SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0212 AM CDT Wed Jul 27 2022
Valid 271200Z - 281200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE OZARKS EASTWARD TO THE MID-ATLANTIC...AND IN PARTS OF THE
CENTRAL HIGH PLAINS...
CORRECTED FOR GENERAL THUNDERSTORM LINES
...SUMMARY...
Thunderstorms associated with marginally severe wind gusts and hail
will be possible today from parts of the Ozarks eastward to the
Mid-Atlantic, and across parts of the central High Plains.
...Ozarks/Mid Mississippi Valley/Ohio and Tennessee Valleys/Southern
Appalachians/Mid-Atlantic...
A mid-level cyclonic flow pattern will be in place today across much
of the north-central U.S., with westerly mid-level flow located from
near the Mississippi River to the Atlantic coast. At the surface, a
very moist airmass will be in place from the Ozarks eastward to the
Mid-Atlantic, where surface dewpoints will generally be in the upper
60s and lower 70s F. As surface temperatures warm, moderate
instability is expected to develop in areas that largely remain free
of morning convection. In response to increasing instability,
thunderstorm coverage will likely increase during the afternoon,
with the greatest convective coverage located near pre-existing
outflow boundaries and along corridors of enhanced low-level
convergence. As low-level lapse rates become steep during the mid to
late afternoon, an isolated wind-damage threat should develop.
However, the greatest deep-layer shear is forecast to remain well to
the north of an east-to-west axis of moderate instability,
suggesting that any severe threat should remain marginal.
...Central High Plains...
Northwest mid-level flow will be in place today across the central
and northern High Plains. At the surface, southeasterly flow across
the central High Plains will help maintain an axis of maximized
low-level moisture from Kansas northwestward into western Nebraska.
Surface dewpoints along this corridor should be mostly in the 60s F.
This will contribute to moderate instability this afternoon, with
MLCAPE likely reaching the 1500 to 2500 J/kg range. Due to
increasing instability, widely scattered thunderstorms will develop
in the higher terrain from eastern Wyoming southward into
north-central Colorado. Other more isolated storms will develop
farther east across the central High Plains. In addition to moderate
instability, forecast soundings this afternoon in the central High
Plains have 0-6 km shear in the 40 to 50 knot range, which is mostly
be due to speed shear in the mid-levels. This should be enough for
an isolated wind damage and hail threat. However, lapse rates at
mid-levels are forecast to remain relatively weak, suggesting any
severe threat should remain marginal.
..Broyles/Weinman.. 07/27/2022
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