####018003242#### AGUS74 KWCO 201503 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 1015 AM CDT SAT APR 20 2024 .Synopsis... Potential for renewed river flooding and isolated flooding impacts in Eastern Texas and the Lower Mississippi Valley... Snowmelt induced elevated flows and river flooding in the Great Basin and Intermountain West... Potential for flooding impacts continues for Puerto Rico and the USVI and is winding down for portions of Alaska... .Discussion... .Eastern Texas and the Lower Mississippi Valley... Heavy rainfall (2 - 4") across portions of eastern TX, northern LA, and central MS today and tonight will bring a threat for new and renewed river flooding as well as isolated flash, urban, and small stream flooding impacts. Top layer soils across eastern TX have dried somewhat (40-65% 0-10 cm RSM, NASA SPoRT), but are wetter across northern LA and central MS (55-80% RSM). Mid-layer soils (10-40 cm) are similar to the top layer soils as far as saturation levels. Some rivers in the area, like the Neches (TX), Sabine (TX/LA), and Big Black (MS), remain in minor to moderate flood stage, and streamflows across the area are above to much above normal (USGS). Considering the antecedent soil conditions, all flooding modes will be possible. New and renewed minor river flooding is possible in upper portions of the Trinity (TX), Neches/Angelina, Brazos/Navasota (TX), San Jacinto (TX), and Sabine river basins, but the rainfall should not significantly affect the ongoing river flooding on the lower portions of the Neches and Sabine rivers in southeast TX/southwest LA. Flash and urban flooding will also be a concern across these regions, especially if/where training convection occurs, and small stream flooding will become more likely as the event progresses. Significant rainfall is not expected in these areas through at least day 6 (Thu), which should allow for recessions on rivers to begin or continue early next week. .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. The Portneuf River at Pocatello, ID is expected to rise above moderate flood stage next week, and the Owyhee River (NV) is forecast to slowly rise above minor flood stage over the next several days. .Puerto Rico and the USVI... The threat for isolated flooding impacts, rapid river rises, and mudslides in steep terrain will continue over the next several days for Puerto Rico as a wet and unstable pattern persists. Though the convection that occurs may not be widespread, wet to saturated soils and elevated streamflows in place suggest that any rainfall that occurs could produce flooding impacts. Urban flooding impacts are also possible for the USVI. .Alaska... Localized minor flooding of small streams and creeks will remain possible across Kodiak Island this morning as light to moderate rainfall continues to fall on saturated soils. Land and rock slides are also possible. //Watson $$