Saturday, Aug 18, 2018

Atlantic Tropical Weather Discussion

National Hurricane Center - Tropical Weather Discussion (Atlantic)

  1. 033
    AXNT20 KNHC 180541
    TWDAT

    Tropical Weather Discussion
    NWS National Hurricane Center Miami FL
    141 AM EDT Sat Aug 18 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 0000 UTC surface analysis and satellite imagery through
    0515 UTC.

    ...SPECIAL FEATURES...

    Tropical Storm Ernesto centered near 50.4N 25.6W at 18/0300 UTC
    or 750 nm N of The Azores moving ENE at 30 kt. Estimated minimum
    central pressure is 999 mb. Maximum sustained wind speed is 40
    kt with gusts to 50 kt. Ernesto is expected to become post-tropical
    overnight, and slight weakening is forecast to occur Saturday
    while Ernesto merges with a frontal zone by Saturday night. On
    this forecast track the post-tropical cyclone and its remnants
    will move across Ireland and the United Kingdom Saturday night and
    early Sunday. See latest NHC forecast/advisory under AWIPS/WMO
    headers MIATCPAT5/WTNT35 KNHC for more details.

    ...TROPICAL WAVES...

    A tropical wave is in the E Atlc with axis extending from 04N-16N
    along 35W, moving W at 20 kt. The wave is in a deep layer wind
    shear environment. Both CIRA LPW and GOES-16 water vapor imagery
    at the lower levels show dry air affecting the wave. These two
    factors are contributing to the lack of convection at this time.

    A tropical wave is in the E Caribbean with axis extending from
    06N-18N along 60W, moving W at 20 kt. The wave is in a deep layer
    wind shear environment, and CIRA LPW imagery shows abundant low
    level moisture associated with it. However, some dry air intrusion
    is noted in the NW wave environment as shown both in CIRA LPW,
    and water vapor imagery at the lower levels. Widely scattered
    moderate convection is from 10N-14N between 53W-61W.

    A tropical wave is in the central Caribbean with axis extending
    from 09N-18N along 76W, moving W at 20 kt. The wave is in a
    moderate deep layer wind shear environment. GOES-16 water vapor
    imagery at the lower levels shows very dry air over the central
    Caribbean. This is limiting convection to isolated moderate
    convection over E Cuba and W Hispaniola from 19N-23N between 72W-
    80W.


    ...MONSOON TROUGH/ITCZ...

    The monsoon trough extends from the coast of W Africa near 13N17W
    to 10N30W to 07N40W. The ITCZ begins near 07N40W and continues to
    08N50W to 10N60W. Besides the convection mentioned in the
    tropical wave section, scattered moderate to isolated strong
    convection is over W Africa from 08N-14N between 04W-18W.
    Scattered showers are within 120 nm of the remainder of the
    monsoon trough and ITCZ.

    ...DISCUSSION...

    GULF OF MEXICO...

    A 1024 mb high is centered over the W Atlantic near 30N69W. A
    ridge axis extends W from the high along 30N to E Texas. 10 kt SE
    surface winds covers the Gulf of Mexico N of 24N. A surface trough
    is over the Bay of Campeche from 22N90W to 16N93W. Scattwered
    moderate convection is from 16N-19N between 92W-95W. In the upper
    levels, an upper level high is centered over SE Louisiana near
    30N90W. Upper level diffluence is over the Yucatan Channel
    producing scattered showers.

    Expect, a surface trough to develop along the Yucatan Peninsula
    during the late afternoons, 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, expect an east to
    west ridge extends across the gulf waters along 30N accompanied
    by gentle to moderate anticyclonic flow that is forecast to
    increase to a fresh southerly breeze across the northwest gulf
    waters on Sun evening, and continue through sunrise on Mon. The
    ridge will then shift south and extend east to west across the
    central waters during the middle of next week.

    CARIBBEAN SEA...

    Two tropical waves are over the Caribbean Sea. See above. A
    surface trough extends over the Gulf of Honduras near 18N86W to
    the E Pacific near 10N86W. Scattered showers are within 120 nm of
    the trough. Surface ridging extends from the Atlantic to the
    northern half of the Caribbean. Fresh to strong winds are over the
    south-central Caribbean. In the upper levels, an upper level low
    is centered over central Cuba near 22N80W. Upper level diffluence
    is over Jamaica and E Cuba enhancing convection.

    Expect, strong nocturnal easterly trades along the northwest
    coast of Colombia through the middle of next week. A tropical
    wave along 76W will continue to move westward across the western
    Caribbean during the weekend. A second tropical wave along 60W
    will continue through the east Caribbean this weekend. A third
    tropical wave in the central Atlantic will reach along 55W on Mon
    night and reach the east Caribbean during the middle of next week

    ATLANTIC OCEAN...

    A tropical wave is over the Atlantic. See above. A 1024 mb high is
    centered over the W Atlantic near 30N69W. A surface trough is over
    the central Atlantic from 32N54W to 26N62W. Scattered showers are
    within 90 nm of the trough. A 1028 mb high is centered over the
    Azores near 38N29W.

    Expect over the W Atlantic for fresh trades to be south of 23N,
    except becoming locally strong along the north coast of Hispaniola
    during the late afternoon into early evening hours. The surface
    ridge axis will shift south to central Florida early next week.

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

    $$
    Formosa