After a nice weekend in Northern Nevada a series of storms will move through the region this week, with the first one coming through Monday into early Tuesday morning. A stronger storm will move through here Wednesday into Thursday. A Winter Storm Watch has already been posted for the second storm beginning Wednesday afternoon and going through late Thursday into early Friday morning. The first storm will be minor overall, because of higher snow levels.
Besides a weak front moving through Monday afternoon and evening, there is not a ton of dynamics to work with Monday, but there is some moisture to tap into from the ocean. The mountains themselves can act as a lifting mechanism, so when you have enough moisture, a weak front is all you really need to get something going in the Sierra. You see your warmest air before a front moves through, which means snow levels will start out fairly high Monday morning in northern California, and will then climb to about 7000 feet in the early afternoon, before reaching lake level late Monday evening into early Tuesday morning. The image below shows the snow levels in purple and peak time for precipitation in blue, which is between noon and 6pm.
Donner is right at the threshold for rain or snow with this storm, which can make impact forecasting a little challenging, but overall I don’t see it being a huge problem during the day. With that being said, if it rains hard enough, evaporative cooling may occur and cause the rain to switch to snow from time to time. Bottom line, I have storm impacts on the low to moderate range for Donner, and I would bring chains just in case. However, the majority of the snow will fall above pass level Monday.
Monday through Tuesday rain totals will range from a trace at the Reno Airport to a quarter of an inch in the hills, to a half inch in places like Truckee and northeast California. Snow totals will be light in most places below 7000ft, and reach a few inches along the pass and up to a foot at the crest.
This first storm is triggered by a cold front coming straight from the west, which is a good direction for the valley to get shadowed out. Or in other words the mountains will get wet and we’ll stay dry. It will be windy in Reno though with gusts in the 30’s, especially when the front moves through between 3-6pm. A Lake Wind Advisory is posted for both Pyramid and Tahoe Monday as winds could be gusting in the 40's.
Temperatures will be in the upper 50’s and low 60’s in the Reno area Monday, but gusty winds will make it feel a tad cooler. By Tuesday morning, the storm will be east of us and skies will begin to clear.
As one storm leaves this week, another one will follow suit. Instead of moving northeast and getting shredded apart like Monday’s system, the second one will hold together and pool in a ton of cold air from the north. Wednesday will be rainy in Reno and rather windy, with snow and rain falling in the mountains as well. With colder air this time around, snow levels will be lower and snow totals will be much higher. With the upper low holding together, there is better dynamics as well. We could also see some spill over in Reno as the low gets closer. We’re still a few days out so it’s too soon for specifics, but it does look like a pretty good storm, to the point I would avoid driving over the pass both days. Make sure to stay tuned to KTVN both on air and online and we'll make sure to keep you up to date with the latest weather information. You can also follow me on Facebook at KTVN Angela Schilling or on Twitter at Angela Schilling. Have a great day.
Source : http://www.ktvn.com/story/36826342/valley-rain-and-mountain-snow-chances-this-week