


Flash Flood Guidance
Issued by NWS
Issued by NWS
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646 AWUS01 KWNH 120221 FFGMPD ILZ000-MOZ000-120700- Mesoscale Precipitation Discussion 0653 NWS Weather Prediction Center College Park MD 1020 PM EDT Fri Jul 11 2025 Areas affected...Central Missouri to Central Illinois... Concerning...Heavy rainfall...Flash flooding possible Valid 120220Z - 120700Z SUMMARY...Diminishing flash flood threat as squall line begins to forward propagate. However, a few hours with ample moisture and remaining unstable air mass will support 2"+/hr rates and spots up to 3" and possible. DISCUSSION...GOES-E 10.3um IR and RADAR animations show the long mostly squall line is starting to show outflow boundary pressing southeastward, increasing perpendicular forward propagation reducing duration of heaviest rainfall and all but eliminating internal cells repeating along the squall axis. A small inflection in the line near Macon county, MO is has some increased intersection/mergers as northern edge is upstream developing or effectively back-building into the southern flank, generally near the highest remaining pool of unstable air which remains about 3500-4000 J/kg. This also matches with increased ageostrophic outflow given a small kink in the upper-level jet streak maximizing right entrance ascent profiles as well. Deep layer moisture axis is nearly aligned with the squall line and low level inflow is nearly parallel from 850mb with surface to 925kt inflow still fairly oblique in ascent angle too. Given the strength and available moisture, sub-hourly rates/totals over 2" will remain for a few more hours before slowly diminish as the squall moves into lower moisture over the Ozark Plateau and into southern IL. Backsheared mid-level shield precipitation will likely allow for additional moderate rainfall with spots of 2-3" totals over the next few hours; and while the FFG values are also increasing further south and east, isolated incidents of flash flooding remain possible though reducing with time. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...DVN...EAX...ILX...LSX...SGF... ATTN...RFC...KRF...MSR...NWC... LAT...LON 40998995 40968933 40648880 40238855 39598871 39058926 38688995 38429054 38049151 37929267 38469375 38839396 39219365 39959195 40429086