A closed upper low over the Pacific Northwest brought gusty winds to portions of the eastern Sierra Nevada and western Nevada from late afternoon on the 19th through the late morning hours of the 20th.
Every event with a place to put it; 3 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.
A closed upper low over the Pacific Northwest brought gusty winds to portions of the eastern Sierra Nevada and western Nevada from late afternoon on the 19th through the late morning hours of the 20th.
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 19, 9:51 PM PST, 20 minutes earlier.
Area Forecast Discussion...UPDATED
National Weather Service Reno NV
951 PM PST Tue Dec 19 2017
.UPDATE...
Quick update to allow the wind advisory to expire in the northern
areas. Winds are continuing to blow, strongest along Highway 395
near Doyle. However, the cold front is about to move through and
snow will commence shortly. Added a wind mention in the winter
weather statement as the winds will continue to blow for another 2
hours or so, especially near Doyle.
Elsewhere, winds are peaking now in Tahoe and the Sierra Front. A
few gusts over 70 mph have already occurred with Washoe Valley
peaking at 86 mph so far. Ridge winds are now over 100 mph at
times and this will continue for the next 3-4 hours. Winds are
still spotty in the valleys, and will continue to be until just
before the cold front arrives. Peak winds for the morning hours
still look good for Mono-Mineral. No changes to the expected snow
along the cold front as it is well in line with the latest models.
The HRRR continues to show the quick burst of snow along the
front.
&&
.PREVIOUS DISCUSSION... /Issued 717 PM PST Tue Dec 19 2017/
UPDATE...
Forecast is generally on track this evening with winds continuing
to increase. Ridge gusts are near 100 mph and we are expecting
them to continue to increase through 10 mph for Tahoe and the
Sierra Front remaining high for 3-4 hours before weakening just
ahead of the front. Mono/Mineral County winds will ramp up after
midnight and peak during the morning hours tomorrow while areas
near the Oregon Border are seeing their peak winds now. That said,
this is not expected to be a widespread wind event with the wind
prone areas seeing the highest winds.
The cold front is still slated to move through, but timing is a
little faster now, by 1-2 hours. Expect passage for Tahoe/Sierra
Front from 4 am to 7 am Wed morning. On the lower valley floors,
it may briefly start as rain then change quickly to snow. A mess
of a morning commute still looks likely for areas from Highway 50
northward. Forecast snow amounts are still in the ball park. The
updates this evening were minor and to convey a more consistent
message in the grids.
AVIATION...Updated for wind shear reports...
Reports of wind shear BLO 200 feet have been observed this
evening near KRNO and have amended the TAF accordingly. Expect
these very low level reports to continue, at least BLO 1000 feet
through 06-07Z. The wind shear will continue all night, and will
not moderate until after the front goes through around 12Z. While
no reports have come in near KTVL/KTRK/KCXP, conditions are likely
similar. No other changes made, except to shorten the period of
highest winds to 3-4 hours overnight instead of 6-8 hours.
PREVIOUS DISCUSSION... /Issued 304 PM PST Tue Dec 19 2017/
SYNOPSIS...
A strong, fast moving, cold front will push through the region
tonight into Wednesday. This will create a period of very gusty
winds, brief but heavy snowfall with very low visibility, followed
by the coldest temperatures of the season.
SHORT TERM...
No major changes to the ongoing forecast, everything still looking
on track. A fast moving winter storm will affect the region
tonight into Wednesday morning with strong winds, widespread snow,
and periods of near-zero visibility. This isn't a huge storm by
Sierra standards, but it will still have significant impacts to
the region including air and road transportation during the
Wednesday morning commute.
Winds are already increasing over the Sierra and beginning to mix
down into the foothills and valleys around Reno-Carson City.
Winds will continue to strengthen tonight and into Wednesday
morning as the cold front approaches, bringing wind gusts up to
50-70 mph along the Highway 395 corridor. The strongest winds will
be right ahead of and along the cold front. High winds in Mono
County will combine with very dry conditions to produce a
particularly dangerous situation with critical fire weather
conditions and very dry vegetation. See our Fire Weather
discussion below for details.
Latest computer models continue to show good consistency in the
timing of the cold front late tonight into Wednesday morning. Snow
will start to move into the northern Sierra late tonight. This
cold front will be very dynamic with strong lift and instability
along the cold front that will bring periods of heavy snowfall,
gusty winds and near-zero visibility during frontal passage. High
resolution models are also showing a high potential for a Narrow
Cold Frontal Rainband (NCFR) that is expected to move through the
Reno-Tahoe area right during the Wednesday morning commute.
