MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time: Thursday 0630

Warning: Freezing rain with slippery roads are being reported between Leavenworth and Stevens Pass.

Current Observations:

24hr Precipitation: raining.  .66” swe, 0” snow

Temperature profile: 36f, base, 36f ridge

Pass level winds: gusty 5-15mph - WSW

Barometer: 1010mbs and slowly falling

Sky: OC, fog

Radar: the radar is lit up this morning with moderate to heavy rain heading in the mountains.

The Forecast: Rain today switching to snow tonight, snow showers tomorrow and Saturday.

Long Range:  Intermittent snow showers with sun breaks will be the weather pattern for the weekend.  The storm track will remain very active for the first full week of 2019.   

  

The Science:  The expected warm front moved east of the Cascade Crest just after midnight last night.  Freezing levels are currently reading +-6000’ with a long fetch of moisture stretching out to the SW. 

A cold front, currently still offshore, is expected to slowly drift east over the next 12hrs. There is a chance of this front occluding which will allow the warm and cold air to mix and thus keep freezing levels from dropping much further than 4000’.    The rain should shift to snow tonight and diminish to intermittent showers tomorrow.

In the long term; the jet stream begins to take a more southerly track.  Low pressure systems, being pushed by the jet, will spin storms up through the PNW next week.   Since this storm track has a southerly orientation freezing levels will be at or above 4000’.   East flow will try and play its part in keeping Stevens insulated… stay tuned.   

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: 1.5”  snow: 2-5” Tomorrow’s 24hr water: .25-.5  snow: 3-5” Trend and Timing: Rain today shifting to snow tonight and then tapering to intermittent showers.

Temperature: Low: 30    High:40 Freezing level: 6000’- 4000’ Trend and Timing:    Freezing levels will begin to fall below 4500’ after 4pm.  FL’s will likely fall to 3000’ by early Saturday morning.

Winds Base: 5-10 WSW Ridge Top: 10-20WSW Trend and Timing: Gusty ridge top winds will begin to diminish tonight.

Glossary Terms: 

·       Storm Water Equivalent (SWE) = how much water is in the snow or rain

·       Triple Point = A frontal system that has a warm front, a cold front and an occluded front that all circulate around a common point.