LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CDT Wed Jul 12 2023
Valid 121200Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
CENTRAL PLAINS INTO THE MIDWEST...
...SUMMARY...
Severe thunderstorms will be possible across much of Missouri,
Illinois, and adjacent portions of the central Plains and Midwest on
Wednesday. Damaging winds and large hail should be the main threats,
with some potential for significant (75+ mph) severe winds across
parts of Missouri and vicinity.
...Synopsis...
A strong shortwave trough will continue across the northern Plains
through this morning. Strong mid-level winds will be present across
parts of the central Plains into the Midwest. At the surface, a
boundary will be situated from Nebraska/Iowa becoming more diffuse
farther eastward into New England.
...Kansas/Missouri...
Convection is expected to be ongoing this morning in parts of
Nebraska and Iowa. Outflow from this convection will delimit the
northern edge of greater severe risk during the afternoon. To the
southwest, a frontal-wave cyclone will move east along the northern
baroclinic zone and push a cold front into central/western Kansas.
The convective outflow and cold front will serve as foci for
additional development during the afternoon. Strong heating of a
moist (upper 60s/low 70s dewpoints) airmass will promote strong
buoyancy (3000-3500 J/kg MLCAPE). Mid-level lapse rates and
low-level moisture will be less favorable with eastward extent to
some degree. Shear across the region will be relatively strong given
the strength of mid/upper-level winds for this time of year. Initial
storms will likely be supercellular and be capable of large to very
large hail. As upscale growth occurs, intense winds will be
possible, some in excess of 75 mph. A more organized wind threat may
occur wherever the buoyancy gradient is located. Enough uncertainty
still exists that an increase in unconditional severe wind
probabilities is not warranted.
...Midwest...
Greater forecast complexity exists for parts of Iowa into Illinois.
Convection will likely be ongoing in Iowa early this morning. The
overall strength of that activity is somewhat uncertain given a
likely more stabilized boundary layer by that time. Remnants of this
activity are expected to generally move eastward. Some
reintensification is possible from northeast Missouri into central
Illinois. However, more modest lapse rates aloft and slightly lower
low-level moisture (particularly farther east) should limit the
spatial extent of the severe risk with time. Strong/damaging winds
will be the primary risk, though isolated large hail is also
possible.
...Lower Great Lakes into New England...
Storms will be possible along the weak surface boundary during the
afternoon. Broad cyclonic flow aloft will provide sufficient shear
for marginally organized convection. Damaging winds will be the main
hazard from locally strong downbursts.
..Wendt/Thornton.. 07/12/2023
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