MD 2007 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF SOUTHERN MINNESOTA INTO FAR NORTHERN IOWA
Mesoscale Discussion 2007
NWS Storm Prediction Center Norman OK
0823 PM CDT Wed Aug 16 2023
Areas affected…portions of southern Minnesota into far northern
Iowa
Concerning…Severe potential…Watch unlikely
Valid 170123Z – 170300Z
Probability of Watch Issuance…20 percent
SUMMARY…Thunderstorms may pose an isolated severe risk for hail
and or a few strong wind gusts this evening. A WW is not
anticipated.
DISCUSSION…As of 0115 UTC, regional radar analysis showed isolated
thunderstorm developing ahead of a southeastward moving cold front
over parts of southern/southwestern MN. Ahead of the front, surface
temperatures in the low 80s were supporting moderate buoyancy around
2000 J/kg of MLCAPE from the 00z MPX sounding. While unstable,
low-level capping was also observed, suggesting storms may be
elevated above the surface, or only realizing part of the
thermodynamic profile. Regardless, shear profiles are quite strong,
with 50-60 kt of effective shear sufficient for organized storms,
including supercells. The strongest storms may be capable of
isolated hail and a few strong/damaging outflow gusts for a couple
of hours this evening.
Confidence in the evolution of the severe risk is low, and related
mainly to uncertainties about the thermodynamic environment. Thus
far, storms have remained closely tied to the cold front, likely
aided by frontal circulations in forcing ascent through the
low-level stable layer. This trend appears likely to continue, with
updrafts located along the advancing front. This would tend to favor
undercutting and a transition to elevated convection with time.
Farther east, cooler temperatures and higher inhibition are also
less favorable for near-surface based convection. Thus, a small
window (next 1-2 hours) may exist for isolated hail and perhaps a
few damaging gusts if the more organized storms can remain along the
front this evening. However, given the uncertainties and the
relatively confined severe risk, a new watch appears unlikely.
..Lyons/Guyer.. 08/17/2023
…Please see www.spc.noaa.gov for graphic product…
ATTN…WFO…ARX…MPX…DMX…FSD…
LAT…LON 44699241 44359224 43859242 43569270 43389325 43299374
43269419 43299462 43359497 43469522 43609543 43839552
44009519 44249452 44629396 45039338 44899282 44699241
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