8:00 Fri Jan 1st no ABS

MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time:  Thursday 0700

Current Observations:

24hr Precipitation:  0

Temperature profile: 25base, 43ridge

Pass level winds: westerly and light

Barometer: 1011mb’s and falling

Sky: mostly clear with high clouds

Radar: Most of the state is dry with incoming moisture off the southern BC coast.  

The Forecast:  Light rain developing overnight with rain turning to snow tomorrow.

Long Range: Intermittent snow showers with much lower temperatures will develop through the weekend.  

  

The Science: The approaching triple point frontal system will begin to push the warm air mass east today.  The inverted temperatures will equalize with daytime temperatures peaking near 50 in the base area.

The approaching storm isn’t packing a ton of energy, and with the warm air in place, this will start out as light rain.  Cooler NW flow filters in tomorrow morning which will drop freezing levels to +-4000’.  With some luck, we will squeeze +-4” of snow out of it by Saturday morning.  

A cold arctic air mass is expected to drop in from the north on Sunday which will bring much cooler temperatures.  Bands of moisture spinning up from the south will mix with this cool air for some hopeful snow showers.    

Forecast confidence is good.   

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: .10  snow: 0 Tomorrow’s 24hr water: .5  snow: 3-5 Trend and Timing: Light rain begins after 7pm with snow mixing in after 7am tomorrow.

Temperature: Low: 28  High: 50 Freezing level: 8000’ – 5000’– 4000’ Trend and Timing:    Cooling begins overnight with freezing levels falling to 4000’ by noon or so tomorrow.

Winds Base: 0-10 W Ridge Top: 5-10 W Trend and Timing: Winds will be light and westerly through tomorrow.

8:00 Thurs Jan 31st no ABS

MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time:  Wednesday 0700

Current Observations:

24hr Precipitation:  0

Temperature profile: 24base,  38 ridges - A temperature inversion is underway with upper air temperatures reading in the upper 30’s with Pass levels in the mid 20’s.

Pass level winds: light and easterly

Barometer: 1013mb’s and falling

Sky: Clear

Radar: Dry with high clouds moving in

The Forecast:  Warmer today with increasing clouds.  Temperatures could reach into the mid to upper 40’s tomorrow with mixed rain and snow arriving early Friday morning.   

Long Range:  A mixed rain and snow event, hopefully turning to snow will begin early Friday morning.  Light snow showers with colder temperatures can be expected for the weekend.   

  

The Science:  A dry warm air mass will drift over the PNW today.  Freezing levels could peak above 7000’.   Luckily there is no moisture associated with this system.

A weakening cold front will push in early Friday morning with moisture in tow. Freezing levels will drop, but too or below 4000’ is still in question.  The moisture will likely start out as light rain below 4500’ with snow mixing in through the day.   Confidence in this is fair.

 The record setting cold air mass sinking in to the middle of the country will makes its way west over the weekend.  The PNW won’t see below zero temperatures, but will see a significant cooling effect. 

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: 0  snow: 0 Tomorrow’s 24hr water: .24  snow: 0-2 Trend and Timing: Dry through early Friday morning.

Temperature: Low: 24    High: 40 Freezing level: 7000’ Trend and Timing:    Freezing levels will peak near at or above 7000’ today.

Winds Base: 0-5 E shifting SW Ridge Top: 0-10 WNW Trend and Timing: Westerly flow will develop today and remain the general wind pattern through tomorrow.

8:00 No ABS Wednesday the 30th, OTD at 8:05 for medical training.

"OTD" = out the door. It's a technical term. 

MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time:  Tuesday 0630

Current Observations:

24hr Precipitation: 0

Temperature profile: 25base, 19ridges

Pass level winds: light to moderate and out of the east

Barometer: 1019mbs and beginning to fall

Sky: Mostly clear

Radar: Clear

The Forecast: We will have to endure a few more days of this dry clear and relatively warm weather.

Long Range:  Dropping freezing levels and snow arrives late Thursday night for a snow day on Friday.

  

The Science:  The high pressure that has brought us this spring like weather is weakening, but will continue to dominate through Thursday.  The general flow will shift southerly over the next 24hrs.  This will erode the cool air trapped in the easterly basin and push freezing levels up to the 6-7000’ tomorrow and Thursday.

