Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 191028

Area Forecast Discussion
National Weather Service Reno NV
328 AM PDT Mon Mar 19 2018


Dry weather is expected through early Tuesday with light valley
rain and higher elevation snow Tuesday afternoon and evening. A
much stronger system for Wednesday night through Thursday night
will bring periods of valley rain and heavy Sierra snow along with
gusty winds. Conditions will turn colder late week for northeast
California and western Nevada, with lower valley snow possible.



Today and Tuesday:

A quiet start to the week is expected today before attention
turns to a solid moderate atmospheric river (AR) storm mid-week.
For today, expect areas of high clouds, light winds and high
temperatures reaching back into the 50s across western Nevada with
mid 40s for Sierra valleys.

Tuesday afternoon and evening, simulations continue to show a
period of warm air advection (WAA) focused over northeast California
and western Nevada, roughly north of Highway 50. Impact-wise, a
relatively light snowfall is expected for Sierra and northeast
California passes, with the Tahoe Basin likely to see a mix or
changeover to rain Tuesday night as the WAA ends and mixing down of
warmer air aloft ensues.

Wednesday and Thursday (AR Storm):

Latest trends have shown a distinct period of a warm storm (higher
snow levels) Wed-Thu followed by colder and shorter duration
systems heading into the next weekend. Overall, looking for a
roughly 24-36 hour period of precipitation from Wednesday through
Thursday evening with a peak precipitation window from Thursday
morning into the early evening.

Snow levels look to start around the 7,500-8,000` vicinity Wednesday
into early Thursday morning from the Tahoe Basin and extending south
through the Sierra in Mono County. Snow levels will begin to fall to
6,500 to 7,000 by Thursday afternoon from Tahoe to Mono County before
dropping below 6,000` by Thursday evening.

The main moisture plume looks to be focused mainly from Mono County
southward. Have increased precipitation amounts with total QPF
amounts Wednesday through Thursday along the Sierra crest in the 2-
3" range across the Tahoe Basin and 3-4" possible across the crest
in southern Mono County. Spillover rainfall is most likely on
Thursday for western Nevada with 0.25"-0.50" possible by Thursday

Gusty winds will also accompany this storm with ridge gusts reaching
over 80 mph by Wednesday and continuing into Thursday. Valleys could
also see wind gusts in the 40-50 mph range particularly through the
highway 395/I580 corridor. Fuentes

.LONG TERM...Friday onward...

The cold air is delayed compared to model runs of the past several
days, not arriving until Friday. However, once it does arrive expect
700 mb temps to fall to around -14 C, with snow levels at all valley
floors and well below normal temperatures. There is a definitive
break in the precipitation between the warmer and colder portion of
the storm with drier air working into the region behind the cold
front Friday morning. Multiple shortwave rotating around the base of
the trough are going to provide the moisture and instability to help
kick off snow showers Friday afternoon through Sunday morning. With
these waves moving through northern CA/NV, the best chances for
showers will be in the Sierra and along and north of I-80 in western
Nevada. Additional qpf is minimal, but light snow accumulations may
continue to bring travel impacts throughout the region especially
during the late evening through early morning hours. A final passing
wave may bring light showers early in the week, but with increasing
model and ensemble spread, confidence is low in this feature. -Dawn



Widespread VFR conditions this morning with scattered mid-level and
broken high level clouds limiting fog formation. The one exception
is around KTRK where patchy freezing fog is likely through 16z.
Winds will generally be light through Tuesday.

A weak system will bring light rain and snow Tuesday afternoon and
evening with slightly lowered ceilings and terrain obscuration
possible. A much stronger storm is on tap for Wednesday and Thursday
with strong and gusty winds, and moderate to heavy mountain snow and
valley rain. Terminals should all just see rain, but expect
widespread mountain obscuration and periods of MVFR (30% chance IFR)
ceilings and visibility. Winds will bring turbulence and wind shear,
with local studies indicating LLWS possible for KRNO during the
southerly winds Wednesday into Thursday. Snow showers are possible
for all airports Friday through Sunday with the potential for
minor accumulations. -Dawn


.REV Watches/Warnings/Advisories...



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