High Wind in Nevada, January 18 to 19, 2021

Area Forecast Discussion
National Weather Service Reno NV
240 PM PST Mon Jan 18 2021

.SYNOPSIS...

A cold front dropping through the region will bring strong
northeast winds tonight and Tuesday with damaging winds possible
in the Sierra. Temperatures will cool closer to seasonal averages.
Quiet weather returns Wednesday and Thursday before the pattern
shifts to a more active one Friday through next week.

&&

.SHORT TERM...

No changes to the forecast. Upper low is expected to track
southwestward across southern NV/CA tonight and off the southern
CA coast Tuesday. The biggest impact will be strong winds through
the Sierra as winds increase aloft (700 MB flow 55-65 kts,
stronger to the west of the Sierra crest) and east surface
pressure gradients tighten (~15 mb) across the same area. This
will push Sierra ridge wind gusts over 100 mph with modest mixing
in the low levels due to cold air advection allowing gusts to
approach 50 mph in Sierra valleys. The high wind warning will
remain in place tonight and early Tuesday morning with tree damage
and downed power lines possible. While winds will begin to slowly
decrease Tuesday afternoon, winds will remain breezy with choppy
lake waters persisting. Winds really back down after sundown
Tuesday as the upper low pulls farther away.

Otherwise, this cold front will be a mostly dry one as it lacks
moisture. Upslope flow late tonight and Tuesday morning will bring
some low clouds to the east slopes of the Sierra mainly south of
Lake Tahoe. Some light snow could be squeezed out of these clouds
for a dusting of snow, primarily west of Highway 395 in High
Sierra.

A shortwave ridge will return Wednesday and Wednesday night with
light winds and moderate to strong valley inversions. Temperatures
will warm a few degrees over Tuesday but nothing close to what we
have been experiencing. Hohmann

.LONG TERM...Thursday and beyond...

Relativity quiet weather continues on Thursday before a strong
front is forecast to move through the region on Friday. This
system is what we tend to refer to as an outside slider since the
core of the low pressure if forecast to slide from north to south
overland, west of the Sierra crest. In general these types of
fronts are on the drier side due to their fast moving nature and
overland trajectory. However the current path does forecast an
area of divergence moving over western Nevada that could bring
accumulating snow to the lower elevations, so we'll be keeping a
close eye on the exact path of this low.

Temperatures will be back closer to January averages over the
weekend with cool northerly flow as shortwave ridging briefly
builds back into the region.

The overall pattern looks to remain active next week with another
front moving into the region as early as Sunday evening
potentially followed by stronger storms during the week. It's
likely we'll see some more cold fronts move in from the north next
week, but there is still a lot of uncertainty in just how much
precipitation they will bring. Bottom line, the large scale
weather pattern next week has big snow potential for the Sierra,
but it also has some bust potential. -Zach

&&

.AVIATION...

Much cooler air will continue to work into the region tonight and
Tuesday with gusty northeast winds and periods of moderate to
severe turbulence and LLWS, especially near the Sierra crest. LLWS
will be most pronounced at KTRK-KTVL, but we have expanded LLWS
into the far western NV terminals of KRNO-KCXP-KMEV for tonight
and early Tuesday morning when the strongest portion of the jet is
overhead (700 mb ridge level winds 55-65 kts) and low level mixing
remains modest, allowing for possible rotors and variable surface
winds on the valley floors. Current forecast shows a general
northeast to east wind 15G25KT (stronger at KTRK/KTVL), but
periods of lighter and more variable winds are possible.

Moisture remains limited, but some MVFR ceilings and periods of
very light snow are still possible along the Sierra from KTVL-
KMMH 06Z-18Z. Snowfall will be spotty and any accumulation will be
very light.

Winds will gradually back off during the day Tuesday with light
snow near the crest ending. Light winds and VFR conditions return
Tuesday night and Wednesday as high pressure moves across the
area. Hohmann

&&

.REV Watches/Warnings/Advisories...
NV...High Wind Warning from 10 PM this evening to 7 PM PST Tuesday
     NVZ002.

     Lake Wind Advisory until 10 PM PST this evening for Lake Tahoe
     in NVZ002.

     Lake Wind Advisory until 6 PM PST this evening for Pyramid Lake
     in NVZ004.

CA...High Wind Warning from 10 PM this evening to 7 PM PST Tuesday
     CAZ071>073.

     Lake Wind Advisory until 10 PM PST this evening for Lake Tahoe
     in CAZ072.

&&

For more information from the National Weather Service visit...
http://weather.gov/reno