Weak warm air advection created light snow across the Sierra and northeast California during the late night hours of the 3rd and early morning hours of the 4th. Additional light snow developed on the afternoon and evening of the 4th and extended into the morning of the 5th as a weak deformation axis developed over the region.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS REV wrote it up.
Weak warm air advection created light snow across the Sierra and northeast California during the late night hours of the 3rd and early morning hours of the 4th. Additional light snow developed on the afternoon and evening of the 4th and extended into the morning of the 5th as a weak deformation axis developed over the region.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Reno, NV wrote its last area forecast discussion before the first event at Dec 4, 3:49 AM PST, 4 hours 11 minutes earlier.
Area Forecast Discussion National Weather Service Reno NV 349 AM PST Tue Dec 4 2018 .SYNOPSIS... Chilly high temperatures will last through Thursday, with low temperatures warmer than average due to cloud cover. Low pressure off the California coast will slowly move inland through Thursday, with chances for light snow persisting through Wednesday before tapering off. The weekend will be dry with milder temperatures before another storm brings more snow and rain early next week. && .SHORT TERM... No major changes to the forecast thinking through Thursday night, with the main impact revolving around chances for LIGHT snowfall accumulations on lower valley floors, mainly tonight. Up until around 3 AM in western NV, warm air advection had produced mainly clouds with just some isolated pockets of light snow or flurries, likely due to a combination of weak lift for precipitation and drier lower layers causing any falling snow to evaporate before reaching the ground (i.e. virga). However, since then a band of light snow has developed across far western Nevada including the Reno-Sparks area, producing a dusting at the Weather Service office (and most likely for the rest of the local area). For the Reno-Sparks area, the light snow should end shortly per radar evidence. Elsewhere across northwest NV and into parts of west-central NV, there is still a chance for more widespread light snow until 5-7 AM as the lower atmosphere there continues to slowly moisten. Meanwhile in northeast CA, light snow has lightly covered some roads per CALTRANS cams but, surprisingly, not so much for the Tahoe area where Truckee reported light snow only briefly. The warm air advection forcing is simulated to dissipate by mid-morning with reduced chances for light snow through the afternoon. This evening, attention turns to the last notable forcing for organized light snow and snow showers. A wave rounding the base of the upper low off the California coast will move into the northern and central Sierra by late evening with broad divergence aloft moving over northeast California and far western Nevada. The NAM, GFS, and EC have all consistently shown an area of light precipitation moving over this region and even the HRRR hints at it tonight. With this in mind, confidence for LIGHT snow tonight in the Sierra, northeast CA, and far western NV is higher than it is for this morning (medium instead of low). Out in the Basin and Range of west-central NV, confidence is lower as that area will be on the periphery of the best forcing so it may wind up just being clouds and a few flurries for that area. With all the above in mind, be prepared for some slick road conditions overnight for far western NV and eastern CA, especially as it only takes a light coating to cause travel headaches. At this time, snow looks to mainly end for western NV well before Wednesday morning's peak commute, but slick spots could remain on less- traveled and secondary roads at least. By Wednesday night and Thursday, snow shower chances currently look to wane substantially as the broad trough axis moves overhead with more nebulous forcing. -Snyder .LONG TERM...Friday through Monday... No significant changes were made for the extended forecast, with dry conditions likely prevailing through the weekend, and the best chances for precipitation still targeted for next Monday-Monday night. A ridge of high pressure developing near the west coast Friday will drift inland across CA-NV through the weekend, followed by another trough of low pressure arriving early next week. From Friday through Sunday, temperatures near seasonal averages are expected, with highs in the 40s and lows in the teens and 20s. Light winds will prevail, resulting in continued valley inversions with poor mixing conditions and possible reductions in air quality near urban areas. The next weather system is primarily on track to arrive by next Monday, with some light snow and rain reaching northeast CA by Sunday night. At this time it doesn't appear to be a very strong storm by Sierra standards, but conditions currently look favorable for periods of light to moderate snow near the Sierra and Tahoe basin, with rain or a rain-snow mix for lower elevations. Depending on the storm's track, the precip could end as a short period of snow by Monday evening in the lower valleys. MJD && .AVIATION... A band of -SN lifting north of KRNO will produce MVFR conditions through daybreak, with additional -SHSN remaining possible thru 18Z mainly for the Sierra terminals, with minimal accumulations possible. A better chance for a steadier period of light snow returns by mid- late afternoon for the Sierra, spreading northward into the remainder of northeast CA and western NV mainly west of US-95 thru tonight, and lifting north of I-80 Wed morning. While this snow is more likely to produce MVFR cigs/vsby, short periods of IFR conditions are also possible. Snow accumulations tonight thru Wed morning look to range from 2-4" for the Sierra terminals, with 1" or less for KRNO-KCXP. A final round of -SN remains possible around KMMH thru Wednesday afternoon-evening, while conditions should improve for lower elevations. For KTVL/KTRK, areas of FZFG could develop Wed night if skies clear out sufficiently. MJD && .REV Watches/Warnings/Advisories... NV...None. CA...None. && For more information from the National Weather Service visit... http://weather.gov/reno
The national radar mosaic for the moment the first event began.
2 winter weather, 1 heavy snow. Local standard time, as filed.
Twenty-four-hour snowfall amounts ranged from 1 to 2 inches at lake level in the Tahoe Basin to as much as 6 inches at the higher elevations around Lake Tahoe.
Twenty-four-hour snowfall amounts ranged from 1.4 inches at the Reno-Tahoe International Airport to 5 inches in northwest Reno and northern Reno. Spanish Springs and Sparks received between 1 to 3 inches of snowfall during the 24 hour period. Significant numbers of traffic accidents occurred in the Reno-Sparks area when temperatures rapidly cooled below freezing during the evening rush hour of Dec 4th. Areas within Carson City received 3 to 3.5 inches of snowfall, while the southwest portion of the Carson Valley received anywhere from 3 to 5 inches of snowfall during the 24 hour period.
CO-OP observer station VRCN2, Virginia City reported 8 inches of snow in a 24-hour period from 4 December 0800PST to 5 December 0800PST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2018Every state in 2018This day in weather historyWarnings in Nevada, December 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 801741, 801793, 801797.