000 AXNT20 KNHC 271800 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 AM EST Fri Jan 27 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. ...SPECIAL FEATURES... A cold front extends from SW Florida to near 23N90W where it becomes stationary along 21.5N94W to 20N95W to 18N94W. Then, the front continues, as a stationary front, across the eastern slopes of the Sierra Madre mountain in Mexico. The cold front will continue to move slowly SE, reaching the Straits of Florida by Saturday morning while the stationary front will lift N as a warm front across the western Gulf. Computer model suggests that a low will form along the frontal boundary over the western Gulf early on Saturday, with a new cold front moving across the Gulf region Saturday afternoon through Sunday. NW to N gale force winds and building seas are forecast S of 25N west of the front Saturday afternoon into Sunday morning. See latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough enters the Atlantic Ocean through Sierra Leone at 07N12W and continues to 06N15W. The Intertropical Convergence Zone axis extends from 06N15W to 03N30W to 01N40W to the South American coast and near the Equator at 51W. Scattered moderate convection is from 00N-05N between 20W-30W, within about 120 nm north of the ITCZ axis between 30N-38N, and from 00N-06N W of 45W. ...DISCUSSION... GULF OF MEXICO... A frontal boundary extends across the Gulf region. Please, see Special Features section for details. Doppler radar indicates a few showers in association with the front across south Florida and regional waters, including the Florida keys. A band of multilayered clouds is related to the front, and visible satellite imagery hints that a weak low is developing across the SW Gulf. Low clouds are aslo noted baking up along the eastern slopes of the Sierra Madre mountain. Currently, N-NE winds in the 15-20 kt range are noted north of the front. In the upper levels, zonal flow and abundant mid-upper level moisture dominate the northern Gulf while a ridge with moderate to strong upper level subsidence and implied dry air mass is noted over the southern Gulf, including SE Mexico and the Yucatan Peninsula. CARIBBEAN SEA... The southern tip of a stationary front is over the NE Caribbean and extends from the northern Leeward Islands to near 16N65W. Moderate to locally fresh NE winds are N of the front. Patches of low level clouds with embedded light showers are noted in association with the frontal boundary affecting the northern Leeward Islands. Part of this activity is also reaching the US/UK Virging Islands. Similar cloudiness is aslo noted across the remainder of the basin, more concentrated south of Cuba and over the Cayman Islands. Moisture associated with the front will continue to affect the NE Caribbean today and tonight while the front is forecast to gradually dissipated across this area through Saturday. Scatterometer data provide observations of near gale force winds near the coast of Colombia ,with fresh to strong winds across the remainder of the south- central Caribbean. These winds are forecast to persist over the next several days, with pulsing winds no near gale force at night near the coast of Colombia. A cold front is expected to reach the Yucatan Channel by Sunday morning. Aloft, a ridge/trough /ridge pattern dominates the basin producing moderate to strong upper level subsidence across the entire region. The upper-level trough extends from the northern Leeward Islands to the Guajira Peninsula and supports the aforementioned stationary front. ...HISPANIOLA... Mostly fair conditions and clear skies prevail over Hispaniola as strong subsidence continues to provide an overall stable environment over the region. On Saturday, expect some increase in moisture, under a SE flow, with the risk of light showers. ATLANTIC OCEAN... A cold front enters the forecast area naer 31N73W and continues SW to south-central Florida into the Gulf of Mexico. A recent ASCAT pass shows very well the wind shift associated with the front as well as moderate to fresh winds on either side of the front, forecast to reach the Straits of Florida by Saturday morning, then stall and weaken. A second cold front stretches from 31N36W to 21N47W, then continues as a stationary front from this point to the northern Leeward Islands. A surge of moisture with embedded light showers is associated with the front over the NE Caribbean. This activity is forecast to drift NW across the NE Caribbean the rest of today and tonight. Between fronts, a 1022 mb high pressure is centered near 27N55W. This system is forecast to move eastward to a position near 28N40W by Saturday morning. The remainder of the area is under the influence of another high pressure of 1025 mb located just NW of the Canary Islands near 30N19W. The high will move NE and away from the forecast region in about 12-24 hours. The next cold front is expected to move off NE Florida on Sunday, reaching a position from 31N73W to the NW Bahamas and western Cuba Saturday afternoon. For additional information please visit http://www.hurricanes.gov/marine $$ GR