Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Sep 16 2025 21:21:56 AWUS01 KWNH 162121 FFGMPD KSZ000-NEZ000-COZ000-170317- Mesoscale Precipitation Discussion 1095 NWS Weather Prediction Center College Park MD 521 PM EDT Tue Sep 16 2025 Areas affected...southwestern Nebraska, northwestern Kansas Concerning...Heavy rainfall...Flash flooding possible Valid 162117Z - 170317Z Summary...Slow-moving convection continues to deepen across the discussion area, with areas of 1+ inch/hr rates noted beneath the strongest storms. Areas of flash flooding are possible through 03Z/10p CDT. Discussion...Scattered thunderstorms were increasing in coverage across the discussion area over the past hour. The storms appear to be focused along low-level convergence near an apparent weak boundary (wind fields shifting from southerly to easterly along an axis from near Holyoke, CO to near Hebron, NE. Along this boundary, 1-1.2 inch PW values, 2000+ J/kg MLCAPE, and steep lapse rates aloft were allowing for intense updrafts and locally heavy rainfall. Most storms were drifting northward amid modest deep layer flow, although a cell near McCook, NE has anchored along this boundary and slowed substantially. Rain rates appear to be at a peak near this storm (exceeding 1.5 inch/hr), and it cannot be ruled out that other storms exhibit this same behavior in the short term. Storms appear to be aided by ascent aloft associated with a weak mid-levels shortwave trough evident in water vapor imagery over northeastern Colorado. This wave will take several hours to traverse the region, and ascent from this feature should continue interacting with the strong instability in place to keep fostering deep convective development. Southerly 850mb flow into the area should continue to maintain the pool of instability. Scattered, slow-moving storms are expected to continue through at least 03Z/10p CDT this evening across the region. Local rain rates exceeding 1.5 inches/hr should readily exceed FFG thresholds.=20 Flash flooding is probable on at least an isolated basis. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4jmi6-Km_tH2OSDdTYFMa-kPDpy9lp1iuYSZIfeFlCsbinrPGu9HfxOBM43lS8NPCTsn= ZCIu9LpzWoZSH2_y_KkSZM0$ for graphic product... ATTN...WFO...BOU...DDC...GID...GLD...ICT...LBF... ATTN...RFC...KRF...NWC... LAT...LON 41370236 40999943 39999801 38879816 39580196=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) .