000 AXNT20 KNHC 191731 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1231 PM EST Sun Feb 19 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 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...ITCZ/MONSOON TROUGH... The Monsoon Trough enters the Atlantic Ocean through Liberia and extends to 04N15W. The ITCZ continues from this point to 04N30W then crosses the Equator at 38W to 01S42W to 01N50W. Scattered moderate to isolated strong convection is noted from 01N-05N between 24W and 28W. Scattered moderate convection can be found from 01N-05N between 30W-40W. ...DISCUSSION... GULF OF MEXICO... The pressure gradient between a high pressure system over the western Atlantic and lower pressures over Texas and NE Mexico is supporting mainly gentle to moderate SE-S winds across most of the Gulf region. The most recent ASCAT pass showed moderate to fresh southerly winds across the NW Gulf. Winds will increase in the western half of the Gulf tonight as the pressure gradient tightens between a ridge extending south across Florida and lower pressures over eastern Mexico. Dense fog was noted this morning along the coastline from Louisiana to the Florida Panhandle, and across the west coast of Florida and parts of south Florida. Parchy fog were seen along the coast of Texas and over the NW Gulf. Computer model suggests that a low pressure system and associated trough will move eastward across the Gulf Tuesday and Wednesday, with a band of moisture extending from SE Louisiana to the Yucatan Peninsula by Tuesday night, reaching the SE Gulf on Wednesday. This will bring an increase in showers across the area with the potential of some thunderstorms. Aloft, SW flow, ahead of a sharp trough over NW Mexico, is transporting mid-upper level moisture across the western Gulf. CARIBBEAN SEA... The San Juan Doppler radar shows a band of showers affecting the north coast of the island and regional Atlantic waters. This band of showers extends into Dominican Republic and is associated with a weakening cold front located north of Puerto Rico. Moisture associated with this front will persist across the Puerto Rico and Dominican Republic through Monday. Another band of moisture is forecast to approach these islands by Monday night in association with a frontal trough currently located east of Florida. Patches of moisture, with embedded passing showers, are noted over southern Haiti and parts of Jamaica. High pressure north of area will support fresh to strong winds near the coast of Colombia and in the Gulf of Honduras during the overnight and morning hours through Tuesday. Gentle to moderate trades will persist elsewhere through Tuesday. A cold front moving across the SW N Atlantic Monday and Tuesday will bring northerly winds across Cuba and the Windward passage Monday and Tuesday. These winds will transport some shower activity. Looking ahead...a band of moisture forecast to move across the Gulf of Mexico Tuesday and Wednesday is forecast by the computer model to reach western Cuba and the NW caribbean on Wednesday. In the upper levels, a westerly flow is noted over Cuba and the NW Caribbean while W-NW winds dominate the remainder of the basin. Mid-upper level moisture is over the NW Caribbean, and Cuba. Strong subsidence is seen on water vapor imagery elsewhere. ...HISPANIOLA... Patches of moisture, with embedded passing showers, are noted over southern Haiti. The proximity of a weakening frontal boundary will produce isolated to scattered showers today. Moisture is forecast to persist across the island on Monday with the risk of showers. ATLANTIC OCEAN... A frontal trough extends from a 1015 mb low pressure located near 31N77W to 27N80W. A sharp short-wave trough supports this feature. A band of showers and thunderstorms is ahead of the trough axis. Lightning data indicate very active weather within this band. The low pressure is forecast to move SE across the forecast area reaching a position near 29N69W by early Monday morning. At that time, the associated frontal trough will extend from the low center to the SE Bahamas. High pressure will build across Florida in the wake of this frontal trough bringing a drier air mass. A cold front enters the discussion area near 31N43W, then extends SW to the waters north of Puerto Rico. A 1022 mb high pressure located near 28N64W follows the front and extends a ridge toward the SE Bahamas and Turks and Caicos Islands. Moderate to fresh NE winds are observed, per scatterometer data, within about 150 nm north of the front between 56W-63W. In about 24 hours, the high pressure will move NE as the aforementioned low pressure system moves SE into the forecast region. The remainder of the Atlantic is under the influence of a ridge, anchored by a 1035 mb high pressure located NE of the Azores. The pressure gradient between this strong high pressure and the front over the central Atlantic supports fresh to strong southerly winds ahead of the front but mainly north of 28N. For additional information please visit http://www.hurricanes.gov/marine $$ GR