Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri May 12 2023 18:15:00 AWUS01 KWNH 121814 FFGMPD MOZ000-IAZ000-NEZ000-SDZ000-130013- Mesoscale Precipitation Discussion 0274 NWS Weather Prediction Center College Park MD 214 PM EDT Fri May 12 2023 Areas affected...much of Nebraska into far southern South Dakota and far western Iowa Concerning...Heavy rainfall...Flash flooding possible Valid 121813Z - 130013Z Summary...Thunderstorms are training across central Nebraska just east of the center of mid/upper low in the area. Areas of flash flooding are possible as convective coverage expands during the afternoon. Summary...A band of persistent thunderstorm activity continues along and just east of a stout mid/upper low over southwestern Nebraska. Individual cells are moving westward within the band, while the overall axis of heavier rainfall was moving only slowly northward. The storms are benefitting from strong low-level easterly flow, which was maintaining an axis of 1000-1500 J/kg MLCAPE in the pre-convective environment while also contributing to 35-40 knots of deep shear to support cellular organization.=20 Within the heavier rainfall band, areas of 1+ inch/hr were begnning to materialize, with local exceedence of FFG noted across parts of Custer, Valley, and Greeley counties per MRMS data. Models/observations suggest that this convective band will continue to expand northward, although the flash flood threat should be limited with northward extent as FFG thresholds increase into the 3-4 inch/hr range across the Sand Hills. Of somewhat greater concern is the potential for any eastward expansion of thunderstorm development across eastern/northeastern Nebraska, which appears likely as insolation is resulting in strengthening instability and deepening convective towers generally along an axis from BUB to LNK. As storms mature in eastern Nebraska, areas of 1-2 inch/hr rain rates should materialize and locally threaten FFG thresholds of 1.5-2.5 inch/hr across the area. The flash flood threat will increase in tandem with this anticipated expansion of convective coverage through 00Z. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9USz-HkAKiCtZ5u1SeZS_0ptJLlQdGSL-A0clXn1wQG-9yBDFA_5JpJDl8DWnczT8rwK= 8nruy7n3Q_07PhKW6IoBk7M$ for graphic product... ATTN...WFO...DMX...EAX...FSD...GID...LBF...OAX...UNR... ATTN...RFC...MBRFC...NWC... LAT...LON 43679864 43439701 42509592 41299543 40509555=20 40509641 40479729 41049853 41199965 41360069=20 41910082 42440064 43279998=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) .