Mountain Weather Forecast

Time and Day: 0600 Sunday

 

The Snapshot: Mostly dry today, snow beginning after midnight and continuing during the day Monday. Heavy snow Monday night and Tuesday with brief warming. 

 

The Science:  A relatively warmer air mass and high clouds have begun to enter the forecast area this morning, with all Stevens Pass weather stations showing temperatures in the high teens. Light snow is falling in the Western Washington lowlands, and some flurries should reach the mountains soon. Much of Sunday will be dry, however. The real action begins this evening as a cold front and upper level low move across our area in strong zonal flow aloft. Behind the frontal passage, which should be after midnight tonight, strong westerly winds should bring moderate to heavy orographic snow showers at Stevens Pass Monday morning and early afternoon. 

After a very brief break Monday afternoon, the next system (stronger and warmer) will approach from the SW. Freezing levels will spike to around 4500' early Tuesday morning and then fall back down behind the front. There may be some cool east flow Tuesday morning which may help to insulate the passes, but a brief period of mixed snow/rain is possible. Moderate to heavy snow will continue during the day Tuesday. 

 

The Long Range: A parade of low pressure systems in westerly and NW flow aloft should continue during the second half of next week. Exact timing is likely to change, but as of now there is moderate snow indicated in each 24 hour period leading up to the weekend. Freezing levels bump back down a little each day, getting closer to 1,000' by the weekend.

 

 

Precipitation Ending at 4am:   Today 24hr water = .25-.5 Snow = 4-6"   Tomorrow’s 24hr water = 1-1.25  Snow = 12-16"   Trend and Timing: Moderate snow will begin after midnight, becoming heavy in the early morning hours Monday, and tapering off Monday afternoon. After a brief break, moderate to heavy snow will begin again Monday night and continue through the daylight hours Tuesday.  Around half of Day 2's precip will be part of Monday's Round 1, and the other half will be during Round 2 Monday night.

24hr temperature ending at 4 am tomorrow:                                        Low:  16   High: 26 Freezing Level: 0'- 2,000'   Trend and Timing:    Freezing level is still at the surface Sunday morning, but should climb out of the basement Sunday afternoon and overnight, but remain well below pass level during the day Monday.

24hr Winds (mph) ending at 4 am tomorrow: Base:  0-5 W, then 15-20 W Ridge Top: 5-15 W, then 30-40 SW   Trend and Timing: Light westerly winds during the day Sunday will increase and switch to SW overnight, becoming strong and gusty at the ridgetops.   DV