MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time: Wednesday 0630

Current Observations:

24hr Precipitation:  .49 swe, 5”snow

Temperature profile: 25base, 22 ridge

Pass level winds: light and easterly

Barometer: has dropped to 1008mb’s

Sky: OC

Radar: Wide spread showers activity moving north

The Forecast:  There will be a brief break in the snow showers today with a period of mixed rain and snow below 5000’ anticipated tonight.  

Long Range: A prolonged dry period will begin tomorrow as high pressure builds over the inland NW. 

  

The Science: The east flow is hanging tough this morning with freezing levels currently around 3500’.  The east flow will give up the fight tonight with the passing of a weakening frontal system.

High pressure building over the inland NW will begin to block and confine the activity to the western waters starting tomorrow.  The weekend is shaping up to be fairly pleasant with partly cloudy conditions, freezing levels around 4500’ and offshore (east) flow.     

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: .75  snow: 3-5 Tomorrow’s 24hr water: .25  snow: 1-3 Trend and Timing: Mixed rain and snow begins this afternoon with the moisture tapering off after 4am tomorrow.

Temperature: Low: 25    High: 32 Freezing level: >.4000’ Trend and Timing:    Freezing levels will rise to +4500’ through the day.

Winds Base: 5-10 E shifting W Ridge Top: 5-15 ESE Trend and Timing: Surface east flow with SE flow aloft will persist through the day.  SW winds kick in with the passing of the front after 4pm today.

Glossary of PNW Weather Terms: 

Storm Water Equivalent (SWE)…. how much water is in the snow or rain

Orographic lift…. an airmass that is lifted as it moves up and over higher terrain. This promotes cloud development, and enhances precipitation.

Dirty Ridge…. a weak, unorganized high pressure ridge.

Advection…. the transfer of heat by the flow of fluid.  For the PNW, this is usually from warm moist air entering the region from the south.

Flow…. wind direction.  In meteorology, the wind direction is always noted where the wind is coming from.   East flow is wind coming from the east; SW is from the south west…