MOUNTAIN WEATHER FORECAST

Time and Day: 1100

The Snapshot:  Brr, single digit temperatures with a stiff east wind today.  High clouds with a few snow flurries tonight, snow tomorrow night, mixed rain and snow Wednesday - Saturday.  

The Science:  The high-pressure ridge that has dominated our weather is beginning to drift into the intermountain west of Idaho and Montana.   This will allow a series of complex storms to slide up along the western slopes of the Cascades starting tomorrow night and continuing through the upcoming weekend. 

Stevens Pass will be the on the front lines of a battle between the approaching warm, moist, and unstable air mass and the cold, dry conditions east of the mountains.  The first front arrives tomorrow night with snow likely into early Wednesday morning.  The next, slightly warmer system enters the mountains Wednesday afternoon with mixed rain and snow falling into Thursday morning.   If the temperatures cooperate, we could squeeze a foot or more of snow out of these storms. 

Storm totals calculations:

Tuesday 4 pm – Wednesday 4 pm  .25 -.5” water  2-5” of snow

Wednesday 4m – Thursday 4 pm   1” of water  4-12” of snow (east flow dependent)

Friday – Snow likely – amounts still in question.

Long Range:  Models are having difficulties nailing down Friday and beyond.  There is potential to have a good snow event if and when a low-pressure trough develops off shore on Friday/Saturday.  Stay tuned as those details develop.   

Precipitation ending at 4 am: Today’s 24hr Water = .10   Snow =  Trace Tomorrow’s 24hr Water = .25   Snow = 2-4  Trend and Timing: Mostly dry with some very light snow through 4 pm tomorrow.  Snow expected late tomorrow night into the early morning hours of Wednesday.

24hr temperature ending at 4 am tomorrow:  Low:  12  High:  24 Freezing level: 2000’ - 4000.' Trends and Timing: East flow will hold surface temperatures well below freezing through tomorrow.   The temperature inversion will continue with rising freezing levels along the western slopes.

24hr Winds (mph) ending at 4 am tomorrow: Base: 5-10 E Ridge Top: 5-10 E   Trend and Timing: Easterly winds will continue through early Wednesday morning.

JM

MOUNTAIN WEATHER FORECAST

Time and Day: 0800 Sunday

The Snapshot:  Expect one more beautiful day before things begin to change tomorrow.   Snow? 

The Science:  High cirrus clouds will begin to move over the PNW tonight as a series of storms begins to make their approach.  The first will arrive tomorrow but split apart as it hits the wall of higher pressure, so not much is expected.  A warm front arrives late Tuesday night with more frontal systems moving through the region for the remainder of the week.

The trick for whether these storms will produce snow or not is east flow.  Tuesday nights front is a warm front with warmer air and a southwest fetch of moisture.  Freezing levels are expected to rise to near 4000’-5000’ along the western slopes. 

Initially, the cold air trapped in the eastern basin will provide east flow temperatures cool enough for snow at Stevens Pass.  Periods of rain and or freezing rain (east of the mountains) should be anticipated.  Storm totals with snow/rain amounts will be posted later today with better intel.    

Long Range:  More systems with similar characteristics will arrive on Thursday and then again on Friday.    A larger warm front is expected to bring higher freezing levels and potentially rain for the weekend.   

Precipitation ending at 4 am: Today’s 24hr Water =  0  Snow = 0  Tomorrow’s 24hr Water = <.10   Snow = trace  Trend and Timing: Dry today with very light snow tomorrow night.

24hr temperature ending at 4 am tomorrow:  Low: 24  High: 30 Freezing level: 3000’ -4000.' Trends and Timing: The temperature inversion will continue until the front pushes through tomorrow night.

24hr Winds (mph) ending at 4 am tomorrow: Base:  0-10 E Ridge Top: 5-10 E   Trend and Timing: East flow will continue through early Tuesday morning.

JM

MOUNTAIN WEATHER FORECAST

Time and Day:  0900 Friday

The Snapshot:   Clear (did you see that moon last night?) with warming through the weekend, snow for the second half of next week.

