Bitterly cold temperatures continue across the region with cold temperature records being set for many locations across the region. The culprit is a cold trough over our area, with decreasing Fraser outflow bringing modified arctic air into the Puget Sound lowlands as well. The coldest temperatures in the region Monday morning can be found at Washington Pass (-17F) and Camp Muir (-14F). Most mountain locations are reporting temperatures in the single digits. 5000 ft temperatures should rise to highs in the upper single digits through mid-teens. Light snow shower activity around Mt. St. Helens, Mt. Adams, and Mt. Hood should decrease and probably end during the morning hours as the trough continues to exit the region, bringing drying NNW flow. High clouds should increase during the afternoon across the region a weak low drops southward off the coast of British Columbia.
This low could bring some very light snow to the Olympics and southern Washington Cascades with moisture potentially lingering much of the day for the Oregon Cascades. We have considerable uncertainty regarding the exact track of the low. We don't know how far north the very light snow will extend. We expect the only slightly more significant snowfall to occur around Mt. Hood where 3-6" of low-density snow could fall through Tuesday. Elsewhere, expect partially clearing skies Tuesday morning for Washington State with high clouds increasing in the afternoon. Temperatures will remain bitterly cold but should moderate slightly west of the Cascade Crest.
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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Monday
Mostly clear to start, then becoming mostly cloudy as mid and high-level clouds increase.
Monday
Night
Mostly cloudy in the evening with a chance of very light snow, then partial clearing overnight.
Monday
Mostly clear to start, then becoming mostly cloudy as mid and high-level clouds increase.
Monday
Night
Mostly cloudy in the evening, then partial clearing overnight.
Monday
Mostly clear to start, then becoming mostly cloudy as mid and high-level clouds increase.
Monday
Night
Mostly cloudy in the evening, then partial clearing overnight.
Monday
Partly cloudy to start, then becoming mostly cloudy as mid and high-level clouds increase.
Monday
Night
Mostly cloudy with a slight chance of very light snow in the early morning hours.
Monday
Mostly clear to start, then becoming mostly cloudy as mid and high-level clouds increase. Light E winds in the morning switching W in the afternoon at the Pass.
Monday
Night
Mostly cloudy in the evening, then partial clearing overnight. Light E or variable wind at the Pass.
Monday
Mostly clear to start, then becoming mostly cloudy as mid and high-level clouds increase. Light E winds in the morning switching W in the afternoon at the Pass.
Monday
Night
Mostly cloudy with a slight chance of very light snow in the early morning hours. Light E or variable wind at the Pass.
Monday
Mostly clear during the morning hours, then becoming mostly cloudy as mid and high-level clouds increase.
Monday
Night
Mostly cloudy in the evening, then partial clearing overnight.
Monday
Mostly clear during the morning hours, then becoming mostly cloudy as mid and high-level clouds increase.
Monday
Night
Mostly cloudy in the evening, then partial clearing overnight.
Monday
Partly cloudy with a chance of snow showers early in the day, southern part.
Monday
Night
Mostly cloudy.
Monday
Light snow showers decreasing during morning hours. Flurries or high overcast possible in the afternoon.
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).