353
FXUS65 KREV 012005
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
105 PM PDT Mon Sep 1 2025

.KEY MESSAGES...

* Above average temperatures with dry conditions expected today
  for Labor Day.

* Areas of smoke and haze may locally impact visibility and air
  quality the next several days due to fires in the southern
  Sierra.

* Thunderstorm chances return Tuesday through the end of the week,
  bringing fire weather concerns tomorrow.

&&

.DISCUSSION...

Smoke from the Garnet Fire in the southern Sierra continues to
infiltrate the area, bringing hazy conditions. Air quality through
the remainder of today and into tomorrow will rely heavily on how
much smoke is produced from the fire today, making it hard to
predict as the fire constantly evolves. For air quality concerns,
please visit airnow.gov.

Afternoon temperatures peak today for Labor Day, with highs in the
mid 90s and 80s across valleys and Sierra communities,
respectively. A slow cooling trend starts tomorrow, but picks up
this weekend as another low pressure system possibly moves into
the area. However, there is plenty of uncertainty on just how that
low will impact us. Models are currently hinting at increased
afternoon wind gusts, primarily in NE CA, far NW NV, and along
ridgelines.

The main concern this week will be daily thunderstorm chances.
However, CAMs are highlighting a chance (10-15%) for early
morning showers (after 4 AM), primarily along the Sierra tomorrow
morning. This could extend from Mono county all the way through
the Tahoe Basin and into NE CA.

Looking more at Tuesday, a shortwave low pressure system off the
coast of California will continue to track inland, helping to
orient a mid-level jet streak along the Sierra Front tomorrow
afternoon. This also aligns with an increase in monsoonal
moisture, driven in from both the aforementioned low and the Four
Corners high. The low will also provide diffluence aloft, which
will allow for thunderstorms to develop. Storms are expected to be
a mix of wet and dry. Brief heavy rainfall is likely primarily
south of I-80, while the threat for dry lightning will be
primarily isolated to NE CA, northern Washoe county, and western
Pershing county. Thus, a Red Flag Warning has been issued. For
more details, please see the product.

Afternoon storm chances continue each day this week through
Friday, but will be lesser in chances and in areal coverage
(10-25%). Stay tuned for more details as we get closer.

-Giralte

&&

.AVIATION...

Smoke from the Garnet Fire will bring periods of visibility
reduction to KMMH today. Other visibility reductions today may
come from slantwise visibility due to haze aloft as well as high
density altitudes.

Dry conditions expected for much of today, with a 10-15% chance
for showers and thunderstorms in the vicinity of KMMH this
afternoon. Stormy conditions return Tuesday, bringing the chances
for visibility reductions from brief heavy rainfall for both
Sierra and Sierra front terminals.

-Giralte

&&

.FIRE WEATHER...

Warm and dry conditions today, with a slight risk of showers and
storms in the eastern Sierra (around 10% or less). Poor RH recovery
through valleys overnight tonight.

Showers and thunderstorms develop Tuesday afternoon as an upper
low brings an increase in moisture and instability. The main
activity will be over the Sierra, NE CA and Western NV. As storms
tend to be more isolated further north, dry lightning and gusty
outflow winds becomes more of a risk, leading to a critical fire
weather pattern.

Further south, the main hazards will be brief periods of moderate
to heavy rainfall, small hail, gusty outflow winds greater than
45 mph, and dry lightning on the edges of the heavier activity.
Although moisture is high for this time of year (90% percentile),
storms are expected to be fast moving, so we are not expecting
the level of flooding seen last week.

Shower and storm activity reduces from Wednesday to around 20% or
less, although there is still the risk of dry lightning and gusty
outflow winds.

-Jim

&&

.REV Watches/Warnings/Advisories...
NV...Red Flag Warning from 1 PM to 11 PM PDT Tuesday NVZ458.

CA...Red Flag Warning from 1 PM to 11 PM PDT Tuesday CAZ270-278.

&&

$$