Although the most intense weather moved through Tuesday and Tuesday night, a cold, snowy pattern continues through Thursday across the Pacific Northwest. Snow levels have lowered to 1500-2000 ft by early Wednesday as vigorous snow shower activity continues (more focused on Washington than Oregon). Expect this activity to continue through around 10 AM Wednesday across the Cascades. A sharp comma-shaped front shifts winds more SSWerly in the mid-morning hours. This will provide a brief decrease in shower activity before a 1-2-hour period of heavy banded precipitation moves through in the midday hours. This precipitation is likely to be heaviest in the southern Washington Cascades and Mt Hood. Behind this front, winds shift back to WSW and then W and increase into the moderate range near and east of the Cascade Crest through Wednesday night. Expect a resulting increase in mountain-enhanced snow showers as these winds pick up. The convergence banding should enhance snowfall rates at times in the southern mountain loop and Stevens Pass area, but models no longer show strong agreement on the exact location of the banding.
Temperatures continue to drop through Thursday morning, bringing the coldest air of the week and snow levels lowering to sea level to 1000 ft during this time. Expect more moderate, low-density snow showers, but with slightly less intensity than on Wednesday and Wednesday night.
Expect an additional 1-2 ft of low-density snow for areas near and west of the Cascade Crest through Thursday.
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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Wednesday
Light to moderate low-density snow showers.
Wednesday
Night
Light to moderate low-density snow showers.
Wednesday
Moderate to occasionally heavy low-density snow showers.
Wednesday
Night
Moderate low-density snow showers.
Wednesday
Moderate to occasionally heavy low-density snow showers. Moderate ridgeline winds at times.
Wednesday
Night
Moderate snow showers, locally heavy in convergence banding. Moderate ridgeline winds.
Wednesday
Moderate to occasionally heavy low-density snow showers. Moderate ridgeline winds at times.
Wednesday
Night
Moderate to locally heavy low-density snow showers. Moderate ridgeline winds.
Wednesday
Moderate low-density snow showers. Moderate ridgeline winds at times, and light W wind at the Pass.
Wednesday
Night
Moderate snow showers, locally heavy in convergence banding. Moderate ridgeline winds. Increasing light to moderate ridgeline and W winds at the Pass.
Wednesday
Moderate to occasionally heavy low-density snow showers. Moderate ridgeline winds at times, and light W wind at the Pass.
Wednesday
Night
Increasing moderate to occasionally heavy snow showers. Increasing moderate ridgeline and light to moderate ridgeline winds at the Pass.
Wednesday
Light to moderate low-density snow showers, heaviest in the afternoon.
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).