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Mesoscale Discussion 0457
NWS Storm Prediction Center Norman OK
0248 PM CDT Tue Apr 12 2022

Areas affected...northeast NE...southeast SD...extreme southwest MN
and northwest IA

Concerning...Severe potential...Tornado Watch likely 

Valid 121948Z - 122115Z

Probability of Watch Issuance...95 percent

SUMMARY...c*nvective initiation is expected by around 21-23z. A
tornado watch will likely be needed in the next hour or so. Severe
thunderstorms capable of large hail, damaging gusts and a few
tornadoes are possible.

DISCUSSION...A surface low is located near the central NE/SD border
as of 19z. A warm front was noted in surface analysis arcing from
the low across northeast NE into southern IA. Meanwhile, the surface
cold front was located across central NE and rapidly approaching the
surface dryline just a few counties to the east. Increasing cumulus
has been noted in visible satellite imagery along the dryline and
across the warm sector to the east across northeast NE. The cumulus
along the dryline has shown modest vertical development where
capping is likely less than further east. As the warm front
continues to lift northward and better quality boundary-layer
moisture works northward in conjunction with strong large-scale
ascent, convection is expected to develop near the triple point by
21-23z. 

Initial convection across southeast SD into southwest MN to near the
NE/IA border may be elevated near/just to the cold side of the warm
front, with a better-quality warm sector remaining quite narrow from
near the MO River into northwest IA. Fast storm motion toward the
northeast could result in these storms rapidly moving away from the
better warm sector as they mature. Nevertheless, strong vertical
shear, steepening midlevel lapse rates and sufficient instability
should support organized supercells capable of large hail and
perhaps strong gusts. Any storm that develops in the better warm
sector or that can anchor to the warm front will access better
low-level shear and see an increased risk for tornado development.
Furthermore, any storm that develops further south along the cold
front/dryline in NE may be higher-based, posing a threat for large
hail and damaging gusts. If any dryline convection persists eastward
into better moisture, these cells also could beco*e surface-based
within the better-quality warm sector with a corresponding increase
in tornado potential. With time into the evening, more linear
convective development is expected near/east of the MO River as the
cold front surges east.

..Leitman/Thompson.. 04/12/2022

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DMX...FSD...OAX...GID...LBF...

LAT...LON   41549539 41399573 41339619 41349690 41479756 41739842
            41849871 42049888 42289887 42589887 43009859 43379823
            43699759 43769701 43769620 43719575 43569542 43219526
            42669516 42089517 41749523 41549539