The Science:  The high-pressure cell parked over the British Columbia interior will continue to produce dry and clear weather for the PNW.  Warmer air flowing up the coast will begin to raise freezing levels to around 4000’ west of the crest while cooler air remains trapped in the eastern basin. (Temperature Inversion)

Long Range:  The pattern begins to change early next week as a series of systems begins to break through the high-pressure ridge.  With help from our friend east flow, the second half of next week could be snowy.  These storms are still far enough out for the models to disagree with the timing and amounts, so stay tuned as those details become more realistic.  

Precipitation ending at 4 am: Today’s 24hr Water = 0   Snow =  0 Tomorrow’s 24hr Water = 0  Snow = 0 Trend and Timing: No precipitation is expected through the weekend.

24hr temperature ending at 4 am tomorrow:  Low: 24   High: 34 Freezing level: +-4000.' Trends and Timing: Temperatures will continue to rise and fall around the freezing mark for the next few days.   Temperature inversions will be likely with freezing levels near 4500’ west of the crest.

24hr Winds (mph) ending at 4 am tomorrow: Base: 0-5 E Ridge Top: 0-10 E   Trend and Timing: Light east flow will continue through the weekend.

JM

MOUNTAIN WEATHER FORECAST

Time and Day: 0800 Wednesday

The Snapshot: Clear, cold and breezy today, continued dry with warming through the weekend, a chance of snow next week.  

The Science:  Cold dry air flowing in from the Frazer River gap (Canada) and high pressure building along Pac NW coast will produce cold, dry and breezy weather at Stevens Pass today.   The high pressure ridge travels east over the next few days with clear, dry, warmer and less windy weather setting up for the extended Holiday weekend.  

Long Range:  A frontal system, developing in the long range models, is expected to enter the region Tuesday or Wednesday of next week.  This is way to far out to have any confidence in the details, but as of now, there is a chance some good snow.   

Precipitation ending at 4 am: Today’s 24hr Water = 0    Snow =  0 Tomorrow’s 24hr Water = 0  Snow =  0 Trend and Timing: Dry through Monday.

24hr temperature ending at 4 am tomorrow:  Low: 16 High: 26 Freezing level: 1500’ -2500’ Trends and Timing: Early morning cold temperatures with fairly good daytime recovery will continue for the rest of the week.

24hr Winds (mph) ending at 4 am tomorrow: Base:  5-10 E Ridge Top: 5-15 E    Trend and Timing: East flow will continue into the weekend.

JM

MOUNTAIN WEATHER FORECAST

Time and Day: 0900

The Snapshot:  Snow ends today.  Cold clear and dry weather is anticipated for the remainder of the week.  The winds will also kick in tonight and tomorrow.

The Science:  Stevens Pass telemetry has 5” of new snow that fell overnight and Seattle is in gridlock. J.   This morning’s radar has the moisture drifting south of Stevens Pass, so for the most part, the snow is done.   As the low-pressure cell moves out today, it will pull a cold, dry air mass to the region.  Increasing pressure gradients will crank up the wind machine tonight with strong easterly winds possible.   

Long Range: Dry and mostly clear weather will prevail over the PNW into early next week.  The next best bet for snow will be during the middle of next week.    

Precipitation ending at 4 am: Today’s 24hr Water = <.25    Snow = 1-2    Tomorrow’s 24hr Water = 0  Snow = 0 Trend and Timing: Snow ends today with dry conditions lasting for the rest of the week.

24hr temperature ending at 4 am tomorrow:  Low: 14  High: 32 Freezing level: 4000’ -  1000.' Trends and Timing: Temperatures will bump up today with freezing levels dropping to 1000’ tonight with cold temperatures settling in.

24hr Winds (mph) ending at 4 am tomorrow: Base: 10-15 E Ridge Top:  10-30 E  gusty Trend and Timing: Easterly/offshore winds are expected to crank up tonight and continue through tomorrow morning.

JM

MOUNTAIN WEATHER FORECAST

Time and Day: 0730 Monday

The Snapshot:  Lowering temperatures and light snow begins tonight and continues through late tomorrow night.   Clear, cold and dry weather will finish the Holiday week.

