Snowfall Report:
An additional 2 inches of snow fell on the upper mountain overnight, as the next storm is just getting started Wednesday morning. That brings the 4-day total to 16 inches up top, with a lot more snow on the way over the next 3 days!
Christmas Storms:
Steady rain & snow are currently falling on the mountain on Wednesday morning. Looking at the satellite imagery, the center of the first low-pressure system is moving northward up the West Coast, with the colder Christmas storm spinning up off the coast of CA.
The moisture streaming north into CA during the day on Wednesday pushes east Wednesday night, and we are still expected a lull between storms with lighter showers or even a few breaks in the precipitation at times later Wednesday into Wednesday night. Then the next storm pushes heavy snow back in on Christmas Day.
The latest model runs show an additional wave spinning up around the center of the low-pressure system off the coast and moving inland Thursday night, bringing another round of steadier snow. Then the center of the low moves inland through Friday with a final round of snow showers that taper off Friday night.
Snow Levels:
The snow levels should fall close to the base by late morning. The latest model runs still show them hovering in that range through Wednesday night. We could see some rain mix in near the base, especially during lighter precipitation. The snow levels finally drop well below the base with the colder storm on Christmas Day.
Total Additional Snowfall:
I assumed only afternoon snow at the base and only a 5:1 ratio Wednesday night in my snowfall forecast, to account for the possibility of some rain. At 8k’ I have the snow ratios around 10:1 on Wednesday and increasing to ~14:1 by Friday. I used that, and the average from the latest forecast model runs for total additional precipitation.
By Saturday morning, we could see an additional 24-31 inches near the base, 41-49 inches near mid-mountain, and 51-61 inches up top. I am expecting the biggest dump of snow to occur during the 24-hour period of Thursday – Thursday night.
Winds:
The winds are not as strong on Wednesday as they were on Tuesday, but are still gusting from the SSW up to 60-70+ mph per the sensors. We are expecting stronger winds again on Thursday with ridgetop gusts up to 80-100 mph. Then dropping through the day on Friday.
The winds turn more southwesterly on Christmas Day with the 2nd storm, which is more favorable for orographic enhancement of the precipitation and snowfall rates, as the colder moist air flows parallel up and over the mountains. If the storm were colder, we would have a shot at higher snowfall totals.
The Weekend:
High pressure starts to build in over the weekend with a drier pattern settling in. We will see mostly sunny days and lighter winds, but cold with highs in the 30s for the lower elevations and 20s for the higher elevations. Nice skiing weather.
End of the Month/Year:
Early next week, high pressure is forecast to get pretty strong over the region. That may warm highs into the 40s near the base Monday into midweek, with 30s for the higher elevations. We could also start to see some overnight temperature inversions.
The chance for moisture to move up from the south looks to hold off until the 1st on the latest model runs, so New Year’s Eve may stay dry. We’ll continue to keep an eye on that.
Long-Range Outlook:
The long-range models continue to show us shifting back towards a negative PNA (West Coast trough) pattern during the 1st week of January, which also lines up with the active phase of the MJO forecast to loop through the Indian Ocean again.
They are still struggling with how far south the trough and storm track will dig down the West Coast. They continue to show a wet pattern for the Pacific NW, but are more “iffy” for northern CA and the northern Sierra.
The operational model runs this morning still show a chance for some moisture to stream up from the south around the 1st, with a storm possibly moving in from the NW around the 2nd, and another around the 6th – 7th of January.
We’ll continue to watch the trends for the pattern and the two storms that are currently showing up during the 1st week of January.
BA
