Atlantic Tropical Weather Discussion

National Hurricane Center - Tropical Weather Discussion (Atlantic)

  1. 000
    AXNT20 KNHC 231801

    Tropical Weather Discussion
    NWS National Hurricane Center Miami FL
    101 PM EST Tue Jan 23 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 1200 UTC surface analysis and satellite imagery through
    1745 UTC.


    Caribbean Gale Warning: The combination of high pressure in the
    central Atlantic and lower pressures over northern Colombia
    will continue to bring pulses of strong to minimal gale force
    NE to E winds along and near the coast of Colombia during the
    overnight hours through Thu night and possibly beyond into the
    upcoming weekend. Seas are expected to be in the 9-14 ft range
    with these winds. Please see latest NHC High Seas Forecast under
    AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.

    Gulf of Mexico Gale Warning: Gale force winds are forecast to
    begin early this afternoon in the far SW Gulf behind a cold front
    that extends from the Florida Big Bend region to 25N86W and to
    23N91W where it becomes stationary to 21N94W and cold front again
    to just SE of Coatzacoalcos, Mexico. A gale warning has been
    issued for the area S of 21N W of the front where minimal NW to N
    gale force winds will occur. The latest model guidance indicates
    that these gale wind conditions will persist longer than
    previously advertised, and will now linger into early Thu
    morning. During tonight, the cold front is forecast to reach from
    the Straits of Florida to across the Yucatan Peninsula, with the
    stationary portion transitioning back to a cold front across the
    southern Bay of Campeche. The cold front will weaken slowly as it
    moves across the SE Gulf Wed, and exiting the area by late on Wed.
    Please see the latest NHC High Seas Forecast under AWIPS/WMO
    headers MIAHSFAT2/FZNT02 KNHC for more details.


    The monsoon trough axis extends from Africa near 06N09W to
    03N19W. The ITCZ continues WSW from 03N19W to cross the equator
    near 29W. Scattered moderate convection is N of the ITCZ within
    30 nm either side of a line from 02N31W to 03N39W. Similar
    activity is within 60 nm S of the ITCZ between 36W-39W.


    ...GULF OF MEXICO...

    A cold front extends from the Florida Big Bend region to 25N86W
    and to 23N91W where it becomes stationary to 21N94W and
    transitions back to a cold front again to just SE of
    Coatzacoalcos, Mexico. A trough just NW of the cold front near
    20N95W extends northwestward to just SE of Tampico. A pre-frontal
    trough is analyzed from just SW of Tampa to 24N86W and to just N
    of the NW side of the Yucatan Peninsula. The pre-frontal trough is
    serving as a focus for active convection. As of 1745Z, scattered
    moderate isolated strong convection is observed along and within
    90 nm SE of the trough. In addition, an upper level disturbance
    riding along a well entrenched southwesterly flow aloft is helping
    to develop and maintain this convection. The latest available
    lightning density data indicates that most of this activity
    contains frequent lightning. Some of this activity may also be
    attendant by gusty winds. Moisture guidance indicates that this
    convective activity will move across the rest of the SE Gulf
    through this evening. The cold front is forecast to move SE of the
    area by late Wed. The high pressure behind it will strengthen as
    is slides eastward across the southern portion of the SE United
    States through Thu. The associated pressure gradient will support
    fresh to strong northerly winds over much of the Gulf through Thu.


    Broad upper level ridging is present across the western half of
    the basin, while broad inverted troughing is noted elsewhere.
    Upper level winds and satellite winds reveal a diffluent flow
    pattern over the SW Caribbean. This appears to support scattered
    moderate convection that is occurring from 10N to 13N W of 81W to
    inland southern Nicaragua and far northern Costa Rica. This
    activity is being sustained further by low-level speed convergence
    present there. Patches of low-level moisture advecting westward
    in the easterly flow are seen over the eastern Caribbean waters,
    and also approaching the northern Windward Islands. Scattered
    showers with gusty winds are possible with this moisture.

    The Ascat pass from 1502Z this morning highlighted a large area
    of fresh to strong NE to E winds over much of the central
    Caribbean, with some winds to near gale force along the coast of
    Colombia. Moderate to fresh trades are noted elsewhere across the
    basin. The pressure gradient associated with high pressure N of
    the area should support fresh to strong NE to E trades W of about
    70W elsewhere outside the gale force winds area described above
    through Thu. Strong NE winds are expected through the Windward
    Passage after Wed. A cold front presently moving through the
    eastern and S central Gulf of Mexico will move across the NW
    Caribbean Wed night. The front is forecast to become stationary
    and gradually wash out from central Cuba to Belize on Thu.
    Strengthening high pressure in the wake of the front will bring
    fresh to strong NE to E winds across the Caribbean, including the
    Atlantic passages by late on Thu, with seas expected to build to
    10 ft.


    High pressure ridging dominates the western Atlantic, with a
    ridge extending westward into northern Florida. A robust mid/upper
    level trough is evident on water vapor imagery extending from a
    cyclonic circulation near 28N53W southwestward to 19N57W, and as a
    shear axis to the eastern Caribbean near 15N65W. At the surface,
    a trough is along 60W N of 24N. Isolated showers are within 60 nm
    of the trough, and over some portions of the eastern Caribbean and
    tropical waters s of 20N W of about 50W. Scattered showers and
    isolated thunderstorms are seen N of 22N between 46W and 54W, with
    a concentrated area of numerous showers within about 30 nm of
    27.2N53W. A weak surface trough is located over the central
    Atlantic along 40W N of 22N. Isolated showers are possible along
    and within 60 nm either side of this trough. Expect shower and
    isolated thunderstorm activity to expand eastward through Thu
    ahead of the mid/upper level trough to near 43W. A cold front is
    on track to move off the NE Florida coast this afternoon, and
    reach from near 31N70W to Straits of Florida late on Wed, from
    Bermuda to central Cuba late on Thu morning. Strong NE winds under
    strengthening high pressure will follow behind the front.
    Numerous showers and isolated thunderstorms with gusty winds will
    precede the cold front.

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