Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 162313

Area Forecast Discussion
National Weather Service Reno NV
413 PM PDT Sun Oct 16 2016


A cold frontal boundary has lowered snow levels below 8,000 feet
with snow now sticking at Donner Pass on I-80. After that boundary
passes by after the next 2 hours, snow levels should remain where
they are or even rise slightly before falling again after
midnight, but latest computer guidance has also come in slightly
cooler for the rest of the night into Monday morning. Radar shows
one more wave of moderate precipitation which will move through
later tonight before the snow and rain tapers off to showers
Monday morning. Thus, a Winter Weather Advisory has been issued
for the Tahoe Basin, through 8 am PDT Monday, with 2 to 5 inches
of snow expected above 7,000 feet. JCM


Periods of moderate to heavy rainfall and will continue through
tonight with gusty ridge winds. Significant snow accumulations
are also expected in higher elevations especially above 8500 feet
with some lighter snows down to 7000 feet. A few showers may
linger through Monday with a chance of showers near the Oregon
Border Tuesday. Otherwise, drier and warmer weather is expected
the rest of the week into next weekend.


.PREVIOUS DISCUSSION... /Issued 237 PM PDT Sun Oct 16 2016/

Heavy rainband is moving through the I-80 and Highway 50 corridors
this afternoon. Rainfall rates are approaching a half inch per
hour at times in the mountains with near a third of an inch an
hour at times into the Western Nevada valleys. For the next few
hours through sunset, expect additional rainfall totals of up to 2
inches in the mountains, 1-1.5 inches in the foothills and 1/2 to
1 inch in the valleys along the Sierra Front. Further east toward
Highway 95, still decent rains for that area but lighter at a
quarter to a half inch. Debris flows are likely off the
Emerald/Little Valley burn scars and many smaller ones have been
reported so far.

With this heavy rain, winds have significantly lessened so have
canceled the wind advisory that will still up for southern and
eastern zones. Still a few gusts to 45 mph near the Oregon border,
but that will end soon as the last band of rain moves in.

That last band will move through from NW to SE beginning around 6
PM and continue into Monday morning. It is associated with the
main cold front, so snow levels which are currently running
8500-9000 feet will lower to 6500-7000 feet by sunrise Monday
morning. We think the greatest accumulations will occur above
8500 feet affecting the highest passes. Down to the major passes
of Donner and Echo, lighter accumulations of 1-3 inches are
possible as the precip ends. With the road surfaces still likely
mild, accumulation to the roads will be lighter so will hold off
on an advisory. Rainfall amounts will be lighter than the band
this afternoon and up to 2 inches near the Sierra Crest with
lighter amounts to the east of about 1/4 to 1/2" in Western

Once that band moves through, it will be much quieter tomorrow
with lighter breezes and only a few remaining showers in the
Sierra and near the Oregon Border. Another system follows for
Monday night into Tuesday, but the brunt of it will be into
Oregon. Kept the chance of showers north of Susanville/Gerlach
with snow levels near 6500 feet. Otherwise, drier elsewhere with
high temps a few degrees below average. Lows will be mild with the
recent rainfall, but fog may be an issue. For now, left it in the
typical fog prone areas of the Martis and Sierra Valleys, but
other areas may need to be added. This would include portions of
Western NV such as near the Carson and Humboldt Sinks.

A much quieter pattern is in store for the extended forecast with
a an upper level ridge building across the West. This will provide
dry conditions, light winds, and warming temperatures heading into
next weekend. The ridging will amplify through Thursday before
turning more zonal aloft over the weekend. As such, we will see a
steady warming through the week with lower and mid 70s for western
Nevada by Thursday into the weekend. Sierra valleys will warm into
the mid and upper 60s through the weekend. Fuentes

Periods of moderate to heavy rainfall will continue tonight
before quieter weather returns on Monday afternoon. IFR conditions
will continue for Sierra terminals KTRK and KTVL tonight in heavy
rainfall with a small break from 02-04z before the next round of
rainfall arrives. Snow levels will fall through the night but
precipitation should remain as rain for all terminals. An
additional 1 to 2 inches of rainfall is possible for KTRK and

At KRNO, KCXP, and KMMH spillover precipitation will continue this
afternoon with the next wave of heavier rainfall expected around 04-
05z. Additional rainfall accumulations of up to 0.50-0.75" are
possible along with periods of IFR conditions. Mountain obscuration
will continue with CIGS being maintained between 3,000-4,000 feet in
moderate rain.

The precipitation has diminished the strongest wind threat but with
winds remaining strong aloft near ridge top level (40-50kts), do
expect areas of turbulence along and downwind of the Sierra.
Periodic wind gusts up to 45mph are possible during breaks in the
rainfall. Winds aloft will substantially diminish after 15z Monday
with winds becoming light through Monday afternoon.

Flying conditions should dramatically improve by mid-day Monday and
remain good for the balance of the week as high pressure moves in
aloft. Note that some morning fog is possible in the Sierra valleys
Tuesday/Wednesday. Fuentes


.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 5 AM PDT Monday for Lake Tahoe in

     Winter Weather Advisory until 8 AM PDT Monday above 7000 feet in

     Flash Flood Watch through late tonight NVZ002-003.

CA...Lake Wind Advisory until 5 AM PDT Monday for Lake Tahoe in

     Winter Weather Advisory until 8 AM PDT Monday above 7000 feet in

     Flash Flood Watch through late tonight CAZ072.



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