High pressure, dry weather, clear skies, and a slow but steady warming trend will define the next few days. Freezing levels will be pegged around 10,000 to 11,000' starting tonight with little change through Tuesday. Ridgeline winds will generally be light, except moderate easterlies for the Mt Hood area tonight through early Monday morning where they are still under the waning influence of a closed upper low for the next 12 hours.
Besides your sunglasses, you'll still want those extra layers as trailheads will still be chilly to start each day. Day or night, the warmest temperatures will be found at upper elevations with widespread temperature inversions and cooler temperatures found along lower slopes and valleys. These temperature inversions will be most pronounced along the east slopes of the Cascades, the Cascade Passes and the Mt Hood area. Temperatures will be slightly warmer on Tuesday with mid-mountain temperatures pushing into the mid-40s.
The last significant storm cycle was over 2 weeks ago but change is on the horizon! We will finally return to a stormier and snowier pattern by the end of the work week. How much snow and for how long is still uncertain. The upper level ridge will start to flatten and shift over the PNW Wednesday night through Thursday. It will still be mild over this period, but we'll start to see freezing levels slowly lower and we should see an increase in high level clouds by Thursday, especially over WA state, as a Pacific frontal system advances.
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).