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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1257 AM CDT Fri Apr 22 2022

Valid 221200Z - 231200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL HIGH PLAINS...

...SUMMARY...
Severe thunderstorms are expected to develop across parts of the
Great Plains into Upper Midwest Friday from late this afternoon
through tonight. Supercell thunderstorms capable of all severe
hazards, including tornadoes and very large hail, are possible,
particularly from the Texas Panhandle into north-central Nebraska.

...Southern and Central High Plains...
A progressive upper-level trough will move quickly
east-northeastward across the Desert Southwest today, as a 80 to 100
knot mid-level jet rounds the base of the trough. The exit region of
the mid-level jet will overspread the southern and central High
Plains this afternoon, increasing large-scale ascent and
strengthening deep-layer shear. This along with a moist and unstable
airmass will make conditions favorable for severe storms.

At the surface, a low will rapidly deepen across northeastern
Colorado today as strong moisture advection occurs to the east of a
High Plains dryline. Surface dewpoints will increase into the upper
50s to lower 60s F by mid afternoon from the Texas Panhandle
northward across western Kansas into west-central Nebraska. This
will contribute to moderate destabilization as surface temperatures
warm during the day, with MLCAPE reaching the 2000 to 2500 J/kg
range. The capping inversion is forecast to weaken by late
afternoon, which will allow for rapid convective development along a
narrow corridor from the central Texas Panhandle north-northeastward
across western Kansas into central Nebraska. Thunderstorms will
quickly grow upscale early this evening, with multiple convective
clusters persisting into the mid to late evening.

In addition to the moderate instability, RAP forecast soundings
along the instability axis early this evening have gradually veering
winds with height in the low to mid-levels, with 0-6 km shear in the
35 to 45 knot range. 0-6 km shear is forecast to steadily increase
as the exit region of the mid-level jet overspreads the central
Plains during the evening. This along with 700-500 mb lapse rates in
the 7.5 to 8.5 C/km range will be very favorable for supercells with
large hail. Hailstones of greater than 2 inches in diameter will be
possible with the more intense supercell updrafts, from west Texas
into southwest Kansas, where instability and lapse rates are
forecast to be most favorable. As the low-level jet strengthens
during the early to mid evening, 0-3 km storm relative helicity will
beco*e increasingly favorable for tornadoes as well. Wind damage is
also expected with the stronger cells. The potential for wind damage
and hail could persist into the late evening, as the mid-level
system moves out into the central High Plains.

...Northern Plains/Mid Missouri Valley/Upper Midwest...
An upper-level trough will quickly move eastward through the Desert
Southwest today as a 80 to 100 knot mid-level jet moves through the
base of the trough. Moderate instability and strong deep-layer shear
will be in place by afternoon, making conditions favorable for
organized severe storms. At the surface, a low will rapidly deepen
across northeastern Colorado today, and move north-northeastward
into western Nebraska. A warm front extending eastward from the low
will advance northward across Nebraska this afternoon and into
southern South Dakota this evening. As low-level convergence
increases near and to the north of the surface low during the late
afternoon, convection will likely initiate and move
north-northeastward across northwestern Nebraska and southwestern
South Dakota. Convective coverage is expected to rapidly increase
across the northern Plains during the evening as the exit region of
the mid-level jet moves into the area from the southwest. The
current thinking is that a line of strong to severe storms will move
eastward through western Nebraska and western South Dakota during
the evening, with supercells developing ahead of the line further to
the east.

NAM Forecast soundings at Valentine, Nebraska near the peak of
instability early this evening have a loaded gun profile with MLCAPE
in the 2500 to 3000 J/kg range. This along with lapse rates
approaching 8.0 C/km in the 700 to 500 mb layer will be favorable
for supercells with large hail. In addition, hodographs are long and
looped with 0-3 km storm relative helicities near 400 m2/s2. This
will be favorable for tornadoes as well with the more dominant
cells, especially as the low-level jet ramps up quickly during the
early evening. Wind damage will also be possible. The threat should
persist through the evening and into the early overnight period as
storms move east-northeastward into the eastern Dakotas late in the
period.

Further east across the Upper Midwest, an isolated severe threat
could develop during the evening along the warm front. However, weak
instability should limit severe threat coverage. Hail and strong
gusty winds will be the primary threats.

..Broyles/Jirak.. 04/22/2022