Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 212129
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
229 PM PDT Tue Mar 21 2017

.SYNOPSIS...

Valley rain and mountain snow showers will diminish tonight but
return by Wednesday, with a slight possibility for thunderstorms.
Additional weather systems are likely Friday into Saturday, and
early next week. Neither storm looks very strong, but could
produce some travel impacts for higher passes. Near to slightly
below average temperatures are expected for the upcoming week.

&&

.SHORT TERM...

Bands of convective showers continue to move across the Sierra and
northeast CA, with lighter showers spreading over parts of western
NV. Snow levels within these heavier bands have briefly dipped to
near Lake Tahoe level, with some slushy accumulations on higher
passes. Otherwise, the prevailing snow level has remained near
7500 feet. The bulk of this convective activity is expected thru
mid-late afternoon, then diminish by sunset. Some higher elevation
sites could receive a few inches of snowfall as the heavier bands
push through, followed by melting after the snow decreases. A few
lightning strikes are also possible, but most thunderstorm
activity is likely to remain west of the Sierra crest.

For Wednesday, upper level trough passage across central CA will
trigger another round of convection west of the Sierra, with bands
of rain and snow showers spreading over the crest into northeast
CA during the morning, then reaching the Tahoe and Reno areas
during the afternoon. Snow levels will be lower (generally
between 5500-6500 feet except briefly dipping to near 5000 feet
in heavier shower bands), but the bulk of the precip is expected
during the afternoon across the main Sierra highways, so travel
impacts will be limited to short periods of slushy conditions
during heavier showers. Snowfall amounts will be limited to less
than 3 inches near the Sierra, with a few sites receiving locally
higher amounts. For lower elevations, precip amounts are expected
to range from 0.10-0.25 inch for northeast CA and foothill areas
of far western NV, with less than 0.10 inch across most western NV
valleys. Rivers and creeks will continue to experience fast flows
(much of this due to reservoir releases rather than from
rainfall) but new flooding is unlikely.

By Wednesday evening, most of the shower bands will shift to areas
south of US-50, with the potential for light snow accumulations
(mainly less than 3 inches) reaching Mono County. Snow levels are
expected to range from 6000-6500 feet, except briefly lower during
heavier shower bands.

Drier conditions will return for Wednesday night and Thursday as
weak ridge moves across the Sierra and western NV. The next storm
system will bring light precip into northeast CA and near the
Sierra crest by late Thursday night, with the majority of the rain
and snow chances expected Friday-Friday night. MJD


.LONG TERM...Friday into Tuesday...

The next shortwave trough for Friday and Saturday continues its
splitting trend with a sharper and more southerly trajectory in the
12z guidance. Main changes in the extended forecast were to continue
to lower and shadow precipitation chances along the Sierra and
western Nevada, and also to drop QPF values through the weekend.

The increased precipitation shadow on Friday will however promote
more winds across the Sierra and western Nevada where gusty winds
around 40-45 mph will be possible across many valley locations. The
southwesterly orientation could result in crosswinds and travel
restrictions for high profile vehicles and will also create
hazardous boating conditions across area lakes.

The heavy Sierra shadow will confine most precipitation to the west
slopes of the Sierra Friday afternoon with some deformation forcing
also triggering precipitation across central Nevada. Snow levels
will generally remain around 6500-7000 feet into Saturday morning.
With the bulk of the precipitation along the Sierra occurring
during daylight hours, accumulations along passes above 7000 feet
should be limited to a few slushy inches, with rainfall for lower
valleys. Spillover rainfall across the Sierra Front including the
Reno, Carson, and Minden region could see a few hundredths to
around a tenth of inch of rainfall.

Showers will diminish through Saturday afternoon but a secondary
wave will provide an additional chance for light showers Sunday
evening into Monday morning. This is a quick moving system and
not looking to produce substantial precipitation amounts at this
time. Fuentes

&&

.AVIATION...

Convective shower bands will produce short periods of IFR
cigs/vsby across the Sierra terminals with rain-snow mix, and
MVFR cigs/vsby for western NV terminals with rain until around 01Z
this evening. Conditions should improve after 01z, except for
lower cloud decks obscuring some mountains. Surface wind gusts
25-30 kt combined with Sierra ridge gusts up to 70 kt will produce
areas of lee side turbulence into this evening.

For Wednesday, another round of convective shower bands will
again produce short periods of IFR cigs/vsby across the Sierra
terminals with rain-snow mix, and MVFR cigs/vsby for western NV
terminals with rain. The most likely timing for these worse
conditions is between 18-00Z for KTRK-KTVL, 20-00z for KRNO-KCXP
and 22-04Z for KMMH.

For Thursday, VFR conditions with mainly light winds will prevail,
before another storm system brings increased weather-related
impacts to aviation by Friday. MJD

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 7 PM PDT this evening for Pyramid Lake
     in NVZ004.

     Lake Wind Advisory until 7 PM PDT this evening for Lake Tahoe in
     NVZ002.

CA...Lake Wind Advisory until 7 PM PDT this evening for Lake Tahoe in
     CAZ072.

&&

$$

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



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