Atlantic Tropical Weather Discussion

National Hurricane Center - Tropical Weather Discussion (Atlantic)

  1. 000
    AXNT20 KNHC 211022

    Tropical Weather Discussion
    NWS National Hurricane Center Miami FL
    622 AM EDT Mon Aug 21 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 0600 UTC surface analysis and satellite imagery through
    1015 UTC.


    A tropical wave extends along 80W S of 21N moving W at 15-20 kt.
    The remnant circulation of Harvey is analyzed as a 1007 mb low
    along the wave axis near 15N80W. Scattered moderate to isolated
    strong convection is from 14N-21N between 78W-86W. Gradual
    development of this system is still possible through Monday night
    while it moves west-northwestward near the coast of Honduras. It
    could become a tropical cyclone again before it reaches the coast
    of Belize or the Yucatan Peninsula early Tuesday. The remnants are
    expected to move into the Bay of Campeche on Wednesday, where
    redevelopment appears more likely due to more favorable upper-
    level winds. Interests in northern Nicaragua, Honduras, Belize,
    and the Yucatan Peninsula should monitor the progress of this
    system. There is a medium chance for this system to become a
    tropical cyclone within 48 hours.


    A tropical wave off the coast of W Africa extends from 21N22W to
    10N22W, moving W at 15 kt. The Hovmoller Diagram shows the
    westward propagation of the wave. In addition, this wave in a
    moist area based on SSMI TPW imagery, and has a well pronounced
    700 mb trough. Scattered moderate convection is from 10N-16N
    between 20W-23W. A 1009 mb low is analyzed ahead of the wave near
    14N27W. It is forecast to move westward in tandem with the wave
    over the next 24-48 hours. Saharan dust is noted W of the wave

    A tropical wave extends from 20N52W to 10N57W moving W at 15-20
    kt. The wave is well depicted on the SSMI TPW animation and 700
    mb streamline analysis. The northern portion of the wave has
    fractured and is analyzed as a surface trough from 24N50W to
    21N52W. No significant deep convection is associated with the
    wave itself, however, scattered moderate to isolated strong
    convection is associated with the surface trough from 20N-26N
    between 48W-53W.

    A tropical wave is over the Yucatan Peninsula, Guatemala, and the
    Eastern Pacific, from 21N90W to 10N91W, moving W at 15-20 kt.
    Subtle troughing is noted on 700 mb streamline analysis, and
    abundant moisture is observed on the SSMI TPW animation. Scattered
    moderate to Isolated strong convection is over the Eastern


    The monsoon trough extends from the African coast near 18N16W to
    14N27W to 09N30W to 06N40W. Besides the convection mentioned in
    the tropical wave section, scattered moderate convection is from
    09N-12N between 24W-29W, and from 05N-08N between 33W-38W.



    Weak surface ridging is over the Gulf of Mexico with axis along
    30N. 10-15 kt easterly surface flow is over the Gulf. A surface
    trough is over the E Gulf from 28N85W to 25N85W. Scattered showers
    are within 120 nm of the trough axis. In the upper levels, an
    upper level low is centered over the E Gulf near 26N88W enhancing
    the showers. Expect over the next 24 hours for surface ridging to
    build over the Gulf. Also expect the upper level low to remain
    quasi-stationary and continue to produce convection. Looking
    ahead, the remnant low of Harvey, currently moving across the
    Caribbean Sea is expected to reach Belize or the Yucatan Peninsula
    on Tuesday, and then move into the Bay of Campeche by the middle
    of the week, where redevelopment appears more likely.


    The primary area of concern across the Caribbean Sea is the
    surface low (remnants of Harvey) that is generating convection over
    the central Caribbean. Please, see Special Features section for
    more details. A tropical wave is over Central America, with axis
    along 90W/91W. Please, see the Tropical Waves section for
    details. A trough of low pressure located across the Atlantic
    waters, north of Hispaniola, combined with abundant tropical
    moisture supports the development of showers and strong
    thunderstorms across parts of Hispaniola, and the S Bahamas. This
    trough and associated moisture will continue to move WNW today.


    Daytime heating, local sea breezes, and mountain upslope lifting
    will combine with available moisture to produce scattered showers
    and thunderstorms across the island mainly during the afternoon
    and evening hours. A trough of low pressure, currently located
    north of Hispaniola will bring increased moisture, cloudiness,
    and precipitation to the island.


    The trough of low pressure north of Hispaniola extends from
    27N71W to 19N72W. This system continues to produce disorganized
    showers and thunderstorms, with fresh to strong winds mainly on
    its northeast side based on scatterometer data. Environmental
    conditions are expected to be unfavorable for development of this
    system during the next day or two, but they could become slightly
    more conducive for development by midweek when the system is near
    the northwestern Bahamas or Florida. This feature is expected to
    move west-northwestward at 15-20 kt during the next few days. A
    pair of tropical waves are between the coast of Africa and the
    Lesser Antilles, and a another surface trough extends from 24N50W
    to 21N52W. Please, see the Tropical Waves section for details.
    The remainder of the Atlantic is under the influence of a ridge,
    with a 1023 mb high located SW of Bermuda near 32N68W. This high
    is forecast to remain quasi-stationary over the next 24 hours.
    Another 1024 high pressure is center over the central Atlantic
    near 32N48W.

    For additional information please visit