High Wind Watch 5, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
321 AM PST Wed Nov 11 2020

.SYNOPSIS...

Quiet weather will continue through Thursday before a fast moving
storm system moves across the region Friday into Saturday,
bringing gusty winds with periods of mountain snow and mainly
light valley rain. Temperatures will remain below average for the
next few days, then rise to a few degrees above average by early
next week along with a possible pause in storm activity.

&&

.SHORT TERM...

Main changes were trending lower with precip and snow amounts for
Friday-Friday night, as the overall storm track appears to be
shifting a bit farther north, favoring the highest precip chances
for northwest CA and the Pacific Northwest.

Dry conditions will prevail today and Thursday with ridge winds
decreasing by this afternoon, then we will transition to a more
active pattern starting Thursday night through the early portion
of the weekend as a couple of shortwaves move into the northwest
US. The first wave on Thursday night is quite weak and less
likely to produce much in the way of precip, with the main effect
being an increase in higher elevation winds producing possible
gusts of 60+ mph for the Sierra ridges around Tahoe.

The second stronger wave is projected to arrive on Friday with a
more substantial increase in winds, and increased precip chances.
There is still a considerable difference on how far south the
strongest winds get, although with the overall trend continuing
to track the main wave farther north, the potential for the
strongest valley winds (gusts up to 50 mph) favor northeast CA
including the Surprise Valley and northwest NV. There are a few
scenarios that indicate a possible short period of 60+ mph peak
gusts for the Surprise Valley and far northwest NV Friday
afternoon-evening as west 700 mb flow across the Warner Mountains
could reach 70 kt. Other lower elevations will still likely catch
some gusty winds although gusts are more likely to be of the
30-40 mph variety, with a small possibility of gusts near 50 mph.
Strong Sierra ridge winds are likely, with peak gusts of 100+ mph
expected Friday night mainly around the Tahoe region. Current
model soundings aren't indicating a very favorable setup for a
downslope wind event into far western NV despite these strong
Sierra winds.

We have continued to trim precip amounts down for the Friday
afternoon-night period with projected totals mainly from
0.25-0.50" for much of northeast CA into the Tahoe basin and far
northwest NV, with up to 0.75" possible near the Sierra crest
west of Tahoe. Precip amounts drop off farther south across Mono
County with up to 0.25" near the crest, while much of western NV
is likely to be shadowed out with minimal amounts--maybe
0.05-0.10" for some foothill locations and northern portions of
the Basin and Range.

Snow levels are projected to rise up to the 6000-7000 foot range
so we expect only rain for lower elevations. This milder air will
limit snowfall amounts (we currently expect less than 1") at Lake
Tahoe level, while the higher elevations may receive up to 6".

Daytime temperatures will remain relatively steady through
Thursday, with near uniform highs of mid 40s-lower 50s from the
Sierra valleys to the lower elevations of western NV. By Friday as
winds increase, highs will likely push upward through the 50s for
lower elevations, while the Sierra valleys and northeast CA
retreat to the lower-mid 40s. Overnight lows will not be as cold
compared to recent nights due to increased cloud cover and
presence of increased mid-level winds limiting full decoupling of
valley winds. MJD

.LONG TERM...Saturday into next week...

Some changes to the long term, mainly to delay the onset of the
storm for next week. This would also entail warmer temperatures
and lighter winds early in the week. Ensembles are now showing
more of a Wednesday timing for next week's storm, but there
remains quite a bit of variability.

For the weekend, Saturday will see breezy winds in the wake of the
storm for Friday night with some showers in the Sierra and near
the Oregon border. Amounts will be light as snow levels will
remain 6000-7000 feet from north to south. A break is expected
Sunday as ensembles show ridging across the area with temperatures
continuing to warm, but remaining near average.

For next week, ensembles are showing more ridging and warming
possible for Monday and Tuesday. At this point, there is fairly
high confidence that Monday will remain dry and mild with temps
5-10 degrees above average. Ensembles remain split on the timing
of the next storm (with a couple members having nothing at all).
For now, we show an onset Monday night into Tuesday, but only with
low chances in northeast California to dry in central Nevada.
Wednesday looks to have better chances with most ensemble members
bringing the storm through that day. However, as mentioned above
there are a couple members that have almost nothing and some
delaying it until Thursday or Friday. We have cautiously raised
precip chances Wednesday with cooler temperatures. X

&&

.AVIATION...

VFR conditions are likely through Thursday afternoon with light
winds. Some gusty ridge winds will continue mainly near the
Oregon border through this morning with mtn wave turbulence, but
no LLWS is anticipated. Winds will begin to pick up in higher
elevations Thursday night, with a further increase Friday through
Friday night. More significant mountain wave turbulence and
periods of LLWS are likely Friday into Saturday.

For the Friday-Saturday storm, periods of MVFR with isolated IFR
conditions are likely in the Sierra Friday afternoon into
Saturday morning, with some mountain top obscurations extending
into western NV. Main precip type is likely to be rain at the
main terminals, although a rain-snow mix is possible for the
Sierra terminals at onset Friday morning before milder air moves
in during the day. MJD

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

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http://weather.gov/reno