• STRMDISC: Tropical Storm Melissa Discussion Number 16

    From COD Weather Processor@1:2320/105 to wx-atlan@lists.illinois.edu on Saturday, October 25, 2025 08:43:48
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    WTNT43 KNHC 250843
    TCDAT3

    Tropical Storm Melissa Discussion Number 16
    NWS National Hurricane Center Miami FL AL132025
    500 AM EDT Sat Oct 25 2025

    During the last center fix of the Air Force Reserve mission into
    Melissa several hours ago, a dropsonde measured a surface pressure
    of 989 mb with winds of 27 kt, suggesting that the central pressure
    has fallen to about 986 mb. The plane did not measure stronger
    winds, but it did not fly through the area due east of the center,
    which is where a nearly coincident ASCAT pass suggested the
    strongest winds would be located. Some westerly shear is still
    evident, but the center is now embedded far enough under the
    Central Dense Overcast to yield Dvorak estimates of T4.0/65 kt from
    TAFB and T3.5/55 kt from SAB. The current intensity is estimated to
    be 60 kt based on all these data. It's also worth noting that an
    eye feature has occasionally been apparent in radar images from
    Jamaica.

    Melissa is currently moving slowly northwestward (310/3 kt).
    Steering currents will remain weak for the next 3 days, and Melissa
    is forecast to drift westward through Sunday night to the south of
    Jamaica. A sharp but still very slow turn toward the north is
    expected Monday and Monday night. Unfortunately, a large majority
    of the latest reliable track models show Melissa making landfall on
    Jamaica in about 72 hours. What's most concerning here is that the
    island is likely to experience a couple of days of heavy rainfall
    and tropical-storm-force winds before the core--and strongest
    winds--even reach the coast. An increase in forward motion is
    expected by days 4 and 5, with Melissa accelerating northeastward
    across eastern Cuba, the southeastern Bahamas, and the Turks and
    Caicos Islands. Although there are some speed differences among
    the models, for the most part the cross-track spread is generally
    small.

    Although some westerly shear is likely to continue for the next few
    days, high oceanic heat content and stronger upper-level
    divergence should be able to support significant strengthening.
    The dynamical model-based Rapid Intensification (RI) indices
    (DTOPS) in particular are quite aggressive, showing a very high
    probability of a 55-kt increase in intensity over the next 48
    hours. In addition, 41 of the 50 Google DeepMind ensemble members
    show Melissa at category 4 or 5 strength by Monday afternoon (60
    hours), which is the same time that the NHC forecast continues to
    show a peak intensity of 135 kt. Although some slight weakening is
    possible after 60 hours, possibly due to the circulation
    interacting with land and/or an eyewall replacement, Melissa still
    has a significant possibility of making landfall on Jamaica as a
    major hurricane. Melissa could maintain major hurricane strength
    when it reaches eastern Cuba, but increased shear should lead to
    weakening below major hurricane strength by day 5.


    Key Messages:

    1. Jamaica: Melissa's slow movement will bring a multi-day period
    of damaging winds and heavy rainfall beginning tonight, likely
    causing catastrophic flash flooding and numerous landslides. There
    is an increasing risk of life-threatening storm surge early next
    week. All preparations should be completed today.

    2. Haiti: Catastrophic flash flooding and landslides are expected
    across southwestern Haiti into early next week, likely causing
    extensive infrastructural damage and potentially prolonged isolation
    of communities. Immediate preparations to protect life and property
    are urged. Strong winds could also potentially last for a day or
    more over the Tiburon peninsula.

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

    4. Eastern Cuba, Bahamas, and the Turks and Caicos: Monitor Melissa
    closely. There is an increasing risk of a significant storm surge,
    damaging winds, and heavy rainfall by the middle of next week. In
    eastern Cuba, the risk of life-threatening flash flooding and
    landslides is increasing.


    FORECAST POSITIONS AND MAX WINDS

    INIT 25/0900Z 16.3N 75.0W 60 KT 70 MPH
    12H 25/1800Z 16.5N 75.3W 75 KT 85 MPH
    24H 26/0600Z 16.7N 75.9W 100 KT 115 MPH
    36H 26/1800Z 16.8N 76.5W 115 KT 130 MPH
    48H 27/0600Z 16.9N 77.1W 125 KT 145 MPH
    60H 27/1800Z 17.2N 77.4W 135 KT 155 MPH
    72H 28/0600Z 17.8N 77.2W 125 KT 145 MPH...S COAST OF JAMAICA
    96H 29/0600Z 20.4N 75.3W 105 KT 120 MPH...SOUTHEASTERN CUBA
    120H 30/0600Z 24.8N 71.6W 90 KT 105 MPH...OVER WATER

    $$
    Forecaster Berg



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