Coulee City, Washington Weather Conditions

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Air Stagnation Advisory View All Alerts

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Current Conditions

  • 22°
  • Overcast
  • Wind: Calm
  • Humidity: 82%
  • Visibility: 10.0 miles
  • Dew Point: 17°
  • Pressure: 30.38 in. +

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Forecast data from the National Digital Forecast Database.

5 Day Forecast

  • Tuesday
  • Partly Cloudy
  • High: 27 °
  • Low: 24 °
  • Partly Cloudy
  • Wednesday
  • Overcast
  • High: 34 °
  • Low: 31 °
  • Overcast
  • Thursday
  • Chance of Rain
  • High: 38 °
  • Low: 29 °
  • Chance of Rain
  • Friday
  • Partly Cloudy
  • High: 42 °
  • Low: 28 °
  • Partly Cloudy
  • Saturday
  • Chance of Rain
  • High: 41 °
  • Low: 31 °
  • Chance of Rain

Forecast for Coulee City, Washington

Updated: 8:52 PM PST on November 30, 2015

Air stagnation advisory in effect until noon PST Friday...
  • Rest of Tonight

    Cloudy. Occasional flurries. Lows 18 to 20. Light wind.

  • Tuesday

    Cloudy. Occasional flurries. Highs in the mid to upper 20s. Northeast wind 5 to 10 mph.

  • Tuesday Night

    Cloudy. A chance of snow in the evening...then snow and freezing rain likely overnight. Snow accumulation up to 1 inch. Ice accumulation of up to one tenth of an inch. Lows in the mid 20s. Southeast wind 5 to 10 mph. Chance of precipitation 70 percent.

  • Wednesday

    Cloudy. A chance of snow and freezing rain in the morning...then a chance of rain...freezing rain snow in the afternoon. Ice accumulation of up to one tenth of an inch. Highs in the lower to mid 30s. East wind 5 to 10 mph. Chance of precipitation 70 percent.

  • Wednesday Night

    Cloudy. Rain and freezing rain likely in the evening...then a chance of rain overnight. Lows in the lower 30s. East wind 5 to 10 mph. Chance of precipitation 70 percent.

  • Thursday and Thursday Night

    Mostly cloudy with a 50 percent chance of rain. Highs in the upper 30s to lower 40s. Lows in the lower to mid 30s.

  • Friday

    Windy. Mostly cloudy with a 20 percent chance of rain. Highs in the 40s.

  • Friday Night

    Mostly cloudy. Lows in the lower to mid 30s.

  • Saturday

    Mostly cloudy with a chance of rain or snow. Highs in the lower to mid 40s. Chance of precipitation 40 percent.

  • Saturday Night through Monday

    Cloudy with a 50 percent chance of rain. Lows in the lower to mid 30s. Highs in the lower to mid 40s.

Severe Weather Alert Descriptions

 Air Stagnation Advisory  Statement as of 9:12 am PST on November 30, 2015

... Air stagnation advisory remains in effect until 4 am PST

* air quality... poor ventilation will result in a build up of
pollutants near the surface. Minor improvements in air quality
will be possible Tuesday night through Thursday... but most areas
will not see improvement until a cold front arrives Friday.

* Timing... through Friday morning.

* Impacts... prolonged periods of stagnant air can hold fine
particulates close to the ground and degrade air quality.

Precautionary/preparedness actions...

An air stagnation advisory indicates that due to limited movement
of an air mass across the advisory area... pollution has the
potential to increase to dangerous levels. Persons with
respiratory illness should follow their physicians advice for
dealing with high levels of air pollution.

During periods of stagnant air... state air quality agencies
highly recommended that no outdoor burning occur and that
residential wood burning devices be limited as much as possible.
According to state air quality agencies... prolonged periods of
stagnant air can hold pollutants close to the ground... where
people live and breathe.

Personal Weather Stations

Personal Weather Stations [Add your weather station!]

Location: Coulee City, Coulee City, WA

Updated: 6:22 PM PST

Temperature: 19.9 °F Dew Point: 19 °F Humidity: 96% Wind: SE at 2.7 mph Pressure: 28.58 in Hourly Precipitation: 0.00 in Windchill: 20 °F Graphs

Location: Adrian, Soap Lake, WA

Updated: 9:38 PM PST

Temperature: 21.2 °F Dew Point: 15 °F Humidity: 77% Wind: Calm Pressure: 30.22 in Hourly Precipitation: 0.00 in Windchill: 21 °F Graphs

Location: APRSWXNET, Ephrata, WA

Updated: 9:16 PM PST

Temperature: 21 °F Dew Point: 17 °F Humidity: 85% Wind: Calm Pressure: 30.32 in Hourly Precipitation: 0.00 in Windchill: 21 °F Graphs

