Tuesday – Wednesday Snow Showers:
A small low-pressure system is undergoing a little cyclogenesis along the jet stream off the coast on Tuesday morning, and moving towards CA. As that system approaches, we are going to see increasing clouds and moisture over the northern Sierra through the day on Tuesday, with snow showers likely increasing through the afternoon.
That low will spin near the coast Tuesday night and Wednesday, stalling near the coast, and eventually falling apart by Wednesday night. That will push some steadier precipitation into the northern Sierra on Tuesday night, and then fading to snow showers, becoming more scattered through the day on Wednesday, and dissipating into Wednesday evening.
Highs in the 30s on the mountain for Tuesday and Wednesday, and near 40 degrees for the lowest elevations near the base on Tuesday. Snow levels will be fluctuating between 6000-7000 ft. Tuesday, dropping to near the base during steadier showers. Then dropping as low as 5500 ft. Tuesday night before rising back up near 6500 ft. by Wednesday afternoon.
Based on the latest forecast model averages, the final snowfall forecast for this storm is for around 2-5 inches at the base, 4-8 inches near mid-mountain, and 5-10 inches up top by Wednesday evening. Some rain could mix in near the base at times, and snow ratios are low overall with wet snow. A bit drier up top.
Thursday – Sunday Forecast:
We are expecting a break between storms through Saturday, with mostly sunny skies through at least Friday, and partly sunny into Saturday. Highs in the 30s for the upper mountain and 40s for the lower elevations near the base.
The trend, among the majority of the forecast models over the past 24 hours, is for the first system in the upcoming storm cycle to drop south off the coast, keeping precipitation well to our west through Sunday. We may see an increase in clouds during the day, but if this trend for the track of the first system continues, we won’t see any gusty winds or snow on Sunday.
Monday Storm:
When a low-pressure system digs deep into a trough off the coast, it can be slower to move east inland, and as it does, we tend to see southerly flow initially. So we will have to watch the trends on timing for snow to initially push into the Sierra. Likely at some point between Monday morning and Monday afternoon, based on the latest trends.
The southerly flow on Monday on the east side of the storm as it moves inland is also not good for forcing and orographics over the northern Sierra, which is why snowfall forecasts are trending down for Monday’s system. Highs in the 30s for the lower elevations and 20s for the higher elevations, with increasing winds through the day.
We’ll continue to watch the trends closely to see when snow could move in, and we will get into potential snowfall details as the first system in the series is within the 5-day forecast window, which will be on Thursday for a Monday start.
Cold Storm Series:
We are still expecting a well-established cold and broad trough over the West Coast by Tuesday through the end of next week. Behind the Monday storm, several more storms will move through from the NW, with the latest model runs showing a final storm around next Friday, with snow showers possibly lingering into Saturday, the 21st.
That would be a 5-day storm series with snow possibly falling each day for up to 6 days in a row. The subsequent systems rotate in from the NW, with WSW winds with each. That motion and flow is much better for forcing and mountain orographic enhancement of the precipitation through the period.
The temperatures will be cold as well, with highs in the 20s for most of the storm series, and even teens for the upper mountain by the middle of next week. That will bring very low snow levels between 2000-4000 ft, and maybe leaning towards the lower end of that, Tuesday through Friday, during the highest precipitation forecasts.
That would bring high snow ratios and would turn inches of precipitation into feet of snow for all elevations by the end of next week. The delay of the start of the storm series until sometime on Monday should be offset by the chance of storms lingering into Friday – Saturday. So the expectations for next week haven’t changed.
It’s still too early to look at snowfall details with any confidence, but all systems are still go for significant powdery snowfall next week. We’ll continue to add more details on the timing and potential amounts of snow as we get closer.
Fantasy Range:
Beyond the 21st through the last week of February, the long-range models continue to show the West Coast trough lifting north with time, and high pressure eventually building in over CA. That would shift the storm track to our north into the Pacific NW through the end of February.
Some of the operational model runs were showing a chance that we could catch the southern half of storms to the north through the 23rd-ish, but the latest trends are for storms to stay to our north beyond Saturday, the 21st.
We’ll continue to watch the trends to see if any storms will dig far enough south for more snow through the end of the month and into the first week of March. But as of right now, the pattern doesn’t look like one that would easily produce any bigger storms for the northern Sierra beyond next week’s storm series.
BA
