Active weather has returned to the Pacific Northwest this morning, as a warm frontal system pushes in over western Washington. Clouds have blanketed most of the region, with precipitation just beginning to arrive in the West North and the Olympics. SW wind has already ramped up along the west side, with stronger gusts recorded on the volcanoes.
Expect a steady increase of rain and high-elevation snow on Tuesday, with heavier precipitation focused around the West North and West Central zones. Snow levels will remain above 5000 feet today, bringing rain for the passes and ski area bases, and snow for the high peaks. Snow levels will gradually drop Tuesday night into Wednesday to as low as 4,000 feet, and continue to drop closer to Pass level by Wednesday evening.
By Wednesday, an upper-level trough digs into the region, transitioning SW flow aloft to WNW, bringing a more favorable direction for the Passes and western front.
Models continue to indicate the potential for a convergence zone setting up along the western front early Wednesday, which would bring a period of locally heavier precipitation. The exact location of this setup is still unclear.
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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Tuesday
Increasing rain and mountain snow, intensifying later in the day. Moderate to strong ridgeline wind.
Tuesday
Night
Rain and mountain snow. Moderate ridgeline wind.
Tuesday
Moderate rain and mountain snow, intensifying later in the day. Moderate to strong ridgeline wind.
Tuesday
Night
Moderate to heavy rain and mountain snow. Moderate ridgeline wind.
Tuesday
Moderate rain and mountain snow, intensifying later in the day. Light to moderate ridgeline wind.
Tuesday
Night
Moderate to heavy rain and mountain snow. Moderate ridgeline wind.
Tuesday
Moderate rain and mountain snow, intensifying later in the day. Light to moderate ridgeline wind.
Tuesday
Night
Rain and mountain snow. Light to moderate ridgeline wind.
Tuesday
Increasing rain and mountain snow. Moderate to strong ridgeline wind, and light W wind at the pass.
Tuesday
Night
Rain and mountain snow. Moderate to strong ridgeline wind, and light W wind at the pass.
Tuesday
Increasing rain and mountain snow. Moderate to strong ridgeline wind, and light W wind at the pass.
Tuesday
Night
Rain, with snow above Pass level. Moderate to strong ridgeline wind, and light W wind at the pass.
Tuesday
Increasing rain and mountain snow. Light to moderate ridgeline wind.
Tuesday
Night
Rain and mountain snow. Light to moderate ridgeline wind.
Tuesday
Building clouds, with a chance of rain and mountain snow late in the day. Light to moderate ridgeline wind.
Tuesday
Night
Rain and mountain snow. Light to moderate ridgeline wind.
Tuesday
Building clouds, with a chance of rain and mountain snow late in the day. Light to moderate ridgeline wind.
Tuesday
Night
Light rain and mountain snow. Light to moderate ridgeline wind.
Tuesday
Building clouds, with rain and mountain snow late in the day. Moderate to strong ridgeline wind.
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).