LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Fri Aug 04 2023
Valid 041200Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
NORTHEAST AND CENTRAL PLAINS...
...SUMMARY...
Severe thunderstorms are possible across parts of the Northeast and
also the central High Plains this afternoon and evening, with a
threat of damaging wind and isolated hail. Additional strong storms
are possible along a broad arc from the central Plains to the
Southeast.
...Northeast...
A mid/upper-level cyclone is forecast to remain centered over Quebec
today, as small-scale vorticity maxima move through the attendant
trough across parts of the Northeast. A weak cold front will move
southeastward across the region this afternoon and evening. Moderate
destabilization will support scattered thunderstorm development
along/ahead of the front through the afternoon, with moderate
mid/upper-level flow resulting in sufficient effective shear for
some storm organization. Initial semi-discrete storms will be
capable of producing at least isolated hail and damaging gusts, with
some tendency for clustering and a transition to primarily a
damaging-wind threat by late afternoon/early evening. Some threat
may approach near-coastal areas before storms weaken later tonight.
...MO/AR into parts of the Southeast...
Multiple clusters of thunderstorms will likely be ongoing later this
morning from parts of MO/AR into the Southeast, as a west to
west-northwesterly low-level jet impinges upon an outflow-reinforced
baroclinic zone. These clusters may pose at least an isolated
damaging-wind threat as they move southeastward during the day, with
a somewhat greater coverage of wind damage possible in areas where
stronger preconvective diurnal heating/destabilization can occur.
Isolated hail also cannot be ruled out, especially where buoyancy is
stronger across parts of MO/AR. Storms may also intensify near a
remnant MCV across northern MO this afternoon and spread
southeastward this evening, with at least an isolated severe
wind/hail threat.
In general, rather weak deep-layer flow/shear will tend to limit
storm organization, and the most favored corridors for somewhat
greater damaging-wind potential (and possible eventual upgrade from
5% wind probabilities) will be dependent on mesoscale details that
remain unclear at this time.
...Central Plains...
Thunderstorm development is again expected across portions of the
central High Plains late this afternoon into this evening, within a
moderately unstable and modestly sheared environment. Storm coverage
may be somewhat greater from southwest SD into western NE, in closer
proximity to a persistent mid/upper-level trough, though isolated to
widely scattered development will be possible into parts of eastern
CO and western KS. With modest westerly flow aloft, effective shear
will likely remain in the 25-35 kt range (higher where winds are
locally backed), sufficient for a few strong multicells and perhaps
a marginal supercell or two. Large hail and localized severe gusts
are expected to be the primary threats.
Guidance varies regarding the extent (if any) of nocturnal low-level
jet intensification later tonight across the central Plains, which
will impact the potential for any organized upscale growth, but some
threat for isolated severe gusts could spread eastward somewhere
across the central Plains late tonight.
..Dean/Moore.. 08/04/2023
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