Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Oct 13 2023 19:46:42 AWUS01 KWNH 131946 FFGMPD ILZ000-IAZ000-140100- Mesoscale Precipitation Discussion 1148 NWS Weather Prediction Center College Park MD 346 PM EDT Fri Oct 13 2023 Areas affected...North-central to East/Southeast Iowa... Concerning...Heavy rainfall...Flash flooding possible Valid 131945Z - 140100Z SUMMARY...Potential for slow moving, nearly stationary cells along the frontal boundary may support 1.5+"/hr rates with localized totals of 2-3". If ideally overlapping with areas of recent rainfall over the last few days, a low-end localized incident or two of flash flooding is considered possible into this evening. DISCUSSION...A well defined deep layer cyclone continues to slowly shift eastward across the Plains today, with the surface low centering across IA. GOES-E WV suite and RAP analysis denotes main core of the upper-low remains toward the SW allowing for favorable DPVA across the region allowing for a new surface low to center near DSM while the cold front continues to press eastward elongating the occluded front more west to eastward through the evening. The warm sector has remained cloudy for much of the day, limiting insolation for increased instability today, yet solid southeasterly moisture flux/isentropic ascent across the boundaries supports 500-750 J/kg of MUCAPE from North-central IA across to southeast IA. Strong directional low level convergence has started to spark development along the cold front and along the length of the occluded front with strongest cells toward Pocahontas county with shallow-topped cells reaching -45C.=20 Moisture flux is not a strong as yesterday, but overall confluence is providing ample moisture enhanced by isallobaric inflow in proximity to rotating low-topped supercells. Deep layer steering is near zero along points through the occlusion axis as the upper-level core slides eastward, this will allow for slow to occasionally stationary cell motions allowing for 1-2 hours of localized duration either by repeating updraft/downdraft cores or a single cell sitting locally. This will allow for 1.5"/hr rates to potentially total to locally 2-3" totals. While the vast majority of Iowa as been dry recently, there are still places particularly further northwest that have seen recent rains (last day or so) and reduced soil capacity and FFG values. As such, a spot or two of FFG exceedance is possible, though cells are likely to exhaust the weak to moderate local instability within 1-2 hours as well. As such, the threat will start toward the northwest and shift eastward as the environment matures and the pivot/intersection of the triple-point shifts eastward with time. As such, an incident or two of low-end flash flooding is considered possible. Note: As cell development expands southward along the cold front=20 into MO and far S IA, cells are likely to be faster moving initially, though should slow as they reach the stationary front increasing localized spin and reducing forward cell motions through the late evening across eastern and southeastern IA.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5GgvINti8mM0cHtkwOlK1-1B2adq5YjHYFvCk4Ygu-mAnSgBTjzvR-8lJShKvgzhQl-t= NG-X9HvnXjudGG6gD7rtNkE$ for graphic product... ATTN...WFO...DMX...DVN...FSD... ATTN...RFC...MBRFC...NCRFC...NWC... LAT...LON 43229447 42429268 41749081 41139083 40989128=20 41069202 41219284 41569340 42619483 43119514=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .