MOUNTAIN WEATHER FORECAST

Time and Day: 0630 Sunday

The Snapshot: Light rain starting soon, switching to moderate to heavy snow and gusty winds during the day and overnight. Calm and mostly dry on Monday.  

The Science: A warm front is currently crossing the North Cascades which will be swiftly followed by the trailing cold front. Cold frontal passage should be midday Sunday. As the low pressure trough crosses Washington State, strong upper level zonal (westerly) flow will support good orographic snow showers with cold air filling in and lowering freezing levels. Convergence is currently indicated by models to set up north of Stevens Pass, near Glacier Peak. However, if this shifts south we could see higher amounts of snow.  

Weak high pressure will build behind the trough ending precipitation Monday morning, this will be short lived as the next moderate warm (5,000' snow level) front will cross Stevens Pass Monday night. There should be cool east flow in place for this event which may keep precipitation as snow for Stevens.  

The Long Range: Active weather continues throughout the week, with fronts every 24-36 hours and fluctuating snow levels.  

Precipitation Ending at 4am: Today 24hr water = .75               Snow = 6-8" (possibly more in convergence) Tomorrow’s 24hr water =  <.25        Snow = 0-2" Trend and Timing: Light rain will start the day, switching to snow mid-morning. Moderate (to heavy if convergence sets up) snow will increase through the afternoon and overnight, ending Monday morning.

24hr temperature ending at 4 am tomorrow: Low: 26 High: 34 Freezing level: 4,000' - 2,000' Trend and Timing: The warmest temperatures of the day should be at daybreak, with cold air rushing in during the day and lowering snow levels overnight.

24hr Winds (mph) ending at 4 am tomorrow: Base: 0-5 E then 10-15 W Ridge Top: 5-10 E then 20-30 W Trend and Timing: Light east winds will shift around the compass rose and become strong and gusty from the west midday and overnight Sunday.   253 Dan