MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Date: Monday, January 27, 2020

Current Observations:

24hr Precipitation: .5” SWE / 5” snow

Temperature profile: 31 base / 27 mid mtn

Pass level winds: Light-mod westerly

Barometer:  1016 rising slowly

Sky: Few clouds

Radar: Spotty showers in the mountains with a convergence zone near Glacier Peak

The Forecast: Mostly dry and mild during daylight hours today, with moderate to heavy snow overnight. Snow showers continuing Tuesday.

The Science: A quick moving trough made landfall overnight and is currently east of the Cascade Crest. It brought a shot of 4” of snow in a couple hours and slightly lowering freezing levels with some colder air aloft. The most recent balloon sounding on the Olympic Peninsula had the freezing level at 3200’, a welcome change from the past few days. A short lived high pressure ridge is sweeping thru this morning, but won’t last long in this progressive pattern. Most of the daylight hours Monday will be dry and calm, however, the next low pressure system is rapidly approaching with the warm front lifting from south to north this afternoon.

The warm front will spread moderate to heavy precipitation across the Cascades after 10pm, reasonably high hourly precip rates can be expected overnight before the trailing cold front swings thru and dials down the intensity. Post frontal westerly flow will keep snow showers going most of the day Tuesday.

Long Range: Similar to the past 24 hours, a transitory ridge will move thru Wednesday morning for a relatively dry start to the day before yet another low pressure cell approaches, bringing moderate snow Wednesday night. A higher amplitude ridge builds behind that for a mostly dry Thursday. Things may get sporty at the end of the week with an atmospheric river event taking shape. Details on exactly where the firehouse will be aimed are still coming together.

Confidence: Fair for snow amounts overnight. Poor for details on timing middle to late in the week.

Values from 4am today through 4am tomorrow.

Precipitation: Today 24hr water: .75-1.0 snow: 8-12” Tomorrow’s 24hr water: .5”   snow: 6-8” Trend and Timing:

Temperature: Low: 27    High: 32 Freezing level: 3000-4000’ Trend and Timing:    There could be some daytime warming, and a slight bump in freezing levels with the warm front passage.

Winds Base: W-E-W @ 5-10 with a few gusts Ridge Top: W-E-W @ 5-15 Trend and Timing: As the low approaches today, winds should shift to easterly thru the Pass. After the low passes tonight they will shift back west as per usual.