Mesoscale Discussion 1965 NWS Storm Prediction Center Norman OK 0449 AM CDT Thu Aug 13 2026 Areas affected...parts of east central Nebraska into central/southwestern Iowa Concerning...Severe Thunderstorm Watch 580... Valid 130949Z - 131145Z The severe weather threat for Severe Thunderstorm Watch 580 continues. SUMMARY...The risk for strong to severe wind gusts continues with an organized cluster of storms moving along and north of the I-80 corridor into central Iowa through 6-7 AM CDT. Trends are continuing to be monitored for the possibility of an additional downstream severe weather watch. DISCUSSION...The relatively compact mesoscale convective system has been generally maintaining intensity and organization, based on latest radar, satellite and lightning data. Intense westerly rear inflow in excess of 80 kt, at least at mid-levels, persists to the southwest of a MCV now crossing the Missouri River near Tekamah, based on radar data from Des Moines. However, peak gusts reaching the surface have weakened based on recent surface observations. Still a gust to 48 kt was recorded at Tekamah, and given current convective trends, there remains potential for downward momentum transfer to contribute to strengthen strong to severe gusts near and north of the I-80 corridor into central Iowa over the next few hours. Stronger forcing for ascent associated with lower/mid-tropospheric warm advection is becoming focused to the rear/southwest of the convective system. As near-surface updraft inflow begins to emanate from a somewhat less moist/unstable air mass across and east of the Greater Des Moines vicinity, potential evolution becomes more uncertain. It is possible instability remains sufficient to maintain vigorous convective development near the eastward migrating MCV. Renewed strong thunderstorm development also might not be out of the question a bit farther to the south and west, closer to the nose of the lingering southerly low-level jet. ..Kerr.. 08/13/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...FSD...OAX... LAT...LON 42189574 42259506 42049382 41599344 41139316 40979384 40949479 40839545 40999609 41699545 42189574 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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