Tahoe Weather Geek
Thursday Dec. 5
The prospects for this weekend’s Sierra storm keep getting better. We are now looking at a good chance of between 12 and 18 inches of snow at the highest elevations of the Sierra Friday night through Saturday.
The low pressure system moving south from the Yukon is expected to pick up a bit of moisture as it sweeps over the Pacific before sliding through the Pacific Northwest, Oregon and California.
The extremely low air temperatures will then work to turn that water into snow at a ratio of close to 20:1. In other words, for every inch of water, we get 20 inches of snow. And the latest models are showing around an inch of water-content to the precipitation likely to fall along the Sierra Crest. That would translate into at 18 to 20 inches of snow, with 8 inches or more possible around the Lake.
Highs Saturday will be in the high teens or low 20s around the Lake with lows in the single digits through the weekend.
The storm should be moving east by Saturday afternoon, but the cold north flow will continue into next week, keeping temperatures well below normal.
By Wednesday the Pacific ridge over the Gulf of Alaska should be breaking down, allowing a low pressure system to move into the Gulf and produce a west flow into the Sierra. This would lead to a slow warming trend, bringing Sierra highs back into the 40s.
That will also direct the storm track into Western Canada through mid week before a system late in the week drops down into California, with a good chance for another round of rain and snow.
Wednesday Dec. 4 2013
The Tahoe Basin is in between a couple of small early season storms today, but it’s not getting a break from the frigid air drifting down from the Arctic. The latest system to move through dumped 6 to 10 inches of great snow at the higher peaks around the Basin, with lesser amounts around the Lake.
Temperatures will remain well below normal through the weekend, with lows below zero in mountain valleys, and the next system is on track to move into the Sierra Friday night or Saturday morning. The forecast models are indicating that this system will be stronger than Tuesday’s storm. With a higher water content — up to an inch possible along the Sierra Crest — and colder temperatures, we might be looking at a foot or more at the higher elevations.
The system should move through during the day Saturday, and the colder temps will remain with us through at least Sunday before the pattern in the Pacific changes and opens the door to more warm air.
Early indications suggest we might see more stormy weather — but with a warmer, moist Pacific flow — later next week.
Tuesday Dec. 3
A cold front moving slowly through Northern California and Nevada will bring a few inches of snow to the Tahoe Basin this morning as temperatures, and snow levels, plunge.
There is not a lot of moisture associated with this system but the cold temperatures will translate that limited moisture into a maximum amount of snow. We are expecting one to three inches along the lake and possibly 4 to 6 inches at the higher elevations.
Most of the action should be wrapping up by late this afternoon as the system moves south.
In it s wake temperatures will drop even further, with lows in the single digits and possibly below zero in Truckee.
The pattern will remain unsettled through the weekend. It’s possible we will see another little storm on Saturday morning followed by another system late Sunday or Monday.
Thursday, Nov. 28
A low pressure system that’s been drifting down the California coast will move into Southern California today, ending any chance of snow showers in the Central Sierra south of Tahoe. High clouds will stream in behind the front, but they offer no threat — or promise — of precipitation.
Temperatures are expected to climb Friday and Saturday and remain mild through the holiday weekend.
The next change in the weather pattern is expected late Monday or Tuesday, when high temperatures will likely plummet by 20 degrees in the span of a day as a cold front sweeps through the Northern Sierra. Winds will kick up Monday ahead of the cold front, and high temperatures will drop back down into the 30s by Tuesday and potentially lower on Wednesday.
Unfortunately, moisture from the Pacific might have a hard time joining with this cold front due to the placement of a ridge of high pressure over the ocean. Some of the computer forecast models are beginning to show the ridge pinching off near southern Alaska, which would allow some moisture to undercut it and merge with the cold front, bringing a better chance of snow to the Sierra. But other models still show the ridge holding firm, so it will be another day or two before we get a better fix on the most likely scenario.
With temperatures aloft extremely cold by Tuesday, and moisture that does make it through will turn to snow at very high ratios, so that’s good news. It won’t take a lot of water to create a significant amount of snow.
Stay tuned for more details on that storm as they emerge.