A warm front will lift northwards today from Oregon into Washington, spreading light to locally moderate precipitation into the Mt Hood region and the south WA Cascades during the day. Precipitation will be slow to reach the northern Cascades but even there, precipitation will begin during the afternoon hours. S-SE winds will locally be strongest along west slopes of the Cascades and Olymipcs. Snow levels will come down to 4000-5000' when precipitation begins.
The most impactful weather feature arrives tonight. A secondary weather feature associated with the same deep low pressure system will move onshore overnight, delivering a potent round of intense precipitation and strong to extreme winds through Tuesday morning. Snow levels will fall to 3000-3500' during the heaviest precipitation with accumulations likely totaling 6-18" through mid-day Tuesday. Showers will continue along the west slopes of the Cascade but slowly taper off Tuesday afternoon. The winds will have a similar slow easing trend during the day Tuesday.
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 cloudy this morning, then light rain and snow developing during the afternoon. Light to moderate ridgeline winds becoming strong in the afternoon.
Monday
Night
Moderate to occasionally heavy rain and snow. Strong to extreme ridgeline winds.
Monday
Mostly cloudy this morning, then light rain and snow developing during the afternoon. Moderate ridgeline winds becoming strong in the afternoon.
Monday
Night
Moderate to occasionally heavy rain and snow. Strong to extreme ridgeline winds.
Monday
Mostly cloudy this morning, then light rain and snow developing around mid-day. Light to moderate ridgeline winds becoming moderate in the afternoon.
Monday
Night
Moderate to occasionally heavy rain and snow. Strong ridgeline winds.
Monday
Mostly cloudy this morning, then light to moderate rain and snow developing during the morning. Light to moderate ridgeline winds becoming strong in the afternoon.
Monday
Night
Moderate to occasionally heavy rain and snow. Strong to extreme ridgeline winds.
Monday
Mostly cloudy this morning, then light rain and snow developing mid-day. Light E-SE ridgeline and Pass level winds becoming moderate in the afternoon.
Monday
Night
Moderate to occasionally heavy rain and snow. Moderate to strong S-SSW ridgeline winds. Light to moderate E winds at Pass level.
Monday
Mostly cloudy this morning, then light to moderate rain and snow developing mid-day. Light E-SE ridgeline and Pass level winds becoming moderate in the afternoon.
Monday
Night
Moderate to occasionally heavy rain and snow. Strong to extreme W Pass level and ridgeline winds.
Monday
Mostly cloudy this morning, then light rain and snow developing early afternoon. Light to moderate ridgeline winds becoming moderate in the afternoon.
Monday
Night
Moderate rain and snow. Moderate ridgeline winds.
Monday
Mostly cloudy this morning, then light to moderate rain and snow developing mid-day. Light to moderate ridgeline winds becoming moderate in the afternoon.
Monday
Night
Moderate rain and snow. Moderate to strong ridgeline winds.
Monday
Mostly cloudy this morning, then light to moderate rain and snow developing in the afternoon. Light to moderate ridgeline winds becoming moderate in the afternoon.
Monday
Night
Moderate rain and snow. Moderate to strong ridgeline winds.
Monday
Cloudy this morning, then light rain and snow developing during the morning. Light to moderate ridgeline winds becoming strong in the afternoon.
Monday
Night
Moderate to occasionally heavy rain and snow. Extreme 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).