The month of December started with a fast-moving upper level low and cold front sweeping east-southeast across north-central Nevada. These features brought snow to western Nevada and the Sierra Nevada.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
The month of December started with a fast-moving upper level low and cold front sweeping east-southeast across north-central Nevada. These features brought snow to western Nevada and the Sierra Nevada.
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 Nov 30, 2:02 PM PST, 9 hours 58 minutes earlier.
Area Forecast Discussion
National Weather Service Reno NV
202 PM PST Fri Nov 30 2018
.SYNOPSIS...
A fast-moving and cold system will bring more snow to the Sierra
and northeast California Saturday, with light snowfall
accumulations for western Nevada. Temperatures will remain cold
into next week with the possibility of additional snow around mid
week.
&&
.SHORT TERM...
No significant changes were made for the storm tonight and
Saturday as its track and timing are generally unchanged. Snow
is not expected to impact roads until after midnight, so travel
this evening will be good weatherwise. The worse travel conditions
will be Saturday morning when the bulk of the snow will fall.
Latest satellite imagery showed the upper low off the British
Columbia coast moving southeast toward the Pacific Northwest. It
is expected to track across WA-OR-ID late tonight and Saturday
with a cold front and upper jet pushing into northeast CA late
tonight and swinging south through the Sierra and western NV
Saturday. Best dynamics from both the upper level jet and
frontogenesis along the front will occur Saturday morning.
Snow will move into Lassen County and far northwest NV overnight
and then quickly to the I-80/Hwy 50 corridors by mid-late morning
and eventually across Mono County during the afternoon. This
storm is fast moving and quite compact which will limit snowfall
potential. However, the snow will be a more powdery kind with the
convective nature of the snow capable of putting down some heavy
snow accumulations in a short period. Heaviest snow is still
expected from Plumas to the Tahoe Basin west of Highway 89 with
lesser amounts farther south into Mono County as dynamics pull
away and the snow band weakens. Once the main band of snow passes,
snow will become more showery which should help conditions
improve in the afternoon, especially across western NV and
northeast CA. The exceptions may be to the south of Pyramid Lake
late Saturday into Saturday night when lake effect snows could
produce some slick roads along I-80 east of Reno. Brisk west to
northwest winds will keep it rather chilly during the day Saturday
with temperatures most areas staying in the 30s. Snow will taper
and end Sunday-Monday with unseasonably cold conditions
prevailing. Hohmann
.LONG TERM...Monday Night through Friday...
There were a few minimal changes made to the forecast this cycle.
Most of the changes involved slight increases to POPs Tuesday in the
warm air advection and some decrease in QPF Thursday across the far
northern CWA.
Both the GFS and ECMWF are still showing a period of warm air
advection creating precipitation late Monday night into Tuesday.
With the models coming into better agreement...we are gaining
confidence in this outcome. The issues will be how early the
precipitation starts and its extent across the region. It is not
really the perfect warm air advection set up for widespread
precipitation. We could see just an increase in low and mid level
clouds until the daytime hours Tuesday based on a more south to
north trajectory. So we have kept the QPF on the lower end of the
range but increased POPs in the Sierra...northeast California and
western Nevada for Tuesday. Right now this would be all snow.
Amounts are sub-advisory.
The next part of the broader system...which the warm air advection
precedes...moves inland late Wednesday into Thursday. Numerical
model guidance has been trending the main low farther south and
showing it closing off briefly over southern California. The ECMWF
is less aggressive with the closing of the low...but is still far
enough south to limit precipitation north of Interstate 80. The
operational GFS is farther south today and thus drier over the far
northern CWA. The GEFS ensemble members are split with some
preferring a more southerly track while some prefer a more
progressive track farther north. With the lack of consistency in
the model guidance...we have opted to make little in the way of
changes. This remains a low confidence event. It still appears
the heaviest precipitation would impact Mono County out into
southern Lyon and maybe back to the north in Alpine County. Wrap
around may develop by late Thursday and produce a period of
upslope precipitation for Mono County as well.
Lastly...after a brief break early Friday...the GFS is showing a
fast-moving open wave impacting the region late Friday. The ECMWF
also shows this wave...but is weaker. We have started adding POPs
for late Friday in response to this feature. This one could also
result in increased winds over the ridges going into next weekend.
&&
.AVIATION...
Breezy west-northwest winds along with lowering ceilings causing
mountain obscurations is what is in store for the rest of this
afternoon and into the evening hours ahead of our next weather
system.
By early Saturday morning, a cold front, associated with a low
pressure trough towards the north, will makes its way through the
Sierra and western Nevada region from the northwest. The overall
duration of this system will be short-lived as the front will make
its way through the region rather quickly. Winds will start out
breezy (10-15 kts) from the south-southwest around 11-13Z before
switching to a northwest direction by 18Z for most area terminals.
At KMMH the front is forecast to reach the southern Mono County
area by late afternoon with very little moisture and instability
left so winds will shift later.
As for precipitation, expect this to be an all snow event as cold
air being dragged southward with the front will be enough to
bring snow levels down to all valley floors for Saturday
morning/afternoon. As mentioned previously, the system moves
through quickly thus making the window of precipitation small.
Cloud cover will thicken over the region as light snow will start
to fall by 12Z for KSVE, KTVL, and KTRK. Intensity is expected to
pick up by 13-14Z, especially for areas around the Tahoe Basin,
where IFR conditions are likely through 21Z with possible
accumulations of 6-8 inches. For KRNO and KCXP, light snow will
start around 13Z and last through 21-22Z with 1-2 inches of
accumulation possible. It is important to note that while snow is
forecast to be light for the western Nevada valleys, snowfall
rates can be heavy at times lowering visibilities quickly,
especially as the front moves through.
Snow showers can linger around for the rest of the day on Saturday
before a break in the active weather for Sunday and Monday.
Overnight FZFG can be an issue for KTRK into the beginning of next
week if winds are calm and cloud cover clears. The pattern does
continue to look active for next week as a trough remains towards
the west. -LaGuardia
&&
.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 11 PM this evening to noon PST
Saturday NVZ005.
Winter Storm Warning from 11 PM this evening to 3 PM PST
Saturday NVZ002.
Winter Weather Advisory from 4 AM to noon PST Saturday NVZ003.
CA...Winter Storm Warning from 11 PM this evening to 3 PM PST
Saturday CAZ071.
Winter Weather Advisory from 11 PM this evening to noon PST
Saturday CAZ070.
Winter Weather Advisory from 4 AM to 3 PM PST Saturday CAZ073.
Winter Storm Warning from 11 PM this evening to 3 PM PST
Saturday CAZ072.
&&
For more information from the National Weather Service visit...
http://weather.gov/renoThe national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
Thirty-six-hour snowfall amounts ranged from 2-4 inches at 6700 feet in Incline Village to as much as a 10 inches at higher elevations around Lake Tahoe (Mount Rose Ski Area).
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: 801238.