AXNT20 KNHC 111808

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
105 PM EST Mon Dec 11 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.


A stationary frontal boundary over the western Atlantic from 30N 63W extends southwestward across eastern Cuba, Jamaica, and into the southwestern Caribbean Sea. A band of cloudiness and showers extends about 120 n mi on either side of the front. Due to the little motion of the boundary, there have been some reports of notable rainfall accumulations, including 2.32 inches observed at Montego Bay, Jamaica, during the last 24 hours. The strong pressure gradient between this front and strong high pressure over Mexico is still producing gale force winds on the west side of the boundary over the Caribbean Sea. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.


The monsoon trough extends from the African coast from Liberia near 07N11W to 7N16W to 7N18W. The Intertropical Convergence Zone axis extends from 7N18W to 3N30W and crosses the Equator near 43W to Brazil near 1S46W. Isolated moderate convection is from 2N-5N between 10W-44W.


Fair weather conditions exist across the entire Gulf of Mexico due to a combination of strong surface high pressure centered over Mexico and a dry air mass aloft. Surface winds are generally light and mostly out of the north for most of the region. By tomorrow, a weak cold front will emerge off the southeastern U.S., which could bring a brief period of fresh W-NW winds over the northern waters. Otherwise, quiet conditions are expected to continue for the next day or two.


The main weather producer across the region is a stationary front that is draped across the western portion of the region. Please read the Special Features section for details about the gale-force winds in the area. West of the front, northerly flow and a few showers exist. Generally tranquil conditions exist to the east of the front, with moderate trade winds and scattered shallow showers covering much of the eastern and central Caribbean Sea. The front is forecast to remain stationary while gradually weakening through mid-week.


Generally fair weather conditions prevail across the island today, while a stationary front remains just to the west of the island across the Windward Passage and eastern Cuba. The front is not expected to move much, so generally similar weather conditions are expected over the island during the next day or two.


A mid-to upper-level trough is lifting out of the western Atlantic Ocean, providing less support for a boundary that is now stationary over the western Atlantic from 30N 63W southwestern to eastern Cuba. A band of clouds and showers is within 180 n mi of the front. Farther east, an upper-level low and accompanying surface trough from 27N 51W to 15N 55W are producing showers and thunderstorms to the east of the surface boundary from 15N to 30N between 41W and 51W. The remainder of the basin is fairly quiet, supported by strong subtropical ridging that is centered just north of the area near 36N 36W.

For additional information please visit http://www.hurricanes.gov/marine

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