sections of Mexico. A ridge will dominate the Gulf region this weekend producing mainly gentle-to-moderate winds in the western Gulf, and light- to-gentle winds in the eastern Gulf, with the exception of moderate winds in the SE waters and the Straits of Florida. Expect increasing winds and building seas by early next week as high pressure strengthens in the western Atlantic Ocean. A thermal trough will develop in the western Yucatan Peninsula during each afternoon. The trough will drift westward across the eastern Bay of Campeche during the overnight hours, and then dissipate in the southwest Gulf waters by late each morning. CARIBBEAN SEA... Please read the SPECIAL FEATURES section for details regarding the Gale Warning near the coast of Colombia. Rainshowers are possible, in areas of broken-to-overcast low level clouds, across the entire area. 24-hour rainfall totals that are listed for the period that ended at 17/1200 UTC...according to the PAN AMERICAN TEMPERATURE AND PRECIPITATION TABLES... MIATPTPAN/SXCA01 KNHC...are: 0.39 in St. Thomas in the U.S. Virgin Islands, 0.18 in San Juan in Puerto Rico, 0.07 in Montego Bay in Jamaica, and 0.03 in Guadeloupe. A tight pressure gradient between a high pressure system that is in the western Atlantic Ocean, and lower pressure in northern sections of South America, will continue to support pulsing winds of minimal gale-force near the coast of Colombia through the forecast period. Fresh to locally strong trade winds are expected elsewhere across the Caribbean Sea. The high pressure will be reinforced by a stronger system on Monday. The stronger system will bring increasing winds and building seas across the eastern and central Caribbean Sea, and the Tropical N Atlantic waters from Monday through Wednesday. ATLANTIC OCEAN... An upper level trough extends from a 25N45W cyclonic circulation center, to 17N50W, to 13N61W in the SE Caribbean Sea. One surface trough is along 31N31W 29N38W 28N45W 26N47W. A second surface trough is along 26N45W 23N44W 20N44W. isolated moderate to locally strong rainshowers are from 22N to 30N between 38W and 46W. Broad surface anticyclonic wind flow covers the Atlantic Ocean from 17N northward from 50W westward. A 1026 mb high pressure center is near 27N66W. An Atlantic Ocean ridge, E-to-W along 27N, will shift gradually N to be along 28N tonight, and then retract eastward, allowing a weak cold front to move off the southeast United States on Sunday. The front will stall quickly and dissipate across the northwestern waters on Monday. Gentle-to-moderate winds will prevail north of the ridge, with moderate-to-fresh winds expected generally south of 25N, except becoming strong along the north coast of Hispaniola and the northern approach to the Windward Passage each evening. The ridge will be reinforced by a stronger high pressure system on Monday. For additional information please visit http://www.hurricanes.gov/marine $$ MT