Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 13 2023 03:08:09 AWUS01 KWNH 130308 FFGMPD SDZ000-NDZ000-130905- Mesoscale Precipitation Discussion 0281 NWS Weather Prediction Center College Park MD 1106 PM EDT Fri May 12 2023 Areas affected...Western SD through Central ND Concerning...Heavy rainfall...Flash flooding possible Valid 130305Z - 130905Z SUMMARY...Additional heavy rains wrapping west across areas of western SD and through much of central ND may result in areas of runoff problems and localized flash flooding overnight. DISCUSSION...Very moist and modestly unstable easterly flow continues to wrap west up across the Northern Plains this evening around the north side of a strong and slow-moving deep layer low pressure system over central NE. This coupled with persistent large scale ascent/forcing over the region continues to help drive multiple rounds of heavy showers and thunderstorms. The latest radar imagery shows the greatest concentration of convection impacting areas from western SD through central ND where there has already been as much as 3 to 5+ inches of rain over the last 24 to 36 hours. Given the slow movement of the deep low center over central NE, and the deeper layer easterly moisture transport regime that is in place, the threat of heavy rainfall will continue through the night. In fact, PWs across the region are already anomalously high with values running 2 to 2.5 standard deviations above normal, and the latest RAP guidance actually shows an increase in an easterly low-level jet overnight with 850 mb flow increasing to 30 to 40+ kts. MUCAPE values of as much as 500 to 750 J/kg are still pooled up across the region this evening, and this coupled with the efficient moisture transport pattern and large scale ascent should still favor areas of convection with heavy rainfall rates that may reach 1 to 1.5 inches/hour. Areas of western SD through central ND have received as much as 3 to 5 inches of rain over the last 24 to 36 hours, and this has led to very moist if not saturated soil conditions. Streamflows are running high across many areas based off the latest USGS analysis, and the 00Z RFC-based gridded FFG values are locally very low and suggestive of highly sensitive soil conditions. The 00Z HREF suite of guidance suggests as much as 2 to 3 additional inches of rain locally overnight along an axis from western SD into central ND. These additional amounts coupled with the sensitive antecedent conditions will foster concerns for areas of runoff problems and a localized threat of flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6YXeku8llsab-peAQ4LY3sznXIMDOT7o4tWKnyCpwUyeqymABkjYtqORENfXzhHXaJIb= anGZpe669aubmLyqskCsKVQ$ for graphic product... ATTN...WFO...ABR...BIS...FGF...UNR... ATTN...RFC...MBRFC...NCRFC...NWC... LAT...LON 48239914 47689831 46909837 46259927 45090035=20 43490117 43020211 43240336 44110399 45270379=20 46570301 47570204 48170068=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .