A cold trough is currently digging south into the area. Showers ahead of the initial front will be spotty today and tonight, mostly we’ll just see clouds increasing and breezy conditions.
The main front begins to move through tomorrow morning from north to south. Snow levels will initially be over 8,000 ft tomorrow morning but will quickly fall to around 5,500 feet or lower in the afternoon. We are thinking 1-3″ of accumulation during the day tomorrow above 7,000 ft.
Thursday night, a favorable northwest flow will setup over the area. This is the part of the system where orographic snowfall will begin to take shape in areas favored by this flow. Snow levels will also fall close to lower valley floors (4,500 ft). There is also expected to be a 26° C temperature differential between the surface water temp of the GSL and the 700mb temps. Generally, the rule of thumb is that we need greater than 18°C difference for the possibility of lake effect. Since we have more than enough difference along with a relatively moist and unstable flow, I think a lake effect event south and southeast of the GSL is looking likely for Thursday night into Friday. Again, lake effect snow is nearly impossible to forecast other than just saying “there’s a chance for it”, but in this case, it’s a strong chance. Accumulations on Thursday night will likely be in the 2-4″ range (above 6K feet) with more possible in areas favored by the NW flow like the Cottonwoods. If lake effect does indeed become a factor, we could see even more.
The storm will start to clear out on Friday leaving a very cold airmass in its wake. Another inch or two is possible in places. This would bring storm totals from tonight-Friday to about 3-6″ with up to 10″ in some favored locations. Not bad for the first week of October!
Drying and warming for the weekend. Models still keep us mostly dry through at least Tuesday. GFS keeps next system to our north, Euro digs it deeper into the area middle of next week. We’ll have to keep an eye on this. But for now, we’ll focus on the snow in the short term . . .