Some big changes are coming our way. The storm track, which for much of May has been well to our north, will drop down for the next week or so, dropping both temperatures and occasional valley rain and mountain snow. For Wednesday, valley temperatures will drop back into the 60s with occasional showers and brisk winds. Snow levels on Wednesday will be quite high, above 8,500′, but those will fall quickly on Thursday, likely to about Lake Tahoe level. Travel over the passes on Thursday could be challenging, and a Winter Storm Warning has been posted on the west side of the Sierra. The valley will see Thursday highs drop to the 50s with rain likely, especially on the west side, as there will be some shadowing. Temperatures rebound a bit into the weekend, but occasional showers are in the extended forecast.

This will be an unsettled weather week, with occasional valley rain and mountain snow and rain. Snow levels will stay well above the valley floor through Thursday, and would even pop above Lake Tahoe a bit here and there, before dropping back to the valley floor by Friday. The mountains do have a Winter Weather Advisory posted starting 10 pm Tuesday which will run through noon on Thursday. It’s a fairly warm storm, so the snow will be wet and heavy.
In the valley, there will be fairly significant shadowing occurring, but some locations could still see several tenths of an inch of rainfall over the next few days. High temperatures stay in the low 50s through Thursday before dropping to the low 40s on Friday, at which time some snow could reach the valley floor, although I don’t expect heavy accumulations all the way down here. Through the course of the week the mountains could pile up anywhere from a few inches at the Lake to two or more feet along the crest of the Sierra.

In a nutshell, a very stormy week. High valley winds will continue for the next couple of days, although probably not quite as powerful as the winds we saw Monday afternoon. A series of storm fronts will slam into the mountains, with snow levels likely to stay above the valley floors for the most part, but should reach down to Lake Tahoe through most of the week. Travel over the passes will be extremely difficult through Wednesday (A Winter Storm Warning is posted for the mountains until early Thursday morning.) In the valley, a High Wind Warning is in effect through this evening. The strong winds will create significant rain shadowing, so rainfall amounts will be mostly limited to the western foothills, although some spillover rainfall should be expected through Wednesday. Temperatures will range from the low 50s to the mid-40s through the rest of the week.

While the weather pattern remains generally unsettled for the next week, the storms moving through the region shouldn’t be as strong as what we’ve had the first six weeks of the year. Scattered snow showers through Thursday, with a possibility of some lake effect snow south of Pyramid Thursday afternoon, could put down anything from a dusting to a few inches of snow in various valley locations. By Friday and Saturday, we get a bit of a break with temperatures warming in the 30s Friday warming into the 40s for the weekend. Another weak to moderate storm moves in Sunday and Monday bringing with it a chance of additional rain or snow in the valleys.

The heavy valley rains from earlier will turn to snow over the next few days…enough to cause a Winter Weather Advisory to be posted for the Reno area until noon Friday. Total valley accumulations will vary greatly depending on the elevation, but could range from a couple of inches near the airport to as much as a foot in the upper foothills. In the mountains, a Winter Storm Warning will extend through the weekend into Sunday afternoon, with high winds and heavy snows once again making mountain travel anything from difficult to impossible. By the end of the weekend, Lake Tahoe could see another couple of feet of snow, with 5-6′ possible in the upper elevations near the crests.

Temperatures will drop dramatically, likely not exceeding 40 degrees through the middle of next week.

There’s a lot of stormy weather left this week, with a wet and warm storm gradually transitioning into a somewhat less wet and somewhat colder storm. Significant rain below the 8,000′ snow level overnight tonight into tomorrow morning has caused an Areal Flood Advisory to be posted for the Lake Tahoe area, as some leftover snow is still clogging up storm drains. As we go through the day on Thursday, snow levels will gradually lower to about 6,500′, and then drop all the way to the valley floor by Friday, although the deepest moisture will be past us by then.
High winds will continue to plague the valleys, and the High Wind Warning continues for western Nevada through Thursday. High wind gusts of 60 mph are possible, with even stronger blasts in the wind-prone areas.

As the valley rain switches over to snow late Thursday night into Friday, precipitation amounts will lessen, but a few additional inches of snow over the course of the weekend is not out of the realm of possibility.