####018004608#### AGUS74 KWCO 271516 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 1015 AM CDT SAT APR 27 2024 .Synopsis... Considerable flooding impacts are possible this weekend across portions of the Central and Southern Plains into the Midwest, with flooding also possible in East Texas and the Lower MIssissippi River Valley... Flooding impacts continue in Puerto Rico... Snowmelt continues in the Great Basin and Intermountain West... .Discussion... .Central and Southern Plains into the Midwest... Considerable flooding impacts are possible today into day 2 (Sat - Sun) across portions of eastern OK, northwest AR, southeast KS, and southwest MO as multiple waves of showers and thunderstorms bring torrential rainfall to the region. Outside of this particular area, flooding impacts are possible through the weekend across much of these regions. The threat for flooding increases today as additional rounds of showers and storms track over the same regions. Past rainfall totals over the last 48 hours (MRMS), approximately 1 - 3+", have already fallen in regions mentioned and have generated minor to isolated moderate river flooding across portions of eastern KS and MO. These repeated rounds of storms will continue to diminish infiltration capacity and expected rainfall (2 - 4", locally higher) will immediately runoff into area creeks and streams, generating flooding impacts, some of which may be considerable. Additional river flooding is expected, as minor to moderate river flooding is now forecast across portions of OK, southeast KS, and southwest MO. Heavy rainfall today will likely worsen ongoing flooding and generate new flooding impacts, such as large areas of standing water in fields, along roadways and at low water crossings, overflowing of ditches and culverts, and flooding in areas of poor drainage. The latest guidance of the National Water Model (NWM) Short Range Forecast (SRF) is signaling scattered rapid-onset flooding probabilities (ROF) between 25 - 50% with locally higher amounts up to 75%. Annual exceedance probabilities (AEPs) are also scattered with most at 50% with local amounts near 2% in areas of southeast KS, south of Topeka. The most consistent signals from the NWM Medium Range Forecast (MRF) have been indicating ROF from eastern OK and AR to portions of eastern KS and much of MO. Corresponding AEPs are as low as 2% in areas of eastern OK, southeast KS, northern and eastern MO and northern AR, which suggests at least locally significant stream rises are possible, especially where convection trains or persists. .East Texas and the Lower Mississippi River Valley... Rain will return to the region on days 2 - 3 (Sun - Mon) and the primary concern for flooding impacts will be in areas across northeast TX, AR northeast LA and west MS. Some areas could see upwards of 2 - 4+" of rainfall (WPC). Soils are saturated through northeast TX and AR (NASA SPoRT) and streamflows are above normal (USGS) as basins continue to recover from previous rainfall events. While some rivers are still in recession others continue to rise, so new and renewed river flooding is a concern, as new minor to isolated moderate river flooding is now forecast across portions of northeast TX. Additional areas of river flooding are possible in areas of heavier rainfall. Outside of the river flooding threat, flash flooding and widespread small stream responses (NWM MRF) are expected. .Puerto Rico... Another day of moderate to locally heavy rainfall will continue to generate flash, urban and small stream flooding impacts through today. Soils are very saturated and streamflows are elevated. With that, rapid river rises and mudslides in areas of steep terrain are also possible. After a brief reprieve on day 3 (Mon), a wet pattern will return mid-next week. .Great Basin and Intermountain West... Elevated flows will continue along area rivers, creeks, and streams across portions of southern ID/UT and northern NV in response to mid-to-high elevation snowmelt. Periods of rainfall through today in areas of ID and UT may cause sharp rises in quick responding streams and creeks, especially in areas where prolonged rainfall materializes. The Portneuf River at Pocatello, ID, is expected to crest in moderate flood stage this weekend. //Kirkpatrick $$