A strong ridge of high pressure remains anchored offshore and will keep us dry through the rest of the week. We have a few subtle wrinkles this morning as east flow through the Cascade Passes and cool southeasterlies down at Mt Hood have temporarily depressed freezing levels to match the cooler east slopes of the Cascades. Mid and upper mountain temperatures are generally above freezing west of the crest and below freezing near and east of the Cascade crest.
As ridgeline winds become more westerly this afternoon, look for temperature inversions/valley fog to continue but the low clouds in the Cascade Passes should mix out/clear and freezing levels and temperatures will rise. Entrenched lowland stratus and valley fog will continue. Along the east slopes of the Cascades, cooler conditions will dominate but as you travel closer to the Cascade crest you can expect milder freezing levels and temperatures.
A "dry" upper level weather disturbance will ripple down the ridge from the NW tonight, spreading high clouds into the region this afternoon through overnight. There will be a temporary dip near and east of the crest in freezing levels tonight but Wednesday should be warmer as the upper level ridge amplifies offshore. Freezing levels further west of the Cascade Crest will stay mild in the short term.
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 sunny in the morning, then partly to mostly sunny with high clouds and filtered sunshine in the afternoon. Areas of valley low clouds and fog.
Tuesday
Night
Partly to mostly cloudy in the evening, then clearing late. Areas of valley low clouds and fog.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with high clouds and filtered sunshine in the afternoon. Areas of valley low clouds and fog.
Tuesday
Night
Partly to mostly cloudy in the evening, then clearing late. Areas of valley low clouds and fog.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with high clouds and filtered sunshine in the afternoon. Areas of valley low clouds and fog.
Tuesday
Night
Partly to mostly cloudy in the evening, then clearing late. Areas of valley low clouds and fog.
Tuesday
Mostly sunny in the morning with a few high clouds in the afternoon. Areas of valley low clouds and fog.
Tuesday
Night
Partly to mostly cloudy. Areas of valley low clouds and fog.
Tuesday
Mostly sunny. Low clouds lower slopes breaking up in the afternoon. Light to moderate E-SE winds at Pass level and ridgeline decreasing in the afternoon with ridgeline winds becoming westerly.
Tuesday
Night
Partly to mostly cloudy. Low clouds at Pass level. Light to moderate east winds at Pass level.
Tuesday
Mostly sunny. Low clouds lower slopes breaking up in the afternoon. Moderate E-SE winds at Pass level and ridgeline decreasing in the afternoon with ridgeline winds becoming westerly.
Tuesday
Night
Partly to mostly cloudy. Low clouds at Pass level. Moderate east winds at Pass level.
Tuesday
Mostly sunny in the morning, then partly to mostly sunny with high clouds and filtered sunshine in the afternoon. Valley low clouds and fog. Higher freezing levels/milder near the Cascade Crest.
Tuesday
Night
Partly to mostly cloudy. Valley low clouds and fog.
Tuesday
Mostly sunny in the morning with a few high clouds in the afternoon. Valley low clouds and fog. Higher freezing levels/milder near the Cascade Crest.
Tuesday
Night
Partly to mostly cloudy. Valley low clouds and fog.
Tuesday
Mostly sunny in the morning with a few high clouds in the afternoon. Valley low clouds and fog. Higher freezing levels/milder near the Cascade Crest.
Tuesday
Night
Partly to mostly cloudy. Valley low clouds and fog.
Tuesday
Mostly sunny. A few high clouds late. Moderate to strong E-SE winds this morning decreasing by late morning. Colder east side of the mountain in the morning.
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).