Hydrologic Outlook
Hydrologic Outlook
IDC059-MTC023-077-093-242100-
Hydrologic Outlook
National Weather Service Missoula MT
216 PM MST Fri Feb 21 2025
...WARM AND WET WEATHER THIS WEEKEND INTO MONDAY WILL INCREASE
SNOWMELT AND RUNOFF, LEADING TO POTENTIAL MINOR FLOODING IMPACTS...
Where: Powell, Deer Lodge, and Silver Bow Counties in Montana and
Lemhi County in Idaho.
What: A significant warm up is expected this weekend into early next
week (February 24). High temperatures will reach into the 40s, with
overnight temperatures near or above freezing. Rapid lowland
snowmelt will lead to ponding of water in low lying areas,
especially in areas of poor drainage and/or in
basements/crawlspaces. Ice jam releases are also a concern on small
streams and/or creeks, and may lead to localized flooding. Rain
showers will bring precipitation totals up to 0.20 inches across
valley areas Sunday into Monday, with upwards of 0.50 inches in the
higher terrain.
When: Beginning Saturday afternoon and continuing through Monday
afternoon. Snowmelt will escalate during the day on Sunday.
Monitor the latest weather and river forecasts from the National
Weather Service at weather.gov/Missoula or water.noaa.gov/wfo/mso.
$$
JK
Hydrologic Outlook
IDC003-045-075-087-ORC001-025-045-231215-
Hydrologic Outlook
National Weather Service Boise ID
515 AM MST Sat Feb 22 2025 /415 AM PST Sat Feb 22 2025/
...RAIN AND LOW ELEVATION SNOWMELT WILL CAUSE RISES ON RIVERS,
CREEKS, AND STREAMS SUNDAY AND MONDAY POTENTIALLY LEADING TO
MINOR FLOOD IMPACTS...
Moderate to heavy rain and low elevation snowmelt Sunday and
Monday will lead to rises on rivers, creeks, and streams across
portions of southeast Oregon and southwest Idaho (particularly
the Weiser River Basin). Saturated or frozen soils in some areas
will increase runoff. Snow and ice may clog culverts and ditches
causing water to back-up and pond in low lying and poor drainage
areas. Additionally, ice jams could develop on any rivers, creeks,
or streams with existing ice cover and cause localized flooding.
Rivers in these areas will continue to run high through next week
with some waterways potentially reaching bankfull.
Stay tuned to the forecast for the latest temperature and
precipitation trends, along with any warnings or advisories that
may be issued.
$$
TL
Hydrologic Outlook
MTC003-009-011-017-025-037-065-067-075-087-095-097-103-107-111-
WYC033-241800-
Hydrologic Outlook
National Weather Service Billings MT
445 PM MST Fri Feb 21 2025
...Overland and Ice Jam Flooding Possible Due To Snowmelt...
A deep and wet snowpack exists across the forecast area. 1 to 4
inches of water is locked in this snowpack. Warmer temperatures
forecast over the coming days will increase snowmelt, releasing
this water. With the ground frozen, water will not be able to soak
in and will run off. Water flowing overland and accumulating in
low lying areas may result in localized flooding. Water flowing
into creeks and rivers will increase the potential for ice jam
development and may result in additional flooding near waterways.
Localized impacts from snowmelt may be ongoing over the western
foothills and valleys. More widespread impacts are possible by the
end of the weekend into early next week as overnight low
temperatures hover above freezing, producing 24 hour snowmelt
potential.
Impacts...Water may accumulate near home foundations increasing
the chance of basement flooding. Plugged culverts, ditches, and
storm drains may result in water on area roadways at times. Water
flowing into creeks and streams will increase the potential for
ice jam development with additional flooding hazards. Unpaved
roads may suddenly thaw and become muddy and impassable. The
severity of the impacts will depend on how quickly the snowpack
melts, how fast the ground thaws, and any precipitation.
Preparation...While flooding is not imminent, if you have not
already done so, now is the time to move equipment and livestock
out of low lying areas, and away from waterways. Move any heavy
accumulations of snow away from structures and take steps to
prevent water from making it into basements. Clear any outside
drains of snow. Do not drive over flooded roadways as the roadbed
may be washed out. Be especially careful driving at night when
water covered roadways are less visible.
Stay tuned to the forecast for the latest temperature and
precipitation trends, along with any warnings or advisories that may
be issued. Please report any flooding to local law enforcement and
have them relay the report to the National Weather Service.
$$
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
WYC003-017-019-029-043-222300-
Hydrologic Outlook
National Weather Service Riverton WY
1150 AM MST Fri Feb 21 2025
...Warm Temperatures this Weekend increasing Snowmelt and Ice Jam
Flooding Potential in North-central WY...
Low elevation snowpack of around 6 to 12 inches exists across much
of the northern portion of the Bighorn Basin including Greybull,
Lovell, Powell, and Cody. This snowpack contains an estimated 2 to 4
inches of Snow Water Equivalent (SWE). Temperatures beginning Sunday
are expected to climb into the mid 40s to low 50s. The warm
temperatures are expected to persist through at least the middle of
next week.
The warm temperatures, combined with the significant low elevation
snowpack, could result in significant melting and injection into
local rivers and streams. Ice break up on the Bighorn and Nowood
Rivers is possible as well, and could lead to ice jamming and
potential resultant flooding.
Similar snowpack also exists across portions of northern Johnson
County. Although the risk for ice jams is lower, ponding of water
and overland runoff could fill culverts and other low-lying areas.
Now would be the time to clear snow, ice, and debris from culverts
and other flow paths to allow runoff to flow away from buildings and
other vulnerable infrastructure. This could include moving deep snow
away from the foundations of buildings, relocating equipment to
higher ground, and moving livestock out of poorly drained or low-
lying areas.
Stay tuned for the latest river forecasts.
$$
Wittmann
Hydrologic Outlook
MTC001-005-007-013-015-027-031-035-041-043-045-049-051-057-059-
073-099-101-221915-
Hydrologic Outlook
National Weather Service Great Falls MT
1203 PM MST Thu Feb 20 2025
...Ice Jams and Localized Lower-elevation Flooding Possible...
Warming temperatures through the weekend and the upcoming work week
will lead changes in river ice conditions and an increased risk of
river ice break-up and the potential of ice jams. Lower elevation
snowmelt and still frozen ground could also lead to some increased
runoff into creeks and rivers, adding to the potential for river ice
breakup. Ice jams are unpredictable and flooding can rapidly occur,
so those with interests along waterways should monitor water levels
over the coming week and take action should flooding occur.
In addition, frozen ground after a prolonged cold period and melting
snow may result in standing water in areas of poor drainage. This
could create difficult access to fields and impact some rural roads.
As temperatures warm further early next week and the ground begins
to thaw, muddy conditions may create additional impacts. The
greatest risk for overland impacts from snowmelt look to be from
eastern portions of Teton and Pondera counties across portions of
Cascade and Chouteau counties and most lower elevation areas in
Judith Basin and Fergus counties, where water equivalent in the
lower elevation snowpack ranges from around 1.0" to as much as 3.0
to 4.0" in portions of Fergus county. These areas are also most
susceptible to overnight temperatures remaining near or above
freezing this weekend into early next week. Across southwest MT,
there is significant water content in the snowpack in the Gallatin
valley, however melting will likely be slower with overnight
temperatures continuing to fall below freezing.
Stay tuned to the forecast for the latest temperature trends, along
with any warnings or advisories that may be issued. Please report
any flooding to local law enforcement. Do not drive over flooded
roadways as the roadbed may be washed out. Turn Around, Don`t Drown.
$$
