Friday should be a quiet weather day ahead of a more complex and active weekend. A high pressure ridge passes over the region resulting in partly to mostly sunny skies along with bands of mid and high clouds. 5000 ft temperatures should top out in the mid 30's for most of our mountain areas. All in all, it should be a nice day.
As we head into the afternoon and evening, clouds increase, thicken, and lower. A narrow atmospheric river (AR) then takes aim at Vancouver Island. The northwestern Olympics and North Cascades seem to sit right on the edge of the main precipitation band. Look for a few showers to develop around midnight, but precipitation will become more steady very early Saturday morning and throughout the day. The main axis of rain and snow appears to stall in the same location for about 30 hrs, but it won't take much of a shift in the exact position of this AR to radically change the forecast.
While most areas stay dry through Saturday, this storm will also drive increasing winds. Strong and gusty southerly winds will dominate locations near and north of Hwy 2, while places south will see increasingly strong W-SW winds. Cloudy and gusty conditions will describe most of our forecast region until the AR finally drifts south late Sunday.
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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Friday
Mostly sunny with passing mid and high clouds. Clouds increasing late in the day.
Friday
Night
Cloud thickening and lowering. Light rain and snow developing after midnight. SW winds becoming moderate and gusty.
Friday
Partly sunny with passing mid and high clouds. Clouds increasing later in the day.
Friday
Night
Clouds thickening and lowering with light rain and snow developing after midnight. Southerly winds increasing significantly and becoming strong and gusty.
Friday
Partly sunny. Clouds increasing in the afternoon.
Friday
Night
Clouds thickening and lowering. A few sprinkles possible in the northern portion of the zone. SW winds becoming light to moderate.
Friday
Mostly sunny with passing bands of high clouds. Light to moderate WNW winds decreasing.
Friday
Night
Becoming cloudy. SW winds becoming light to moderate.
Friday
Partly sunny with passing high clouds. Westerly flow through the Pass.
Friday
Night
Cloudy. Pass winds light and variable.
Friday
Partly to mostly sunny with passing high clouds. Light to moderate westerly winds.
Friday
Night
Becoming cloudy. Light and variable pass level winds.
Friday
Partly sunny with periods of high and mid clouds. Increasing clouds in the afternoon. W winds becoming light to moderate.
Friday
Night
Mostly cloudy. Winds becoming WSW light to moderate.
Friday
Mostly sunny with passing bands of high clouds. Light to moderate WNW winds.
Friday
Night
Becoming cloudy. Winds turning WSW and increasing to moderate and gusty.
Friday
Mostly sunny with passing bands of high clouds. Light to moderate WNW winds decreasing.
Friday
Night
Becoming cloudy. Light to moderate westerly winds.
Friday
Mostly sunny with passing bands of high clouds. Light to moderate NW winds decreasing.
Friday
Night
Becoming cloudy. Winds turning WSW and becoming moderate and gusty.
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).