Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun May 28 2023 21:19:26 AWUS01 KWNH 282119 FFGMPD NEZ000-SDZ000-MTZ000-WYZ000-290130- Mesoscale Precipitation Discussion 0369 NWS Weather Prediction Center College Park MD 518 PM EDT Sun May 28 2023 Areas affected...Northeast WY...Southeast MT...Western SD...Far Northwest NEB... Concerning...Heavy rainfall...Flash flooding possible Valid 282120Z - 290130Z SUMMARY...Slow moving thunderstorms with 1-1.5"/hr rates crossing low FFG pose possible localized flash flooding conditions. DISCUSSION...GOES-E WV depicts a NW-SE elongated mid-level shortwave across the Black Hills with convergent apex of the wave located favorably within entrance of 50-60kt 3H jet streak shifting toward the north-northwest across E MT. This has been providing a broad area of ascent with solid divergent outflow to maintain weak low level convergence and updraft maintenance both to cells along the western portions of the Black Hills as well as other banded features across Northeast WY, though stronger northwesterly flow has allowed for some greater cell motions for those. The area remains on the western periphery of enhanced deep layer moisture through the southern Plains, and while instability and moisture has been reduced compared to yesterday, there remains ample deep layer moisture for some moderate rainfall rates and small hail generation, both contributing to increased runoff on the ground. Hourly rates up to 1-1.5"/hr and slow motions may account for some localized totals up to 2" over the next few hours, particularly closer to the shortwave/weaker mid-level steering flow. AHPS precipitation anomalies are well above normal due to recent heavy rains, with 7 day values over 300-400% and 200-300% of normal for 2 weeks, suggesting fairly saturated ground conditions supporting FFG values less than 1.5"/3hr across NE WY and western portions of the Black Hills. As such, increased run-off is probable and scattered incidents of flash flooding are considered possible over the next 3-4hrs before the instability exhausted and cells propagate on outflow seeking remaining instability further east (where FFG values are higher) Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-IsAx2l1BbrXB7uObmQk3MaXTNoxGWIS4T2Tj39WkV33p_RC0oKGaiys5FLWY2B9Rais= 7tB0kqvQnfj8Rzw4vjNjhD4$ for graphic product... ATTN...WFO...BYZ...CYS...UNR... ATTN...RFC...MBRFC...NWC... LAT...LON 45950604 45950519 45780444 45500395 44900364=20 44070314 43230274 42620339 42800464 43670554=20 43930566 44460583 44730603 44870633 45020672=20 45430688 45750670=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) .