The Science:  A slow moving cold front tracking south from the BC interior will bring light snow to Stevens Pass tonight.  Bands of snow will continue until this storm moves south into Oregon late tomorrow night.  Because the center of the low-pressure cell is inland, this system is not picking up very much moisture; therefore only a few inches of snow can be anticipated.

A dry, cold, arctic airmass will be dragged into the region tomorrow night with the coldest temperatures of the year possible.  Freezing levels could hit 500’ with temperatures in the low teens or even single digits possible.

Long Range:  High pressure strengthens on Wednesday setting up a prolonged dry period lasting through the Holiday weekend.  There are signs showing up in the long range models of an active wet weather pattern beginning early to mid next week. 

Precipitation ending at 4 am: Today’s 24hr Water =  .25   Snow =  1-3  Tomorrow’s 24hr Water = < .5  Snow = 2-4  Trend and Timing: Light snow will begin this afternoon and continue through tomorrow.

24hr temperature ending at 4 am tomorrow:  Low: 20  High: 30 Freezing level: +- 3000 Trends and Timing: Temperatures will remain in the mid 20’s through tonight and then fall sharply tomorrow night.

24hr Winds (mph) ending at 4 am tomorrow: Base: 0-10 W  Ridge Top: 5-10 W shifting E Trend and Timing: Light westerly flow today will shift easterly tomorrow and strengthen.  Strong easterly winds will be possible tomorrow afternoon and evening.

JM

MOUNTAIN WEATHER FORECAST

Time and Day: 0900

The Snapshot:  Dry with mostly clear conditions will prevail through the weekend. Snow likely on Monday, dry and cold to end the Holiday week.  

The Science:  High pressure building over the Cascade Mountains will bring mostly dry and clear weather to the area for the weekend.  East/off-shore flow will keep the temperatures cool through tomorrow.  Warmer air aloft will invade tomorrow pushing freezing levels to near 5500’.  Therefore, expect a beautiful dry and relatively warm weekend. 

Long Range:  A cold front will descend south along the BC coast on Monday producing snow and low temperatures.  As of now, 4-8” of snow is possible from this storm.  Dry and cold arctic air moves in on Wednesday; Stevens Pass could see single digit low temperatures on Turkey day.  

Precipitation ending at 4 am: Today’s 24hr Water = 0   Snow =  0 Tomorrow’s 24hr Water = 0  Snow = 0 Trend and Timing: There are a few light snow showers showing up on the radar this morning. Other than that, dry conditions will prevail through Sunday.

24hr temperature ending at 4 am tomorrow:  Low: 20  High: 30 Freezing level: 2500’ – 4500.' Trends and Timing: Temperatures will remain in the 20’s today and then to rise to near 40 tomorrow with the aid of the sun.

24hr Winds (mph) ending at 4 am tomorrow: Base: 0-5 E Ridge Top: 0-10 E   Trend and Timing: East/offshore flow will continue through the weekend.

JM

MOUNTAIN WEATHER FORECAST

Time and Day: 0700 Thursday

The Snapshot:  Dry with clearing.

The Science:  The atmosphere will stabilize today under rising pressure.  Therefore, the PNW will move into a dry and mostly clear weather pattern through the weekend.  Cool east flow will keep surface temperatures at or below 32^0f for the next few days.  Morning fog will also be common at Pass level. 

Long Range: A weak cold front descends along the BC coast early next week with a chance of some snow for the Cascade Mountains; this system is not particularly potent, so no significant snow is expected at this time.  Long range models also have cold arctic air flowing out of the Frazer River Valley next week; this could drop surface temperatures into the low teens or even single digits on Thanksgiving Day.

Precipitation ending at 4 am: Today’s 24hr Water = .10    Snow = trace Tomorrow’s 24hr Water =  0 Snow =  0 Trend and Timing: The few light snow showers this morning will end later today.  Dry through the weekend.

24hr temperature ending at 4 am tomorrow:  Low: 22   High: 28 Freezing level: +-3000’ Trends and Timing: Surface temperatures will stabilize in the mid 20’s through Saturday morning.  Clear early morning conditions could allow low temperatures to drop into the upper teens.

