After a couple of quiet days, another round of wintry weather is expected to impact the Sierra and western Nevada this weekend. The latest satellite image continues to show a low developing off the northern California coast. This system will bring a round of light to moderate snow to much of the area by Friday night. Currently, accumulations look to be on the order of several inches over the eastern Sierra and the Carson Range, with 1-2 inches in the local Carson City area by Saturday morning. Most areas will see a break in the snow Saturday with increasing southwest winds of 15-25 mph.
Another very cold low will drop south along the Pacific coast into the longwave trough over the west dragging very cold air once again to the area. Snow will begin to increase Saturday night through Sunday afternoon along with gusty southwest winds. This system will not bring as much snow to the area as the storm earlier in the week, but current estimates are another 1-3 feet in the Sierra and Carson Range and another 3-6 inches in the local Carson City area. This storm will have similar characteristics for western Nevada, where some valleys may see a couple of inches and other areas will see much greater amounts. The attached operational GFS model depicts that a decent band of snow may persist somewhere between I 80 and US 50 before pivoting and sinking south. The NBM text (National Blend of Models) currently shows significant amounts of liquid precipitation for the local Carson City area in the range of ½ to ¾ of an inch, which would yield significant amounts of snow, with snow ratios of about 15:1. That would yield 9 inches to around a foot of snow, but that looks a bit high at this point, so we’ll have to monitor to see the latest trends over the next 24-48 hours.
If that wasn’t enough, after a few lingering snow showers through Monday, another potentially major winter storm may impact the area beginning about Wednesday through at least Friday. While the forecast models show some uncertainty, there is increasing confidence for this storm to be a major warm rain event for the Sierra and western Nevada. For the sake of brevity, the 18Z GFS operational and other model runs shows the warm pattern for this event. The satellite image above shows abundant subtropical moisture from a low near the Hawaiian Island. This all bears watching as we have a deep snowpack over much of the area. Some other scenarios keep us on the colder side of the jet for more heavy snow depending on how the polar and subtropical jets phase together. Currently, more forecast simulations bring in a warm atmospheric river event, which could trigger a significant runoff event.
In summary there are a lot of significant weather events shaping up through at least mid-month. As usual, there is great uncertainty after about 3 days out on the overall evolution of the storm for next week. There will be more updates forthcoming as conditions change.