8:00 No ABS Tuesday Jan 1

Previous post about 7:30 start was inaccurate. See you at 8. 

MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time: Monday 0600

Current Observations:

24hr Precipitation: .15swe, 2”of snow fell since yesterday afternoon

Temperature profile: 17f base, 16f ridge

Pass level winds: light and out of the east

Barometer: has risen to 1023mb’s 

Sky:  partly cloudy with clearing

Radar: dry conditions state wide

The Forecast:  The sun will make its last appearance of the year today.  Cold temperatures are moving in with dry weather expected through Wednesday.

Long Range: Enjoy the next two days because another wet warm system (similar to this past weekend) is taking shape.  Snow begins late Wednesday night with rain and wind anticipated on Thursday.   

  

The Science: The barometric pressure hitting 1023mbs is indicative of the high pressure ridge moving into the region.  Thus the skies are clearing and the atmosphere is drying and stabilizing.  Enjoy.  

The cold, dry air that has moved in from the interior west won’t stick around for long as warmer SW flow begins to make a push.  Wednesday/Thursday’s developing storm has very similar characteristics as this past event.   The winds don’t looks as strong but they will be in play.  Details are still developing, so for now, expect snow Wednesday night changing to rain on Thursday and then back to snow on Friday. 

Confidence in this event is fair to good.

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 Wednesday morning.

Temperature: Low: 14    High: 24 Freezing level: +-500’ Trend and Timing:    Temperatures will recover into the mid 20s’ today with freezing levels slowly rising tomorrow.

Winds Base: 0-5 E shifting W Ridge Top: 5-10 E shifting W Trend and Timing: East flow today will shift westerly early tomorrow morning.

7:30 No ABS the last day of 2018! (Monday the 31st)

MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time: Sunday 1100

Current Observations:

24hr Precipitation:  1.48”(swe) fell since 4pm yesterday with 7” of new snow in the base area.

Temperature profile: 28b, 23r

Pass level winds: 5-10 W

Barometer: 1015mbs and rising

Sky: OC, with patchy fog

Radar:  There are some remnant snow showers lingering in the convergence zones with clearing and drying to the west.

The Forecast: Decreasing snow, wind and temperatures today.  The year will end and begin under dry and partly cloudy weather.  

Long Range: The next round of precipitation will arrive late Wednesday with warming temperatures.   

  

The Science:  A high pressure ridge will strengthen over the region today.  Some cold air from a dry, arctic air mass sinking into the Intermountain West (Montana) will find its way into the eastern basin over the next 24hrs.   Freezing levels will drop to or below 1000’ with mostly dry and clear conditions developing over the Cascade Mountains.

The next storm (low pressure system) of interest is developing along a southerly storm track.  This is expected to arrive late Wednesday night into Thursday with another round of rising freezing levels and mixed rain and snow.

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: .25  snow: 2-4 Tomorrow’s 24hr water: 0  snow:0 Trend and Timing: Diminishing snow showers today.

Temperature: Low: 14    High:26 Freezing level: 3000’-1000’ Trend and Timing:    Freezing levels will drop below 1000’ tonight with cold temperatures rising on Tuesday.

Winds Base: 0-5 NE Ridge Top: 5-10 WNW shifting E Trend and Timing: Winds will diminish today and shift easterly overnight.

MOUNTAIN WEATHER FORECAST - delay

Stevens Pass Mountain Weather Forecast

Day and Time: Sunday 0500

Note:  The formal forecast will be delayed due to avalanche control.

The Gist: Cooling with diminishing snow showers today.  Dry with clear periods tomorrow and Tuesday. 

Current Observations:

24hr Precipitation: 2.54 swe, 6” snow in base,  +-10” on upper ridge.

Temperature profile: 29b,

Pass level winds:  5-15 W gusty

Barometer: 1011mb and slowly rising

Sky: OC

Radar: Snow showers persisting in the convergence zones with dry patches over Puget Sound.

6:15 ABS Sunday the 30th

Mountain Weather Forecast

Stevens Pass Mountain Weather Forecast

Day and Time: Saturday 0630

Current Observations:

24hr Precipitation:   .6” (5” snow on upper mountain, turned to rain after midnight)

Pass temperature:  38 base, 35 upper mountain

Pass level winds:   Strong and gusty from the west/southwest

Barometer:  Dropped to 1015

Sky:   Overcast/raining

Radar:  Showers over the Cascades and Olympics, relatively dry in the Puget Sound at the moment

The Forecast: Rain showers and windy during the day Saturday. Mixed precip Saturday afternoon turning to all snow Saturday evening and night with continued strong and gusty winds. Light snow showers and cool on Sunday.

