• STRMDISC: Tropical Depression Three Discussion Number 1

    From COD Weather Processor@1:2320/105 to wx-atlan@lists.illinois.edu on Friday, July 04, 2025 20:35:26
    398
    WTNT43 KNHC 042035
    TCDAT3

    Tropical Depression Three Discussion Number 1
    NWS National Hurricane Center Miami FL AL032025
    500 PM EDT Fri Jul 04 2025

    The wind circulation associated with the low pressure area east of
    the coast of north Florida has become stronger, with aircraft and
    scatterometer data indicating a well-defined circulation with
    maximum winds near 30 kt and a radius of maximum wind of about
    80-90 n mi. The system has also developed persistent convection east
    and southeast of the center. Based on these developments,
    advisories are being started on Tropical Depression Three. The
    cyclone is currently being affected by 20-25 kt of southwesterly
    shear caused by a mid- to upper-level trough not far to the west.

    The initial motion is uncertain due to some reformation of the
    center, with the best estimate of 360/2 kt. During the next 24 h,
    the cyclone should move slowly north-northwestward on the northeast
    side of a developing mid- to upper-level low over the northeastern
    Gulf. After that time, the system should be steered northward with
    a gradual increase in forward speed. This motion should bring the
    center near or over the coast of South Carolina Sunday morning. A
    generally northward motion should then continue until the system
    dissipates over land. While the guidance generally agrees with this
    scenario, there is considerable spread in both the forecast
    direction and speed, with the HWRF being a notable right outlier.
    The forecast track is in best agreement with the GFS and the HCCA
    corrected consensus model.

    The current shear is expected to diminish on Saturday as the
    upper-level trough moves westward away from the cyclone and the
    upper-level winds become southerly. However, the upper-level winds
    are forecast to become convergent, which may limit the amount of
    convection the system produces. Most of the guidance shows some
    development as the system approaches the coast, so the intensity
    forecast calls for modest strengthening to a tropical storm before
    the cyclone makes landfall. This forecast is a little below the
    intensity consensus.

    Key Messages:

    1. Tropical storm conditions are possible in the watch area
    beginning Saturday and continuing through Sunday morning.

    2. Heavy rainfall across the coastal Carolinas will cause some flash
    flooding from Saturday through Monday. Isolated to scattered flash
    flooding could occur within more urbanized areas along the coastal
    plain of the Carolinas.

    3. The system is expected to bring rough surf and rip currents to
    much of the Carolina coastline during the next couple of days.


    FORECAST POSITIONS AND MAX WINDS

    INIT 04/2100Z 30.8N 79.0W 30 KT 35 MPH
    12H 05/0600Z 31.3N 79.1W 30 KT 35 MPH
    24H 05/1800Z 31.7N 79.5W 35 KT 40 MPH
    36H 06/0600Z 32.4N 80.0W 35 KT 40 MPH
    48H 06/1800Z 33.7N 80.0W 30 KT 35 MPH...INLAND
    60H 07/0600Z 35.0N 79.6W 25 KT 30 MPH...POST-TROP/INLAND
    72H 07/1800Z...DISSIPATED

    $$
    Forecaster Beven


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