Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu May 11 2023 00:31:53 AWUS01 KWNH 110031 FFGMPD SDZ000-NDZ000-MTZ000-WYZ000-110530- Mesoscale Precipitation Discussion 0254 NWS Weather Prediction Center College Park MD 831 PM EDT Wed May 10 2023 Areas affected...Northeast WY...Far Southeast MT...Far Southwest ND...Far Northwest SD... Concerning...Heavy rainfall...Flash flooding possible Valid 110030Z - 110530Z SUMMARY...Persistent but stationary forcing to limit cell motions while increasing moisture flux initially before growing upscale into a larger complex later overnight. DISCUSSION...GOES-E WV suite depicts a broad cirrus shield within the northwestern apex of the larger scale ridge across much of WY into SE MT. Embedded are a few overshooting tops occasionally peaking below -55 to -60C with strong GLM and NLDN lightning clusters. Tds have risen into the low to upper 40s with an anomalous values in the 850-700mb with a strong gradient along the Laramie Range noted in the CIRA LPW. Further aloft, strong easterly flow shows a maxima in the 700-500 layer as well across east central WY into into central WY Valley resulting in well above normal total PWat Values between .5-.7" or about 2-2.5 standard deviations. However, the low level moisture flux convergence is very strong with 15-25kts of low level flow from the southeast and east intersecting a stationary front between BYG/GCC to CPR to RKS. Strong FGEN forcing has allowed for convective initiation through the evening with a few cells to be very slow moving saturating the local profile. Rain rates of 1-1.5"/hr are probable with those cells and while localized appear to have resulted in some localized enhanced MRMS Flash responses in Natrona county. While hail contamination is likely with the MRMS values, the actual localized totals are probable to still have enhanced values over 400 cfs indicative a possible localized flash flooding.=20 Recent trends also denote additional thunderstorm development/expansion across north and northeast WY into SE MT as stronger/better diffluence aloft approaches the area from the south and southeast and convergence maximizes along the stationary front. This is expected to increase low level flow and aid eastward propagation out of the terrain, while supporting upscale growth into one or two larger clusters/complexes. As initial evaporation saturates the profile, similar to the ongoing stationary cells, the overall area should become more conducive for rates of 1-1.5"/hr. Cell mergers and localized hang-ups due to storm scale flow/interactions may allow for this localized pockets of totals over 1.5-2". Given much of the area of concern have low 1hr FFG values, with most of the area at or below 2.5"/3hrs, localized flash flooding is becoming increasingly possible into the early overnight period. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_d4dOC2nkXcMpbWcpkPqrkj0JcRSOJjjngYYRzU8HVlKKNV-VlODBDIAzCdAlNx5P_N5= vACPvXoJ8G9f7DELm6JJAiA$ for graphic product... ATTN...WFO...BIS...BYZ...CYS...RIW...UNR... ATTN...RFC...MBRFC...NWC... LAT...LON 46550313 46120247 45500270 44430414 43150422=20 42120463 41950545 42480611 42990662 43200753=20 43690796 44400757 45720606 46400418=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) .