NOAA Forecast

National Weather Service

National Hurricane Center - Tropical Weather Discussion (Atlantic)

  1. 452
    AXNT20 KNHC 211205

    Tropical Weather Discussion
    NWS National Hurricane Center Miami FL
    805 AM EDT Tue Aug 21 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 0600 UTC surface analysis and satellite imagery through
    1145 UTC.


    An eastern Atlantic tropical wave has its axis extending from
    05N36W to 13N36W to 19N54W, moving westward at 10-15 kt.
    Scattered moderate convection is noted from 08N to 10N between 25W
    and 32W.

    A tropical wave over the eastern Caribbean has its axis along
    63W/64W south of 19N, moving westward at 15 to 20 kt. Scattered
    moderate convection trails the wave within 30 nm of a line from
    11N59W to 11N62W.

    A western Caribbean tropical wave has its axis extending along 83W
    and south of 20N, moving westward at 10-15 kt. Only isolated
    showers and thunderstorms are noted within 60 nm east of the wave.


    The monsoon trough axis extends from coast of Senegal near 14N16W
    to 10N20W, then to 08N40W. The intertropical convergence zone
    continues westward to the mouth of the Orinoco River near 09N61W.
    No significant convection is noted.



    Weak ridging reaches across the northern Gulf of Mexico along
    roughly 27N, maintaining light to gentle breezes and 1 to 3 ft
    seas. Gentle to moderate easterly flow is noted elsewhere south
    of the ridge. Latest NWS mosaic radar display shows isolated
    showers and thunderstorms across much of the eastern part of the
    gulf, mainly due to a weak trough over that area. Scattered to
    numerous showers and thunderstorms are active along the coast of
    Mexico in the far southwest Gulf, related to the normal
    evening/overnight trough that sets up off Yucatan and moves
    westward, but also largely enhanced by an upper low centered over
    the southwest Gulf.

    The Yucatan surface trough will persist each afternoon, then
    drift westward across the southwest gulf waters during the
    overnight hours accompanied by a fresh east to southeast wind
    shift with the trough dissipating along 96W during the late
    mornings. Otherwise, high pressure ridging will remain
    across the northern gulf waters, with the associated gradient
    producing gentle to moderate anticyclonic flow.


    The pressure gradient across the area will maintain fresh to
    strong winds over the south central Caribbean off the coast of
    Colombia and across the Gulf of Venezuela through Thu. Moderate
    to fresh trades will continue elsewhere through Thu.

    The tropical wave along 83W will move across the rest of
    the western Caribbean tonight. The tropical wave along 63W/64W
    will move across the central Caribbean late Tue through Wed night
    and enter the eastern part of the central Caribbean Thu.


    Over the western Atlantic, a surface trough is analyzed from near
    30N72W to 24N76W in the central Bahamas, supported in part by an
    upper trough over the same area. Another trough extends from
    32N57W to 27N67W, and another one from near 32N42W to 24N51W.
    Scattered showers and isolated thunderstorms are north of 23N
    between 59W and 75W. The subtropical ridge is displaced slightly
    north to along 31N, north of the troughs.

    High pressure ridging will continue over the basin through the
    next several days. The trough extending across the central
    Bahamas will continue westward through this evening. Scattered
    showers and isolated thunderstorms along and near the trough will
    affect mainly the western and northwestern sections of the Bahamas
    through tonight.

    Farther east, 1027 mb ridging is centered near 34N41W, supporting
    generally moderate north to northeast winds north of 20N. Saharan
    dust and associated dry air noted mainly east of 50W is
    inhibiting convection from developing across the eastern and
    central Atlantic.

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