Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 14 2025 21:27:01 AWUS01 KWNH 142126 FFGMPD KSZ000-NEZ000-150200- Mesoscale Precipitation Discussion 1086 NWS Weather Prediction Center College Park MD 526 PM EDT Sun Sep 14 2025 Areas affected...South-Central Nebraska...Adj Northwest Kansas... Concerning...Heavy rainfall...Flash flooding possible Valid 142130Z - 150200Z SUMMARY...Very slow moving thunderstorms capable of 1.5"/hr with possible short-term mergers up to 2"/hr locally may result in scattered 2-4" totals over the next few hours before eventual increased propagation eastward. DISCUSSION...GOES-E WV suite shows core of mid-level closed low over the southern Sand Hills of Nebraska, with a smaller scale vorticity center rotating around the northern into the northwest quadrant of the larger parent. This has sharpened the southern base of the larger scale center, allowing for early afternoon clearing to enhanced insolation and increase broader pool of unstable air with narrow pool of 2000 J/kg CAPE be maintained across south-central Nebraska, along and east of the slow moving frontal zone. With bulk of stronger mid-level forcing and solid eastern side meridional jet, the unstable air south of the Sand Hills still has sufficient moisture angled back toward a weak surface inflection near McCook. Tds in the mid 60s and total PWat values of 1.25 to 1.4" fluxed on slightly backed surface to boundary layer flow has maintained solid deep layer moisture flux convergence for isolated cells (southwest Custer county over the last few hours) to start increasing in coverage, expanding into far northwest KS. Hourly rates of 1.5"/hr are likely and with very slow cell motions nearly directly under the steering flow axis, shows only very slow eastward propagation over the next few hours. As such, localized totals of 2-4" are becoming more probable, given slow motions and remaining instability/moisture pool downstream.=20=20 Limiting factor toward flash flooding is, typical of the region, soil conditions being near the Sand Hills. However, lower FFG south of the main Hills region through the Platte River Valley and across into N KS are 1.5"/hr and generally 2-2.5"/3hrs; given area is in prolonged drought with 0-40 cm soil saturation ratios below 10%, the top portions may have become a bit more hydrophobic, and given intensity of rates, may result in increased runoff and possible incidents of localized flash flooding. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8_b5T0SXqTS89SLz4voo1SPwFglBjbJ3oDM0DNN0FtBhAwfsXU4v67guPn3hTcr_BhZo= b8LHzZCmWIdTm_6KCMzV5IY$ for graphic product... ATTN...WFO...GID...GLD...LBF... ATTN...RFC...KRF...NWC... LAT...LON 41859888 41659855 40579862 39569922 39420057=20 40000109 40710098 41180063 41390032 41779966=20 =20=20=20=20=20=20=20=20=20=20=20=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .