Atlantic Tropical Weather Discussion

National Hurricane Center - Tropical Weather Discussion (Atlantic)

  1. 000
    AXNT20 KNHC 190003

    Tropical Weather Discussion
    NWS National Hurricane Center Miami FL
    703 PM EST Sat Nov 18 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 1800 UTC surface analysis and satellite imagery through
    2345 UTC.


    A cold front will reach the NW Gulf of Mexico tonight and will
    move across the remainder of the Gulf through Monday. Strong high
    pressure building behind the front will generate gale force winds
    over the SW Gulf waters S of 25N to the west of the front beginning
    1200 UTC Sunday and persisting through Sunday night. See the
    latest high seas forecast under AWIPS/WMO headers HSFAT2/FZNT02
    for more details.


    The monsoon trough extends from the African coast near 08N13W to
    05N21W. The Intertropical Convergence Zone axis extends from
    05N21W to 06N40W to 06N57W. Scattered moderate convection is from
    03N to 06N between 16W and 35W.



    A broad ridge extends from the SW N Atlc across the Florida
    Peninsula and into the Gulf approximately to 93W. The ridge
    supports light to gentle SSW winds E of 93W and SSW moderate flow
    westward ahead of the next cold front that is coming off the Texas
    and Louisiana coasts tonight. CIRA LPW and GOES-16 water vapor
    imagery continue to show deep layered dry air basin-wide, which is
    supporting clear skies. The cold front will sweep across the Gulf
    through Monday. Gale force winds are forecast over a portion of
    the SW Gulf Sunday behind the front. Please refer to the special
    features section for more details.


    The base of a middle to upper level trough extending from the W
    Atlc reaches the NW Caribbean where it support a weak surface
    trough from the NE Yucatan Peninsula near 20N87W to the Gulf of
    Honduras near 15N83W. Shallow moisture in this region of the basin
    support isolated showers 90 nm either side of the trough axis.
    Latest scatterometer data showed a low center just N of the Mona
    Passage from which a surface trough extends SW to 15N71W. In the
    south-central basin, a 1008 mb low is off the coast of Colombia
    near 11N74W from which a surface trough extends northward to
    southern Hispaniola. This elongated area of low pressure prevails
    underneath an upper level ridge that supports diffluent flow and
    thus scattered showers and tstms across the NE Caribbean,
    including Puerto Rico and the Virgin Islands. Isolated showers are
    between 68W and 74W, including Hispaniola and the Mona Passage. High
    pressure over the western Atlantic is supporting moderate to
    fresh NE winds over the northwestern Caribbean. Mainly light to
    gentle winds cover the remainder of the Caribbean. The area of low
    pressure in the southern basin will stall through early morning
    morning while it weakens to a surface trough that will move
    westward through the middle of the week.


    Isolated showers are across the island tonight being supported by
    an elongated area of low pressure focused on a 1008 mb low just N
    of the Mona Passage with associated surface trough extending SW to
    southern Hispaniola adjacent waters. Showers will continue through
    Monday as the area of low pressure drifts NE over the Atlc waters.


    A broad ridge over portions of the NW Atlc waters extends SW
    across the SW N Atlc supporting fair weather and NE to E moderate
    to fresh winds. Over the central Atlc forecast waters a stationary
    front extends from 30N40W to a 1008 mb low near 27N50W. A surface
    trough then extends from the low SW to another 1008 mb low
    pressure center located just N of the Mona Passage. These
    features are supporting a large area of showers N of 22N between
    37W and 56W and S of 23N between 55W and 69W. High pressure of
    1019 mb centered near 26N25W dominates the eastern Atlantic. Over
    the next 24 hours the lows will move NE with convection spreading
    east. SW winds will increase to 20 to 25 kt N of 30N east of 70W
    Sunday as a cold front approaches the region.

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