Snow levels will crash down to all valley floors early Wednesday
morning. Snowfall rates in the NCFR will reach rates of 2-4"
inches per hour. Luckily, the front will move through rather
quickly which will limit the overall snow amounts across the
region. Conditions will change rapidly and may take people off-
guard during the early morning hours, especially "down here" in
Reno-Sparks-Carson City. Anyone with travel plans Wednesday
morning should try to leave early and allow for extra time to
reach their destinations or postpone travel until later in the
morning after the front has passed. Latest estimates of the cold
frontal timing is as follows:
* Susanville-Lassen: Midnight to 3am Wednesday
* Lake Tahoe: 2am to 10am Wednesday
* Reno-Carson: 5am to 8am Wednesday
* Mammoth Lakes: 2pm to 5pm Wednesday
Several inches of snow are expected in the Sierra with up to 8-12
inches above 7000 feet at pass level. In the lower valleys of
northeast CA and western NV, expect to see anywhere from 0.5" to
3" on the valley floors with localized areas up to 5" above 5000
feet in the foothills. Snow amounts south of Highway 50 will be
much less, with only a dusting up to 3 inches of snow possible.
Could see up to a few inches of snow around Mammoth.
Showers will continue Wednesday afternoon, with a potential for
light upslope snow showers in Mono County and lake effect snow
Wednesday night into Thursday morning. We will need to keep an
eye on the lake effect potential off of Pyramid Wednesday night,
as the northerly flow will transition to more northeasterly flow
Thursday morning and potentially bringing more snow into the North
Valleys and Spanish Springs. Hoon
LONG TERM...Friday and beyond...
Ridge in the eastern Pacific will continue to be the determining
factor for weather over the next week. There does appear to be some
potential for the ridge to amplify enough so that system can
undercut into the west coast by early next week, which of course
will be just in time for post-Christmas travel. If you have travel
plans on Christmas Day or on Tuesday be sure to keep an eye on the
forecast.
The placement of the ridge will continue to encourage cold, moisture-
starved systems dropping out of the north into the Sierra and
western Nevada. Temperatures will remain at or below normal,
especially Saturday-Sunday as a new batch of cold air advects in
from the northeast. Temperatures will also be heavily dependent on
the amount of snowfall that we receive from the cold front late
tonight into Wednesday morning. Regardless, now is the time to
prepare for much colder temperatures (highs in the 30s for much of
the Sierra and western Nevada) and potentially sub zero low
temperatures for colder valleys. Be sure to provide shelter to
vulnerable communities as well as pets or animals.
The GFS and ECWMF are both showing a weakness in the ridge
developing as it amplifies across the west. This may allow a weak
low pressure system to move through the Sierra and western Nevada
Christmas Day into Tuesday. Confidence remains low for now, but be
sure to keep an eye on it if you have travel plans. This would not
be a major system if it does occur, but would create travel
headaches for those returning home the day after Christmas. -Edan
AVIATION...
A quick hitting storm will move through the region late tonight
through early Wednesday bringing strong gusty winds and chances for
snow.
WINDS: Southwest winds will increase across the ridges this
evening and continue to ramp up overnight ahead of a strong cold
front for early Wednesday morning. A period of LLWS is expected
this afternoon and evening. The strongest winds will be after
sunset today and just ahead of the cold front early Wednesday
morning. We are still forecasting a 2 to 3 hour window between
midnight and 6am for the Tahoe Basin/Sierra Front airports and 4am
and Noon for the eastern Sierra of Mono County where wind gusts
may exceed 50 kts (locally 60-65kt). Behind the front, surface
winds will decrease but will still remain a brisk 15-25 kts.
Turbulence will likely still be a concern Wednesday as upper level
winds do not decrease until late Wednesday night.
SNOW: Model simulations have been consistent with developing a band
of snow along the cold front early Wednesday morning. Moderate
snowfall amounts are expected for the northern Sierra. For western
NV airports and KMMH, up to 2 inches will be possible and 2 to 5
inches for Tahoe terminals. For any given location, this will be a
quick burst of snowfall with intense snowfall rates of 2-4"/hr
not out of the question. For the Sierra and northeast CA snowfall
will generally last 2-4 hours, elsewhere about 1 to 2 hours,
before quickly tapering once the cold front moves south across the
region. Hohmann/Hoon
FIRE WEATHER...
A particularly dangerous fire weather situation is setting up for
Southern Mono County. High winds are expected late this afternoon
into Wednesday morning. While these winds will occur across most
of the area, the biggest concern is over Southern Mono County.
Little rainfall has occurred so far this winter and fuels remain
very dry, in contrast to the heavy rains received north of Highway
50 in November.
