ACUS11 KWNS 231929
SWOMCD
SPC MCD 231928=20
SDZ000-NEZ000-WYZ000-232130-

Mesoscale Discussion 1220
NWS Storm Prediction Center Norman OK
0228 PM CDT Fri Jun 23 2023

Areas affected...Portions of eastern WY...southwestern SD...and the
NE Panhandle

Concerning...Severe potential...Watch likely=20

Valid 231928Z - 232130Z

Probability of Watch Issuance...80 percent

SUMMARY...A few tornadoes, very large hail, and severe wind gusts
appear increasingly likely this afternoon as robust thunderstorms
develop. Watch issuance is likely.

DISCUSSION...Convection has begun to develop along both the Laramie
and Bighorn Mountains in WY this afternoon as large-scale ascent
associated with a shortwave trough overspreads the northern High
Plains. Additional robust thunderstorms, including a couple of
supercells, are ongoing across central WY in a weakly unstable but
strongly sheared environment. The airmass downstream of this
activity across eastern WY into southwestern SD and the NE Panhandle
is slowly destabilizing. But, persistent low-level cloud cover has
hampered daytime heating across these areas to some extent. Still,
very steep (8 C/km or greater) mid-level lapse rates have overspread
the northern High Plains, and around 1500-2500 J/kg of MLCAPE is
already present based on 19Z mesoanalysis estimates.

Deep-layer shear of 40-50 kt will easily support supercell
structures with any convection that can be sustained.
East-southeasterly low-level upslope flow should continue across
southeastern WY and the NE Panhandle along/near a surface warm
front/outflow boundary. Better tornado potential may be focused over
this area through the rest of the afternoon into the early evening,
as the backed and slightly stronger low-level flow should promote
sufficient low-level shear for updraft rotation and a few tornadoes.
Very large hail (2+ inches in diameter) will also be a threat with
supercells given the favorable mid-level lapse rates and
strengthening southwesterly flow at mid/upper levels.

The severe wind threat will probably remain fairly isolated this
afternoon, before eventually increasing by this evening as one or
more clusters form with a strengthening south-southeasterly
low-level jet. Given the increasing severe threat anticipated this
afternoon, watch issuance will likely be needed within the next
couple of hours.

..Gleason/Guyer.. 06/23/2023

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!5gQqKi_a1Q8CKu_PBoy7-fEyA5NPQAgBFm0-EKbDo_Xips185-8To2DGVKEVd0keM6FXePiLL= Le2h_Lb4o7oK6WC8is$ for graphic product...

ATTN...WFO...UNR...CYS...

LAT...LON 42180544 42890598 44750583 44690471 43980361 42770292
41660294 41090334 41120503 42180544=20


=3D =3D =3D
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