Carson City weather update: Valley snow coming, could create mess for motorist commutes

A winter storm expected to bring several feet of snow to the Sierra is underway, with rain along the western Nevada valley floors areas around Carson City expected to turn to snow later Monday that could cause commute and travel problems well into Tuesday, according to the National Weather Service.

A Winter Storm Warning has been issued for the greater Reno, Carson City and Carson Valley areas as well as into Lyon and Storey counties from 5 p.m. Monday to 10 a.m. Tuesday. Snow has already began building in the Sierra and around Lake Tahoe, with up to 8 feet possible by Tuesday in the higher elevations.

Down in the valleys and lower elevations, National Weather Service forecasters say total snow accumulations of 2 to 6 inches below 5,000 feet, 5 to 10 inches between 5,000 and 5,500 feet, and 10 to 20 inches above 5,500 feet including the Virginia City Highlands. Locally heavier totals possible east of Lake Tahoe across I-580 and US-395 from south of the Mt. Rose Highway junction to Carson City.

Travel could become very difficult, with a sharp drop in snow levels and visibility most likely between 8 and 11 pm this evening. The hazardous conditions could impact this evening's commute above 5,500 feet, and will likely affect the Tuesday morning commute for all areas. Winds will be gusty through Monday afternoon, particularly for wind prone locations along the US-395 corridor. Travel restrictions for high-profile vehicles are possible.

The weather service advises that motors planning to travel Monday evening through Tuesday should prepare for long delays, especially during commute times. Check with NDOT for the latest chain or snow tire requirements before traveling.

Check the latest road conditions with Caltrans and NDOT. For Carson City area updates see CarsonWeather.com. The latest road conditions can be obtained by calling 5 1 1.

Here is the Monday morning weather discussion update from National Weather Service forecasters about what to expect in the coming days. For updates to the discussion go here.

A major winter storm with areas of strong winds, significant snow in the Sierra, and rain changing to snow for lower elevations Nevada remains on track through Tuesday. Lengthy travel delays in the Sierra are expected with full road closures possible. Another colder winter storm is expected late Wednesday into Thursday with additional travel impacts expected.

In the short term, snow levels have fluctuated around 6,000 to 6,500 feet so far this morning, resulting in a mix of slushy and wet conditions around the Tahoe basin, with snow covered roads above these elevations. Farther north into northeast CA, the snow level appears to be in the 5,000 to 5,500 foot range. Some enhancement of the precipitation band will occur through the morning with more favorable upper level jet dynamics arriving, which should help pull snow levels down about 500-1000 feet.

Farther south into Mono County, the snow just began to accumulate at Mammoth Mountain after 9 pm but an increase in coverage and intensity should also occur during the next few hours.

Then for the rest of today, it's go time with constant moderate to heavy snow in the Sierra (1-2"/hour snowfall rates) generally near and above 6,000 feet around Tahoe and above 6,500 feet for Mono County, and higher elevations of northeast California. For Western Nevada, the guidance has been varied with the extent of the spillover moisture, but our current overall analysis appears to favor more rain than not for the main urban corridor of I-580/US-395.

Farther south into Mineral-southern Lyon and eastern Mono counties, shadowing and strong winds aloft will lead to some strong downslope wind gusts from mid-late morning into this evening. See our latest High Wind Warning statement for more details on this damaging wind potential, which will impact travel on US-95 for those who are trying to drive around the snow-covered Sierra routes.

The strongest forcing will arrive with the cold front passage by late afternoon across northeast CA and through the evening for the remainder of the Sierra and western NV, shifting to south of US-50 after midnight. While guidance varies in the timing of this front, the latest high resolution appears to indicate the most likely passage between 8-11 pm from northwest to southeast.

Anyone driving across Reno, Carson City, and Minden between these times could see an abrupt drop in visibility and worsening road conditions with an intense snow band (with a few lightning flashes also possible), then snow continues overnight into the early morning, also spreading into west central Nevada.

