A stronger cold front with a weak/low end Atmospheric River brought gusty winds as well as heavier rain and snow to the Sierra and western NV late Monday PM, Nov 8, through Tuesday AM, Nov 9.
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The episode as NWS REV wrote it up.
A stronger cold front with a weak/low end Atmospheric River brought gusty winds as well as heavier rain and snow to the Sierra and western NV late Monday PM, Nov 8, through Tuesday AM, Nov 9.
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 8, 1:56 PM PST, 6 hours 34 minutes earlier.
Area Forecast Discussion
National Weather Service Reno NV
156 PM PST Mon Nov 8 2021
.SYNOPSIS...
A vigorous fast moving storm pushes into the region this evening
into Tuesday with gusty winds as well as heavier rain and snow. Be
prepared for travel delays and wintry conditions over mountain
passes. Warm and dry conditions return for the remainder of the
week as high pressure rebuilds overhead.
&&
.SHORT TERM...through Tuesday Night...
While the overall forecast for the storm tonight into Tuesday
remains largely intact, the latest high resolution guidance
suggests a few adjustments:
* Snow amounts in the Tahoe basin below 7000 feet and Mono County
near US-395 will be bumped up a bit, with a decent shot of 1-3"
and locally up to 6" later this evening prior to a changeover to
cold rain overnight. Not all of this snow will stick to roads
though.
* Western Lassen/central Plumas-Sierra counties are also in line
for a few inches of evening snow prior to a rain changeover (or
precip tapering to showers). While there may be a few short-
duration travel impacts on some roads west of Susanville-
Portola above 5000 feet, they don't appear sufficient for an
advisory, so we'll cover this in the Special Weather Statement.
* Rainfall amounts bumped up to about 0.20"-0.40" along the US-395
corridor from Susanville-Reno-Bridgeport, most likely occurring
during a 2-4 hour time window early Tuesday morning.
Today's quiet weather will change quickly by this evening, as
a storm system with a tap of deeper moisture arrives to bring
travel and recreation impacts to the region. Wet roads and gusty
winds will make for a slower than usual Tuesday AM commute for
lower elevations, with some slushy conditions around the Tahoe
basin and parts of northeast CA especially prior to midnight, and
snow covered roads over most Sierra passes. Winds ramp up this
evening, followed by a period of rain and snow tonight and Tuesday
morning, then tapering to showers during the day and ending by
Tuesday evening.
Winds...
The period for stronger wind gusts to 40-60 mph in the advisory
areas should kick in this evening and continue overnight. Even
though some spillover rain is likely, these winds will persist in
some areas. A bit of a downslope signature (stable layer
near/above 700 mb and a slight wind speed decrease with increased
height within this layer) is apparent on model soundings tonight,
with about a 20-30% chance for peak gusts near and above 60 mph
mainly for the wind prone areas along US-395/I-580 from Reno-
Washoe Valley southward to the Bridgeport area. Winds should
decrease but remain gusty through Tuesday afternoon. Sierra ridge
gusts could peak around 100 mph tonight.
The Snow Level Challenge...
Dry air below the initial moisture surge should allow snow levels
to start as low as 5000-6000 feet in the Sierra and northeast CA,
due to wet bulb effects at precip onset time around 6-8 pm. As
this main moisture surge arrives overnight, we should see snow
levels rise to at least 6500 feet in northeast CA, and 7000-8000
feet for the Sierra from Tahoe southward. However, the higher
resolution models develop an isothermal layer near freezing as the
warm air advection kicks in. This could lead to large (1000 feet
or so) swings in the rain/snow line in the Sierra as precipitation
intensity increases/decreases. While we think most travel impacts
due to snow covered roads will occur above 7000 feet, there could
be a mix of wet or slushy roads in the Sierra down to near 6000
feet especially from mid-evening until around midnight. Check out
the latest Winter Weather Advisory for snow accumulation details.
Liquid amounts...
Ensemble guidance has focused in on 1.5-2.0" totals along the
Sierra crest from Plumas-Eureka State Park/Yuba Pass to Tioga
Pass, and 0.50-1.25" for western Lassen County, Tahoe Basin and
near Mammoth. A few higher-end scenarios indicate amounts 0.5-1.0"
above these projections, but the short duration of this event
reduces this heavier precip potential. For western NV, we
anticipate about 0.20-0.40" along the main urban corridor, with
lesser amounts to the east and higher totals possibly near 1"
in the foothills west of US-395. Rainfall rates mainly in the
0.10"-0.25"/hour range should limit river flooding and most debris
flow concerns on burn scars, especially with the snow levels
potentially holding to lower elevations for a few extra hours
tonight. MJD
.LONG TERM...Wednesday onward...
There are chances (20-40%) for showers Wednesday in northeast CA
and northwest NV north of a Portola-Gerlach line as a weak
shortwave brushes over the top of a developing high pressure
ridge. This ridge over CA/NV continues to develop Thursday through
at least the rest of this week, likely diverting any Pacific
moisture north into OR/WA. Therefore, for the second half of this
week we expect periods of high clouds and generally light winds.
Afternoon temperatures should be seasonably warm along with cool
nights and limited mixing.
The aforementioned ridge will likely persist through the coming
weekend and into next week as well; so, benign weather conditions
will also most likely persist. However, ensemble cluster analysis
indicates a 25% chance for the ridge to flatten next week possibly
allowing shortwaves to move through westerly flow across north
CA/NV. This "alternate scenario" could result in an uptick of
winds for early next week along with a return of low end
precipitation chances.
Looking even further out: there are some early indicators for an
AR to return possibly for the following week (starting Nov. 21)
but this is a very low confidence scenario this far in advance.
JCM
&&
.AVIATION...
Strong mountain wave activity returns this afternoon/evening and
persists through Tuesday morning. The mountain wave could get
quite strong this evening into early Tuesday morning with LLWS
potential rather high especially for the eastern Sierra and
western NV terminals. With this set-up KRNO could see a period of
strong south winds and LLWS 03z-15z Tuesday.
Snow could impact KMMH, KTVL, and KTRK tonight as freezing levels
may be slow to rise. Accumulations could be 3 inches of heavy wet
snow before changing to rain. Expect some MVFR conditions at times
with light-moderate rain at western NV terminals 06z-15z Tuesday.
Conditions improve Tuesday afternoon except for possible
lingering showers in the Sierra and northeast CA through Tuesday
evening. A few showers could return north of KSVE Wednesday, but
otherwise a high pressure ridge brings a dry air mass Wednesday
through at least the rest of this week. JCM
&&
.REV Watches/Warnings/Advisories...
NV...Winter Weather Advisory from 4 PM this afternoon to 7 AM PST
Tuesday NVZ002.
Wind Advisory from 6 PM this evening to 4 AM PST Tuesday NVZ003.
CA...Winter Weather Advisory from 10 PM this evening to 10 AM PST
Tuesday CAZ073.
Winter Weather Advisory from 4 PM this afternoon to 7 AM PST
Tuesday 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 rain, 1 high wind. Local standard time, as filed.
Trained spotter 3 mi WSW of Gardnerville Ranchos reported 0.81 inches of rainfall measured in 12 hour period.
Wind gust of 70 mph recorded by Mesonet station, Slide, 0.9 mi E of Mount Rose Summit (DRI).
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2021Every state in 2021This day in weather historyWarnings in Nevada, November 2021
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: 987092, 987093.