24hr Winds (mph) ending at 4 am tomorrow: Base:  0-5 E Ridge Top:    Trend and Timing: Winds have shifted easterly today and will continue through tomorrow.

JM

MOUNTAIN WEATHER FORECAST

Time and Day: 0630 Wednesday

The Snapshot: The wind and snow will begin to diminish today.  Light snow tonight, dry and warmer Friday through the weekend. 

The Science: What a storm! 70-80mph wind gust recorded along the ridge tops with a gazillion buckets of rain.   4” of snow fell overnight with a few more possible today.   A storm tracking along the southern border will spin a band of snow up through the Central Cascades tonight into early tomorrow morning. 

Long Range: A weak high-pressure ridge is expected to bring dry weather to the PNW starting on Friday.  The weekend is trending dry and warm with cooler weather and light snow developing next week.

Precipitation ending at 4 am: Today’s 24hr Water = .25   Snow = 2-4  Tomorrow’s 24hr Water = .10  Snow =  1-2 Trend and Timing: Snow showers will weaken today with light snow developing tonight.  Snow will taper off tomorrow.

24hr temperature ending at 4 am tomorrow:  Low: 22  High: 26 Freezing level: +-3000.' Trends and Timing: Freezing levels have fallen to 2500’ and will continue to hover between 2500’ and 3000’ for the remainder of the week.

24hr Winds (mph) ending at 4 am tomorrow: Base: 5-15 W Ridge Top: 10-30 W   Trend and Timing: The winds will continue to be strong this morning and begin to diminish this afternoon.

JM

Weather Update

No major change to this morning’s forecast.

3.4” of rain has fallen since midnight.  Rain totals will likely top 4” within the hour.  5000' winds are cranking with gust to 40+.   Ugh.

Rain is expected to begin to turn to snow this afternoon with 4-8” of snowfall overnight. With the current slushy on the ground, not much accumulation is expected with tonight’s snow.

Snow showers will remain in the forecast with a few inches possible through Thursday morning. 

Long Range:   The overall pattern begins to change on Friday with drier and less active weather developing for the Thanksgiving week.   There is a weak low-pressure system expected to arrive on Monday, but long range models are having it weakening and splitting as it enters the region.  

MOUNTAIN WEATHER FORECAST

Time and Day: 0800 Tuesday

The Snapshot:  A bit damp and windy today.  The heavy rain changes to snow tonight, intermittent snow showers will be possible through Thursday morning.  Drier and cooler weather will end the week. 

The Science:  The 8” or so of snow we receive last night is quickly being washed away by the heavy rain. The rain took over around midnight and will continue through most of  the daylight hours. 

A cold front will swing through this evening changing the rain to snow.  Moderate to heavy snow can be expected as the front approaches, but the moisture will shift to showers once the front moves east of the mountains. Freezing levels are expected to fall below 4000’ this evening with snow falling into the early morning hours.  A low-pressure system tracking along the Oregon/Washington border tomorrow night, will spin weak bands of moisture north; there will be little love for Stevens Pass with just a few inches of snow likely.  The week will end dry and cool as an upper-level high-pressure ridge begins to build Thursday afternoon.     

Long Range:  This past wet weather madness will shift to a drier pattern starting on Thursday and will likely continuing into early next week.    

Precipitation ending at 4 am: Today’s 24hr Water = 2   Snow = 4-8  Tomorrow’s 24hr Water = .25   Snow = 2-4 Trend and Timing: Rain turns back to snow sometime after 4 pm today.  Snow will slowly shift to showers through the night and eventually taper off tomorrow.

24hr temperature ending at 4 am tomorrow:  Low: 24  High: 40 Freezing level: 7000’ – 3000.' Trends and Timing: Freezing levels are expected to drop below 4000’ this afternoon.  Surface temperatures should remain below freezing for the remainder of the week.

24hr Winds (mph) ending at 4 am tomorrow: Base: 10-20 W gusty Ridge Top:   20-40 W gusty Trend and Timing: Strong winds will continue into tonight.  The winds mellow out tomorrow.

JM