Location: Ephrata Mike, Ephrata, WA

Updated: 9:35 PM PST

Temperature: 21.9 °F Dew Point: 18 °F Humidity: 86% Wind: Calm Pressure: 30.42 in Hourly Precipitation: 0.00 in Windchill: 22 °F Graphs

Location: Grand Coulee, WA [Spring Canyon Rd.], Grand Coulee, WA

Updated: 9:35 PM PST

Temperature: 23.5 °F Dew Point: 18 °F Humidity: 78% Wind: SE at 2.0 mph Pressure: 30.35 in Hourly Precipitation: 0.00 in Windchill: 24 °F Graphs

Location: FDR Estates, Grand Coulee, WA

Updated: 9:38 PM PST

Temperature: 23.7 °F Dew Point: 20 °F Humidity: 85% Wind: ESE at 6.9 mph Pressure: 30.36 in Hourly Precipitation: 0.00 in Windchill: 16 °F Graphs

MSN Maps of:

Temp: Dew Point: Humidity Wind Pressure Hr Precip -

NWS Forecaster Discussion

Area forecast discussion 
National Weather Service Spokane Washington 
310 PM PST Monday Nov 30 2015 

low clouds and areas of fog will be common in valleys. Strong 
high pressure will contribute to air stagnation and cloudy skies 
in The Lowlands through Tuesday. A weak frontal system is 
expected to bring a chance of light wintry precipitation Tuesday 
night into Wednesday...with a wetter system moving in Wednesday 
afternoon into early Thursday. The combination of the two weather 
systems will likely produce light to moderate snow near the 
Cascades and over the northern Washington mountains. There will 
also be a threat of freezing rain across western portions of the 
Columbia Basin, Wenatchee valley and Okanogan Valley. Wet but 
warmer weather is expected from Thursday afternoon and into the 



Tonight through Tuesday...a pair of weak upper level disturbances 
pass over the ridge of high pressure over the area but do little 
other than to force a bit more snow flurries out of the stratus 
and add a bit more cloud cover for the mountains and elevations 
above 4000 feet mean sea level which are poking above the low stratus clouds 
which remain entrenched over the valleys and lowlands below 4000 
feet MS. Having more flurries occurrence usually means that the 
fog will remain less prevalent and ceilings will rise a little bit 
and there will be a very slight warming trend in daytime high 
temperatures for Tuesday relative to those of today. /Pelatti 

..light to moderate snows possible over portions of the inland 
northwest as well as areas of freezing rain between Tuesday night 
and Thursday... 

Tuesday night through Thursday...confidence is quite high that the 
stable ridge which has Sat over the inland northwest for the past week 
or so will begin to break down or shift into western Montana. This 
will result in an increasing threat of precipitation as the mid 
level flow pattern turns increasingly southwesterly and brings 
Pacific moisture into the region. The first threat of 
precipitation arrives early in the evening at the Cascade crest 
and moves steadily eastward into Wednesday morning. This feature 
is fairly progressive and expected to weaken into the ridge over 
Montana. Consequently the chances for the heaviest precipitation 
will likely occur over northern and western portions of the 
forecast area, including the Cascades. Precipitation amounts won't 
be all that heavy with the heaviest amounts expected to occur over 
Chelan, Okanogan and Douglas counties, where anywhere from 
0.10-0.20 inches of liquid is expected. Initially the 
precipitation will fall as all snow, however a slug of above 
freezing air is expected to slowly wedge its way into the southern 
portions of the Columbia Basin and perhaps the Wenatchee area by 
Wednesday morning. This could bring some light freezing rain to 
locations such as Moses Lake, Ritzville, and Vantage as the warm 
wedge rides over the sub-freezing air near the ground. This would 
likely impact much of I-90 across this area so travel problems are 
certainly possible. Farther north all the precipitation will fall 
as snow with 1 to 3 inches possible over the northern valleys with 
an less than inch over the vast majority of the region. Overall 
this is a fairly minor system but the threat of ice could produce 
moderate impacts. 

The bigger problem with the forecast is the second system which 
is expected to move in from the southwest in the form of a warm 
front on Wednesday. This system is expected to pack much more 
moisture and potentially more problems. The 12z GFS and 12z NAM 
brought the warm front into the Lower Basin, and Wenatchee area 
before sunset and push it slowly north toward the Canadian border 
by Thursday morning. Meanwhile the European model (ecmwf) and Canadian models hold 
off any threat of significant precipitation until Thursday 
morning. This is a big difference to say the least and would have 
large impacts on the area weather. If the GFS and NAM solutions 
were correct, we'd be looking at moderate precipitation amounts 
with the sub-freezing air holding stubbornly near the ground. 
There is the other question as to how long would this sub-freezing 
air remain near the ground as the winds aloft increase steadily. 
Near the Cascades we expect the freezing air to remain the longest 
and deepest as there is a good offshore pressure gradient which 
will reinforce the cold-air damming. Moderate snow amounts would 
be possible especially over Okanogan, Chelan, and Douglas 
counties. The warm wedge of air aloft would also transition the 
snow to freezing rain especially for the Columbia Basin, Wenatchee 
area, Waterville Plateau, and Okanogan Valley. The warm air aloft 
could also move into the northern Washington and Idaho valleys 
late Wednesday night resulting in a smaller risk of snow changing 
to freezing rain. Farther east and south the transition from snow 
to rain would be more steady, so for places like Spokane, Pullman 
and Ritzville we'd be looking at snow amounts less than an inch 
with more liquid than snow. Of course this is assuming the NAM and 
GFS solutions are correct. That is a big if at this point. 

