Hydrometeorological Discussion
Issued by NWS Tuscaloosa, AL
Issued by NWS Tuscaloosa, AL
035 AGUS74 KWCO 261508 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 1008 AM CDT WED JUN 26 2024 .Synopsis... Additional rounds of rainfall in the Central Plains and the Upper and Middle Mississippi Valley... Flash flooding possible in the Four Corners region and Northeast...Snowmelt induced flooding continues in Alaska... .Discussion... .Central Plains and the Upper and Middle Mississippi Valley... Widespread moderate to major river flooding is ongoing and/or forecast across southeast SD, southern MN, and northern IA. Record flooding is ongoing and forecast along the Minnesota and Des Moines rivers. Much of the ongoing major river flooding is in recession, but as the flood wave routes downstream and additional rainfall is forecast, flooding impacts on main stem rivers, including the Mississippi and Missouri rivers, is still to come. Over the next three days, additional rainfall of 1 - 4" is forecast across eastern NE and KS, southern IA and northern MO, though the heaviest bullseye of QPF is currently forecast to be south of the worst of the ongoing flooding. This region received 1 - 3" (locally higher) of rain over the last 24 hours, saturating soils, especially in southern IA and northern MO (70 - 90% RSM, 0 - 10 cm RSM, NASA SPoRT). Additional rainfall in this region will likely be rapidly converted to runoff into streams, rivers, and low-lying areas. Streamflows in this region are around normal, though there are locations along the mainstem Mississippi River where major flooding is forecast. Within-bank rises to area streams are likely, and some localized flooding impacts are possible. Western IL is still on the drier side and should be able to absorb the rainfall, at least initially, without significant flooding impacts. Flash and urban flooding is possible anywhere heavy rainfall persists or storm training sets up. There is potential for locally heavy rainfall forecast day 6 (Mon) across MN and northern IA. This area will have some time to recover from ongoing impacts before this next event, but will need to be monitored closely, given the vulnerable antecedent conditions. .Four Corners... Moisture will persist over the region throughout the week, particularly in parts of NM, AZ, and western CO, leading to locally heavy rainfall and the potential for flash flooding. Areas that receive multiple rounds of rainfall are more susceptible to flooding impacts as soils reach saturation. The highest flood threat is in areas with recent burn scars, slot canyons, dry washes, and regions where training and more persistent storms occur. .Northeast... Isolated incidences of flash and urban flooding today and again on day 4 (Sat) are possible across the region as multiple frontal boundaries generate scattered showers and storms. Outside of urban areas, the Adirondacks and northern New England (VT/NH/ME) are most vulnerable to hydrologic responses given wet soils (60 - 75% RSM, 0 - 10 cm NASA SPoRT) from recent rainfall and terrain enhancement. Specifics in terms of placement and magnitude of potential flooding impacts still remain uncertain, and will be dependent on rainfall amounts and duration. .Alaska... Warming temperatures continue to cause snow and ice melt at high elevations, leading to rivers running high in areas across Southcentral AK. Minor flooding on the Chilkat River near Klukwan continues into early this week, with ample snow available to melt. Minor river flooding is expected on the Skwentna and Yentna Rivers through the week. Also, high water continues on the Nuyakuk River near Dillingham. //Ayala $$