Monday – Tuesday:
A cold front moved through Sunday night and ushered in colder air along with a dusting of snow. We’ll have lighter winds and mostly sunny skies with highs in the 30s for the lower elevations, and 20s for the higher elevations.
Wednesday – Friday Atmospheric River:
A strong low-pressure system is going to strengthen off of the Pacific NW coast Wednesday through Friday and will direct a strong jet stream with an atmospheric river (AR) of moisture into northern CA Wednesday through Friday.
We have been watching this potential since last week and watching closely to see how far south the southern edge of the heavy precipitation will push into the northern Sierra. The latest model runs are coming into better agreement that the southern edge will reach the mountain by Wednesday and continuing into Thursday before tilting north of us Thursday night, and back south again Friday.
We will see strong winds with ridgetop gusts up to 80-100+ mph all 3 days. That will help to blow in warm moist air with highs into the 40s for the lower elevations and 30s for the higher elevations. The forecast models don’t agree on how heavy the precipitation will be but the average is showing 3-4 inches of total liquid falling on the mountain through Friday afternoon.
The snow levels could start out around 7000-7500 ft. initially later Tuesday night into Wednesday morning and could be around 7500-8000 ft. through Wednesday afternoon. But then the warmer air flows in and they could rise up to around 9000-10,000 ft. Wednesday night through Friday morning, and possibly dropping down to 8000-9000 ft. by afternoon.
We are expecting mostly rain below 8000 ft. through Friday. Near 8000 ft. we could see 6-12 inches of wet snow Wednesday – Wednesday night before turning to rain and melting Thursday into Friday morning, and then maybe a little wet snow accumulation Friday afternoon.
Forecasting in AR events like this one is extremely complicated as you have to forecast for the snow levels and snow ratios on top of the precipitation amounts. The forecast is likely to fluctuate through the week as we see exactly how far south the AR sets up for Wednesday – Friday.
Saturday – Sunday:
The AR shifts south through the Sierra Friday night into Saturday with a cold front moving through bringing in colder air and dropping snow levels below lake level by Saturday morning. A second wave with heavier precipitation could move through on Sunday.
Overall we are expecting significant snowfall for the weekend between Friday night and Sunday night. The forecast models are showing around 3-4 inches of total precipitation during this time frame. I am going to hold off on making a detailed snowfall forecast until Tuesday morning. I am expecting the forecast to be for snow measured in feet if the current forecasts hold.
The winds are likely to remain strong into Saturday morning before hopefully coming down some later in the day into Sunday. With the mountain forecast to open on Friday, the rain, winds, and heavy snow could affect weekend operations, so stay tuned to the home page & social media for updates.
Thanksgiving Week:
The latest forecasts on the long-range models show a high-pressure ridge in the northeast Pacific Thanksgiving week with a trough over most of the U.S. That should keep the colder air around and the door open to at least some weak systems with more snow showers. Some model runs show a decent storm around Thanksgiving, so we’ll keep an eye on that.
Long-Range Forecast:
The long-range models suggest that high pressure builds in over the West Coast as we go into the beginning of December, possibly bringing a less active pattern and slightly milder temperatures. We’ll continue to watch the trends on that.
BA
