Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 031043

Area Forecast Discussion
National Weather Service Reno NV
343 AM PDT Wed Jun 3 2020


Temperatures remain well above average through Friday before
falling off this weekend as strong low pressure moves into the
West. Shower and thunderstorm chances continue each afternoon and
evening through Thursday south of Highway 50 before expanding to
much of the region Friday into the weekend. Winds increase
starting this afternoon with stronger winds Friday and Saturday.



Not much change to the forecast thinking through Friday. It will
remain well above average temperature-wise through Friday with
breezy afternoons and evenings along with chances for thunderstorms
each day...south of Highway 50 through Thursday and then up to
around I-80 Friday. If this is enough for you, I won`t be offended
if you stop reading now. However, if you desire more details, you
can read more below...

Turning to the current conditions, low pressure continues to spin
off the southern/Baja California coast with a high-level deformation
axis bisecting Nevada a bit south of Highway 50. There is some
evidence of the lifting from this axis in the form of some high
clouds that have formed over Mono and Mineral counties. As we go
into the afternoon, this axis is expected to aid in lift/instability
aloft which, when combined with strong heating, should enhance the
chance for a few thunderstorms well south of Highway 50 and west
of Highway 95. Flow aloft will be quite light under the deformation
axis with storm motions generally 10 mph or less so narrow cores
of heavy rainfall are possible in stronger storms; also, as usual
with storms, there will be the threat for a few cloud-to-ground
lightning strikes, small hail, and outflow gusts to around 40 mph.

North of the thunderstorm threat area today, the main features
will be the toasty temperatures (lower valley highs upper 80s to
mid 90s) and the fairly typical summer breezes of 20-30 mph from
mid afternoon into the evening.

Thursday remains warm to hot for valleys under ridging aloft.
Thunderstorm chances look to drop off with the lack of the little
bit of extra help from the upper forcing that we expect for today.
Still, a couple garden-variety cells cannot be ruled out in Mono,
Mineral, and southern Lyon counties. Afternoon and evening winds
Thursday remain fairly typical for this summer-like pattern.

Friday, the low off the southern California coast lifts toward
the region and tries to phase with an incoming broad upper level
low dropping down from the northeast Pacific. The southern upper
low gets here first and produces more upper level diffluence and
forcing and should bring more moisture north into the region.
Showers and thunderstorms should be more widespread by Friday
evening, reaching north to around Interstate 80 to the east of
Reno-Sparks and Carson City. Increased shear in the middle levels
of the atmosphere could lead to more organized storms by late
afternoon and early evening. While we should see wetting rains in
the heavier storms, dry lightning strikes are possible outside of
cores along with strong outflow gusts. That could be problematic
for fire weather as larger-scale background winds are expected to
gust 25-35 mph Friday and increase more for Saturday. -Snyder

.LONG TERM...This weekend into next week...

A cold late season trough is still on track to impact the region
with gusty winds, much colder temperatures, and chances for showers
this weekend into early next week. A shortwave ridge follows into
the middle of next week for dry and warmer conditions. Another
trough could bring another round of breezy conditions toward the
end of next week. Only minor changes were made this morning as
both the GFS/ECMWF and their ensembles continue to be in overall
agreement with the large scale pattern.

* WINDS: Winds increase Saturday as much cooler temperatures
  arrive and thermal gradients tighten. In addition, winds aloft
  will be ramping up as 100+KT upper jet begins to nose into the
  northern Sierra. MOS guidance continues to show 10m winds of 28
  kts at KRNO Saturday afternoon and even the national blended
  ensemble is showing some decent wind gusts as well. Widespread
  southwest to west winds 20-30 mph with gusts 40-45 mph are
  probable with ridge winds increasing and gusting over 70 mph.
  Winds shift more to the northwest in the colder airmass Sunday
  but will remain brisk. Biggest impacts will be Saturday/Saturday
  evening with turbulence and LLWS for aviation, rough waters on
  area lakes, strong cross winds for high profile vehicles, and
  possible reduction in visibility in blowing dust across west
  central NV. Also, while humidity levels will be coming up,
  strong winds will still be capable of driving fires where fuels
  are ready. Winds decrease Monday-Wednesday.

* TEMPERATURES: Temperatures will cool significantly this weekend
  with model spread fairly tight for high temperatures Sunday and
  low temperatures Monday morning, considering this is still 5 days
  out. While it is not extremely rare to get a cold front like this
  in early June, the change in temperatures from this week will be
  quite noticeable with some model scenarios pushing high
  temperatures down into the 50s to low 60s by Sunday with brisk
  northwest winds making it feel even colder. Those heading out to
  the Sierra high country should prepare for very cold and blustery
  conditions as temperatures will struggle to reach into the 30s. As
  the trough moves east Sunday night and skies clear, a very dry
  airmass will be conducive to very cold conditions with freezing
  temperatures looking likely early Monday for all colder valleys,
  including valleys in western NV. Another cold night Monday night
  may bring patchy freezing temperatures again although not as
  widespread. This ahead of a warmup for mid next week.

* SHOWERS AND THUNDERSTORMS: The current track of the upper low and
  associated jet put the best chance of showers from I-80 north this
  weekend although instability close to the low`s center may be
  sufficient for a few thunderstorms/snow pellet showers as far
  south as Highway 50 Sunday. Snow levels fall as low as 5000 feet
  early Sunday so that some locations around the Tahoe Basin and
  higher passes of northeast CA may see a little snow with some
  light accumulation possible at the higher Sierra passes around
  Lake Tahoe Saturday night into early Sunday morning.




Typical afternoon breeziness today will further increase Thursday
and Friday as a trough approaches the southern California coast.
Valleys could see gusts reaching 25-30 kts, including all terminal
sites. Winds will be stronger on Saturday with a jet nosing in
overhead and another area of low pressure digging into the Pacific
Northwest. Gusts may reach 30-40 kts Saturday with enhanced potential
for turbulence, mountain wave activity, and wind shear. Breezy winds
to continue on Sunday as well. Winds have the potential to bring
areas of blowing dust Thursday through Saturday, especially across
the central Nevada Basin and Range.

Thunderstorms are the other concern with today and Friday looking to
have the best chances, and the greatest coverage Friday. The main
focus for storms today will be over the higher terrain of Mono/Alpine
Counties, with the potential for storms to reach as far north as
the Tahoe Basin. There is little forcing on Thursday so expecting
any development to be terrain focused and weak. A wave on Friday
will bring better chances for thunderstorm development along the
Sierra north through the western Nevada Sierra Front. As west winds
increase, this will likely push storms eastward into central Nevada
by late afternoon. -Dawn/Hohmann


.REV Watches/Warnings/Advisories...


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