A strong warm front approaching the region will bring a significant warm-up to the region over the next 36 hours along with heavy precipitation very stormy conditions.
Temperatures remain cool across the forecast region with temperatures in the upper teens to mid 20s at most NWAC weather stations. Light snow has reached southern parts of the forecast region. Snowfall should intensify and expand northward throughout the day. Strong W ridgeline winds Wednesday morning should decrease fairly quickly into the light to moderate as the warm front lifts northward. Increasing moderate snowfall will focus on Mt. Hood today, spreading northward to the southern Cascade volcanoes during the afternoon. Light snowfall could reach as far north as highway 20 by the end of the day. Snowfall may be limited in the Mt. Hood area by mid-level warming temperatures which have produced some periods of freezing rain Tuesday night.
Heavy snowfall should impact the entire region as precipitation moves northward Wednesday night. Southern areas should see a changeover to rain at lower to mid-elevations. East flow should keep areas near the Cascade crest plenty cold for snow.
Precipitation intensities peak Wednesday morning with 2-3" per hour snowfall rates likely from the mountain loop southward to Mt. Hood. However, warming temperatures will battle entrenched cold air and moderate E flow. The result will be messy with areas as far north as Stevens Pass seeing mixed precipitation for a little while. Snoqualmie Pass likely starts the day with heavy snowfall, then shifts to sleet or freezing rain before changing to rain from around noon onwards. Elevations above 4000-5000 ft can expect 2 ft or more of snow by the end of the day on Thursday.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
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Wednesday
Cloudy with light snow developing and increasing from late morning onwards.
Wednesday
Night
Increasing moderate to heavy snow with a changeover to rain at lower elevations. Increasing ridgeline winds with strong gusts.
Wednesday
Cloudy.
Wednesday
Night
Light snow in the evening, becoming heavy overnight.
Wednesday
Light snow showers tapering in the morning, then light snow developing in the afternoon.
Wednesday
Night
Increasing light to moderate snow in the evening becoming heavy overnight.
Wednesday
Light snow showers transition to steady light snow by the afternoon. Strong ridgeline winds near the Cascade Crest early in the day.
Wednesday
Night
Heavy snow becoming very heavy overnight at Paradise and White Pass. Moderate to heavy snow at Crystal. Strong ridgeline winds with extreme gusts developing overnight.
Wednesday
A few light snow showers are possible in the morning, then light snow developing around mid-afternoon. Light to moderate W wind at the Pass becoming light and switching E by the end of the day.
Wednesday
Night
Light to moderate snow in the evening becoming very heavy overnight. Increasing light to moderate E wind at the Pass.
Wednesday
A few light snow showers are possible in the morning, then light snow developing around early afternoon. Moderate W wind at the Pass becoming light and switching E by the end of the day.
Wednesday
Night
Moderate snow in the evening becoming very heavy overnight. Increasing light to moderate E wind at the Pass.
Wednesday
Cloudy with a few snow flurries possible.
Wednesday
Night
Light snow in the evening becoming heavy overnight.
Wednesday
Periods of snow showers or light snow.
Wednesday
Night
Moderate snow becoming heavy overnight.
Wednesday
Light snow developing and increasing.
Wednesday
Night
Moderate snow becoming heavy overnight.
Wednesday
Increasing moderate snow. Decreasing moderate to strong ridgeline winds.
Wednesday
Night
Heavy snowfall changing to rain as snow levels rise rapidly. Increasing strong ridgeline winds.
The NWAC program is administered by the USDA-Forest Service and operates from the National Weather Service Forecast Office in Seattle. NWAC services are made possible by important collaboration and support from a wide variety of federal, state and private cooperators.
The 5000’ temperature forecast does not imply a trend over the 12 hr period and only represents the max and min temperatures within a 12 hr period in the zone. The 6-hr snow level forecast, the forecast discussion, and weather forecast sections may add detail regarding temperature trends.
The snow level forecast represents the general snow level over a 6 hr time period. Freezing levels are forecast when precipitation is not expected.
*Easterly or offshore flow is highlighted with an asterisk when we expect relatively cool east winds in the major Cascade Passes. Easterly flow will often lead to temperature inversions and is a key variable for forecasting precipitation type in the Cascade Passes. Strong easterly flow events can affect terrain on a more regional scale.
Ridgeline winds are the average wind speed and direction over a 6 hr time period.
The wind forecast represents an elevation range instead of a single elevation slice. The elevation range overlaps with the near and above treeline elevation bands in the avalanche forecast and differs per zone.
Wind direction indicates the direction the wind originates or comes from on the 16-point compass rose.
Water Equivalent (WE) is the liquid water equivalent of all precipitation types; rain, snow, ice pellets, etc., forecast to the hundredth of an inch at specific locations. To use WE as a proxy for snowfall amounts, start with a snow to water ratio of 10:1 (10 inches of snow = 1 inch WE). Temperatures at or near freezing will generally have a lower ratio (heavy wet snow) and very cold temperatures can have a much higher ratio (dry fluffy snow).