The ECMWF, Canadian, and new 18z GFS hint at a much slower arrival 
of the warm front with little if any precipitation until early 
Thursday morning, we would still see the possibility of some mixed 
winter precipitation ahead of the warm front including in the 
Spokane area but the switch would occur fairly quick. All models 
concur that 850 mb temps and consequently snow levels skyrocket as 
the front comes in so significant snows won't be the problem if 
the latter solutions verify. By Thursday afternoon, 850 mb temps 
soar to well above zero for all locations except near the 
Cascades, so rain would become the primary precipitation type. 
Needless to say the confidence for this forecast is quite low. We 
will hold off on winter highlights for now and focus our efforts 
via social media and weather stories. Fx 

Friday through Monday...models are similar showing a mean long 
wave trough over the western states through the weekend with 
several disturbances moving through the general flow. It's in the 
finer details where we start to see some differences in timing and 
strength of each wave. 

For the wave on Friday it looks like another wet system through 
the day and into Friday evening. An embedded upper level trough 
will move through the region. The lower east slopes and deep basin 
will likely see some shadow effect off the Cascades but still 
could pick up a hundredth or two of precipitation. For the 
mountains there will be the possibility of between a quarter to a 
half inch of precipitation. Snow levels will result in 
precipitation as rain below 3000 feet and rain above, with 3-5 
inches of snow possible. The exception would be the Methow Valley 
where cooler air is expected o be locked in that valley. 10-15 mph 
southwest winds will allow good mixing with temperatures rising 
into mid 30s to mid 40s. 

Saturday through Monday...the confidence in the forecast is rather 
low at this time. Model guidance is similar showing that several 
waves will move through the mean trough, however the timing and 
strength of each individual wave is quite suspect. So this portion 
of the forecast is pretty generalized. At this time it looks likes 
the best chance for precipitation will be Saturday night and 
Sunday. Warm air advection in southwest flow will allow snow 
levels to increase to between 3k-4k feet so precipitation would be 
as valley rain and mountain snow. Temperatures will be on the warm 
side of normal. Stay we get closer to the weekend we 
will have a better idea and just what the weather will hold. Tobin 


18z tafs: stratus with some fog mixed in underneath and flurries 
falling out of it all at times will continue to influence the 
aviation area for the next 24 hours while mountains and terrain 
roughly above 4000 feet mean sea level will see sunny/clear conditions. The 
ceilings may drop to MVFR to IFR at times but generally rise a bit 
when flurries drop out of them. Some improvement Tuesday afternoon 
may occur as a weak disturbance runs across the aviation area with 
high likelihood it will allow for more flurries to fall out of the 
stratus and allow ceilings to rise some. /Pelatti 


Preliminary point temps/pops... 
Spokane 18 30 25 35 33 43 / 0 10 20 60 50 30 
Coeur D'Alene 17 32 25 36 34 45 / 0 0 20 50 50 40 
Pullman 20 33 27 37 33 48 / 0 10 20 60 40 30 
Lewiston 22 36 28 41 35 50 / 0 10 10 40 30 20 
Colville 17 30 23 35 32 35 / 0 10 50 70 70 70 
Sandpoint 16 30 23 34 32 37 / 0 0 20 60 50 50 
Kellogg 16 31 23 35 33 40 / 0 0 10 50 50 20 
Moses Lake 18 31 26 33 33 40 / 10 10 60 50 60 40 
Wenatchee 19 29 24 33 32 34 / 10 10 80 60 80 50 
Omak 17 29 24 34 32 34 / 10 10 80 50 90 70 


Otx watches/warnings/advisories... 
Idaho...air stagnation advisory until noon PST Friday for central 
Panhandle mountains-Coeur D'Alene area-Idaho Palouse-Lewis 
and southern Nez Perce counties-Lewiston area-northern 

Washington...air stagnation advisory until noon PST Friday for east slopes 
northern Cascades-lower Garfield and Asotin counties-Moses 
Lake area-northeast Blue Mountains-northeast mountains- 
Okanogan Highlands-Okanogan Valley-Spokane area-upper 
Columbia Basin-Washington Palouse-Waterville Plateau- 
Wenatchee area. 



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