Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 262251

Area Forecast Discussion
National Weather Service Reno NV
251 PM PST Thu Jan 26 2023


Patchy low clouds, freezing fog, and some air quality concerns in
urban valleys will continue through Friday morning with a nice, but
brief warm up for Friday afternoon highs.  Temperatures will sway
back down later this weekend as a slider like system drives across
the region. Therefore look for increasing snow showers and gusty
ridge winds Sunday through Monday as well as colder temperatures
the first half of next week.



Freezing fog will continue around Mono Lake basin with and areas
of patchy freezing fog forming around the Martis Valley.
Increasing west- northwest upper winds will increase over the
region Friday ahead of a dry upper short wave that dives south
over CA/NV that afternoon and evening. Wind gusts across the
higher ridges of the Sierra crest will rise to 50-70 mph. These
winds could bring some impacts to those recreating in the back-
country and regional ski resorts as the higher gusts coupled to
the still cold temperatures will drag wind chills above 7000 feet
around the Lake Tahoe basin and eastern Sierra down into the
single digits to slightly below zero later Friday afternoon into
the evening.

But all is not lost to the cold yet! Friday still looks to have a
modest, but nice warm up into the high 40s to near 50F for most
lower western Nevada valleys. Areas around the Honey Lake Valley to
include Susanville, CA and the Black Desert in central Washoe county
could see the warmest temperatures across the region rising into the
low 50s.

Now switching gears back to winter, a deeper, more dynamic, and
slightly more moist slider-like system will drop south into CA/NV
Sunday. Model simulations project that this winter disturbance will
bring a colder, but more modest round snow-wise, of winter
conditions to the region. A closed low circulation and frontal
wave will drop into northeast CA and travel south across the
Sierra crest Sunday morning. The remainder of the cold front will
punch into western NV Sunday and Sunday evening, bringing bands of
light to moderate snow showers to most areas east of Sierra crest
into western NV.

SNOW: Probabilistic guidance shows higher snow accumulations over
the Sierra crest with mountain passes seeing at least a 40-60%
chance of 4-6 inches of new accumulating snow. Areas around the Lake
Tahoe basin also have a 40-60% chance for 2-4 inches of new snow
with a one in four chance of slightly higher accumulations
elsewhere over that area. Areas of northeast CA west of US-395
should receive 4-6 inches of new snow, whereas areas east of
US-395 should mostly see 1-2 inches of new snow with some areas
above 5000 feet receiving up to 3 inches. The eastern foothills
above 5000 feet have a chance (30%) of seeing 1 to 2 inches of
new accumulations with the rest of western NV seeing something
from at least a trace an inch of newly laden snow. Areas around
the eastern Sierra into the west-central NV have a one in three
chance of up to an inch of accumulating snow.

TEMPERATURES: The very cold Canadian air that will drive south
behind the cold front early next week will bring some of the coldest
temperatures for January to the region. Monday morning lows will
drop into the low to middle teens for most lower valleys of
western NV with eastern Sierra foothills dropping into the single
digits. Some Sierra valleys will even bottom out below zero for
that brief period before sunrise. Monday highs for lower valley
areas, however, will only reach into the mid to upper 20s. To put
in context how cold these temperatures will be, the forecast high
of 26F for Monday at the Reno-Tahoe International Airport, NV
will be one degree colder than the forecast high at McMurdo
Station, Antarctica, which is forecast to rise to a balmy 27F.

IMPACTS: Storm impacts will be confined mostly to those traveling
and recreating in the Sierra Sunday into Sunday evening as periods
of snow will make travel difficult for most areas. The Monday
morning commute could still see impacts due to icy, slick conditions
over mountain passes as well as roads and highways across western
Nevada. There also remains the slight chance (<15%) of some lake
effect snow showers filtering off Pyramid lake early morning Monday
that spreads a light coating close to an inch of accumulating snow
southwest and south along I-80 from Fernley, NV to the USA Parkway.

FURTHER OUT:  High pressure will once again build back into the
western US. Ensemble and blended guidance do project a modest
recovery in temperatures region-wide by mid-week with
accompanying lighter winds and drier conditions. But the same
guidance is signaling for a chance of a wetter pattern on the
horizon later next week



* Mono Lake will continue to have IFR-LIFR conditions for CIG/VIS
  as a bank of freezing fog and low status looks to persist across
  the Mono Basin overnight hours into Friday morning. Model
  soundings show little change as strong inversion caps moisture
  across the area through the overnight hours. The Martis Valley
  will see a return of patchy freezing later this evening and the
  potential for IFR-LIFR conditions to KTRK overnight tonight
  through Friday mid-morning.

* LLWS and turbulence concerns will increase over Sierra terminals
  Friday afternoon and evening as a dry short wave trough passing
  over the region. FL100 winds are forecast to top at 30-35kts
  before receding to <20kts after 03Z.

* A weak winter storm will drop through the region Sunday-Monday
  and bring snow showers to Sierra terminals. These snow showers
  look to bring brief periods of IFR-LIFR CIG/VIS conditions after
  12Z Sunday into Sunday evening. Model guidance projects a band
  of light to moderate snow showers pushing south into the Great
  Basin that will bring brief periods of MVFR-IFR conditions to
  western Nevada terminals after 12Z Sunday morning that tapers
  off by late afternoon.



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