Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 15 2025 23:35:57 AWUS01 KWNH 152335 FFGMPD NDZ000-MTZ000-160535- Mesoscale Precipitation Discussion 0451 NWS Weather Prediction Center College Park MD 735 PM EDT Sun Jun 15 2025 Areas affected...Portions of Central and Eastern MT Concerning...Heavy rainfall...Flash flooding possible Valid 152335Z - 160535Z SUMMARY...Heavy showers and thunderstorms are expected to develop and grow upscale into a progressive convective complex this evening while advancing out across the MT High Plains. DISCUSSION...The late-day GOES-W visible satellite imagery shows convection initiating and expanding in coverage across central MT as a rather vigorous upstream shortwave trough approaches the region and interacts with an unstable boundary layer with MLCAPE values of 1500 to 2500 J/kg. Some MLCIN is still evident late this afternoon which may temper some of the initial stages of convective development, but as stronger forcing with the shortwave arrives and the low-level jet increases across southeast MT in close proximity to a developing wave of low pressure, there should be a considerable amount of upscale convective growth going into the evening hours. Supercell thunderstorms with notable severe weather hazards including large hail and damaging winds (please see SPC's WW #418 and recently issued MD #1305 for more details) may also be capable of producing sufficiently heavy enough rainfall rates and totals over the next several hours for there to be at least some isolated areas of flash flooding. The PWs across the region are near the 90th percentile of climatology, and with an increase in low-level moisture transport this evening, the rainfall rates may reach as high as 1 to 2 inches/hour. The environment this evening will be conducive for cell-mergers as the larger scale convective mass gradually takes on an MCS-related evolution and forward propagates downstream through eastern MT. Some rainfall totals of 2 to 4 inches will be possible as the event unfolds and convection locally becomes more concentrated, and this is supported by the 12Z/18Z HREF guidance. The HREF is also showing a corridor of rather high 1-hour and 3-hour FFG exceedance probabilities based on these totals. Therefore, the potential will exist over the next several hours for there to be at least some isolated areas of flash flooding in addition to the regional severe weather concerns. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4WxFmj--hot4-u_M4NgNv7Kfu7ddb83Dft7juoTw2mKNXuuAwzUTTvjH7pqx_k3wwhPl= 3-g8eAcmEcgN0416fMEqfAA$ for graphic product... ATTN...WFO...BIS...BYZ...GGW...TFX... ATTN...RFC...KRF...NWC... LAT...LON 48970768 48620591 48000473 47260400 46130407=20 45380530 45370690 45670859 46231010 46991078=20 47921055 48650945=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .