Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 16 2025 05:58:35 AWUS01 KWNH 160556 FFGMPD SDZ000-NDZ000-MTZ000-161100- Mesoscale Precipitation Discussion 0454 NWS Weather Prediction Center College Park MD 156 AM EDT Mon Jun 16 2025 Areas affected...portions of southeastern MT into west-central ND and northwest SD Concerning...Heavy rainfall...Flash flooding likely Valid 160555Z - 161100Z Summary...Localized hourly totals of 1-2" to continue, resulting in short-term (3-4 hour) totals of 2-4" (with higher isolated totals possible). Isolated to scattered flash flooding likely (and may be locally considerable). Discussion...A forward propagating mesoscale convective system (MCS) and associated mesoscale convective vortex (MCV) are translating eastward from MT into ND/SD at this hour. While the strongest convection is currently ongoing in a sparse observational environment (due to a lack of surface observations and poor radar coverage with the MRMS radar quality index near 0, given surrounding radars scanning around ~20k feet AGL), GOES-East 1-min mesoscale sector imagery indicates persistent cold cloud tops with active overshooting tops (which are also apparent via MRMS with 30 dBZ echo tops persistently near ~60k feet). The mesoscale environment near and downstream of the MCS/MCV is characterized by ML CAPE of 1000-2000 J/kg, precipitable water values of 1.2-1.4" (between the 90th percentile and max moving average, per BIS sounding climatology), and significant deep layer (0-6 km) shear of 40-50 kts (also near the 90th percentile). Substantial differential divergence (850-250 mb) with a 25-35 kt low-level jet to the southwest (over central ND) providing moderate moisture transport and ample divergence aloft (via an idealized coupled right-entrance region and left exit region jet steaks) will continue to maintain an impressive MCS (with the aforementioned shear and instability combined with a 850-300 mb mean wind of 15-20 kts resulting in MCS maintenance probabilities of 60-70%). While accurate precipitation estimates are difficult to determine with the lack of quality near-surface radar data, the system has a history of localized 1-2" hourly totals (with some training/repeating of these amounts possible in the vicinity of the MCV). The 00z HREF members are in decent agreement going forward (0.5" exceedance 10-100 km neighborhood EAS probabilities of 30-45% through 09z), and more recent hourly runs of the HRRR and experimental RRFS are in even better agreement (generally indicating localized totals of 2-3", though some RRFS runs indicate isolated totals as high as 3-6"). Isolated to scattered instances of flash flooding are likely (with 40-km neighborhood HREF 3-hr FFG exceedance probs of 40-50%, which may be too low given RRFS output) and some flooding may be locally significant (as 3-hr 100-yr average recurrence interval QPF is indicating to be 2.5-3.0", having at least a 25% chance to be realized). Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9COJHjkJIl7eW_uD21W0Q_8eZF2s8_PmJuAuZOXECS95hFDNW4EEx6sbRUxWvbCBtlmx= x3GYaIBJ9FKeRGWo9LvpkBw$ for graphic product... ATTN...WFO...ABR...BIS...BYZ...GGW...UNR... ATTN...RFC...KRF...MSR...NWC... LAT...LON 48700285 48700169 47930053 47319979 46429941=20 45529958 45110147 45040319 45100527 45930532=20 46970485 47530439 47950358=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .