An onslaught of moisture focuses on Oregon and southern Washington with 1-3" of precipitation arriving as a warm front lifts northward Sunday morning. Brace for rapidly rising snow levels and a period of heavy rain and high-elevation snow. Snow levels have already risen above the tops of the ski areas around Mt Hood. The warming will be rapid along the west slopes of the Washington Cascades, but a trailing cold front will bring an end to the warming, with less moisture arriving to the northern Washington Cascades along with a briefer period of warming as well. As a result, Mt Baker base and Washington Pass likely remain all snow. The story will be more complex in the central Washington Cascades where warm air over-runs colder air, but with E flow bringing cooler air through the mountain gaps at lower elevations, a period of sleet or freezing rain is likely before the changeover to rain at places like Stevens and Snoqualmie Passes.
Post-frontal showers will be light Sunday night with snow levels dropping around 2000 ft for Washington State and less cooling for Mt Hood.
A stronger and more prolonged warm and wet system arrives early Monday with a second strong warm front lifting northward. Expect another round of rain, high-elevation snow, and more widespread very heavy precipitation than on Sunday. Precipitation totals should be in the 1-2.5" range across the west slopes of the Cascades on Monday.
Weather Forecast
Olympics
West North
West Central
West South
Stevens Pass
Snoqualmie Pass
East North
East Central
East South
Mt. Hood
Use dropdown to select your zone
Sunday
Light rain and high elevation snow becoming showery or ending in the afternoon. Moderate ridgeline winds.
Sunday
Night
Mostly cloudy with a chance of rain or snow re-developing in the early morning hours. Decreasing light ridgeline winds.
Sunday
Moderate rain and snow. Increasing moderate ridgeline winds.
Sunday
Night
Light rain and snow showers decreasing or ending. Moderate ridgeline winds become light.
Sunday
Moderate to occasionally heavy rain and snow. Rising temperatures. Ridgeline winds become moderate to occasionally strong.
Sunday
Night
Light rain and snow showers decreasing or ending. Moderate ridgeline winds become light.
Sunday
Heavy rain and snow becoming showery by the afternoon. Light to moderate ridgeline winds become moderate from mid-morning onwards.
Sunday
Night
Light rain and snow showers decreasing or ending. Moderate ridgeline winds become light.
Sunday
Moderate to heavy rain, wintry mix, and snow. The changeover to rain likely takes place by 1 PM. Light ridgeline winds become moderate. Light E winds shift W at the Pass during the afternoon.
Sunday
Night
Light rain and snow showers decreasing or ending. Moderate ridgeline winds become light. Light W wind at the Pass shifts E overnight.
Sunday
Moderate to heavy rain, wintry mix, and snow. The changeover to rain likely takes place by 11 AM. Light ridgeline winds become moderate. Light to occasionally moderate E winds shift W at the Pass during the afternoon.
Sunday
Night
Light rain and snow showers decreasing or ending. Moderate ridgeline winds become light. Light W wind at the Pass shifts E overnight.
Sunday
Light snow early becomes moderate rain and snow from mid-morning onwards. Light ridgeline winds become moderate.
Moderate rain and snow, heaviest in the late morning hours. Snow transitions to rain at lower and middle elevations by the end of the day.
Sunday
Night
Light rain or snow showers taper overnight, mainly near the Cascade Crest. Strong ridgeline winds decrease into the moderate range.
Sunday
Moderate rain and snow, heaviest in the morning hours, becomes showery late in the day. Snow transitions to rain at lower and middle elevations by the afternoon.
Sunday
Night
Mostly dry in the evening, then light rain and snow re-develop in the early morning hours. Moderate ridgeline winds become light.
Sunday
Very heavy rain and high-elevation snow peak in intensity mid-morning. Strong ridgeline winds.
Sunday
Night
Tapering rain and high-elevation snow showers during the evening. Light to moderate rain and high-elevation snow re-develop in the early morning hours. Ridgeline winds decrease from strong to moderate.
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).