SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Tue Jun 21 2022
Valid 212000Z - 221200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHEAST KANSAS
TO SOUTHEAST IOWA...
...SUMMARY...
Isolated to scattered damaging winds and isolated large hail will be
possible from northeast Kansas to southeast Iowa between about 5 to
10 PM CDT.
A broad cu field has developed from northwest Missouri into
north-central Wisconsin along and ahead of a cold front in the
region. Thus far, only occasional robust convective attempts have
occurred, and failed across Wisconsin. Expect this trend to continue
given the veered surface flow ahead of the cold front across the
region. However, if any storms can develop, the environment is
favorable for strong, rotating updrafts with MLCAPE around 2500 J/kg
and ~35 knots of effective shear per SPC mesoanalysis.
Farther southwest, more northerly post-frontal winds have resulted
in stronger convergence which should lead to more convective
coverage than farther north. Between 1930-20Z, a more confined line
of cumulus has developed across northeast Kansas per visible
satellite. This likely represents the frontal location and should
provide the focus for thunderstorm development this evening. Latest
HRRR solutions indicate thunderstorm development between 22-23Z
which seems appropriate based on satellite trends. Multicell
clusters remain the expected storm mode with a primary threat for
damaging winds.
..Bentley.. 06/21/2022
.PREV DISCUSSION... /ISSUED 1127 AM CDT Tue Jun 21 2022/
...Central KS to IA/IL/WI border area...
A corridor of boundary-layer dewpoints in the upper 60s to lower 70s
will be maintained immediately ahead of a cold front, trailing off
with western extent into KS where it intersects the dryline. Large
buoyancy with MLCAPE from 2000-3500 J/kg will likely develop amid
hot surface temperatures warming into the mid to upper 90s from
northeast KS northeastward, with lower buoyancy but a deeper-mixed
boundary layer into central KS. While the entire region will remain
well removed from the direct influence of a shortwave trough over
southern Manitoba moving into northwest Ontario, an MCV over NM will
drift towards the south-central High Plains. A belt of confluent
mid-level southerlies ahead of this feature transitioning to modest
west-southwesterlies with northeast extent on the periphery of
stronger flow over the north-central states may provide sufficient
deep-layer shear for multicell clustering with convection that
develops along the front. This appears most probable from northeast
KS into southeast IA where steep low-level lapse rates and DCAPE to
near 1500 J/kg would favor isolated to perhaps scattered downbursts
producing 50-70 mph wind gusts during the early evening. Isolated
quarter to golf ball-sized hail should be a secondary threat in
terms of coverage and most likely with initial robust updrafts.
...Eastern Upper/northern Lower MI into eastern WI...
Low-level convergence is consistently forecast to remain weak along
this portion of the cold front pushing east across the region, with
largely veered winds. As such, signals for convective development
are sparse across morning guidance. Nevertheless, stronger
deep-layer flow along with a plume of steep mid-level lapse rates
will support a conditionally favorable setup for isolated severe
hail and wind.
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