A strong cold front, developing in the Gulf of Alaska, will charge through late Thursday night.  This will drop freezing levels and provide some nice snowfall for Friday.   

Confidence in the timing and swe amounts is still fair but is improving with each model run.   

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: 0  snow: 0 Tomorrow’s 24hr water: 0  snow: 0 Trend and Timing:

Temperature: Low: 26    High: 40 Freezing level:  3000’-7000’ Trend and Timing:    Freezing levels will slowly rise over the next 24hrs.

Winds Base: 5-10 E Ridge Top: 5-15 E Trend and Timing: Gusty easterly winds will diminish tonight and shift WSW tomorrow.

8:00 No ABS Tuesday the 29th

MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time:  Monday 0630

Current Observations:

24hr Precipitation: 0

Temperature profile: 29 base, 23 ridge

Pass level winds: light and out of the east

Barometer: 1026mbs steady 

Sky: clear

Radar:  clear

The Forecast:  More sunshine today but with cooler temperatures.  The same but with some added high level clouds can be expected tomorrow.

Long Range:  Snow for Friday and Saturday? Possibly.    

  

The Science:  Easterly flow, that formed overnight, has begun to usher in cooler air from the interior west. This change is due to the center of the high pressure drifting east toward the intermountain west and a weak cut-off low forming along the Oregon Washington border.   Disturbances trying to make their way east will still be blocked or split by this feature through early Thurssday.

Thursday through Saturday, the northern jet stream makes a visit to the Gulf of Alaska. This will provide a period of NW flow with a few winter storms forming within the jet.

Good confidence is still a day or two out, so for now, we can anticipate some potential measurable snow heading into the weekend.   Stay tuned.   

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: 0  snow: 0 Tomorrow’s 24hr water: 0  snow: 0 Trend and Timing: 0

Temperature: Low: 24    High: 32 Freezing level: +-2500 Trend and Timing:    Freezing levels will drop to +- 2500’ today.  Daytime temps will recover to near freezing with the aid of the sun.

Winds Base: 5-10 E Ridge Top: 5-15 E Trend and Timing: Gusty easterly winds will persist through the next 24-36hrs.

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…

The Inter-mountain West….. the region between the Rock Mountains and the Cascade Mountain ranges.  Mainly Idaho and Western Montana.

Puget Sound Convergence Zone….. This is formed when large scale westerly flow splits around the Olympic Mountains and then converges over Puget Sound.  The flow then accelerates up the river valley’s enhancing the orographic effect at the Passes. 

Occluded Front…..The boundary that separates the cold air mass behind a cold front and the warm air associated with a warm front. When the cold front overtakes the warm front it occludes.

High/Low Pressure…. High pressure is associated with sinking air that rotates clockwise. High pressure often results in dry and clear weather.  Low pressure is rising air that rotates counter clockwise and results in condensation, cloud formation and precipitation.

Atmospheric Stability….. A stable atmosphere is associate with high pressure or the inability for air to rise.  Instability or an unstable atmosphere forms under low pressure or rising air

8:00 No ABS Monday the 28th

Mountain Weather Forecast

Stevens Pass Mountain Weather Forecast

Day and Time: Sunday 0700

Current Observations:

24hr Precipitation:   0”

Pass temperature:  34 base area / 42 upper mountain

Pass level winds:  Light, westerly

Barometer:   1022

Sky:  Clear

Radar:  No precipitation in Washington State

The Forecast: Sunny, warm, and mild with decreasing winds Sunday. Inversion conditions developing Sunday night and continuing Monday.

Long Range:  The ridge starts to flatten by the middle of next week, bringing increasing clouds and lowering freezing levels. It departs entirely by the end of the week, allowing Pacific storms to return to our lexicon.

  

The Science: Main forecast problem for the next 24 hours is when the east flow will begin. The high pressure ridge axis remains a bit offshore this morning, and should move inland this afternoon, changing pressure gradients enough that east flow will develop thru Stevens Pass. This should bring the normal complement of base area fog and below freezing temperatures, with warm air and sun above the inversion line.

