A large area of vertically stacked low pressure continues to amble southward toward California, where it will reach by Wednesday. As we head into springtime and the storm track becomes less vigorous, lingering cutoff low-pressure centers become more common.
The parent low spawned a smaller-scale circulation center lifting northward off the Washington Coastline Tuesday morning. A band of somewhat continuous snow over the southern Washington Cascades through the southern Olympics should weaken as it lifts northward but could bring areas of the Cascades an inch of snowfall. The southern Olympics could see 1-4" of snow as southerly flow and moisture wrapping around this small circulation take relative aim at this region.
Periods of light snow linger from the central Cascades northward Tuesday evening before clearing out. Another light band of snowfall ejecting from the parent low bring very light snowfall to the southern parts of our forecast region Tuesday night.
On Wednesday, moisture and instability from the low off California combine with an incoming shortwave trough arriving from the NW. This could touch off isolated and locally slightly more intense shower activity on Wednesday, particularly during the afternoon.
Temperatures should be near seasonal norms throughout the forecast period. With relatively cool air aloft and more clouds than sun both Tuesday and Wednesday, expect areas with sunshine to be 5-10F warmer than areas with cloud cover.
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
Mostly cloudy with periods of light snow. Heavier in the southern part of the Olympics.
Tuesday
Night
Partly cloudy with a chance of light snow showers lingering into the evening.
Tuesday
Mostly sunny early, then becoming mostly cloudy by afternoon.
Tuesday
Night
A chance of light snow in the evening, then mostly clearing skies.
Tuesday
Mostly sunny early, then becoming mostly cloudy by mid-morning. A chance of light snow at times in the afternoon.
Tuesday
Night
A chance of light snow in the early evening, then becoming mostly clear.
Tuesday
Mostly cloudy with periods of light snow most likely through the early afternoon.
Tuesday
Night
Partly cloudy with periods of light snow after midnight.
Tuesday
Mostly sunny early, then becoming mostly cloudy by mid-morning. A chance of light snow at times in the afternoon. Light E winds at the Pass.
Tuesday
Night
A chance of light snow in the early evening, then becoming mostly clear. Light E winds at the Pass.
Tuesday
Mostly sunny early, then becoming mostly cloudy by mid-morning. A chance of light snow at times in the afternoon. Light E winds at the Pass.
Tuesday
Night
A chance of light snow in the early evening, then becoming mostly clear. Light E winds at the Pass.
Tuesday
Mostly clear in the morning, then becoming mostly cloudy with a chance of light snow late in the day.
Tuesday
Night
Periods of light snow in the evening, then remaining partly cloudy.
Tuesday
Mostly sunny early, then becoming mostly cloudy by mid-morning. A chance of light snow at times in the afternoon.
Tuesday
Night
A chance of light snow in the early evening, then becoming partly to mostly clear.
Tuesday
Mostly cloudy with periods of light snow.
Tuesday
Night
Partly cloudy with periods of light snow at times.
Tuesday
Mostly cloudy with periods of light snow in the morning hours.
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).