####018003522#### AGUS74 KWCO 161515 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 915 AM CST FRI FEB 16 2024 .Synopsis... Flooding impacts return to California this weekend...Potential for localized flooding impacts in Florida this weekend...River flooding continues across Texas, Lower Mississippi Valley, and the Southeast... Flash and urban flooding impacts across American Samoa through Monday... .Discussion... .California... Flash, urban, and small stream flooding impacts are possible on days 2 - 5 (Sat - Tue) across the region as a series of storm systems bring periods of moderate to heavy rainfall (5 day totals of 2 - 5", WPC). Antecedent conditions are primed for hydrologic responses, particularly in areas along the CA coast, given above normal rainfall over the past two weeks (4 - 8"+ departures from normal, RFC QPE). The expected rainfall, combined with vulnerable antecedent conditions, will likely diminish current in-soil and/or channel storage capacity, leading to immediate runoff into area streams and urban areas and subsequent flooding. River rises and isolated minor river flooding is also possible, especially across the North Coast and in the Sacramento Valley. Guidance from both the GFS and the NBM-forced National Water Model (NWM) has been consistently suggesting the potential for scattered small stream responses along the CA Coast, the Central Valley, and across portions of the Transverse Ranges, with peak flows primarily occurring on days 4 - 5 (Sun - Mon). Corresponding annual exceedance probabilities (AEPs), per the High Flow Magnitude forecast, are primarily near/at the high water threshold (1 - 1.6 ARI) suggesting that most rises (at least initially), should remain within channel however, some significant rises (AEPs down to 2%) are noted across the Central Valley and the Central Coast, including some streams in the Sacramento and San Francisco Bay metro areas, indicating some higher risk of flooding impacts in these areas. The greatest risk of flooding will be in urban areas and in streams draining steep terrain. The magnitude of the flooding remains somewhat uncertain, but more robust responses cannot be ruled out in areas of heavier rainfall. .Florida... A low pressure system is expected to bring periods of moderate to locally heavy rainfall this weekend increasing the potential for localized flash and urban flooding impacts for portions of east-central and southern FL. Most of the state remains relatively dry, and in combination with karst topography and sandy soils, will help mitigate any widespread flood impacts and limit the threat to urbanized and flood-prone locations. .East Texas, Lower Mississippi Valley, and the Southeast... Ongoing minor to moderate river flooding will persist through the weekend across these regions. While most locations have crested, some slower responding rivers will continue to slowly rise over the next several days as flows route downstream. With no significant precipitation expected across these areas through at least day 7 (Thu), recessions will continue unimpeded with many locations falling out of flood stage by early next week. .American Samoa... Flash and urban flooding impacts are possible through day 4 (Mon) due to periods of heavy rainfall. //Freeman $$