A warm, moist air mass continues to stream into the region on SW flow as an atmospheric river event wanes across the region. The final wave of moisture exited the region Monday night with a trailing, narrow band of precipitation streaming into northern Oregon for more continuous rain and high elevation snow on Tuesday. Across Washington State, rain and high elevation snow shower activity should be heaviest in the morning hours, particularly across the central Cascades. Snow levels remain slightly lower (4500-5000 ft) in the northern Cascades and Olympics today, but around 6500 ft in the Mt. Hood area.
Shower activity becomes mostly light across Washington State from Tuesday afternoon through Tuesday night while steadier precipitation continues with the stalled rain band over northern Oregon.
Temperatures gradually cool as the offshore trough gets closer to the coast on Wednesday with snow levels lowering to 3500-5000 ft by the afternoon. The rain band over northern Oregon should weaken, leading to periods of rain/snow for Mt. Hood.
Expect the chance for convective showers and graupel each afternoon as cooler air moves in aloft.
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
Light rain and snow showers.
Tuesday
Night
Light rain and snow showers.
Tuesday
Decreasing moderate rain and snow showers.
Tuesday
Night
Light to moderate rain and snow showers.
Tuesday
Moderate rain and snow showers.
Tuesday
Night
Light rain and snow showers.
Tuesday
Moderate rain and snow showers with Crystal mostly rain shadowed and light showers at White Pass.
Tuesday
Night
Light rain and snow showers, heaviest at Paradise.
Tuesday
Moderate rain and snow showers, heaviest during the morning hours. Light W winds at the Pass.
Tuesday
Night
Light rain and snow showers. Light and variable wind at the Pass.
Tuesday
Moderate rain and snow showers, heaviest during the morning hours. Light W winds at the Pass.
Tuesday
Night
Light rain and snow showers. Light and variable wind at the Pass.
Tuesday
Decreasing light rain and snow showers.
Tuesday
Night
Light rain and snow showers.
Tuesday
Decreasing light rain and high elevation snow showers. Strong ridgeline winds.
Tuesday
Night
Light rain and snow showers.
Tuesday
Light rain and high elevation snow showers. Strong ridgeline wind gusts.
Tuesday
Night
Light rain and snow showers.
Tuesday
Moderate to heavy rain and high elevation snow. Strong ridgeline wind gusts.
Tuesday
Night
Moderate rain and high elevation snow with a cooling trend 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).