The warm wet weather pattern continues today as another wave of precipitation pushes into the region. Expect stormy conditions all across the mountains with periods of heavy precipitation and strong winds. For locations in the Olympics, west of the Cascade Crest, and near Mt Hood, this will be a primarily rain event, with snow only at the highest elevations. For everywhere else, the storm becomes much more complicated.
Considerably warmer air continues to make its way into the mountains and tries to displace the very cold air pool still holding strong east of the Cascade crest. At Stevens and Snoqualmie, moderate to strong E winds will draw this below-freezing air into the passes and create very strong temperature inversions all along the highway corridors. This is the perfect setup for a dangerous freezing rain event with significant ice accumulations. Along the east side of the Cascades, warm air has already made its way into the mid-elevations from Ahtanum Meadows to the Wenatchee Mts. With cold air trapped below, this should also result in freezing rain. As warmer temperatures continue to force their way further north, similar conditions could develop in other areas. The cold air should hold on in the Methow region for most of Saturday maintaining mostly snow.
A shift to westerly flow through the mountain passes Saturday evening will finally flush out any remaining pockets of cold air east of the Cascades and bring rain to all but the highest peaks. Post-frontal showers linger overnight as a transient ridge passes quickly overhead. This should allow for a bit of drying and maybe a few breaks in the clouds on Christmas morning.
Any pause in the action will be short-lived. A warm front will lift northward Sunday and bring yet another round of rain to our region. Right now this doesn't look like a particularly impressive feature. During the afternoon it should bring light rain and high-elevation snow primarily to the volcanoes and north Cascades.
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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Saturday
Stormy. Rain and high-elevation snow heavy at times. Strong SW winds decreasing slightly in the afternoon.
Saturday
Night
Cloudy with isolated showers. Light to moderate SW winds.
Saturday
Stormy. Rain and high elevation snow, heavy at times. Strong S winds becoming SW.
Saturday
Night
Cloudy with showers. Moderate W winds decreasing and becoming SW.
Saturday
Stormy. Rain and high elevation snow, heavy at times. Moderate SW winds.
Saturday
Night
Cloudy with showers. Moderate to strong SW winds decreasing.
Saturday
Stormy. Rain and very high elevation snow, heavy at times. Moderate to strong SW winds.
Saturday
Night
Cloudy with scattered showers, heaviest near the volcanoes. Moderate to strong SW winds decreasing overnight.
Saturday
Stormy with significant freezing rain. Moderate E flow at Pass level. Rain and moderate SW winds at ridgelines.
Saturday
Night
Turning to all rain at the Pass. Westerly flow. Cloudy with scattered showers.
Saturday
Stormy with significant freezing rain. Moderate to strong E flow at Pass level. Rain and moderate to strong SW winds near ridgecrest.
Saturday
Night
Westerly flow at Pass level, turning precipitation to rain. Moderate to strong W ridgeline winds decreasing slightly.
Saturday
Stormy. Mixed precipitation possible including freezing rain near the crest. Moderate SW winds increasing in the afternoon.
Saturday
Night
Showers with rain and freezing rain possible. Moderate to strong W winds.
Saturday
Storm with heavy precipitation near the crest. Mixed rain/snow and freezing rain likely. SW winds becoming strong in the afternoon.
Saturday
Night
Cloudy with showers. Mixed precipitation and freezing rain becoming mostly rain overnight. Strong W winds decreasing.
Saturday
Stormy with moderate to occasionally heavy precipitation near the crest. Mixed rain/snow and freezing rain becoming all rain. SW winds becoming moderate to strong.
Saturday
Night
Rain showers near the crest. Moderate to strong W winds decreasing.
Saturday
Stormy. Rain and high elevation snow, heavy at times. Strong and gusty SW winds increasing.
Saturday
Night
Scattered showers. Strong W winds decreasing slightly.
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).