####018002515#### AGUS74 KWCO 221512 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 1015 AM CDT MON APR 22 2024 .Synopsis... Continued threat of flooding impacts in Puerto Rico... Potential for flooding impacts later this week in the Central Plains and Mid-Mississippi Valley... Elevated flows associated with snowmelt in the Great Basin and Intermountain West... .Discussion... .Puerto Rico... The threat for isolated flooding impacts, rapid river rises, and mudslides in steep terrain will continue at least through day 5 (Fri) for Puerto Rico as a wet and unstable weather pattern persists. Wet to saturated soils and elevated streamflows suggest that any rainfall that occurs could produce flooding impacts. Urban flooding impacts are also possible for the USVI over the same period. .Central Plains and Mid-Mississippi Valley... There is potential for flooding impacts starting day 4 (Thu) and continuing into early next week as periods of convection and locally heavy rainfall move through the region. The GFS and NBM-forced National Water Model (NWM) are both signaling small stream responses across portions of southern MN, IA, WI, IL, MO, and AR starting days 4 - 7, but as the event progresses and conditions become more saturated there is potential for more widespread flooding impacts, supported by the GFS and NBM-forced NWM signaling peak flow arrival times in the days 8 - 10 range. In southern WI and northern IL rivers are still receding from recent flooding, and streamflows are above climatological normals (USGS), increasing confidence in potential flooding impacts in this region. GFS and NBM QPF are reasonable in comparison to WPCs QPF guidance, increasing confidence that widespread small stream response may be possible late this week into next week. Potential training and higher rain rates will be the main drivers of impacts, and mostly dry antecedent conditions will likely mitigate initial hydrologic response. .Great Basin and Intermountain West... Elevated flows on area rivers, streams, and creeks will persist as mid to high-elevation snowpack continues to melt out (SNODAS). The Portneuf River at Pocatello, ID is expected to rise above major flood stage this weekend, and the Owyhee River (NV) is forecast to slowly rise above minor flood stage over the next several days. //Ayala $$