A closed upper level low off the shore of southern California moved inland across the Southern Sierra Nevada on the 8th and 9th, bringing snowfall to locations above 7500 feet in Mono County.
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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.
A closed upper level low off the shore of southern California moved inland across the Southern Sierra Nevada on the 8th and 9th, bringing snowfall to locations above 7500 feet in Mono County.
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 Jan 7, 1:25 PM PST, 14 hours 35 minutes earlier.
Area Forecast Discussion
National Weather Service Reno NV
125 PM PST Sun Jan 7 2018
.SYNOPSIS...
A potent low pressure system will bring another round of
significant precipitation to the region Monday and Tuesday. Travel
in the Sierra will become difficult at times due to heavy rain
and snow early Monday morning through Tuesday. Dry and warm
conditions will return for the end of the week and through next
weekend, with a return to wet weather probable by mid next week.
&&
.SHORT TERM...
One more quiet mid-winter day today. Then with Monday-Tuesday
comes our first beefy winter storm in nearly two months. Here's
the key points:
* Simulations have been fairly consistent on trajectory and
moisture tap with this more southern track system, slinging warm
air and plentiful moisture northward into our region. So it's
nearly a done deal we'll see widespread moderate to heavy
precipitation Monday-Tuesday even in normally rain shadowed
areas such as eastern Sierra valleys and Hawthorne. Precipitation
onset for most areas looks to be Monday morning, as early as
daybreak. Rises on rivers and even some minor flooding of prone
spots and small streams in W Nevada is feasible. Main rivers not
expected to near monitor or flood status.
* What is not a done deal are snow projections. The battle of warm
air from the south and cold air closer to the low remains far
from decided. This yields some pretty meaningful ranges in snow
potential between 6,000-8,000 feet. Example: South Lake Tahoe
could see no snow accumulation or nearly 6-8" by sundown
Tuesday. This all depends on the snow-level drop Monday night
into Tuesday morning. Also snow levels Monday morning at precip
onset could start lower than projected due to antecedent cool
airmass east of the Sierra crest (cold air damming idea). Temps
so far today running nearly 10 degrees below expectations due to
cloud cover and limited mixing.
* Above 8,000 feet we have high confidence in a big snow pickup,
especially for the eastern Sierra which is great for the current
meager snowpack situation! Below 6,000 feet we can't rule out
some light snow in foothills of W Nevada early Monday morning
and again Tuesday but overall high confidence in little/no snow
issues.
* Bottom line is plan for a wet couple days Monday-Tuesday. Anyone
with travel plans in the Sierra Monday night or Tuesday should
look at alternates or expect delays and chain controls. Commutes
Monday and Tuesday will take longer than normal due to rain and
mountain snow. For lower elevation areas in W Nevada now is the
time to clear out gutters, drains, ditches of debris before
rainfall and runoff. Today is also a good day to take down those
last Christmas outdoor decorations without it being a wet mess.
-Chris
.LONG TERM...Wednesday onward...
Light residual snow showers will continue on Wednesday with
lingering moisture as the upper low quickly exits across the plains.
There is a weak system that skirts across Oregon on Thursday night
into Friday morning, but the Sierra and western Nevada will only see
an increase in clouds and small chances for light rain near the
Oregon border. Otherwise, ridging returns by Friday and through the
weekend for a bit of a dry and mild break.
Luckily, simulations are trending towards the ridge being rather
transient. Height anomalies suggest that troughing will return to
the west coast by the following week. This along with a strong,
elongated jet stream across the Pacific directed towards the west
coast would suggest wet weather returning during the week of Jan 15.
Longer range forecast models are already showing this scenario as
well. -Dawn/Edan
&&
.AVIATION...
Generally light winds at the surface and aloft through tonight. High
clouds ahead of the next storm will continue to increase in coverage
across the region through Tuesday.
This storm will bring increasing southerly winds along with valley
rain and mountain snow. Although ridge winds will be noticeably
stronger, this storm will be mainly a precipitation event rather
than a windy one. Anticipate turbulence Monday through Tuesday,
especially across the Sierra; however the southerly flow will not be
as conducive to mountain wave activity as southwest or west flow
would be.
Periods of moderate to heavy rain at terminal sites will produce
MVFR-IFR conditions along with widespread mountain obscuration
Monday through Tuesday. Precipitation is expected to remain as rain,
outside of KMMH where it is likely rain will turn to snow by Tuesday
morning with several inches of wet snow accumulation possible.
-Dawn
.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 10 PM Monday to 7 PM PST Tuesday
above 7000 feet in NVZ002.
CA...Winter Storm Warning from 4 AM Monday to 7 PM PST Tuesday above
7000 feet in CAZ073.
Winter Weather Advisory from 10 PM Monday to 7 PM PST Tuesday
above 7000 feet in 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.
Mammoth Mountain and June Mountain Ski areas reported between 12 to 18 inches of snowfall in 24 hours with mesonets in the area below 7500 feet reporting between 0.60 to 0.97 inches of rain in 24 hours.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2018Every state in 2018This day in weather historyWarnings in California, January 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 2026-10-01. Each event’s entry at NCEI: 737663.