AGUS74 KWCO 141948 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 300 PM CDT TUE APR 14 2026 ...Considerable flooding impacts ongoing in the Mariana Islands... Considerable rain- and snowmelt-driven small stream and river flooding in the Upper Great Lakes with additional flooding into the Middle Mississippi Valley possible... .Mariana Islands... No change this afternoon for the Mariana Islands as a Considerable flood category remains as Typhoon Sinlaku moves through the region, bringing widespread heavy rainfall. Periods of torrential rain and embedded thunderstorms through Wednesday are expected to produce significant flash flooding, with current forecasts indicating the highest rainfall totals of 10 - 18" near the center of the storm. The storm is currently tracking through Tinian and Saipan, but Guam will be impacted by the outer rain bands that are expected to drop an additional 5 - 10" of rain. This prolonged rainfall will continue to saturate soils, increasing the potential for mudslides, especially across central and southern Guam. Substantial coastal impacts are also expected across the CNMI. .Upper Great Lakes into the Middle Mississippi Valley... Considerable river and small stream flooding is ongoing and forecast across the Upper Peninsula and northern portions of Lower Michigan through the week due to a combination of rainfall and rapid snowmelt. Warm temperatures, combined with multiple rounds of rainfall and saturated soils, will enhance runoff, leading to additional rises on small streams and rivers across the region. Additionally, widespread moderate to major river flooding is likely, some of which is expected to breach record stages. Elsewhere in the region, minor river flooding is ongoing with new and renewed river small streams and flooding possible through the week. Continued rainfall has helped to prime the hydrologic environment, increasing the potential for additional responses from rainfall later in the week. .Puerto Rico and USVI... Due to diminishing rainfall, Puerto Rico and the USVI have been removed from the Flood Hazard Outlook. //Ducre Additional National Water Center products are available at www.weather.gov/owp/operations $$