000 AXNT20 KNHC 221759 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1259 PM EST Mon Jan 22 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 1745 UTC. ...SPECIAL FEATURES... Gale Warning: The combination of central Atlantic high pressure with lower pressures over the NW and central Caribbean Sea will allow for of A tight pressure gradient will the present NE to E trades in the SW Caribbean near the coast, and to within about 90 nm of the coast of Colombia, to increase to minimal gale force beginning late tonight and into Tue morning before subsiding back to strong winds in the late morning hours. Seas are expected to building to the range of 10 to 13 ft with these winds. These winds are expected to pulse back to gale force again late Tue night into Wed morning. Model guidance indicates that the pulsing of the strong trades to minimal gale force will continue through the rest of the week as an area of strong high pressure from the Gulf of Mexico surges southeastward across the NW and central Caribbean behind a forecast cold front, with the associated gradient fairly tight enough to induce these winds in the upcoming days. Please see the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. Gale Warning: A gale warning is forecast to become in effect early on Tue afternoon for the SW Gulf in the wake of the next cold front that pushed off the coast of Texas this morning, and is over the NW Gulf coast as of early this afternoon. The cold front will reach from near SE Louisiana to near Tampico, Mexico early this afternoon, from the Florida Big Bend to the eastern Bay of Campeche tonight, from the Straits of Florida to the Yucatan Peninsula to Veracruz, Mexico on Tue night, then move to the SE of the area on Wed. Minimal gale force NW to N winds of 25 to 35 kt are forecast for the extreme SW Gulf near the coast of Veracruz beginning early on Tue afternoon, then diminish to strong winds late on Tue night. The gale force winds are expected to return briefly to the same area on Wed night, then diminish significantly on Thu. Please see the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...MONSOON TROUGH/ITCZ... The Monsoon Trough axis extends from far western Africa to the Atlantic Ocean near 06N09W and continues to 01N19W. The ITCZ begins near 01N19W and extends to 02N32W to coast of S America at 01N49W. Scattered moderate isolated strong convection is within 120 nm N of the ITCZ between 33W-35W. Scattered moderate convection is elsewhere within 180 nm N of the axis between 33W- 35W, and within 30 nm either side of a line from 02N25W to 03N30W. ...DISCUSSION... ...GULF OF MEXICO... A cold front moved off the Texas coast early this morning, and as of 15Z extends along a position from just E of Lake Charles, Louisiana to 28N94.5W to Brownsville, Texas. The cold front is quickly catching up to a pre-frontal squall line that is about 30 nm to its east. Latest mosaic NWS doppler radar imagery shows scattered showers and isolated thunderstorms along the squall line. A batch of scattered showers and thunderstorms is increasing out ahead of the squall line while moving east- northeastward within 30 nm either side of a line from 30N89W to 28N91W to 26N92W. Behind the front, conditions rapidly dry out as the leading edge of strong high pressure center over the western United States is nosing eastward on the heals of the front. The cold front will reach from near SE Louisiana to near Tampico, Mexico by early this afternoon, and rapidly reach the far SE Gulf waters on Tue night, and move to SE of the area on Wed. The gradient associated with the aforementioned strong high pressure will support fresh to strong northerly winds over much of the Gulf through Wed, outside the gale warning portion of the far SW Gulf as described above under Special Features. ...CARIBBEAN SEA... Isolated showers and thunderstorms are seen over portions of the NW Caribbean assisted by diffluence aloft. Fresh to strong winds were noted in the latest scatterometer data over much of the central Caribbean, with the strongest winds confined to along and near the coast of Colombia. Moderate to locally fresh trades are noted elsewhere across the basin. The pressure gradient provided by high pressure N of the area should allow for fresh to strong NE to E trades to occur W of about 70W elsewhere of the gale force winds as described above under Special Features through late Wed night. Strong NE winds are expected through the Windward Passage after Wed. A cold front that is moving across the western and central Gulf of Mexico will enter the NW Caribbean Wed night, followed by increasing strong NE winds and with seas building to around 10 ft. ...ATLANTIC OCEAN... Ridging dominates the western Atlantic anchored by a 1025 mb high pressure center analyzed at 31N60W, with a ridge extending westward to 31N71W and to the far NE Gulf of Mexico. A large surface trough extends from near 29N72W to 26N75W to just N of eastern Cuba at 22N77W. A rather robust mid/upper level trough is evident on water vapor imagery to extend from a cyclonic circulation near 33N64W through 32N65W to 26N68W and to eastern Cuba. Upper-level dynamics related to a jet stream branch that to the E of the trough is tapping abundant available deep layer moisture between 64W and 70W resulting in scattered showers and isolated thunderstorms northward of Hispaniola to 25N, and also from 20N to 26N between 65W and 70W. Isolated showers and thunderstorms are elsewhere N of 19N between 60W and 70W, along with patches of rain. The cyclonic circulation near 33N64W is forecast to dive southeastward to the central Atlantic near 24N46W by Wednesday, with the mid/upper trough sharpening in the process. Expect favorable dynamics in play to allow for the present shower and thunderstorm activity and rain patches to expand eastward through Wed ahead of the trough as it reaches from the cyclonic circulation southwestward to near 10N50W at that time. The 1025 mb high is forecast to slide eastward to just SE of Bermuda by early on Tue in response to a cold front that approaches the SE United States. The cold front will move off the NE Florida coast on Tue afternoon. The front will reach from near 31N73W to the Straits of Florida on Wed morning, and from Bermuda to central Cuba on Thu morning. Strong NE winds under high pressure will follow in behind the front. Scattered to numerous showers and thunderstorms with gusty winds will precede the front. To the E, another upper level cyclonic circulation is near 27N42W with a trough stretching to 22N36W and to near 17N30W. At the surface, a stationary front is located over the E central Atlantic from near 32N38W to 26N43W to 24N46W where it becomes fractured to 22N59W. A surface trough is to the SE of the front from 26N42W to 20N43W. Divergence aloft E of the upper level cyclonic circulation is helping to trigger off scattered showers and thunderstorms from 24N to 28N between 37W and 40W. Isolated showers and thunderstorms are elsewhere N of 23N between 35W and 41W. The upper level cyclonic circulation is forecast to lift out to the NE through Wed night and weaken while its related trough dampens out. Isolated showers are near and within about 60 nm N of the fractured frontal boundary. A low-level disturbance is clearly observed on visible satellite imagery to be located near 21N63W. It is moving rapidly westward while weakening. Isolated showers are within 60-90 nm of the disturbance. A 1034 mb high pressure system to the NE of discussion is at 38N14W. It extends a ridge southwestward to 32N27W and to near 26N38W. The high will remain nearly stationary over the next 24 hours, then begin to slowly shift southward and weaken thereafter. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre