• STRMDISC: Hurricane Erin Discussion Number 35

    From COD Weather Processor@1:2320/105 to wx-atlan@lists.illinois.edu on Wednesday, August 20, 2025 02:34:58
    682
    WTNT45 KNHC 200234
    TCDAT5

    Hurricane Erin Discussion Number 35
    NWS National Hurricane Center Miami FL AL052025
    1100 PM EDT Tue Aug 19 2025

    Erin has become a little better organized during the past several
    hours. Conventional satellite imagery shows persistent strong
    convection near and to the north of the center, while microwave
    overpasses and reports from an Air Force Reserve Hurricane Hunter
    aircraft indicate that the eyewall is trying to re-form. However,
    these changes have not yet resulted in a tighter inner core wind
    field, and the maximum 700-mb flight-level winds of 107 kt were
    measured about 100 n mi from the center. Based on this, the
    flight-level winds closer to the center, and satellite intensity
    estimates, the initial intensity is decreased to a possibly generous
    85 kt.

    The initial motion is now 340/10. The hurricane remains situated in
    a weakness or break in the subtropical ridge, and it is expected to
    turn northward along the western side of the ridge on Wednesday.
    After that, Erin should turn northeastward with some acceleration
    as it moves into the southern part of the mid-latitude westerlies
    over the north Atlantic. There are no significant changes to the
    forecast track through 72 h, and this part of the track lies near
    the center of the tightly-packed track guidance. After 72 h, the
    there is more spread, and the consensus models have shifted a
    little northward. In response, this portion of the track has been
    shifted to the north.

    For the next 36 h, Erin will be in an environment of light to
    moderate vertical shear and strong upper-level divergence. Much of
    the intensity guidance suggests the hurricane should strengthen
    during this time, if the spread-out wind field can become more
    concentrated near the re-formed eyewall. On the basis of this
    happening, the new intensity forecast calls for slow strengthening
    during the first 36 h. However, an alternative scenario is that the
    central pressure falls considerably without a lot of increase in
    the winds as the hurricane grows larger. After 36 h, increasing
    shear and the start of extratropical transition should cause
    weakening, and Erin is now forecast to become an extratropical low
    by 96 h.

    It should be noted that the 34- and 50-kt wind speed probabilities
    beyond 36 hours in the text and graphical products are likely
    underestimating the risk of those winds occurring. This is because
    the forecast wind field of Erin is considerably larger than average
    compared to the wind field used to derive the wind speed probability
    product.

    KEY MESSAGES:

    1. Erin is expected to produce life-threatening surf and rip
    currents along the beaches of the Bahamas, much of the east coast of
    the U.S., Bermuda, and Atlantic Canada during the next several days.
    Beachgoers in those areas should follow advice from lifeguards,
    local authorities, and beach warning flags.

    2. Storm surge flooding and tropical storm conditions are expected
    in the North Carolina Outer Banks beginning late Wednesday or
    Wednesday night, where Tropical Storm and Storm Surge Warnings are
    in effect. The storm surge will be accompanied by large waves,
    leading to significant beach erosion and overwash, making some roads impassible. Tropical storm conditions are possible along the
    southeastern coast of Virginia, where a Tropical Storm Watch is in
    effect, on Thursday.

    3. Tropical storm conditions are possible in Bermuda on Thursday and
    Friday where a Tropical Storm Watch is in effect.

    4. Interests along the U.S. Mid-Atlantic and southern New England
    coasts should also monitor the progress of Erin as strong winds are
    possible Thursday and Friday.


    FORECAST POSITIONS AND MAX WINDS

    INIT 20/0300Z 27.7N 73.0W 85 KT 100 MPH
    12H 20/1200Z 29.3N 73.5W 90 KT 105 MPH
    24H 21/0000Z 31.6N 73.4W 95 KT 110 MPH
    36H 21/1200Z 33.8N 72.2W 100 KT 115 MPH
    48H 22/0000Z 35.9N 69.8W 95 KT 110 MPH
    60H 22/1200Z 37.7N 66.3W 90 KT 105 MPH
    72H 23/0000Z 39.3N 62.4W 80 KT 90 MPH
    96H 24/0000Z 42.5N 53.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
    120H 25/0000Z 44.8N 42.6W 50 KT 60 MPH...POST-TROP/EXTRATROP

    $$
    Forecaster Beven


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