Area Forecast Discussion
Issued by NWS Reno, NV
FXUS65 KREV 141028
Area Forecast Discussion
National Weather Service Reno NV
228 AM PST Sat Jan 14 2017
Conditions remain colder and benign through early next week.
The next significant weather period is expected to begin Wednesday
of next week. There will be potential for heavy mountain snow and
lower elevation flooding as a moderate atmospheric river moves
into the Sierra and western Nevada from Wednesday night through
the end of the week.
No major changes were made to the existing forecast. Cloud cover
is limiting fog formation while easterly flow and orographical
lift continue to support a fairly widespread low level cloud deck
along the Sierra Front into the Sierra itself. As a result of
these clouds, temperatures are dropping more slowly tonight; we
may end up a bit warmer than forecast. Still, temperatures are
colder than recent conditions with the potential for more cold
temperatures tonight into tomorrow morning.
Precipitation chances were trimmed to the extent of the Sierra as
models project a westerly, off-shore track for an approaching
wave Sunday. 10-15% chances of flurries and a rare snow shower
were left in the forecast for Sunday afternoon mainly due to the
amount of residual low level moisture and weak vorticity
advection. It will not take much to kick off a few flurries in the
Sierra even with the primary influence of the wave well west of
the region. Do not expect any accumulation or really many impacts
outside of increasing cloud cover. Boyd
.LONG TERM...Tuesday through Friday...
Primary changes made to the extended period this cycle were to
increase pops a bit for Wednesday through Friday and also increase
QPF a bit for Wednesday/Thursday. Confidence is increasing in next
week`s system and its potential to produce mountain snow and valley
Tuesday is the only dry day in the extended as a short wave ridge is
over the region early on. This ridge flattens and allows over
running precipitation to move into the northern part of the forecast
area by Tuesday evening. This spreads south overnight ahead of the
main upper low that will be the big player in next week`s weather.
Strong gusty winds are possible ahead of this low by early
Wednesday...but the strongest winds are likely to be Wednesday
afternoon and evening east of the Sierra and across the higher
ridges. Winds could gust 50+ mph in the valleys. Snow levels start
in the 7000-8000 foot range...except over Mono/Mineral counties
where they will be slightly higher Wednesday. The trend in the model
simulations has been to hold these snow levels at this level for a
longer period of time...finally dropping them late Wednesday night
or early Thursday morning to the valley floors behind a cold front.
The period of heaviest precipitation has been fairly consistent in
the simulations and stretches from Wednesday evening through
Thursday morning. Contrasting this system to the most recent one we
see that there is not as much precipitation and the period of
heaviest precipitation is shorter. Still...below 6000 feet we are
likely to have some snow cover and soils remain nearly saturated.
Any precipitation of moderate to stronger intensity...and we should
have a good period of spill over later Wednesday evening...is likely
to result in minor flooding near small streams and in low lying
areas in the far western Nevada and northeast California valleys.
The main stem rivers do not appear highly susceptible to flooding
with this one with one exception. The Middle Fork Feather may again
have flooding issues this time around as its headwaters see rain in
the Sierra Valley.
Snow showers lingers into Thursday. Another push of moisture brings
moderate to heavy snow back to the Sierra Friday. This is also
likely to produce showers in the lower elevations.
Temperatures climb above normal by early Wednesday before falling
back below normal for Thursday and Friday. 20
Lingering low clouds are maintaining MVFR conditions in some areas
along and south of I-80 this morning. With low level east to
northeast flow in place it will take some time to scour these clouds
out of the region...but eventually they will dissipate. Patchy
freezing fog has developed around KMMH this morning and should
remain a possibility through about 14/17 UTC. Light winds today with
VFR conditions by afternoon.
Models are still hinting at a weak system dropping south through
California Sunday. This could bring a few snow showers to the Sierra
with periods of MVFR conditions at KTRK/KTVL/KMMH.
Then a ridge develops for Monday with light winds. Freezing fog is
again possible Sunday night into Monday for KTRK. 20
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