Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jun 25 2025 06:58:19 AWUS01 KWNH 250657 FFGMPD IAZ000-NEZ000-SDZ000-251255- Mesoscale Precipitation Discussion 0510 NWS Weather Prediction Center College Park MD 255 AM EDT Wed Jun 25 2025 Areas affected...Central and Eastern NE...Western and Central IA Concerning...Heavy rainfall...Flash flooding possible Valid 250655Z - 251255Z SUMMARY...Multiple rounds of heavy showers and thunderstorms going through the early morning hours may produce sufficient rainfall for isolated to scattered areas of flash flooding. DISCUSSION...A shortwave impulse along with an attendant wave of low pressure along a front will continue to advance east going through the early morning hours and will drive a relative broad area of heavy shower and thunderstorm activity. Strong warm air advection/isentropic ascent with the aid of a southwest low-level jet of 30 to 40+ kts continues to surge poleward over a pre-existing outflow boundary across northern KS and northern MO and into closer proximity of the aforementioned front which extends across central to northeast NE and through north-central IA. This is yielding persistent moisture and instability transport ahead of the surface low and is favoring an elongated axis of elevated convection. MUCAPE values are on the order of 500 to 1000+ J/kg, with PWs that are locally 1.75 to 2 inches. These are generally in the 90th to 95th percentile of climatology and are helping to favor high rainfall rates of 1.5 to 2 inches/hour with the stronger convective cells. Over the next several hours going through the early morning time frame, there should continue to be bands of heavy showers and thunderstorms advancing gradually off to the east and northeast across central to eastern NE and into western and central IA as the upstream shortwave energy and low center arrives. The low-level jet is forecast by the RAP guidance to gradually veer a bit with some additional strengthening of it at least through the predawn hours. This may favor some localized backbuilding and training of convection in time. The 00Z HREF and 18Z REFS data have some differences with respect to the placement of the heaviest rainfall over the next 3 to 6 hours, with the HREF axis south of the REFS, but they both support additional high rainfall rates and some storm totals going through 12Z (7AM CDT) that could reach 3 to 5 inches where more focused areas of cell-training occur. FFG values are generally rather high across most of the MPD area, but the HREF/REFS consensus shows some 20 to 40 percent probabilities of seeing the 3-hour FFG values exceeded and especially across western and central IA. As a result, the thinking is that there may be some concerns for isolated to scattered areas of flash flooding going through the early morning hours. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_oKyAqScDqt4nFYQ3Q1tv50_ylXgVLh6WSbgbMqCwDfRvlNMsufw54Lt2qTva8pj6ST6= sWLdWQ7l9ZF7b9wVXa-uqX0$ for graphic product... ATTN...WFO...DMX...FSD...GID...LBF...OAX... ATTN...RFC...KRF...MSR...NWC... LAT...LON 42999530 42999372 42529261 41799244 41299320=20 40849516 40599696 40599859 40869923 41539922=20 42279829 42819659=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .