Most locations are in for a cloudy, dry, and breezy day. A mild atmospheric river (AR), pointed at Vancouver Island, slowly drifts southward on Saturday. This will bring rain and snow first to the Olympic Mountains and eventually to the West North zone. While precipitation totals aren't impressive during the day, the greater initial impacts come from moderate to strong and gusty ridgeline winds. While most areas should experience cloudy conditions, areas further east and south could see partly sunny skies with filtered sunshine.
The AR seems to sag even further south overnight, bringing rain and snow to the Central Cascades. However, the main focus of precipitation is quite narrow and sharp. This means, unless it's pointed right at you, you might not see much precipitation, and small shifts in its aim could have big impacts on water totals. There is quite a spread in the weather models as to the exact position of the rain/snow. Precipitation seems most certain for areas near and north of Hwy 2. Conversely, areas near and south of Hwy 12 should stay dry. Overnight snowlevels, tend to hover between 4500-5500 ft.
Precipitation lifts back northward on Sunday. This time period suffers from the same uncertainty due to the narrow band of intense rain/snow. Warmer air works its way into the region causing snowlevels to slowly but steadily climb throughout the day. Much like Saturday, areas further south and east stay dry and could experience more filtered sunshine.
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
Cloudy with light rain and snow developing. Heaviest in the western Olympics. Moderate to strong and gusty winds.
Saturday
Night
Rain and high elevation snow. Could be heavy in the Western Olympics. Light to moderate SW winds.
Saturday
Cloudy with light rain and snow developing in the afternoon. Strong and gusty SSW winds.
Saturday
Night
Cloudy with rain and snow, could be heavy at times. Moderate SSW winds becoming stronger overnight.
Saturday
Cloudy, with the chance of a few sprinkles late in the day in the northern end of the zone. Moderate winds becoming stronger in the afternoon.
Saturday
Night
Rain and snow, could be heavy at times. Moderate winds decreasing.
Saturday
Partly to mostly cloudy, with clouds thickening in the afternoon. Moderate SW winds increasing in the afternoon.
Saturday
Night
Light rain and high elevation snow mainly north of Hwy 12. Moderate SW winds.
Saturday
Cloudy. Temperature inversions to start the day. Light to moderate SW ridgeline winds. Light east flow at Pass level.
Saturday
Night
Cloudy with generally light rain and snow. Light to moderate SW ridgeline winds. Light easterly flow at Pass level.
Saturday
Becoming cloudy. Temperature inversions in the morning. Moderate SW ridgeline winds. Light to moderate easterly flow at Pass level.
Saturday
Night
Cloudy with rain and snow developing overnight. Moderate SW ridgeline winds. Light easterly flow at Pass level.
Saturday
Partly to mostly sunny in the morning, becoming mostly cloudy in the afternoon. Moderate SW winds.
Saturday
Night
Cloudy with a few showers mainly near the crest. Light to moderate SW winds.
Saturday
Becoming cloudy with clouds thickening in the afternoon. Moderate SW winds becoming stronger in the afternoon.
Saturday
Night
Cloudy with rain and snow showers, mainly near the crest. Moderate to strong SW winds decreasing.
Saturday
Partly sunny with filtered sunshine, clouds increasing in the afternoon. Moderate SW winds
Saturday
Night
Partly to mostly cloudy. A few isolated showers possible mainly near Bumping Lake. Moderate to strong SW winds decreasing.
Saturday
High thin clouds with filtered sunshine. Moderate SW winds becoming stronger in the afternoon.
Saturday
Night
Generally high thin clouds. Weak temperature inversions possible. Moderate to strong SW winds increasing overnight.
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).