Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jun 29 2023 20:03:50 AWUS01 KWNH 292003 FFGMPD NEZ000-SDZ000-COZ000-WYZ000-300130- Mesoscale Precipitation Discussion 0604 NWS Weather Prediction Center College Park MD 403 PM EDT Thu Jun 29 2023 Areas affected...Eastern WY...Southwest SD...Western NEB...Northeastern CO... Concerning...Heavy rainfall...Flash flooding possible Valid 292000Z - 300130Z SUMMARY...Supercells will start becoming capable of intense rain-rates (up to 1.5-2"/hr) crossing areas of above normal precipitation, posing widely scattered risk for flash flooding incidents through late evening. DISCUSSION...GOES-E WV suite denotes the northern Central High Plains of E WY/N CO are within a favorable upper-level pattern for broad scale ascent in the northeast quadrant of a weakening mid-level trof. Increasingly favorable upper-level divergence is starting to overspread the area, increasing low level/upslope inflow to the region with typical cyclogenesis in the lee of the Laramie Range. Solid surface/low level moisture flux is pumping well above average moisture with Tds in the mid to upper 50s into the higher terrain, converging along higher terrain with mountain circulation developing across the E WY and the Black Hills. As noted by MCD and Tornado Watch issued by SPC, vertical shear is more than sufficient for rotating updrafts/supercell structures with strong updrafts fed by unstable environment with MLCAPE of 1000-1500 J/kg. This will be key for cell motion and moisture flux convergence as individual cells mature over the next few hours. The deep layer moisture and strengthening moisture flux convergence (responding to isallobaric flow near supercell updrafts) should allow for rates of 1.5"/hr occasionally reaching 2"/hr. Deep layer mean steering will be generally 10-20kts (stronger to the south and east). Additionally, right moving cells/Bunkers propagation vectors may also slow forward motions allowing for some increase duration for localized stripes of 2-3", particularly after 21-22z, when localized mid-level drier profiles will become saturated through depth, reducing evaporative loss with the first few up/down draft cycles in the maturing supercells.=20 AHPS 14-day anomalies remain well above normal in the 300-600% range across much of the region suggesting saturated upper to mid-level soils making them a bit more hydrophobic to these higher intense rain-rates increasing run-off. Much of the area of concern have hourly FFG of 2" or lower. So widely scattered to scattered incidents of flash flooding are considered possible through the evening hours. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5HUMvyuujk8LSrbnjRdrh9WHpqrdYxskK6NfC6o5JXTwHn42UjhqwY9JtXxOK6Z3XmZ3= qbvDd1Fpv4albcgM6-fZkx8$ for graphic product... ATTN...WFO...BOU...CYS...LBF...RIW...UNR... ATTN...RFC...MBRFC...NWC... LAT...LON 44540573 44520422 44360302 43700250 43280245=20 42930247 41820277 41250231 40570269 39890357=20 40110492 41760591 43270726 44320687=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) .