000 AXNT20 KNHC 201127 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 627 AM EST TUE DEC 20 2016 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 0600 UTC surface analysis and satellite imagery through 1115 UTC. ...SPECIAL FEATURES... ..GULF OF MEXICO GALE WARNING... A stationary front extends from 31N76W through 28N82W to 24N90W to the Bay of Campeche near 18N93W. Gale force NW to N winds are occurring S of 22N and W of the front with seas of 10 to 17 FT. The gale force winds are forecast to continue through tonight. Please read the Atlantic high seas forecast, that is listed under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for further details. ...THE ITCZ/THE MONSOON TROUGH... The Monsoon Trough extends from the coast of Africa near 07N12W to 06N14W. The ITCZ begins near 06N14W and continues along 02N30W to 04N40W to 05N53W. Scattered moderate to isolated strong convection is from 04S to 10N between 25W and 50W. ...DISCUSSION... ...THE GULF OF MEXICO... Middle to upper level ridging covers the entire Gulf of Mexico with water vapor imagery depicting a belt of moisture over the central basin and abundant moisture over the Bay of Campeche associated with the tail of a stationary front. The stationary front extends from 31N76W through 28N82W to 24N90W to the Bay of Campeche near 18N93W where scattered showers are S of 20N. A strong pressure gradient is between the front and broad high pressure across the eastern U.S., extending SW along Mexico. This continue to support gale-force winds in the SW Gulf and fresh to near gale winds S of 26N W of the front. Please refer to the SPECIAL FEATURES section for information about gale-force winds and associated seas. Both Geocolor and IFR satellite imagery suggest the presence of dense fog over the NE basin, which is being confirmed by surface observations. This traduce to a visibility of less than 3 miles, thus marine traffic in this region must exercise caution. Winds and seas will gradually subside over most of the Gulf today with strong to near-gale force winds remaining along the coast of Mexico S of 20N. ...THE CARIBBEAN SEA... An upper level ridge dominates the western Caribbean while an upper trough is over the remainder basin. The upper trough along with patches of shallow moisture moving across the E basin support scattered to isolated showers over the Virgin Islands and Puerto Rico. Water vapor imagery show strong dry air subsidence across most of the basin, which is supporting overall stable conditions and fair weather elsewhere. A tight pressure gradient between high pressure across the Atlantic Ocean and climatological lower pressure in Colombia supports fresh to near gale-force winds from 10N to 18N between 70W and 83W with seas to 10 ft. Fresh to strong E-NE winds are across the remainder basin, including the Windward and Mona Passages. No significant changes expected through Wednesday. ...HISPANIOLA... Water vapor, CIRA LPW and SSMI TPW imagery continue to show very dry air over the Island, which continue to favor fair weather. However, patches of shallow moisture moving across the NE Caribbean will reach the Dominican Republic later morning, thus enhancing showers during the afternoon hours. ...THE ATLANTIC OCEAN... A stationary front extends from 31N76W through 28N82W to 24N90W to the Bay of Campeche near 18N93W. Broken to overcast low and mid level clouds with embedded showers are noted within 90 nm either side of the front in the SW N Atlc waters. Fresh to strong northerly flow is to the W-NW of the front. Otherwise, a surface ridge dominates the remainder Atlc waters being anchored by a 1039 mb high W of the Azores Islands. For winds and seas associated with both the front and the strong ridge please read the Atlantic high seas forecast listed under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos