A warm front has moved over the Cascades early Sunday morning, bringing rising temperatures and increased moderate rain and snow. Precipitation should become heavy in many areas during the day on Sunday as increased moisture moves in behind the warm front. Radar imagery shows thick clouds streaming into the region with very continuous precipitation on the radar. The bulk of the precipitation is aimed at the Washington Cascades with Mt Hood on the fringe to the south. W Winds will continue to ramp up Sunday through the mountain gaps and with downsloping along the east slopes of the Cascades. Snow levels should continue to rise slowly and we expect a changeover to rain at Snoqualmie Pass by mid-morning. Snow levels should linger in the 3500-4000 ft range today, so many areas above 4000 ft will see 1 ft or more of snowfall on Sunday.
The moisture re-orients slightly more WSW and lifts slightly northward Sunday night as a trough and cold front approaching from the NW. This will bring very heavy rain and snow from Snoqualmie Pass to Mt. Baker and likely the Mt. Rainier area as well. Winds continue to increase into the moderate to strong (locally very strong) range.
The cold front moves through the region from NW to SE on Sunday and should reach Mt. Hood by the end of the day. Snow levels peak just in advance of the front around 4500-5000 ft in most areas early in the day. Precipitation becomes more showery behind the front later in the day.
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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Sunday
Light rain and snow. Strong ridgeline wind gusts.
Sunday
Night
Moderate to heavy rain and snow. Strong ridgeline wind gusts.
Sunday
Moderate rain and snow becoming heavy. Strong ridgeline wind gusts.
Sunday
Night
Heavy rain and snow. Strong ridgeline wind gusts.
Sunday
Increasing heavy rain and snow. Strong ridgeline wind gusts.
Sunday
Night
Very heavy rain and snow. Moderate to strong ridgeline winds.
Sunday
Increasing heavy rain and snow at Paradise and White Pass. Increasing light rain and snow at Crystal.
Sunday
Night
Increasing heavy rain and snow at Paradise and White Pass. Increasing light rain and snow at Crystal.
Sunday
Increasing heavy rain and snow. Light to occasionally moderate W wind at the Pass.
Sunday
Night
Very heavy rain and snow. Moderate W wind at the Pass.
Sunday
Increasing heavy rain and snow. Light to moderate W wind at the Pass.
Sunday
Night
Very heavy rain and snow. Moderate W wind at the Pass.
Sunday
Increasing light to moderate rain and snow.
Sunday
Night
Heavy rain and snow.
Sunday
Increasing heavy rain and snow. Strong ridgeline winds.
Sunday
Night
Heavy rain and snow. Strong to very strong ridgeline winds.
Sunday
Increasing moderate rain and snow. Strong ridgeline wind gusts.
Sunday
Night
Moderate rain and snow. Strong ridgeline wind gusts.
Sunday
Increasing moderate to heavy rain and snow. Strong ridgeline winds.
Sunday
Night
Moderate rain and snow. Strong ridgeline wind gusts. Strong to very 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).