Hydrologic Outlook
Hydrologic Outlook
ORZ049-050-502-503-505>507-509-WAZ029-030-521>523-230115-
Hydrologic Outlook
National Weather Service Pendleton OR
324 PM PST Fri Feb 21 2025
...MODERATE RAIN AND SNOWMELT DUE TO WARMING TEMPERATURES WILL LEAD
TO RISES ON STREAMS AND RIVERS THROUGH MONDAY AFTERNOON...
Synopsis: Rain and high mountain snow from and multiple systems this
weekend and early next week will lead to rising water levels on area
streams and rivers. Rainfall amounts of 2 to 5 inches are expected
in the Cascades and 1 to 3 inches in the eastern Oregon mountains.
In addition, temperatures will be rising to the 40s and lower 50s in
the mountains which will lead to snow melt adding even more water to
area rivers and streams. The National Water Model is highlighting
high water on numerous smaller streams and creeks, but streamflow
amounts are generally only slightly higher than high water
thresholds.
What: Precipitation fed by an atmospheric river and snow melt due to
warmer temperatures this weekend into early next week will lead to
rises on area creeks, streams and rivers. Rivers are low enough so
that most rivers will remain below bankfull. However, the Walla
Walla River at Touchet and the Naches River at Cliffdell are
expected to exceed bankfull late Sunday night before receding Monday
and Tuesday. Another concern will be rapid rises on smaller streams
and creeks due to heavier downpours and snowmelt. This could lead to
debris flows on recent burn scars and over steep terrain.
The Walla Walla River at Touchet has a 44 percent chance of
exceeding bankfull but less than a 5 percent chance of reaching
minor flood stage. It is expected to reach bankfull late Sunday
evening and remain there through Tuesday morning.
The Naches River at Cliffdell has a 29 percent chance of exceeding
bankfull but less than a 5 percent chance of reaching minor flood
stage. It is expected to reach bankfull late Sunday evening and
remain there until dropping below bankfull Monday afternoon.
The Klickitat River at Pitt is forecast remain below bankfull, but
model probabilities give it a 13 percent chance of rising above
bankfull and a 9 percent chance of reaching minor flood stage. All
other river forecast points have a less than a 10 percent chance of
exceeding bankfull.
When: Rain will begin tonight and continue through Monday with the
heaviest rain expected Saturday night and Sunday.
Where: The Upper and Lower East Slopes of the Washington and Oregon
Cascades, The Simcoe Highlands, The Northern and Southern Blue
Mountains, The Blue Mountain Foothills of Washington and Oregon,
Wallowa County and the Grande Ronde Valley.
This Hydrologic Outlook will be updated as needed due to changing
conditions.
$$
GP
Hydrologic Outlook
IDC003-045-075-087-ORC001-025-045-231215-
Hydrologic Outlook
National Weather Service Boise ID
515 AM MST Sat Feb 22 2025 /415 AM PST Sat Feb 22 2025/
...RAIN AND LOW ELEVATION SNOWMELT WILL CAUSE RISES ON RIVERS,
CREEKS, AND STREAMS SUNDAY AND MONDAY POTENTIALLY LEADING TO
MINOR FLOOD IMPACTS...
Moderate to heavy rain and low elevation snowmelt Sunday and
Monday will lead to rises on rivers, creeks, and streams across
portions of southeast Oregon and southwest Idaho (particularly
the Weiser River Basin). Saturated or frozen soils in some areas
will increase runoff. Snow and ice may clog culverts and ditches
causing water to back-up and pond in low lying and poor drainage
areas. Additionally, ice jams could develop on any rivers, creeks,
or streams with existing ice cover and cause localized flooding.
Rivers in these areas will continue to run high through next week
with some waterways potentially reaching bankfull.
Stay tuned to the forecast for the latest temperature and
precipitation trends, along with any warnings or advisories that
may be issued.
$$
TL
Hydrologic Outlook
ORZ101>128-WAZ201>211-231215-
Hydrologic Outlook
National Weather Service Portland OR
257 AM PST Sat Feb 22 2025
...PERIOD OF WET WEATHER WILL LEAD TO RISES ON RIVERS AND INCREASE
CHANCES FOR URBAN FLOODING...
An series of frontal systems will bring heavy rainfall to northwest
Oregon and southwest Washington through Monday. Heavier rain will
begin with the arrival of a front this afternoon, and intensify
tonight into Sunday. After a brief lull in precipitation late Sunday,
another strong system will bring additional moderate to heavy
rainfall on Monday. This will lead to rises on rivers and creeks,
especially for rivers draining the Willapa Hills and Oregon Coast
Range through Monday. Main stem rivers may be delayed to respond, and
flooding may occur beyond this time frame.
There is around a 20-30% chance of the Wilson River, the Grays River,
and other localized quick responding coastal rivers of reaching minor
flood stage by late Sunday or early Monday. More widespread river
flooding is not expected, but increases in forecast precipitation
amounts could lead to additional rises on area rivers if heavier
rainfall stalls over the area for a longer period of time.
Heavy rainfall along the Cascades combined with snowmelt will lead to
an enhanced risk of landslides.
Heavy rainfall may also lead to ponding of water and localized urban
flooding, especially in low-lying areas or other poor-drainage areas.
Heavy rainfall will also increase the potential for landslides in
areas of steep terrain. The probability of debris flows is currently
low as rainfall rates are not expected to meet thresholds over areas
that have been burned by wildfires over the past few years.
Shifts in the forecast storm track can change the outlook and
probabilities for river flooding, so be sure to monitor
weather.gov/portland for the latest weather updates, as well as any
watches, warnings, or advisories that may be issued. To view the
latest river forecasts, visit water.noaa.gov/wfo/pqr.
$$
CB