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: 0  snow: 0 Tomorrow’s 24hr water: 0  snow: 0 Trend and Timing: No precipitation expected for the next 48 hours.

Temperature: Low: 28   High: 42 Freezing level: 8,000’ Trend and Timing:    Warm all day Sunday. Cooling Sunday night and Monday.

Winds Base: Light W, then E 5-10 Ridge Top: 15-20 W, then E10-20 Trend and Timing: Wind will become light and variable Sunday afternoon, switching to easterly Sunday night and Monday.

7:30 No ABS Sunday the 27th

Mountain Weather Forecast

Stevens Pass Mountain Weather Forecast

Day and Time: Saturday 0700

Current Observations:

24hr Precipitation:   0”

Pass temperature:   31 degrees

Pass level winds: Light from the west

Barometer:  Steady at 1029 mb’s

Sky: Clear

Radar: no precipitation showing

The Forecast: Sunny, warm, and clear today. Truly June-uary.

Long Range:  The enormous high pressure ridge will remain in place for the next several days, east flow should develop Sunday for typical inversion type conditions possible. The ridge begins to breakdown in the middle of next week, allowing a return to winter by the end of the week.

  

The Science: An obvious high pressure ridge is parked over the West coast, pushing any and all weather systems well north of us. The pressure gradient supports onshore flow today, so the sunny and warm temperatures should be felt at Stevens Pass today along with the rest of the state. East (offshore) flow looks to develop Sunday for potential pass level inversion conditions.

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: 0  snow: 0 Tomorrow’s 24hr water: 0  snow: 0 Trend and Timing: No precip expected for several days.

Temperature: Low:  31   High: 40 Freezing level: 10,500’ Trend and Timing:    Strong daytime warming, freezing levels lowering a bit for Sunday.

Winds Base: 5-10 W Ridge Top: 10-20 W Trend and Timing: Consistent moderate westerly winds Saturday.

7:30 Sat Jan 26th no ABS

MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time: Friday 0700

Current Observations:

24hr Precipitation: 0

Temperature profile: 31base, 26 ridge

Pass level winds: light westerly

Barometer:1025mb’s and on the rise 

Sky: mostly clear

Radar:  

The Forecast: While the Upper Midwest goes into the deep freeze with -25f to -35 degrees below zero forecasted, the west coast could see record high temperatures.  Temperatures could hit 50^0f during the peak of the day tomorrow.  

Long Range:  This stretch of dry weather will continue through most of next week. Cooler air from the east will move in on Sunday and Monday for some freezing temperatures.

  

The Science: A high amplitude ridge, currently parked off of the PNW waters, will ease its way inland over next 24hrs.  The main feature of interest is the unseasonably warm air mass associated with this high pressure system.  Freezing levels over Westerly Washington could peak above 10,000’ with Pass temperatures hitting 40’s or even 50 degrees tomorrow.

Cooler offshore (east) flow will bring temperatures back to normal on Sunday with a melt freeze cycle developing early 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 weather will persist.

Temperature: Low: 30    High: 40 Freezing level: + 6000’ Trend and Timing:    Temperature will continue to climb today with freezing levels topping 8000’ tomorrow.

Winds Base: 0-10 NW Ridge Top: 5-15 NW Trend and Timing: Pass level winds will be light with gusty ridge top winds possible.

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…

The Inter-mountain West….. the region between the Rock Mountains and the Cascade Mountain ranges.  Mainly Idaho and Western Montana.

Puget Sound Convergence Zone….. This is formed when large scale westerly flow splits around the Olympic Mountains and then converges over Puget Sound.  The flow then accelerates up the river valley’s enhancing the orographic effect at the Passes. 

Occluded Front…..The boundary that separates the cold air mass behind a cold front and the warm air associated with a warm front. When the cold front overtakes the warm front it occludes.

High/Low Pressure…. High pressure is associated with sinking air that rotates clockwise. High pressure often results in dry and clear weather.  Low pressure is rising air that rotates counter clockwise and results in condensation, cloud formation and precipitation.

Atmospheric Stability….. A stable atmosphere is associate with high pressure or the inability for air to rise.  Instability or an unstable atmosphere forms under low pressure or rising air.