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AGUS74 KWCO 081248
HMDNWC

National Hydrologic Discussion - EXPERIMENTAL
NWS National Water Center - Tuscaloosa AL
648 AM CST MON DEC 8 2025

.Update...

Minimal expansion of the Limited Impacts area was done in southern WA to
expand the selections from the Yakima area to Kennewick to account for the
slight increase in the riverine flood threat in that area. Otherwise, the
anticipated considerable flooding threats continue across the western
foothills of the Cascades (WA) to Puget Sound. Rain and snowmelt is still
anticipated to cause localized flooding issues across northern ID into
western MT this week as well.

//JEC

Previous Discussion as Follows...

Considerable flooding expected, with landslides possible across portions of
the Pacific Northwest beginning late Monday and will continue through the
week...Rain and snowmelt may generate urban and small stream flooding
across portions of the Northern Rockies this week...

.Pacific Northwest...
A series of frontal systems will bring periods of heavy rainfall through at
least mid-week across western WA and OR with considerable river flooding
and widespread urban and small stream flooding expected. The flooding
impacts will be greatest on Monday night through Wednesday of next week
when the heaviest rainfall (daily totals of 2 - 5", locally up to 7") are
expected. Soils are saturated and daily rainfall through the week will
sufficiently prime the hydrologic environment. Due to the saturated soils,
landslides in the steep or mountainous terrain are possible mid-week as
heavy rainfall lingers across the region. Widespread minor to scattered
major river flooding is forecast with rapid rises beginning to occur late
Monday evening, particularly in the foothills of the Cascades and will
continue through the end of the week. Many of the rivers and streams are
forecast to experience multiple peaks throughout the week as multiple
rounds of rainfall move across the basins. While the magnitude and extent
of responses continues to fluctuate somewhat due to the timing of the
event, confidence in Considerable flooding impacts remains high.

.Northern Rockies...
Multiple rounds of rainfall and snowmelt may generate urban and small
stream flooding across portions of northern ID and southwestern MT Monday
night through Thursday. A Limited impacts area was added across this region
given an issuance of a flood watch and potentially significant amounts of
SWE loss (up to 2") over the next several days.

//JDP

Additional National Water Center products are available at
www.weather.gov/owp/operations

$$