LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Sat Jul 22 2023
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WESTERN AND CENTRAL KANSAS...
...SUMMARY...
Thunderstorms associated with strong wind gusts and hail will be
possible today across parts of the Southeast, Great Plains, Upper
Midwest and Arizona.
...Southeast...
An upper-level trough will move eastward across the Ohio and
Tennessee Valleys today, as a cold front advances slowly southward
across the Gulf Coast states. Near and to the south of the front,
surface dewpoints will be in the lower to mid 70s F. As surface
temperatures warm in this moist airmass, moderate instability will
likely develop. Scattered thunderstorms are expected to form along
and near an east-to-west axis of instability this afternoon.
Deep-layer shear is expected to be less than 30 knots in most areas,
suggesting that any severe threat will remain unorganized. As
low-level lapse rates steepen during the afternoon, the stronger
multicells could produce a marginal wind-damage threat. The storms
will move southeastward through the immediate coastal areas of
Alabama and the Florida Panhandle during the mid to late afternoon.
The threat could persist into the early evening across parts of
southern Georgia and southern South Carolina.
...Great Plains/Mid Missouri Valley/Upper Midwest...
Northwest mid-level flow will be in place today across the central
U.S., as a cold front moves southward through the central Plains.
Surface dewpoints ahead of the front near 60 F, will likely result
in a pocket of moderate instability across Kansas by afternoon.
Isolated to scattered thunderstorms will develop near the front and
move southward into the moderate instability. Forecast soundings at
21Z near and south of the instability axis in western Kansas suggest
supercells will be possible, with MLCAPE near 2500 J/kg, and 0-6 km
shear in the 35 to 40 knot range. This environment, combined with
low to mid-level lapse rates around 7.5 C/km will be favorable for
isolated large hail. Wind damage will also be possible, mainly as
cells mature during the late afternoon and early evening.
Further to the northeast across the mid Missouri Valley and Upper
Midwest, a relative narrow corridor of instability will likely
develop during the afternoon along and just ahead of the cold front.
Thunderstorms that form near the front will move south-southeastward
into the stronger instability during the late afternoon. A few of
these storms could produce hail and marginally severe wind gusts.
...Arizona...
A mid-level anticyclone will be in place today across much of the
Desert Southwest. At the surface, a relatively moist airmass will be
in place across southern Arizona, where MLCAPE is forecast to
increase into the 1000 to 1500 J/kg range. Thunderstorms appear
likely to form in the higher terrain of southwest New Mexico, and
move westward across southern Arizona late this afternoon and early
this evening. A hot and nearly dry adiabatic temperature profile
could contribute to strong downdraft accelerations with single and
multicell storms. Wind-damage is expected to be the primary threat,
with threat coverage remaining relatively low.
..Broyles/Bentley.. 07/22/2023
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