LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0744 AM CDT Fri Aug 04 2023
Valid 041300Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE
NORTHEAST...MISSOURI...AND CENTRAL HIGH PLAINS...
...SUMMARY...
Scattered severe thunderstorms are possible across parts of the
Northeast, Missouri, and the central High Plains later today through
early tonight.
...Northeast...
An upper trough will remain anchored over Quebec today, as an
embedded mid-level impulse shifts east from the Upper Saint Lawrence
Valley across New England. To the southwest of this impulse, pockets
of more robust insolation will result in a moderately buoyant air
mass from PA across the Hudson Valley into southern New England with
MLCAPE of 1000-2000 J/kg. Scattered thunderstorms will develop
towards midday north of the larger buoyancy plume, and become
widespread during the afternoon as they spread east-southeast. While
low-level flow will be weak, the presence of strong mid to upper
winds coincident with peak instability will favor mid-level updraft
rotation in several semi-discrete cells centered on northeast PA to
southern NH. Isolated severe hail will be possible, with a tendency
for clustering primarily supporting a damaging-wind threat from
mid-afternoon to early evening. Clusters should approach coastal
areas and tend to weaken near/just after sunset.
...MO vicinity...
An MCV over north-central KS attendant to a decaying MCS will drift
east into northern MO this afternoon. Convective outflow has spread
into eastern KS through northern OK, but should slow its progression
as the cold pool further wanes this morning. A high PW air mass
characterized by low to mid 70s surface dew points ahead of this
outflow to the persistent northwest/southeast baroclinic zone across
MO should support a confined corridor of large buoyancy at peak
heating. Most 00Z HREF members and recent HRRR guidance indicate
redevelopment of thunderstorms near the MCV by late afternoon, with
activity potentially intensifying towards the larger CAPE air mass
in central to southern MO. Adequate signal exists to upgrade both
the tornado and wind probabilities, but with moderate uncertainty on
the overall spatial extent and intensity of these threats.
...Central High Plains...
To the south of a low-amplitude mid-level impulse drifting over the
northern High Plains, convergence along a surface trough from
southwest SD to northeast CO should strengthen this afternoon.
Isolated to scattered thunderstorms are expected along this trough
with a moderately unstable and modest deep-layer shear environment
ahead of it. Those should be sufficient for multicell clusters and a
few transient supercell structures capable of producing mainly
isolated large hail and severe gusts. The lack of a stronger
nocturnal low-level jet intensification and increasing MLCIN over
the lower Great Plains will probably limit the severe threat to a
marginal one tonight.
...Southeast...
A broad swath of thunderstorm clusters are ongoing from parts of GA
to southeast MO along a northwest/southeast-oriented baroclinic
zone. One of these clusters may grow upscale later this morning into
the afternoon, closer to the larger buoyancy impinging from the
Mid-South and Lower MS Valley. In general, weak deep-layer
flow/shear will tend to limit storm-scale organization, and the most
favored corridors for somewhat greater damaging-wind potential will
be dependent on mesoscale details that remain unclear at this time.
..Grams/Broyles.. 08/04/2023
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