000 AXNT20 KNHC 172321 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 621 PM EST Tue Dec 17 2019 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... A cold front extends from 30N84W to 18N93W. Gale force winds will continue through Wednesday afternoon in the southwestern Gulf of Mexico, mainly south of 22N and west of 93.5W. Elsewhere behind the front, winds of 25-30 kt will continue through tonight, with frequent gusts to gale force south of 26N and west of 87W. Seas of 11-17 ft will occur over portions of the southwestern Gulf of Mexico through Wednesday morning. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for further details. ...MONSOON TROUGH/ITCZ... The ITCZ passes through the coast of Sierra Leone near 08N13W to 01N17W to 01N35W. Scattered moderate convection is seen from 02N-05N between 18W-32W. GULF OF MEXICO... A cold front extends from the eastern Florida Panhandle near 30N84W to the south-central Gulf of Mexico near 23N91.5W to 18N93W. Gale force winds are behind the front over the southwestern Gulf. Winds of 25-30 kt are over the remainder of the Gulf behind the front. See the section above for details on the Gale Warning. Scattered moderate convection is seen over the NE Gulf of Mexico north of 25.5N and east of 86W, as well as portions of northern and central Florida, east of Tallahassee and north of Lake Okeechobee. The strongest of this convection is a NE-SW squall line located about 60-120 nm ahead of the front from Jacksonville to Clearwater to 26N85W. The convection is being enhanced by upper-level diffluence. Scattered showers are elsewhere north of 25N and east of 88.5W near the front. Scattered moderate convection is also along the front from 21N-23N between 91.5W-93W. A surface trough over the Yucatan Peninsula is inducing scattered moderate with isolated strong convection over the northern Yucatan Peninsula, Yucatan Channel, and waters of the SE Gulf of Mexico, south of 24N between 83W-88W. The squall line from Jacksonville to Clearwater to 26N85W, as of 17/2300 UTC, will continue racing east-southeast across the rest of the eastern Gulf through late tonight. The front will move southeast across the Gulf and extend from Tampa Bay Florida to central Yucatan tonight, before moving southeast of the area Wed. Northerly gale force winds and very large seas will prevail behind the front, mainly W of 90W, through late Wed. Winds and seas will diminish over the central and western Gulf Thu and Thu night. Strong NE to E winds will continue over the Straits of Florida after the frontal passage Thu through Fri night. Low pressure may develop over the eastern Gulf Fri night and move across Florida this weekend. A heavy rainfall event is expected now through Wed for the Mexican states of Chiapas, Tabasco southern portions of Campeche. Heavy rain is also expected to affect northern and central Guatemala, much of Belize, and northwestern Honduras tonight through Thu. Currently, rains have already begun over much of the Yucatan Peninsula, Belize, and northeastern Guatemala. In Mexico, the maximum rainfall amounts may range from 4 to 6 inches. The most intense rainfall is expected on Wed through Thu morning, from NW Honduras to central Guatemala, where a maximum of 6 to 8 inches is likely, with isolated totals of 10 to 12 inches possible due to strong topographical forcing. These rains will likely cause localized flooding. A few mudslides are possible. CARIBBEAN SEA... A surface trough over the Yucatan Peninsula is inducing scattered moderate with isolated strong convection over the Yucatan Channel as well as the east coast of the Yucatan Peninsula and Belize. Elsewhere in the NW Caribbean, scattered showers extend to beyond the Cayman Islands, mainly north of 16N between 79W-85W. In the far SW Caribbean, the east Pacific monsoon trough is inducing scattered moderate with isolated strong convection south of 11N between 73W-84W, including over Panama. Scattered light to moderate showers are seen over Puerto Rico and Hispaniola. The ASCAT pass from late Tuesday morning shows fresh to locally strong winds across the eastern and central Caribbean, east of 81W. High pressure northeast of the region will maintain fresh to strong trade winds and building seas from the tropical north Atlantic west of 55W to the south central Caribbean through Sat. A strong cold front will move through the Yucatan Channel late Wed, then across the far northwest Caribbean before stalling and weakening from central Cuba to central Honduras by late Thu. Fresh to strong northerly winds will accompany the front. Looking ahead, another front may move across the southern Gulf of Mexico and approach the northwest Caribbean by late Sat, but the precise timing remains uncertain at this time. ATLANTIC OCEAN... A cold front extends from the east-central Florida Panhandle to the central Gulf of Mexico. A pre-frontal squall line extends from Jacksonville to Clearwater Florida. Another line of tstorms ahead of that extends over the western Atlantic from near 29.5N80W to Cape Canaveral to just north of Lake Okeechobee. Expect these pre-frontal thunderstorms to continue moving eastward through tonight, extending between 75W and the east coast of Florida. The bulk of the moderate to strong storms will remain north of 27N. The cold front will move off the southeastern U.S. coast late tonight, reach from near 31N70W to western Cuba on Wed night, and then from 27N65W across the central Bahamas to central Cuba on Thu night. Strong north to northeast winds and building seas are expected across much of the forecast waters following the frontal passage. The front will gradually stall over the central waters Fri and Fri night. Elsewhere, scattered showers and cloudiness extends over Puerto Rico, Hispaniola, and the waters south of 23N between 64W-71W. Farther east, a cold front currently extends from 32N35W to 30N41W to 28N56W, and continues as a stationary front to 28N62W. Isolated showers are along and within 90 nm ahead of the front, mainly east of 47W. A 1024 mb surface high near 27N50W extends ridging over the remainder of the central and eastern tropical and subtropical Atlantic. Looking ahead, fresh to strong easterly winds may persist Sat across much of the western part of the area and NW Bahamas to northeast Florida as low pressure develops in the Gulf of Mexico and tracks in a general east to northeast direction. Exact timing and location of this low remains uncertain. $$ Hagen