Atlantic Tropical Weather Discussion

National Hurricane Center - Tropical Weather Discussion (Atlantic)

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    AXNT20 KNHC 181627

    Tropical Weather Discussion
    NWS National Hurricane Center Miami FL
    1226 PM EDT Wed Oct 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 1200 UTC surface analysis and satellite imagery through
    1745 UTC.


    A tropical wave is in the central Atlc with axis extending from
    13N27W to 06N29W, moving W at 10 kt. The wave came off the coast
    of Africa a couple of days ago very weak, however disorganized
    convection has augmented and latest scatterometer data show fresh
    to strong winds associated with it. Satellite derived data
    indicate the wave is in a strong vertical wind shear environment.
    However, shallow moisture and middle to upper level diffluence
    support scattered moderate convection and isolated tstms from
    08N-13N between 22W-31W.

    A tropical wave is in the E Caribbean with axis extending from
    17N61W to 07N61W, moving W at 20 kt within the last 24 hours. The
    wave is in a region of moderate to strong vertical wind shear.
    However, shallow moisture in the E basin along with upper level
    diffluent flow support scattered heavy showers and tstms from
    09N-15N between 60W-65W.

    A tropical wave is in the E Caribbean with axis extending from
    18N66W to inland Venezuela near 08N66W, moving W at 10-15 kt. The
    wave is in a region of moderate to strong vertical wind shear.
    The wave is underneath an upper level low that supports
    scattered heavy showers and isolated tstms from 14N to 18.5N
    between 65W-68W, including eastern Puerto Rico.

    A tropical wave is moving across Central America with axis
    extending from 16N83W across Nicaragua to 06N83W, moving W at 15
    kt. The wave is in a region of low to moderate vertical wind
    shear and CIRA LPW is showing abundant moisture associated with
    it at the lower levels. This environment is supporting numerous
    heavy showers and scattered tstms from 08N-14N between 80W-86W,
    including Nicaragua.


    The monsoon trough extends from the African coast near 08N13W to
    07N19W. The Intertropical Convergence Zone axis extends from
    07N19W to 09N27W, then resumes near 08N32W continuing along to
    06N47W to 08N57W. Aside convection associated with the tropical
    wave in the central Atlc, scattered moderate convection is from
    07N-14N between 52W-60W.



    A stationary front extends from the southern Florida peninsula
    near 26N81W westward to 25N90W then curves SW to the Bay of
    Campeche near 18N94W. The front is supported aloft by a middle
    to upper level trough progressing eastward over the E CONUS
    seaboard and SW N Atlc waters. Scattered moderate convection is
    within 240 nm S of the boundary between 80W-86W and in the
    eastern Bay of Campeche. Isolated showers are within 210 nm N of
    the boundary E of 87W. High pressure builds behind the front
    supporting northerly fresh to strong winds in the western half
    Bay of Campeche and in the NE Gulf. The front is expected to
    weaken today and gradually become diffuse by early Thu. Fresh to
    strong winds will prevail through tonight and then decrease into
    moderate to occasional fresh through the end of the week.


    A middle to upper level high covers the western half of the
    basin proving stability and fair weather, except S of 18N W of
    80W where a tropical weather support numerous to scattered heavy
    showers and tstms. An upper level low covers a great portion of
    the eastern half of the Caribbean supporting scattered heavy
    showers in the vicinity of two tropical waves, one along 67W and
    another near 62W. See tropical waves section for further
    details. Convection associated with these waves is forecast to
    impact the Lesser Antilles, Puerto Rico and Hispaniola today
    through early Thursday. Otherwise, moderate to fresh trades
    across the central and eastern basin are expected to gradually
    increase through the end of the week as high pressure N of the
    are strengthens.


    Dry air subsidence from aloft support mainly fair weather across
    the Island. However, isolated showers and tstms are starting to
    enter the Dominican Republic and adjacent waters as a tropical
    wave, currently moving across Puerto Rico, continue to move west.
    Scattered heavy showers and tstms associated with the wave are
    forecast to affect the Island this evening through Thursday


    A stationary front extends from 30N72W SW to the southern Florida
    peninsula near 25N80W, which is expected to meander while
    gradually dissipating through early Thursday. The front is
    supported aloft by a middle to upper level trough. Isolated
    showers are occurring W if the front and within 75 nm E of it.
    Farther east, an upper level low support a pre-frontal surface
    trough from 30N65W to 25N70W as well as scattered showers from
    22N-32N between 60W-70W. The remainder of the central and eastern
    Atlc are under the influence of a surface ridge anchored by a
    1030 mb high centered near 32N35W.

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