Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 132133
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
133 PM PST Sat Jan 13 2018

.SYNOPSIS...

Dry conditions and above average temperatures are expected through
the weekend with high pressure over northeast California and western
Nevada. Winds increase Monday ahead of a modest, fast-moving system
for Monday night and Tuesday. A much stronger system is expected to
bring gusty winds, mountain snow, and valley rain and snow Thursday
into Friday.

&&

.SHORT TERM...

High pressure will maintain mild and dry weather through Monday.
High temperatures will stay 10-15 degrees above seasonal averages
with highs reaching the mid and upper 50s across western Nevada and
Sierra valleys. High pressure then weakens late Monday as troughing
approaches the west coast and sends the first in a series of low
pressure systems by early Tuesday morning.

Ahead of the low, winds on the ridgetops will increase with breezy
conditions developing across valley locations through the day on
Tuesday. Although precipitation amounts with this system aren`t
substantial, it will still create some travel slow downs and
possible chain controls across Sierra passes with a few inches of
snowfall possible through Tuesday morning. If you have travel plans
during this time frame, continue to monitor the forecast for
updates.

Did increase precipitation totals across the Sierra and also
rainfall amounts across western Nevada where light spillover
rainfall signatures are looking a bit better. This is looking like a
quick moving system, so much of the precipitation will be
diminishing by Tuesday afternoon and evening. Fuentes

.LONG TERM...Wednesday and beyond...

After a short break in between storm systems on Wednesday with
temperatures well above average and a slight increase in winds
late in the day, the next (stronger and colder) storm system is
still on track to move into the region Thursday into Friday. This
storm is still on track to produce the first meaningful snowfall
of this season--not only for the Tahoe basin/Sierra valleys, but
also possibly for lower elevations of western NV/eastern CA. The
main impacts will be the risk of poor visibility especially in the
Sierra from Thursday afternoon into early Friday morning due to
gusty winds and powder- like snow (snow to liquid ratios generally
about 12-15 to 1). Travel impacts will likely include the peak
commute times Thursday evening (mainly 5500+ feet) and Friday
morning (all elevations).

Winds will increase late Wednesday night into Thursday ahead of the
cold front, as 700 mb flow increases to near 55 kts. While a short
period of gusty south winds is possible in far western NV early
Thursday morning, the peak winds are most likely to occur during the
day Thursday. The strong jet stream moving into far northern CA,
combined with a significant pressure/thermal gradient will all be
favorable for producing gusts of 50+ mph in lower elevations and
Sierra ridge winds over 100 mph.

Snow levels will drop during the day Thursday across northeast CA-
far northwest NV, then reach the I-80 corridor by late afternoon or
evening. The timing of this changeover will determine the impacts
across the Tahoe-Reno-Carson vicinity. Typically, storm systems
accompanied by a strong Pacific jet stream take the faster track, so
we are leaning toward a quicker cold front passage. Travel impacts
could affect foothill areas by early evening, and even reach some
valley floors as soon as midnight and continue through the Friday
morning commute. Snow amounts of up to a foot or more are likely in
the Sierra above 7000 feet, along with several inches of snow down
to Lake Tahoe level and even to near 5500 feet. light snow
accumulations may be possible for the Friday morning commute.

Next Friday looks to be chilly (although forecast highs of 30s to
lower 40s are more typical for January) with brisk west to northwest
winds and isolated-scattered light snow showers. Medium range
guidance hints as a possible secondary shortwave passage across
eastern CA, which could produce some localized heavier snow shower
bands Friday afternoon/early evening. The cold air mass over the
warmer lake water could also support enhanced snow shower bands
downwind of larger lakes.

For next weekend, cooler temperatures are likely to prevail while
weak disturbances may produce very light snow showers. It appears
likely that an overall unsettled pattern with fast moving weather
systems will continue further into late January, with temperatures
unlikely to return to the warm values occurring this weekend. MJD

&&

.AVIATION...

VFR conditions can be expected through the weekend as a ridge of
high pressure sets up right over the region. Light winds and clear
skies with the exception of some scattered, high cirrus clouds
will be the result. Due to the clear skies and calm winds
overnight, early morning fog may be a possibility on Sunday in the
Martis Valley and near KTRK.

The ridge will begin to break down by Monday as a trough from the
west makes its way towards the region. As a result, cloud cover
will increase along with southwesterly wind gusts in the 15-20 kt
range.

Another, but stronger system is on track for Thursday of this
upcoming week. Please see the long term section for additional
details. -LaGuardia

&&


.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$

For more information from the National Weather Service visit...
http://weather.gov/reno



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