February 29, 2020

MOUNTAIN WEATHER FORECAST


Stevens Pass Mountain Weather Forecast
Date: Saturday, February 29, 2020


Current Observations:
24hr Precipitation:  .57” SWE / 8” snow        
Temperature profile: 30 base / 26 mid mtn     
Pass level winds: Light westerly                     
Barometer: 1012 rising slowly                        
Sky:  Overcast, snowing lightly                                  
Radar: Spotty convergence showers throughout the crest.


The Forecast: Diminishing showers and cool this afternoon. Partly sunny and dry tomorrow with daytime warming.  

The Science: A low pressure trough deepens and sags southeast today, turning upper level flow northerly. NW post-frontal winds should diminish today, with cooler and drier air advection this afternoon and tomorrow. We’ll see if an afternoon convergence zone keeps the snow showers going. Either way the day should finish with clearing skies and tomorrow should start out dry and partly sunny.

Long Range: The next system rides over a flat high pressure ridge Sunday night/Monday. Snow is likely Monday, although amounts aren’t particularly impressive. Active weather continues throughout the week with a wetter system arriving Wednesday.

Confidence: Fair for today’s afternoon convergence activity.

Values from 4am today through 4am tomorrow.
Precipitation:
Today 24hr
water: .25-.5 (.25 already received) snow: 4-6” (4” already received)

Tomorrow’s 24hr
water: .10-.25   snow: 1-3”

Trend and Timing:
Snow showers ending this afternoon, mostly dry tomorrow, light snow possible after midnight Sunday.

Temperature:
Low: 22   High: 28
Freezing level: 2000-1000’

Trend and Timing:   
Freezing levels dropping tonight, remaining cool tomorrow with some daytime warming.
 
Winds
Base: W 5-15
Ridge Top: WNW 20-30 with gusts, then W 10-15

Trend and Timing:
Post-frontal winds should rapidly diminish Saturday afternoon and become light Saturday night and Sunday.

7:30 No ABS Sunday March 1


February 28, 2020

6:15 Start Sat Feb 28th ABS

MOUNTAIN WEATHER FORECAST



Stevens Pass Mountain Weather Forecast
Friday, February 28, 2020, 0900

Current Observations:
24hr Precipitation:        0
Temperature profile:     32 base, 36 ridge
Pass level winds:             light WSW
Barometer:                    1016mb’s and falling
Sky:                     clear with high cirrus clouds moving in                                       
Radar:  dry throughout the region with the approaching cold front a few 100 miles offshore.


The Forecast:  Increasing clouds, falling temperatures and snow tonight.  Snow showers persist tomorrow with Sunday trending dry.

The Science:  Visible satellite images show a district shear line of clouds out a head of the approaching cold front tracking ENE.  The current temperature inversion will be quickly be overtaken by strong, cool, unstable westerly flow this afternoon.  The Puget Sound convergence zone is expected to develop with periods of moderate snow for Stevens Pass overnight.  The precipitation will transition to showers during the early morning hours with moderate passing snow showers through the day tomorrow.     

Long Range. Sunday will be mostly dry with sun breaks.  Several storms are poised to bring significant snow to the Cascades next week.  Early calculations show 40+ inches of snow possible starting on Monday and lasting through the week.   **  Winter isn’t done with us yet.

Confidence:  Fair due to orographic snow amounts.  

Values from 4am today through 4am tomorrow.
Precipitation:
Today 24hr
water:  .5-.75 snow:  6-10 (depending on convergence)

Tomorrow’s 24hr
water:  .5  snow: 3-6

Trend and Timing:
Snow begins after 4pm today and becomes moderate overnight.  Snow shifts to showers after 4am tomorrow with intermittent showers through the day.


Temperature:
Low: 26   High: 40
Freezing level: 6000’ – 2500’

Trend and Timing:   
Freezing levels will peak +-6000’ this afternoon and then quickly fall below 4000’ tonight.  Temperatures will remain below freezing through Sunday.

 
Winds
Base: 5-10 W increasing
Ridge Top: 10-20+ W  strengthening

Trend and Timing:
Winds increase tonight and sustain through 10am or so tomorrow.


February 27, 2020

8:00 Start Fri Feb 28th no ABS

MOUNTAIN WEATHER FORECAST




Stevens Pass Mountain Weather Forecast
Thursday, February 27, 2020, 0830

Current Observations:
24hr Precipitation:        0.02swe,  0 snow
Temperature profile:     33 base, 
Pass level winds:   
Barometer:                    1026mb’s and holding
Sky:                 overcast with very light snow falling                                                  
Radar:       dry in the mountains with rain falling Bellingham north


The Forecast:  Mostly dry today and most of tomorrow with temperatures peaking near 40 today.   Snow arrives tomorrow night with snow showers persisting through Saturday. 

