MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time: Friday 0730

Current Observations:

24hr Precipitation:  0

Temperature profile: 31base,  28 ridge

Pass level winds:  Light ENE

Barometer: 1017mbs  steady

Sky: pass level fog

Radar: dry in the mountains with moisture moving north along the NW coast.

The Forecast: We can expect partly cloudy skies with temperatures near freezing through the weekend.  

Long Range: This dry and relatively warm stretch of weather will continue through the middle of next week with a potential change starting Thursday.

  

The Science:  The high pressure building over the inland NW will strengthen today.  This will block and split any disturbances from reaching the mountains. East west pressure gradients along the Cascade Crest will increase over the weekend.  This will provide gusty easterly flow through the Pass and allow freezing levels to hover around 4000’.  

          Confidence is good in the weekend forecast.

Long range models have the high pressure weakening next week with a potential change in the pattern starting on Thursday.  This is a loooong ways out so confidence is low beyond Tuesday of next week.

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: 0  snow: 0 Tomorrow’s 24hr water: 0  snow: 0 Trend and Timing: Dry through the weekend.

Temperature: Low:28     High: 34 Freezing level: +-4000’ Trend and Timing:    Freezing levels will hold around 4000’ with the aid of east flow through the weekend.

Winds Base: 5-10 E Ridge Top: 5-10 E Trend and Timing: East flow will strengthen 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…

Blocking ridge…. This is where a large ridge of high pressure sets up a virtual wall of pressure.  This redirects or prevents and weather disturbances from getting through.