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 www.spc.noaa.gov 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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