Mountain Weather Forecast

Weather Synopsis for Wednesday & Tuesday

An unusually high-amplitude December ridge continues to dictate our weather on Wednesday. Expect another day of sunshine with temperatures warmer than Tuesday in most areas. A huge temperature gradient exists across the Cascades: A pool of cold air (teens to low thirties) remains up to about 5000 ft to the E of the Cascades, while areas to the west enjoy temperatures in the upper thirties to low 50's. For example, at 6 AM, Mt. Baker Pan Dome was 53 degrees, while Washington Pass base was in the ice box at 16 degrees (a 37 degree temperature difference). Meanwhile, Washington Pass Upper station was above freezing at 33 F. The warm air is increasingly winning the battle of the two air masses as the cold air pool gradually moderates and becomes increasingly shallow. Freezing levels (aloft) should be 10000-12000 ft in most areas by afternoon.

The pressure gradient across the Cascades is most intense around 7 AM this morning, which is when we expect strong winds through mountain gaps to peak. Alpental Summit has seen 30-50 mph sustained winds, with gusts up to 60 mph. Other places exposed to east flow, including Mission Ridge and White Pass have also seen some strong winds.

Clear skies continue Wednesday night as the pressure gradient and winds relent more rapidly. Mild temperatures should continue overnight in most areas, with only valley locations E of the Crest and the lower slopes of the passes experiencing colder temperatures.

On Thursday, winds gradually shift SW in advance of a fizzling, approaching shortwave trough as the high pressure ridge axis continues to shift away to the east. This shortwave should bring in some mid-level clouds and a slight chance of an afternoon rain shower for Hurricane Ridge. Expect mild temperatures in most areas, but freezing levels will be 1000-2000 ft lower than on Wednesday.