• STRMDISC: Tropical Storm Melissa Discussion Number 14

    From COD Weather Processor@1:2320/105 to wx-atlan@lists.illinois.edu on Friday, October 24, 2025 20:54:34
    991
    WTNT43 KNHC 242054
    TCDAT3

    Tropical Storm Melissa Discussion Number 14
    NWS National Hurricane Center Miami FL AL132025
    500 PM EDT Fri Oct 24 2025

    After the previous advisory, the last couple of aircraft fixes from
    the C-130 indicated that Melissa likely completed a center
    relocation as a very large burst of deep convection with cloud tops
    below -90C rotated up-shear of the center. This evolution was also
    nicely captured on the GOES-19 mesoscale sector, where GLM lightning
    flashes, which had been parked down-shear earlier in the morning,
    started to rotate cyclonically along Melissa's eastern flank,
    indicating convection was finally starting to wrap around the
    low-level vortex. A GMI microwave pass at 1527 UTC also hinted at a
    nascent inner core feature on the 37 GHz channel as the convective
    burst wrapped around the center. Before the Air Force Hurricane
    Hunters left Melissa, they measured a peak flight level wind of 59
    kt, and a pressure down to 997 mb, supporting the 50 kt intensity
    for the intermediate advisory. However, given the improvement of
    Melissa's structure since that time, the initial intensity is being
    raised to 55 kt for this advisory, in best agreement with the
    T3.5/55-kt Dvorak intensity estimate provided by TAFB. Another Air
    Force Reserve and a NOAA-P3 reconnaissance mission will be in the
    storm tonight to provide more data on Melissa's intensity and
    structure.

    Now that the center is becoming better aligned with its mid-level
    vortex, it also appears the tropical storm has finally turned more
    northward, with an estimated motion of 360/2 kt. The synoptic track
    reasoning remains similar to this morning, with a slow motion
    expected to continue in the short-term due light steering currents,
    due to competing mid-level ridges to the southeast and northwest of
    Melissa. After 24 hours, the mid-level ridge located to the
    northwest is expected to strengthen to the north of Melissa, and the
    guidance is coming into better agreement on a very slow westward
    motion through 72 hours. Beyond that time frame, a strengthening
    mid-latitude trough expected to move into the Southeastern U.S.,
    providing a path for Melissa to turn northeastward out of the
    Caribbean Sea into the southwestern Atlantic by the end of the
    forecast period. The track guidance this cycle has shifted a bit
    eastward beyond day 3, and is also notably faster than before.
    However, it should be stressed that there remains a substantial
    amount of along track spread. On the forecast track, Melissa could
    potentially be near Jamaica by day 4 and move across Cuba before the
    end of the forecast period, though the timing of this track remains
    more uncertain than usual.

    Compared to yesterday, the UW-CIMSS shear estimates have dropped
    from 25 kt a day ago to 15 kt currently with mid-level shear also
    decreasing. This reduction in shear, in combination with the
    dramatically improved structure of Melissa this afternoon, suggests
    that the system is ready to take advantage of other favorable
    environmental conditions (30-31 C sea-surface temperatures, a
    moistening deep-layer environment). The intensity guidance is
    sharply higher this afternoon in the short-term, and it appears that
    Melissa could begin a period of rapid intensification (RI) at any
    time. The NHC intensity forecast responds to this guidance change by
    explicitly show RI earlier and continuing over the weekend. The
    forecast now shows a 135 kt peak in 60 h, and there is a distinct
    possibility that Melissa could become a Category 5 hurricane during
    this time period. In fact, the latest 12z Google DeepMind ensemble
    distribution shows the majority of its members reaching this lofty
    intensity. After that time period, inner-core structural changes are
    likely to cause fluctuations in intensity, and land interaction in
    both Jamaica and Cuba will likely lead to some weakening by the end
    of the forecast. The NHC intensity forecast is on the high side of
    the guidance envelope, and closest too the Google DeepMind ensemble
    mean (GDMI).

    Key Messages:

    1. Jamaica: Due to Melissa's slow motion, a prolonged multi-day
    period of damaging winds and heavy rainfall resulting in potentially catastrophic flash flooding and numerous landslides is likely to
    begin late Saturday or Sunday. There is an increasing risk of
    life-threatening storm surge when the center of Melissa nears
    Jamaica early next week. Preparations to protect life and property
    should be rushed to completion.

    2. Haiti: Heavy rainfall will result in catastrophic flash flooding
    and landslides across southwestern Haiti into early next week.
    Extensive damage to roads and buildings is expected, potentially
    isolating communities for an extended period of time. Immediate
    preparations to protect life and property should be taken. Strong
    winds could also potentially last for a day or more over the Tiburon
    peninsula of Haiti.

    3. Dominican Republic: Heavy rainfall could produce potentially
    catastrophic flash flooding and numerous landslides in southern
    portions of the Dominican Republic.

    4. Eastern Cuba and Bahamas: Interests in Cuba and the Bahamas
    should monitor the progress of Melissa since there is an increasing
    risk of a significant storm storm surge, damaging winds, and heavy
    rainfall by the middle of next week. The risk of life-threatening
    flash flooding and landslides in eastern Cuba are increasing.


    FORECAST POSITIONS AND MAX WINDS

    INIT 24/2100Z 16.0N 74.3W 55 KT 65 MPH
    12H 25/0600Z 16.2N 74.4W 65 KT 75 MPH
    24H 25/1800Z 16.4N 74.8W 85 KT 100 MPH
    36H 26/0600Z 16.5N 75.5W 105 KT 120 MPH
    48H 26/1800Z 16.5N 76.0W 120 KT 140 MPH
    60H 27/0600Z 16.5N 76.6W 135 KT 155 MPH
    72H 27/1800Z 16.8N 77.4W 135 KT 155 MPH
    96H 28/1800Z 17.9N 77.4W 120 KT 140 MPH...INLAND IN JAMAICA
    120H 29/1800Z 21.5N 74.8W 95 KT 110 MPH...OVER WATER

    $$
    Forecaster Papin



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