Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 151117

Area Forecast Discussion
National Weather Service Reno NV
317 AM PST Mon Jan 15 2018


High pressure will maintain dry conditions and above average
temperatures for the Sierra and western Nevada today. Ridgetop winds
will increase later today ahead of a fast-moving storm for late
tonight and Tuesday. A stronger and colder storm system will bring
gusty winds with snow and rain Thursday into Friday.



After one last mild and dry day today, the storm door finally
opens with an initial storm late tonight and Tuesday morning.
Latest simulations continue to show a quick-hitting storm that
lacks a significant moisture tap. Although there will be some rain
and snow associated with this system, it will be quick and rather
weak compared to more typical winter storms.

For storm total precipitation, we expect 0.50-0.75" near the Sierra
crest, and 0.25-0.50" in the Tahoe Basin and across NE California.
Amounts across western NV could vary from a few hundredths in
Mineral County to 0.10-0.25" north of I-80, especially as the storm
is weak and may not spillover efficiently into western Nevada. Snow
levels will be around 7,000 feet tonight and Tuesday morning, with
up to 4 inches of snow possible for areas above 7,000 feet. This
storm isn`t much of a wind producer either, but it will be a
noticeable difference from the light winds we have been having.
Sierra ridge wind gusts will be around 40-55 mph this afternoon, and
valley wind gusts will generally be around 20-30 mph by Tuesday

Precipitation with this storm will be over by Tuesday night with no
showers expected on Wednesday. Wednesday will be a brief break
between storms, but Sierra ridge gusts will be on the increase ahead
of the next stronger storm. Increasing gusty winds across Sierra
ridges to around 100 mph by late Wednesday will result in the
increased probability for moderate-severe turbulence and wind shear
in the lee of the Sierra. -Edan

.LONG TERM...Thursday and beyond...

Bottom line up front...Winter is coming. Forecaster confidence is
high regarding winter impacts to the region Thursday into Friday.
If you have travel plans over the Sierra Thursday-Friday, you
should be paying close attention to the forecast, as cold
temperatures with snow and gusty winds are likely. There is also
potential for light snow even down to the valley floors for the
Friday morning commute.

Finally, after such a warm winter so far we will see a big change
in the pattern for the end of the week and going through the end
of January as the jet stream shifts into CA/NV. A stronger storm
system with a weak to moderate atmospheric river (AR) will move
into the Sierra and western Nevada Thursday and Friday bringing
beneficial snow to the Sierra. Models have slowed down the system
slightly, which will actually increases the high wind potential
for western Nevada on Thursday. Winds gusts in the valleys over 50
mph are likely with Sierra ridges seeing winds over 100 mph.

This storm is shaping up to be a pretty solid storm by Sierra
standards. Nothing unusually huge, but potential for 1 to 2 feet
of snow in the High Sierra above 7000 ft along with anywhere from
several inches up to a foot of snow down to Lake Tahoe level and
even around 5500 ft. As the cold front pushes through the region
Thursday night into Friday morning, snow levels will fall to most
valley floors, including light snow amounts for Reno-Sparks-Carson
City for the Friday morning commute. Lower snow levels will also
mean high snow ratios in the Sierra, which will increase the
potential for blowing snow and low visibilities over the Sierra
passes Thursday night into Friday. Blustery conditions and snow
showers will remain through the day on Friday as the instability
remains under the low pressure--even potential for lake effect
snow showers downwind of Tahoe and Pyramid.

Colder temperatures remain in place through the weekend as well,
with another strong winter storm system on the horizon for
Sunday-Monday. The Pacific jet stream will reload and bring
another beneficial storm to boost the Sierra snowpack. Details
still remain pretty fuzzy, but good confidence that we will see
another round of moderate to heavy mountain snow, a mix of valley
rain/snow possible, along with a period of strong winds Sunday.



High clouds increasing today as a low pressure system approaches
the West Coast. VFR conditions expected today with overall light
winds up to 15kts. Sierra ridge winds begin to increase this
evening as the low pressure moves in.

A weak, fast moving storm will move into the region late tonight
into Tuesday. A period of MVFR conditions is possible late tonight
into Tuesday morning for KTRK/KTVL as the front moves through the
region, with mountain snow and rain. Mountain obscuration and
icing are also be possible into early Tuesday morning. Increasing
wind gusts up to 25kt at area terminals and ridge gusts up to
50kts over the Sierra Crest Tuesday will also bring a threat of
mountain turbulence along and downwind of the Sierra Crest.

A second, stronger winter storm will push into the region
Thursday into Friday with a period of strong winds, rain and
mountain snow. -Hoon


.REV Watches/Warnings/Advisories...


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