• DAY3 3/5 Risk US Midwest

    From Mike Powell@618:250/1 to All on Sat Apr 26 09:45:00 2025
    ACUS03 KWNS 260742
    SWODY3
    SPC AC 260741

    Day 3 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0241 AM CDT Sat Apr 26 2025

    Valid 281200Z - 291200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
    IOWA INTO SOUTHEAST MINNESOTA AND WESTERN WISCONSIN...

    ...SUMMARY...
    An outbreak of severe weather is likely across portions of the
    Midwest and Upper Midwest. Large hail, severe wind gusts, and strong
    to intense tornadoes are likely.

    ...A tornado outbreak with the potential for strong to intense
    tornadoes is possible on Monday...

    ...Midwest into the Upper Midwest...
    A strong mid-level jet streak will move rapidly northeastward from
    the Southwest to the Upper Midwest on Monday. As this occurs, a
    surface low will deepen and move from the northern Plains to the
    northern Great Lakes. Strong southwesterly lower tropospheric flow
    will advect high theta-e air northward across the Midwest and into
    parts of the Upper Midwest. Broken to scattered cloud cover will
    support surface heating and strong destabilization across the warm
    sector in Iowa and into southeast Minnesota and western Wisconsin.

    Severe storms may develop as early as mid-day across western
    Minnesota and western Iowa on the nose of a 70-80 knot mid-level jet
    streak. These storms may begin as supercells, but mode may become
    more linear as the cold front intersects the dryline across
    Minnesota during the afternoon. Even if mode is more linear,
    embedded tornadoes will be possible given the strengthening
    low-level shear.

    Farther south and east, a more discrete mode will be favored within
    a weakly capped warm sector. As lower tropospheric flow strengthens
    through the day, the warm sector will expand rapidly northeastward,
    creating a broad warm-sector featuring moderate to strong
    instability and very strong (60+ knots) shear. Increasing forcing
    during the afternoon should be sufficient to overcome weak capping
    across the warm sector. Therefore open warm sector supercells will
    be possible in addition to supercells along the eastward advancing
    dryline. Any supercells which can develop within this increasingly
    favorable environment Monday afternoon/evening will be capable of
    strong to intense tornadoes. By late evening, a squall line will
    likely overtake much of the discrete convection as the cold front
    advances rapidly southeast. Severe wind gusts and embedded tornadoes
    will remain possible through the late evening and perhaps into the
    overnight hours.

    ...Central/Southern Plains...
    A strongly unstable and strongly sheared warm sector will exist
    along and east of the dryline from eastern Kansas southward to West
    Texas. Forcing is much weaker than farther north with only weak
    height falls along the dryline. However, most guidance shows minimal
    inhibition along the dryline and at least isolated storm
    development, perhaps aided by some nocturnal low-level jet increase
    during the evening. Any supercells which develop will pose a threat
    for all severe hazards including the potential for strong tornadoes.

    ..Bentley.. 04/26/2025

    $$
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