The Science:  The next 24-36hrs will be fairly quiet with mild temperatures.  A cut-off low pressure cell with an embedded cold front will track into southern BC tomorrow.  Cool unstable NW flow will be pulled along its southern boundary; thus, expect falling temperatures, good orographic snowfall (convergence) and windy conditions heading into the weekend.  Snow totals are in questions due to the convergence dynamics… Snow showers, gusty winds with freezing levels -+2500’ will be the weather game on Saturday. 

Long Range. Sunday will be mostly dry with some remnant snow showers in the morning.  Next week will be very active with multiple storms.  Freezing levels will be on the cusp of rain vs snow for the start of this storm cycle with cooling later on in the week.    

Confidence:  Good short term, poor long term.

Values from 4am today through 4am tomorrow.
Precipitation:
Today 24hr
water: 0 snow:  0

Tomorrow’s 24hr
water: .5 -.75   snow: 6-8

Trend and Timing:
Dry through the night with snow arriving after 4pm tomorrow.


Temperature:
Low: 32   High: 40
Freezing level: 6000’

Trend and Timing:   
Freezing levels will top out near 6000’ today and remain above pass level through tomorrow afternoon.

 
Winds
Base: 0-5 W
Ridge Top: 5-10 W

Trend and Timing:
Light westerly flow expected through tomorrow.


February 26, 2020

8:00 Start Thurs Feb 26th no ABS

MOUNTAIN WEATHER FORECAST




Stevens Pass Mountain Weather Forecast
Wednesday, February 26, 2020, 0830

Current Observations:
24hr Precipitation:        .09 swe, 1” snow
Temperature profile:     32 base, 28 ridge
Pass level winds:            light, westerly – gustier on the upper ridges.  
Barometer:                    1025mb’s and inching up
Sky:  Pass level fog with broken midlevel clouds and snow showers.                       
Radar:   Intermittent snow showers falling at Stevens Pass with mostly dry conditions everywhere else.    


The Forecast:  Diminishing snow showers today with partial clearing tonight.   Temperatures will be in the lower 30’s with warmer temperatures expected tomorrow and Friday.

The Science:  A weak front is passing over the crest this morning producing some intermittent snow showers.  The barometric pressure rises behind the front which will begin to dry up the precipitation.   Warm air advections from the south will make its way north over the next 24-36hrs pushing freezing levels to +-5000’ by tomorrow afternoon.  No significant moisture is expected through Friday noon.

The next weather feature of interest arrives last Friday with the arrival of a strong cold front.  Falling temperatures and snow can be expected on Saturday.  Early precipitation values Friday 10pm through Sunday 4am show +-1” swe, 10-12” snow.    

Long Range.  Snow on Saturday with Sunday trending dry. 

Confidence:  Good.  

Values from 4am today through 4am tomorrow.
Precipitation:
Today 24hr
water: .10 snow: 1   

Tomorrow’s 24hr
water: .10   snow: trace

Trend and Timing:
The snow showers will diminish today with mostly dry conditions setting up.


Temperature:
Low: 28   High: 34
Freezing level: +-4000’

Trend and Timing:   
Freezing levels will hover around the 4000’ elevation through tomorrow.  Freezing levels rise above 5000’ tomorrow afternoon.

 
Winds
Base:  0-10 W
Ridge Top: 5-10 W 

Trend and Timing:
Westerly flow will be the wind pattern through tomorrow.


February 25, 2020

8:00 No ABS Wednesday the 26th


MOUNTAIN WEATHER FORECAST




Stevens Pass Mountain Weather Forecast
Tuesday, February 25, 2020, 0930

Current Observations:
24hr Precipitation:          .02swe,  0 snow
Temperature profile:        24 base, 24 ridge
Pass level winds:                light, ESE
Barometer:                      1028mb’s and holding
Sky:                                  high clouds                                                   
Radar:  mostly dry with some light scattered rain showers showing up along the coast


The Forecast:  Mostly dry and sunny today with increasing clouds, rising temperatures, and light mixed rain and snow possible tonight.   The rest of the week will be mostly dry with warming temperatures.

The Science:  A warm front will approach the region today with light precipitation in tow.  A weak passing high pressure ridge will move in tomorrow for a few days of generally dry, benign weather.  A cold front makes its way in on Friday with some snow and cooler temperatures preparing for the weekend.  

Long Range. Snow on Saturday with models providing mixed signals beyond.    

Confidence:  Good.  

Values from 4am today through 4am tomorrow.
Precipitation:
Today 24hr
water: .25 snow:  0-2 

Tomorrow’s 24hr
water: .10   snow: trace

Trend and Timing:
Light mixed rain and snow will be possible tonight with drying tomorrow.  


Temperature:
Low: 24   High:  36
Freezing level: +-4000’

Trend and Timing:   
Freezing levels will peak near 4000’ this afternoon and stay consistent through the night.

 
Winds
Base: 0-5 E shifting W
Ridge Top:   0-10 ESE shifting W

Trend and Timing:
Weak east flow at the surface will shift westerly with the passing of the front this afternoon.


8:00am Start for Friday 3/29/2024 No ABS

 Warm and dry weather is on the way.