Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 09 2023 19:03:23 AWUS01 KWNH 091903 FFGMPD SDZ000-NDZ000-MTZ000-WYZ000-100100- Mesoscale Precipitation Discussion 0451 NWS Weather Prediction Center College Park MD 302 PM EDT Fri Jun 09 2023 Areas affected...Northern High Plains Concerning...Heavy rainfall...Flash flooding possible Valid 091900Z - 100100Z SUMMARY...Thunderstorms developing along and north of a stalled frontal boundary may produce rainfall rates up to 2"/hr. Slow moving storms may produce flash flooding, particularly in areas with sensitive soils. DISCUSSION...GOES-16 satellite imagery showed a bubbling field of towering cumulus along a differential heating boundary in both southern ND and northern SD, as well as thunderstorms over the Black Hills. As daytime heating continues, residual CIN should run its course and additional storms are likely to form in the following areas: along a surface trough that extends as far north as southeast MT, a differential heating area residing in northern SD, and along the stalled front near the SD/NE border. MLCAPE will be on the order of 1,000-2,000 J/kg and PWs rising to 1.25" north of the area of low pressure and approach 1.5" in central SD by late afternoon. Mean storm motions are quite weak (hovering around 5 knots, 10 knots at their fastest speeds). There is little vertical wind shear present, which will make pulse storms the primary type of thunderstorm activity. However, there will be plenty of storms to be had as forward propagating outflows act as triggers for new convection into the evening hours. Latest 12Z HREF depicts a strong signal for 6-hr QPF > 10-yr ARI in western and central SD with probabilities as high as 70% between 18-00Z and 00-06Z. How the latter of those six hour blocks comes to fruition will be dependent upon storm mode and where additional surface based triggers are. Current 1-hr FFGs are as low as 1-1.5", but much of west-central SD is closer to 2". The available instability and moisture content would support up to 1.5"/hr, which could challenge FFGs in parts of western/northern SD and southern ND. Some portions of central SD also dealt with periods of rain earlier this morning. Given these factors, thunderstorms this afternoon and into this evening may cause flash flooding. Poor drainage areas, locations with more sensitive soils, and in more developed/urbanized communities are most susceptible to possible flash flooding. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_t4ydT9GH_QLjRnjA61AI8eeCSVa1vEwPdhywOsFjoKDDj_8C68JNoXgvIlvkG1jx2Qw= IW6o2AJ7LUyrt_m6cpuQUV8$ for graphic product... ATTN...WFO...ABR...BIS...BYZ...FSD...UNR... ATTN...RFC...MBRFC...NWC... LAT...LON 46910308 46840170 46180045 45409970 44709926=20 44019899 43379924 43210048 43390179 43460319=20 43710395 44500450 45420422 46390393=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) .