SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1240 AM CDT Sat Apr 23 2022
Valid 231200Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN
PLAINS/UPPER MISSISSIPPI VALLEY TO THE SOUTHERN PLAINS...
...SUMMARY...
Severe thunderstorms are possible Saturday through Saturday night in
a corridor from parts of the northern Plains/Upper Mississippi
Valley to the southern Great Plains. This will include a risk for
hail, damaging winds, and a few tornadoes.
...Northern Plains/Upper MS Valley...
Considerable amount of convection continues early this morning
across the northern/central High Plains ahead of a pronounced upper
trough ejecting across the Rockies. Latest model guidance suggests a
large area of mid-level height falls will overspread the
northern/central Plains with focused corridor of 180-210m 12hr falls
forecast across NE/SD through late afternoon. This feature will
dislodge a lee surface low over western NE which will track into
northeast SD by 18z, then southeast ND by 24/00z. Primary zone of
warm-advection convection has shifted well north of I-90 at 0530z
and lower 60s surface dew points are expected to hold across much of
the warm sector immediately ahead of the surface low. It appears
strong surface heating will contribute to strong low-level heating
across the central High Plains, extending into southeast SD by late
morning. With surface-3km lapse rates steepening by early afternoon,
a narrow wedge of destabilization is forecast ahead of the low
across eastern SD/southeast ND/western MN. Forecast soundings
exhibit weak inhibition within a strongly sheared environment, and
latest thinking is isolated supercells should develop between 17-18z
then race north-northeast. Large hail can be expected with this
activity along with some threat for wind and even a few tornadoes.
...Eastern KS/Southern Plains...
With the primary short-wave trough ejecting across northern
latitudes, trailing cold front should arc south-southwest across
central KS into the OK Panhandle by 24/00z with a notable dryline
likely mixing across western OK/northwest TX. This front is expected
to aid convection initially across western IA/southeast NE into
eastern KS by late afternoon. While large-scale forcing for ascent
will not be particularly significant south of KS, intense
post-dryline heating should remove inhibition for isolated
thunderstorms along the dryline by late afternoon. Forecast
soundings suggest this may occur between 22-23z and subsequent
movement would be northeast off the dryline toward I-35 during the
evening across OK. A few storms may also form farther southwest
along the boundary over northwest TX but coverage should be
considerably less. Although, several HREF members do develop more
convection across west TX by late evening, possibly in response to
delayed weak height falls into this portion of the southern Plains
late. Hail should be the primary risk along with some wind, and even
a threat for a tornado or two.
..Darrow/Karstens.. 04/23/2022
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