000 AXNT20 KNHC 200604 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 105 AM EST Fri Jan 20 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 0000 UTC surface analysis and satellite imagery through 0530 UTC. ...SPECIAL FEATURES... A cold front is over the W Atlantic from 32N59W to 25.5N66W to 28N76W moving east. Gale force winds S to SW winds of 30 to 35 kt are noted N of 27N within 90 NM east of the front. W to NW winds of 25 to 35 KT were noted N of 29N west of the front to 67W. Seas were 8 to 12 FT. Gale force winds are forecast to persist E of front for the next 48 hours. See latest NWS High Seas Forecast under AWIPS/WMO headers HSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 07N11W to 04N11W. The Intertropical Convergence Zone continues from 04N11W to 02N30W to the coast of South America near 02S43W. Scattered moderate isolated strong convection is from 02S-03N between 35W- 44W...and from 01S-05N between 25W-33W. ...DISCUSSION... GULF OF MEXICO... As of 2100 UTC a dissipating cold front extended from near Lake Charles Louisiana to 25N97W with scattered moderate convection within 90 NM of the front. A prefrontal squall line with numerous showers and thunderstorms extended from Biloxi Mississippi to 27N91W. Scattered showers and isolated thunderstorms were noted within 60 NM east of the front. Generally fair conditions prevailed over the remainder of the Gulf. Fresh to strong S to SW winds were noted ahead of the prefrontal squall line with light and variable winds behind the dissipating front. Winds along the immediate coast of Texas were turning more to the southeast in advance of a stronger area of low pressure over northern Texas. In the upper levels, a sharpening negatively-tilted mid-to upper level trough extends from a cyclonic circulation over Kansas SSE into the far NW Gulf. Strong upper level subsidence was sweeping around the base of the trough along the upper Texas coast. Strongly diffluent flow was noted ahead of the trough axis over the northern Gulf which aided in maintaining the pre-frontal squall line. CARIBBEAN SEA... A 1422 UTC ASCAT scatterometer pass indicated 20-25 KT trade winds over the Caribbean Sea S of 17N between 70W and 80W with stronger winds of 25-30 KT within 90 NM of the coast of Colombia. Moderate to locally fresh winds were noted elsewhere over the basin. Scattered low-topped showers were noted inland over Nicaragua, Honduras, and Guatemala. Otherwise mostly fair conditions prevailed. In the upper levels, an upper level ridge is over the W Caribbean W of 72W with a downstream upper level trough over the E Caribbean. Very strong subsidence dominated the entire Caribbean. ...HISPANIOLA... Strong upper level subsidence prevailed in the vicinity of the island with moderate NW flow aloft. The 12Z rawindsondes from San Juan, Puerto Rico and Santo Domingo both verified the existence of very dry air above 800 MB. Precipitable water values of 0.92 and 0.65 inches were noted at the respective locations. Little change is expected over the next 24 hours. ATLANTIC OCEAN... A weak 1017 mb high is centered over the Bahamas near 25N77W. A cold front is presently over the W Atlantic from 32N59W to 25N66.5W to 28N76W moving east. Scattered showers and isolated thunderstorms were noted within 90-120 NM east of the front. Strong winds were noted either side of the front with gale force winds occuring N of 27N within 90 NM east of the front and N of 29N to 67W. Refer to the special features section above for additional information. A dissipating stationary front is over the far E Atlantic extending from 32N26W to 28N43W. 1025 MB high pressure centered near 33N31W was bridging through the front and dominated the flow over the Atlantic from the ITCZ between the coast of Africa and 45W. For additional information please visit http://www.hurricanes.gov/marine $$ Mundell