MOUNTAIN WEATHER FORECAST

 0830 Friday

The Snapshot: Light rain/snow mixture today. The precipitation gradually increases tomorrow.  Expect heavy mixed precipitation tomorrow night with rain on Sunday.  Snow Sunday night and Monday.  

The Science:  The first line of moisture is entering the north Puget Sound area this morning with light rain already falling in the mountains. Strengthening westerly flow will gradually increase the moisture during the next 24-36 hrs. A large warm air mass with a bunch of moisture is leading the charge. So expect heavy precipitation and high winds to begin late tomorrow night and last through Sunday.  The leading edge of the arctic cold front is now schedule to move past the mountain late Sunday afternoon or evening. Snow starts late in the day on Sunday and continues through Monday. 

Storm totals by 4pm Sunday exceed 3” of water.  How much of this will be rain?  That is the question of the day.  An additional 1-2” of water or 1-2 feet of snow will be possible by the end of Monday.  Storm details will be more fine-tuned tomorrow.

4-7day Long Range:  A cold arctic air mass dropping in from the Canadian interior pushes all the moisture south on Tuesday with high pressure developing over the PNW.   This translates to a very cold dry week. There are signs of another system entering the stage next weekend.

 

Precipitation:   Water by 4am = .25  Snow equivalent = 1-2     Total inches of water by noon tomorrow = .25 -.5 Total inches of snow by noon tomorrow = 2-4   Trends and Timing:   Rain with snow mix above 4500’ will begin today. With some luck, the upper mountain will mostly snow.  Intermittent showers continue through the night with precipitation intensifying during the day.

Base Temp and Freezing levels:                                        Low: 32   High: 34 Freezing level: +-4500      5000’   Trend and Timing:   Freezing levels will hover around 4500’ tonight.  Temperatures will be just above freezing tomorrow with freezing levels spiking up to 6000’ on Sunday morning.

Winds:   Base: 0-5 W   Ridge Top: 5-10 W     Trend and Timing:   Winds will not be much of a factor until Sunday.  A high wind event is expected to accompany Sunday’s storm.