710
FXUS65 KREV 311943
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
1243 PM PDT Thu Jul 31 2025

.KEY MESSAGES...

* Thunderstorm chances decrease today and Friday with isolated
  storms mainly north of Susanville and Pyramid Lake both days.

* Mainly dry conditions prevail this weekend with an increase in
  afternoon winds Sunday, leading to elevated fire weather
  concerns.

* Warmer conditions return next week with temperatures back to
  seasonal averages by mid-week.

&&

.DISCUSSION...

Upper level trough continues its north-northeastward track away
from our area, although it`s still not a complete exit with one
wave ejecting across far northwest NV this afternoon-evening, and
another wave brushing across northeast CA-northwest NV Friday
afternoon.

These weak disturbances will keep the shower and thunderstorm
chances going mainly north of a Susanville-Pyramid Lake line and
across northern Pershing County this afternoon and evening, with
peak activity between 2-7 PM. Coverage isn`t expected to be as
widespread and most storms will move more quickly to the east-
northeast compared to yesterday. This would reduce the risk of
persistent heavy rain and flash flooding, but increase the
potential for lightning strikes outside of rain cores and continue
the threat for gusty outflow wind gusts of 50+ mph, including
possible blowing dust across northern Pershing County.

For Friday afternoon-evening, shower and storm coverage will be
even more sparse (10-20% chance) across northeast CA/northwest NV
as moisture and instability decreases. However, a few showers may
redevelop in northern and eastern Pershing County during the
overnight hours into early Saturday AM as the final upper
disturbance sweeps through.

Elsewhere across eastern CA and western NV, shower and storm
chances are rather low (5-10%) for the rest of today and drop off
to near zero for Friday. By Saturday, drier southwest flow will
finally end the thunderstorm threat for northeast CA/northwest NV,
although a stray shower or two could scrape across the OR border
Saturday afternoon.

Attention then turns to Sunday when the next upper level trough is
projected to push across the northwest US, with the southern edge
of this system clipping far northeast CA/northwest NV. The more
northerly track compared to the past week`s activities will lead
to less convection (only 10-20% chances from the Surprise Valley
northward to the OR border) but increased winds with gusts 30-35
mph and lowering humidity across much of western NV and the
eastern Sierra. This will bring more wind-related impacts for
recreation and travel, and elevated fire weather concerns which
are highlighted in the Fire Weather section below.

The latest timing pushes the peak winds through Sunday afternoon-
evening, with lingering winds overnight near the OR border. Monday
is likely to return to more typical PM breezes with a dry air
mass prevailing. A few ensemble members were a little slower with
the trough`s departure and keep the potential for isolated
showers/storms near the OR border Monday, but this scenario
appears to be trending downward.

Temperatures continue to run a bit below average with highs
mainly in the lower 90s for lower elevations and upper 70s-near 80
for Sierra communities each day through Tuesday, except Monday is
looking about 4-8 degrees cooler. For mid-late next week, a warmup
is expected as high pressure expands across the southwest US and
parts of the Great Basin, with highs climbing to the mid-upper 90s
for lower elevations and lower-mid 80s near the Sierra. MJD

&&

.AVIATION...

VFR conditions prevail at all the main terminals as a drier air
mass filters into the region. Winds generally light with typical
afternoon gusts near 20 kt each day through Saturday, although a
brief passing shower near KRNO could bring slightly enhanced
gusts through 00Z this afternoon. Stronger gusts of 25-30 kt are
more likely to return to the main terminals by Sunday afternoon.

Farther north, isolated showers and thunderstorms are expected
this afternoon from KSVE-KLOL northward (15-25% chance) with
higher chances up to 50% closer to the OR border. Main hazards
continue to be gusts to 35-45 kts, small hail and frequent
lightning. This activity winds down around 02-04Z. Showers and
a few storms return to these same areas on Friday afternoon, but
become more sparse in coverage, with chances dropping to 10-20%.
MJD

&&

.FIRE WEATHER...

Thunderstorm chances return again, mainly north of Susanville-
Pyramid Lake and across the northern half of Pershing County.
These areas have received varied amounts of rainfall in the past
week, so while isolated lightning outside precipitation cores
could still produce a few ignitions, the potential for rapid fire
spread or growth to large fire size is low (less than 10%). Storm
chances in these same areas decrease further on Friday as
moisture and instability becomes more limited.

A drier west to southwest flow returns this weekend as another
deeper trough swings across the northwest US on Sunday. Moisture
will be more limited for eastern CA-western NV so we`re not
expecting much thunderstorm activity, but winds will trend upward.
Wind gusts of 25-35 mph are likely on Sunday with a 40-70% chance
of peak gusts exceeding 30 mph. Those winds combined with minimum
relative humidity below 15% across much of western NV, portions of
eastern Lassen and Mono Co. will lead to elevated fire weather
conditions. In addition, the gusty winds could spread holdover
fires from the recent lightning activity this past week, while
vegetation (especially grass and thinner brush) starts to dry out
after being a few days removed from the most recent rainfall. MJD

&&

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

$$