Long Range:  An upper level ridge begins nudging in on Sunday afternoon, turning flow northerly and bringing a dry and cool end to 2018. Monday and Tuesday should be calm with freezing levels in the 2000’ range and partly cloudy. The next active weather period arrives Wednesday night with a warm front.

  

The Science: The warm up and switch to rain has arrived as advertised. With no east flow in place, the advection of warm air turned the precipitation to rain overnight. Rain showers should continue during the day Saturday with strong, gusty winds as the associated cold front approaches. Frontal passage looks to occur Saturday afternoon, most likely bringing a burst of moisture and more gusty winds. Behind the front, cold air sinks in over the PNW in northwesterly flow aloft. This favorable wind direction should drive orographic showers throughout the night on Saturday. A convergence zone will likely set up, but currently looks to be a bit to the south of Stevens Pass. As high pressure builds on Sunday, drier and cooler air will slide down the ridge bringing a cool day and tapering light snow showers.

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water:  1.0”   snow: 6-8” Tomorrow’s 24hr water:  LT .25  snow: 1-3” Trend and Timing: Rain turning to mixed precip Saturday afternoon, all snow after 4pm and overnight.

Temperature: Low: 25    High: 38 Snow level: 5500’-2500’ Trend and Timing:    Snow level should lower in the afternoon, becoming all snow after 4pm.

Winds Base: 15-25 W Ridge Top: 35-45 SW/W, with stronger gusts Trend and Timing: Strong southwest winds should continue Saturday morning, with a slight lull in the afternoon before increasing again Saturday night.

AC call off 7:30 Sat ABS

6:15 Sat Dec 29th ABS

MOUNTAIN WEATHER FORECAST

Stevens Pass Mountain Weather Forecast

Day and Time: Friday 0730

Current Observations:

24hr Precipitation:  0

Temperature profile: 23b/ 22r

Pass level winds: 5-10 W

Barometer:  Holding around 1022mb’s 

Sky:  Mostly clear with high clouds to the west

Radar:  A band of light moisture, out ahead of the main front, is beginning to reach the western slopes.

The Forecast:  Increasing snow today changing to rain tonight and back to snow tomorrow afternoon.  Snow showers diminish and eventually taper off on Sunday.  Surface temperatures could top 36⁰ f after midnight. 

High wind advisory: The winds will increase tonight with 30-50kt winds possible after midnight.  High winds persisting through at least noon tomorrow.

Long Range: The last few days of the year will be mostly dry with clear periods under high pressure.  

  

The Science:  An impressive storm with a long fetch of moisture stretching to the SW is approaching.  A warm front with SW advection will sag and possible stall over the regions today.  Top freezing levels associated with this system are reading in the +5500’ range.  Strong 4-5000’ westerly flow will fill in behind the front with strong ridge top winds expected.  

A cold front will swing through tomorrow afternoon/evening, dropping freezing levels and leaving snow showers in its wake.  A high pressure ridge builds over the region on Sunday with the New Year starting out dry with clear periods.  

Values from 4am today through

 4am tomorrow.

Precipitation: Today 24hr water: 1”   snow: 8-12 Tomorrow’s 24hr water:  1” snow:  4-8 Trend and Timing: The snow begins in a few hours and intensifies this afternoon.   The rain window is timing out to be between midnight and noon.

Temperature: Low:  23   High: 36 Freezing level: 2000’ – 5500’ Trend and Timing:    Freezing levels will slowly rise today and peak near 5500’ around midnight tonight.  Freezing levels fall back below 4000’ tomorrow afternoon.

Winds Base: 0-5 E shifting W Ridge Top: 10-20 W Trend and Timing: Weak east flow will briefly develop today and shift westerly and strengthen tonight. Winds gust could exceed 50mph during the early morning hours.

7:30 Fri Dec 28th no ABS

TOMORROW'S STORM FORECAST

  Some details on tomorrow storm.  It is shaping up to be quite sporty. 

The snow begins after 7am tomorrow and increases through the day.  Storm Water Equivalent (SWE) will be around 1” by 4am Saturday with another  1” by 4am Sunday.  

Snow: 6-10” by midnight, switching to mixed or all rain after midnight and back to snow after 4pm Saturday.  An additional 4-6” by Sunday morning.

Freezing levels will start out at 2000’ tomorrow and slowly rise to 4000’ by midnight and then 5500’ by 4am Saturday morning.  Freezing levels will fall back below 4000’ after 4pm Saturday.  

The winds will be in play as well with 5000’ winds pushing the +40knot range through the morning hours of Saturday. 

Confidence is fair to good.  

Note: The models are beginning to agree on the height of the freezing levels (+-5500”) but disagree on the timing, duration and intensity of the precipitation.  They should come into alignment with tonight’s model run.   Confidence should be better in tomorrow morning’s forecast.