Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jun 10 2023 01:19:25 AWUS01 KWNH 100119 FFGMPD SDZ000-100617- Mesoscale Precipitation Discussion 0453 NWS Weather Prediction Center College Park MD 918 PM EDT Fri Jun 09 2023 Areas affected...Central and Western SD Concerning...Heavy rainfall...Flash flooding possible Valid 100117Z - 100617Z Summary...Slow moving convection may pose an isolated to scattered flash flood risk over the next several hours across portions of central and western South Dakota. Discussion...Across portions of central and western SD slow moving convection is ongoing along an axis of enhanced lower level convergence near a surface trough and ahead of southward dropping cold front. Shear profiles are pretty weak, but strong upper level diffluence is noted across the region...likely allowing cells to persist/organize a bit more than the weak shear would otherwise allow. In the lower levels an area of low pressure over western SD is likely enhancing convergence...and it is the persistence of this convergence combined with the mid/upper forcing that will support some slow moving convection across the area for the next several hours. Activity is currently slow moving and exhibiting some backbuilding/training characteristics as cells build into the ongoing convection within the low level easterly flow. MLCAPE is currently around 1500-2000 J/KG within this inflow region, which should support several more hours of convection that will only slowly progress eastward. Thereafter eroding instability should result in a gradual weakening trend, with the cold front pushing south of the region as well. The 18z HREF neighborhood probabilities of 3"+ are over 40%, and EAS probabilities of 1" are 25-35%. This supports the idea of localized amounts exceeding 3" across central/western SD, with the elevated EAS probabilities indicating some organization of this heavy rain. Amounts of this magnitude are also supported by recent HRRR runs and MRMS QPE estimates. The HREF probabilities seem a bit displaced to the north of reality, while the 23z HRRR is doing a better job (although possibly a bit too far south). While this region has not been as wet over the past couple weeks as MT, isolated to scattered FFG exceedance is still expected, which may result in some flash flood impacts over the next few hours. Chenard ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_U3HQNYULB1QQniwCsDR1VQdxGuw2KwVAqTddWu_qXUWOl3qj6nlpu7t-olA9qEgsMgF= Zwxno7TU2p_vp8eAjFOT9PI$ for graphic product... ATTN...WFO...ABR...UNR... ATTN...RFC...MBRFC...NWC... LAT...LON 45410305 45300250 45020134 44780043 44609968=20 44359945 43739963 43390045 43460123 44210231=20 44640289 45220323=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) .