The strongest winds are expected tonight into Wednesday morning
ahead of the cold front. There is also downslope potential with
it, and very dry air ahead of the front. At this point we are
looking at peak gusts up to 70 mph and the biggest threat will be
along the 395 corridor south of Mono Lake. In addition, with the
very dry air ahead of it, RH will likely remain 10 to 20% in some
areas into Wednesday morning.
The cold front moves through Wednesday morning with some snow near
the Sierra Crest, but little spilling over to the east. While RH
will briefly come up, subsidence on the backside will bring very dry
air back into the area with RH possibly dropping into the teens
again Wednesday afternoon after a brief recovery. Winds will switch
to the north and be weaker. However, areas susceptible to north
winds such as the Owens and Chalfant Valleys will see strong winds
continue. Gusts with the north winds will be 50-55 mph in these
areas.
Given the strength of the winds, the very dry air, and fuel
susceptibility, a Red Flag Warning is in effect for Southern Mono
County. This is a particularly dangerous situation given the
strength of the winds and the low humidity with very rapid fire
spread possible (like the Round Fire in 2015).
&&
.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory until 10 AM PST Wednesday NVZ005.
High Wind Warning until 4 PM PST Wednesday NVZ001.
Winter Weather Advisory from 1 AM to 1 PM PST Wednesday NVZ002.
Wind Advisory until 1 AM PST Wednesday NVZ002.
High Wind Warning until 1 AM PST Wednesday NVZ003.
Winter Weather Advisory from 1 AM to 1 PM PST Wednesday
NVZ003-004.
CA...Winter Weather Advisory until 10 AM PST Wednesday CAZ070-071.
High Wind Warning until 4 PM PST Wednesday CAZ073.
Red Flag Warning until 7 PM PST Wednesday CAZ273.
Winter Weather Advisory from 1 AM to 1 PM PST Wednesday CAZ072.
Wind Advisory until 1 AM PST Wednesday CAZ072.
&&
For more information from the National Weather Service visit...
http://weather.gov/renoPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RENO NV
802 PM PST TUE DEC 19 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0712 PM NON-TSTM WND GST 4 NNW LAKEVIEW 39.26N 119.83W
12/19/2017 M59 MPH WASHOE NV MESONET
NDOT STATION ON US-395A IN WASHOE VALLEY.
0659 PM NON-TSTM WND GST 3 SW NEW WASHOE CITY 39.27N 119.82W
12/19/2017 M86 MPH WASHOE NV MESONET
NDOT STATION IN WASHOE VALLEY.
0657 PM NON-TSTM WND GST 1 NNW LAKEVIEW 39.23N 119.81W
12/19/2017 M65 MPH WASHOE NV MESONET
NDOT STATION IN SOUTH WASHOE VALLEY.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RENO NV
851 PM PST TUE DEC 19 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0657 PM NON-TSTM WND GST 1 NNW LAKEVIEW 39.23N 119.81W
12/19/2017 M65 MPH WASHOE NV MESONET
NDOT STATION IN SOUTH WASHOE VALLEY.
0659 PM NON-TSTM WND GST 3 SW NEW WASHOE CITY 39.27N 119.82W
12/19/2017 M86 MPH WASHOE NV MESONET
NDOT STATION IN WASHOE VALLEY.
0707 PM NON-TSTM WND GST 5 W STEAD 39.65N 119.98W
12/19/2017 M63 MPH WASHOE NV MESONET
NDOT STATION IN COLD SPRINGS, 5 W STEAD.
0712 PM NON-TSTM WND GST 4 NNW LAKEVIEW 39.26N 119.83W
12/19/2017 M59 MPH WASHOE NV MESONET
NDOT STATION ON US-395A IN WASHOE VALLEY.
0750 PM NON-TSTM WND GST 4 NNW WASHOE CITY 39.38N 119.83W
12/19/2017 M69 MPH WASHOE NV MESONET
RAWS SENSOR AT GALENA FIRE STATION, SW RENO.
0752 PM NON-TSTM WND GST 1 N WASHOE CITY 39.34N 119.81W
12/19/2017 M71 MPH WASHOE NV MESONET
NDOT STATION AT BROWNS CREEK BRIDGE ON I-580.
&&The national radar mosaic for the moment the first event began.
3 high wind. Local standard time, as filed.
Mesonet DYLC1 2 miles north of Doyle reported a wind gust of 61 mph.
Rolled over semi truck due to high winds via California Highway Patrol incident information page. Winds at a nearby mesonet (C4643-Lee Vining) reported a wind gust of 57 mph at 2330PST.
Mesonet TADC1 2 miles northeast of Donner Peak reported a wind gust of 61 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2017Every state in 2017This day in weather historyWarnings in California, December 2017
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: 732314, 732316, 732313.