ACUS11 KWNS 120938
SWOMCD
SPC MCD 120937
ILZ000-IAZ000-NEZ000-121030-

Mesoscale Discussion 1947
NWS Storm Prediction Center Norman OK
0437 AM CDT Wed Aug 12 2026

Areas affected...parts of eastern Nebraska...central and southern
Iowa

Concerning...Severe Thunderstorm Watch 573...

Valid 120937Z - 121030Z

The severe weather threat for Severe Thunderstorm Watch 573
continues.

SUMMARY...Strong to severe surface gusts remain possible, mainly
northwest through north of Omaha, perhaps into the Omaha area,
through 5-6 AM CDT. New thunderstorm development, including an
evolving cluster or two, appears possible across central/southern
Iowa through 6-8 AM, accompanied by a risk for severe hail and
perhaps gradually increasing potential for strong to severe surface
gusts. Trends will be monitored for the possibility of a downstream
severe weather watch.

DISCUSSION...Likely due to the presence of substantive mid-level
inhibition and weak low-level forcing for ascent, the initially
intense cluster of storms has undergone notable weakening the past
couple of hours. However, a notable 2-hourly surface pressure rise
on the order of 5-6 mb, within the evolving cold pool across the
O'Neil into Norfolk vicinity, has been maintained near/beneath the
remnant MCV, and may continue to be accompanied by stronger surface
gusts at least another hour or two, near/northwest through north of
Omaha.

Otherwise, the east-southeastward propagating convectively augmented perturbation has contributed to some southward suppression of the
elevated mixed-layer plume, and the lower-level baroclinic zone
along which the deeper boundary-layer moisture is concentrated.
Forcing for ascent associated with low-level warm advection
downstream of the perturbation is beginning to support some ongoing
increase in thunderstorm development near/north of I-80 across
central Iowa. Closer to a 20-40 kt west-southwesterly 850 mb jet
axis, guidance suggests a further increase in thunderstorm
development is probable through 11-13Z. Given potential inflow of
seasonably moist air supportive of most unstable CAPE at least on
the order of 2000+ J/kg, the evolution of another vigorous upscale
growing cluster appears possible, eventually becoming accompanied by
increasing risk for strong to severe surface gusts.

..Kerr.. 08/12/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!7Za6xwrPCm0sUxEJrBNFbibO0v1vZBAp1uS2vAcTQD5vYxGrBcQ7-DNprV_fZcYmxo4SocEatJpvVCGpo3VumsKVcm4$ for graphic product...

ATTN...WFO...DVN...DMX...FSD...OAX...

LAT...LON 40679409 40999551 41239633 41429698 41859669 42439671
42269530 42169440 42309296 41809138 41209088 40839162
40999310 40679409

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


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