Some enhancement off Lake Tahoe could bring localized heavier snowfall totals south of Reno into Washoe Valley, Carson City, and Virginia City. We'll send an update to the Winter Storm Warning/Winter Weather Advisory this morning with updated snowfall projections (similar amounts for most areas, except bumping up totals a bit for the Reno, Carson valleys and foothills). We will also include the West Central NV Basin and Range into the Winter Weather Advisory as latest blended guidance indicates 55-60% probability of 2" snowfall for Lovelock and Fallon.

For the Sierra, this enhanced snow band could bring snowfall rates of 3"/hour or greater at times this evening into early Tuesday, combined with strong winds (gusts 40-60 mph with 100-120 mph for exposed Sierra ridges) producing whiteout conditions and potential highway closures. Avoid any travel through the Sierra and Tahoe regions tonight.

Liquid precipitation totals (including snow water equivalent) for this storm are indicated below, with localized higher amounts also possible. Some of this precip has already fallen especially over eastern California.

— Surprise Valley/Northwest-West Central NV: 0.50-1.00"

— Far western NV cities/US-395 north to Susanville: 1.50-2.50"

— Foothills west of Reno-Carson/US-395 in Mono County: 2-4"

— Tahoe basin/Truckee, SW Lassen, E Plumas/Sierra counties: 3-6"

— Sierra crest from Yuba Pass southward to Mono County: 4-8"

For the remainder of Tuesday, snow showers will be on the decrease from north to south, with chilly temperatures expected in all areas due to the fresh snow cover. Lows will be mainly in the single digits and teens even with widespread cloud cover preventing ideal radiational cooling. Watch for icy spots Tuesday night into Wednesday morning.

Wednesday through the end of week and beyond
A break in the weather looks to occur early Wednesday other than some isolated to scattered snow showers over the Sierra. Attention then turns toward another notable winter storm hitting the Sierra and western Nevada Wednesday afternoon into Thursday. This storm will not be as intense compared to the current storm. However, it will bring another period of considerable snowfall to the Sierra and a lesser amount of snow to western Nevada.

Forecast confidence remains moderate with this system due to some slight differences in snow levels and timing between ensemble solutions. We will discuss the impacts to our region in the following sections: (1) snow and (2) winds; then conclude with a discussion about the weather beyond Friday.

Snow
The GEFS, EC-ENS, and CMC-ENS Ens slightly differ in the position of the base of the upper level trough as it swings through northern California Wednesday night into Thursday morning. About 20% of the ensemble clusters (mainly EC-ENS) favor a warmer trajectory (trough base is more poleward on its swing through northern Nevada). Even with this uncertainty, we are still moderately confident in 1 to 2 feet of accumulating snow in the Sierra, especially above 7,000 feet.

In western Nevada, several inches of accumulating snow are possible above 5,000 feet, with enough to cover valley floors. The heaviest snows will fly Wednesday afternoon into Thursday morning in the Sierra and Wednesday evening through Thursday morning for the lower valleys of western Nevada. Anticipate travel impacts for both aviation (turbulence/LLWS/icing) and ground (especially in the Sierra).

Wind
Winds will increase starting Wednesday evening, peak after midnight into Thursday, and gradually taper off Thursday afternoon. Gusty periods are expected with localized wind impacts mainly in wind-prone areas. Wind gusts in the lower valleys will range 30-40 mph with a moderate potential of seeing some gusts to 50 mph in the Sierra. Sierra ridges will see gusts greater than 100 mph. Impacts on aviation, recreation, and high-profile vehicles are a sure bet.

Weather beyond Friday: An upper level ridge will build into the Western US Friday with gusty northeast winds possible along the Sierra crest, fair skies, and slightly colder temperatures. Early next week and onward, the synoptic pattern continues to look active. Above normal precipitation and slightly below normal temperatures are expected.