Mesoscale Discussion 1898
Issued: · Valid: –
Summary
Far east-central Iowa and northern Illinois may experience severe thunderstorms with large hail and damaging wind gusts this afternoon.
Product Text
000 ACUS11 KWNS 101747 SWOMCD SPC MCD 101747 ILZ000-IAZ000-102015- Mesoscale Discussion 1898 NWS Storm Prediction Center Norman OK 1247 PM CDT Mon Aug 10 2026 Areas affected...Far east-central IA and northern IL Concerning...Severe potential...Watch possible Valid 101747Z - 102015Z Probability of Watch Issuance...40 percent SUMMARY...Portions of far east-central Iowa into northern Illinois are being monitored for some increase in severe-thunderstorm potential this afternoon. If sustained storms can evolve, severe wind gusts and large hail will both be possible. DISCUSSION...The latest surface analysis and visible satellite imagery indicate a W/E-oriented stationary boundary extending from east-central IA across northern IL. The earlier 12Z ILX sounding sampled robust capping at the base of the EML, though temperatures are warming into the lower/middle 80s amid upper 70s dewpoints, and continued heating should further erode inhibition. Steep midlevel lapse rates accompanying the EML atop the rich PBL moisture is yielding strong to locally extreme surface-based buoyancy along the boundary. Isolated thunderstorms are evolving along the boundary in far east-central IA, where surface convergence is maximized. While remaining inhibition and generally weak large-scale forcing for ascent cast uncertainty on the longevity of this activity and the development of additional storms this afternoon, the aforementioned buoyancy and around 30-40 kt of effective shear will conditionally support organized storms including supercells. Any sustained storms will pose a risk of large hail and severe wind gusts. Currently, confidence in sustained storms is highest over eastern IA and vicinity, where some influence of large-scale forcing for ascent preceding an approaching midlevel wave is evident. The need for a watch is uncertain, though convective and environmental trends are being monitored. ..Weinman/Hart.. 08/10/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...DVN... LAT...LON 41148980 41199035 41359106 41569136 41939136 42289095 42419004 42388864 42238813 41778774 41178801 41118859 41148980 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