Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 30 2023 01:36:01 AWUS01 KWNH 300135 FFGMPD NEZ000-COZ000-WYZ000-300700- Mesoscale Precipitation Discussion 0605 NWS Weather Prediction Center College Park MD 934 PM EDT Thu Jun 29 2023 Areas affected...Southeast WY...Western NEB...Northeast CO... Concerning...Heavy rainfall...Flash flooding possible Valid 300130Z - 300700Z SUMMARY...A few more hours of favorable development that may track through areas that experienced heavy rainfall earlier this evening maintaining a low-end flash flooding risk into the early overnight period. DISCUSSION...A mature MCS continues to track fairly quickly eastward into the core of the Sand Hills of Northern Nebraska in the coming hours. A few cells developing along an effective warm frontal-like boundary are remaining stationary prior to the main oncoming thunderstorms. Spots of intense rainfall with up to 3" are possible with the combination of the precursory cells and the main developing squall line. Flash flooding is not likely, with exception of urban centers like Valentine and towns that dot NEB rt 2. However, there does remain a potential for scattered flash flooding incidents upstream across SE WY, W NEB into NE CO, where heavy rainfall has already fallen and intersection with newer developing cells. GOES-E WV suite shows a weak positive tilt trough angled across WY into UT with broad southwesterly flow across the CO Rockies. Weak impulses emerging from a standing wave/jet are shifting out the higher terrain into increasingly diffluent flow across NE CO with responding low level flow still remaining strong for upslope flow. Two axes of increasing development were noted in satellite and RADAR; strong moisture convergence along the tail end of the outflow reinforced convergence boundary extends from Morrill county back across Laramie county into the southern Laramie Range. Pooled moisture and about 45 to 60 degrees of surface convergence intersecting favorably to the boundary as initiated new convection as far back as N and S Albany county. Deep layer steering flow is not perfectly parallel to the convergence boundary, but may still provide a track for repeating, including across areas affected by earlier rounds this evening. Rainfall efficiency is expected to be slightly lower but 1-1.5"/hr rates/totals across saturated grounds may induce localized flash flooding. Additionally, further south, a similarly oriented line of convection through Adams county, CO has seen a similar backing of flow from the southeast at 15-20kts with mid-50s Tds supporting ongoing heavy rainfall. Additionally, new updrafts have formed across the Front Range and are beginning to mature with some better low level moisture flux. A few more hours of development along with a similar training profile will maintain a risk of localized flash flooding conditions with 1-1.5" totals (perhaps near 2" with the most mature cell along the leading edge. Lower FFG within the South Platte River Valley are also a bit more prone to these rates with a slightly above average probability of exceedence in the next few hours. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-StDCUQiCaf5aJSR_M3NM-0_59txLG54gWU2VOsO5GpMf6u4lhQQVw-yGJ-mU07YNklp= FfR98vUXBk3r-CWBqRfH33c$ for graphic product... ATTN...WFO...BOU...CYS...GLD...LBF... ATTN...RFC...MBRFC...NWC... LAT...LON 42910111 42859974 42269958 41140074 40400175=20 39970243 39560356 39440547 40450548 41140565=20 41770611 42290572 42610485 42850301=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) .