Lake Wind Advisory 16, NWS Reno, NV

Area Forecast Discussion...UPDATED
National Weather Service Reno NV
1047 AM PST FRI MAR 11 2016

.UPDATE...

No significant updates are planned for this morning. We did bump
winds up for the rest of the morning to the south of Hwy 50 as
winds were already gusting around 45 mph. Light snow continues to
fall above 6000-7000 with rain below these levels, mainly vicinity
of Sierra crest and areas north of I-80.

Satellite imagery showed next system just off the northern CA
coast at mid morning with a large area of rain and high elevation
snow moving across CA in advance of system. 12z GFS/EC indicate
system will hold together as it tracks across the Sierra into
southern NV with a tight north-south baroclinic zone developing
over western NV late this afternoon. Snow will increase along the
crest this afternoon as strong south winds/shadowing prevail
farther to the east in the lower elevations. As the front/upper
dynamics swing across and the airmass destabilizes further with
upper trough, snow levels will lower to around 5000 feet with snow
spilling over briefly along the Hwy 395 corridor through Mono
County and foothills of Mineral County. Wet roads will generally
be the rule through early afternoon. However, where heavier snow
occurs and as we get closer to sundown (after 2 pm), snowfall
accumulations become more likely, especially at Sierra passes.

Quick peek at this weekend points to a slightly colder and still
very wet storm, especially from Alpine County northward.
Significant snowfall for the Tahoe Basin northward to western
Lassen County will create adverse travel conditions with strong
winds Sat-Sun likely to impact lakes, high profile vehicles and
air traffic. Confidence continues to increase and additional
headlines/upgrades are likely with the afternoon forecast package.
Hohmann

&&

.PREVIOUS DISCUSSION... /Issued 231 AM PST FRI MAR 11 2016/

SYNOPSIS...

A series of winter weather systems will impact the region this
weekend. Gusty winds can be expected each day with periods of
mountain snow and valley rainfall today and Saturday. The best
chances will occur Sunday into Monday. A dry and warmer trend
will then become established for the remainder of next week as
high pressure rebuilds.

SHORT TERM...

A large swath of precipitation continues to spread across northern
California early this morning with recent surface observations
recording upwards of 0.5-0.6" of rainfall so far. Radar estimates
indicate as high as 0.75-1.0" of liquid across far western Lassen
and central Plumas Counties. This has resulted in rises on the
Susan River near Susanville but latest river gauge readings have
maintained flows below monitor stage and on a decreasing trend.
Additional liquid accumulations between 0.25-0.5" are possible
across far western Lassen County through this afternoon. There may
be a possibility for some minor flooding of creeks and small
streams in Lassen and Eastern Plumas Counties, but no significant
flooding is expected.

For the rest of today, a shortwave trough axis will dig along the
California coastline which will confine and pivot the precipitation
along western Lassen County this morning before spreading across the
Sierra this afternoon and evening. Gusty winds will be the main
impact this today as a surface low develops across central Nevada.
Winds will be most pronounced across Mono and Mineral counties where
south southwesterly wind gusts of 45-50 mph will be possible. A Lake
Wind Advisory is in place today for Lake Tahoe where gusty winds
will create hazardous boating conditions. Strong and gusty winds are
expected again on Saturday and Sunday so hazardous conditions will
likely remain on both Tahoe and Pyramid through the weekend.

Although today's system has shown less of a splitting tendency from
24 hours ago, it will still possess a healthy mountain shadow with
much of the snowfall remaining along and just east of the crest.
Snowfall amounts across the Sierra crest will remain in the 4-8"
range with the higher end of that range expected more towards Mono
County. Localized amounts up to 10" are possible mainly along the
higher peaks of Mono county through tonight.

A brief break between systems will occur on Saturday but strong and
gusty winds will again be expected particularly north of I-80.
The next moisture plume will push across western Lassen County by
Saturday afternoon and Sunday, but will again feature a substantial
mountain shadow until the main shortwave trough produces the
heaviest push of precipitation and spillover Sunday evening into
Monday morning. Substantial travel impacts across the Tahoe basin
can be expected as early as Saturday evening and continue through
Sunday. Sunday evening through Monday morning looks to be the
period of heaviest snowfall and greatest travel impacts through
the Sierra, as a Winter Storm Watch remains in effect for this
period. Snow levels will hover near 6,000' through Sunday before
falling to near 5,000' by Monday morning. If you have travel plans
through Monday morning, check the forecast often and be prepared
for travel delays in the Sierra. Fuentes

LONG TERM...Monday through Thursday...

Main adjustments in the extended were reducing precip chances Monday
and Monday night, as medium range guidance has relatively good
agreement for quicker exit of the weekend's storm system to the
northeast. We will still have likely pops Monday near the Sierra and
into western Lassen county, but this is weighted more toward the
morning period.

Along with the storm's quicker exit, temperatures would not be as
cold with snow levels less likely to drop to valley floors from I-80
southward. However, brisk winds should to continue through Monday
evening (gusts generally 35-45 mph) as pressure gradient behind the
cold front will remain rather tight.

From Tuesday through Thursday, guidance is in solid agreement for a
dry period with decreasing cloud cover and a steady warming trend, as
ridge rebuilds off the west coast then moves inland later in the
week. This process is projected to occur more quickly compared to
previous guidance, so we generally sped up the warming trend by
about one day. By later next week, highs in lower elevations could
push above 60 degrees, with some of the warmer scenarios coming
close to 70 degrees. Winds will mainly be light, although ridge
winds from the east may increase moderately Tues night-early Wed
when the ridge axis is west of the Sierra crest. MJD

AVIATION...

Winds will continue to produce turbulent conditions for the next few
days with the strongest gusts likely this weekend, especially Sunday.
Periods of LLWS are also likely especially during the night and
morning hours when surface winds subside, but stronger winds persist
at ridge level and foothill locations. Lee side rotors may also
produce shorter duration LLWS during the afternoon hours as well,
especially at KRNO-KCXP.

After a short break in precip this morning, snow will return to
the Sierra terminals (KTVL-KTRK-KMMH) this afternoon and evening,
bringing IFR cigs/vsby at times. For lower elevations including KRNO-
KCXP, a shorter period of rain is expected later today with possible
MVFR cigs.

Unsettled weather will return to the Sierra this weekend with
best chances for snow or a rain-snow mix at the Tahoe terminals from
Saturday afternoon thru Sunday night. Farther south along the
Sierra, snow may hold off until Sunday while lower elevations
appear to be mainly shadowed out before rain pushes through Sunday
evening-overnight. MJD

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 6 PM PST this evening for Lake Tahoe in
     NVZ002.

     Winter Storm Watch from Saturday afternoon through Monday
     morning NVZ002.

CA...Winter Storm Watch from Saturday afternoon through Monday
     morning above 5500 feet in CAZ071.

     Lake Wind Advisory until 6 PM PST this evening for Lake Tahoe in
     CAZ072.

     Winter Storm Watch from Saturday afternoon through Monday
     morning CAZ072.

&&

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http://weather.gov/reno