239
FXUS65 KREV 292029
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
129 PM PDT Tue Jul 29 2025

.KEY MESSAGES...

* Scattered showers and thunderstorms this afternoon and evening
  pose a risk of heavy rain and flooding, gusty outflow winds,
  small hail, and frequent lightning.

* Shower and isolated thunderstorm activity continues later
  tonight through Wednesday morning, with increased storm coverage
  once again Wednesday afternoon and evening.

* Thunderstorm chances will decrease Thursday and Friday, with a
  drying trend and possible increasing breezes over the weekend.

&&

.DISCUSSION...

The series of upper level trough passages continue through
Wednesday, resulting in continued shower and thunderstorm chances
for the next couple of days. For today, coverage will increase
especially after 2 PM this afternoon, with the most favored areas
extending from the eastern Sierra (Alpine/northern Mono counties)
northward across the Tahoe basin and the Reno-Carson-Minden area
mainly through 6 or 7 PM (20-40% chances). Most storms then
advance northward across northeast CA and northwest NV during the
evening. However, as we`ve seen the past couple of days, the 7-9
PM time frame has been a flash point for isolated but impactful
storms across parts of far western NV, with a weak zephyr boundary
apparently producing a focus area for sustaining this convection
after sunset. Yesterday the bulk of the rain/hail stayed mainly
east of Reno-Sparks (although producing quite a lightning show),
but today this risk could shift closer to more heavily populated
areas again, with a 10-20% potential of a repeat performance
similar to Sunday`s event. Instability is similar to recent days,
with CAPE values of 500-1000 J/kg over the eastern Sierra,
northeast CA/northwest and far western NV capable of producing
small hail and heavy downpours with stronger storms, and even a
10-15% chance of up to 1" diameter hail at a cell`s peak
intensity. Downdraft CAPE up to 1500 J/kg across the Basin and
Range could yield stronger outflow gusts to near 60 mph in these
areas at times from late afternoon-early evening, and even into
the late evening if the aforementioned strong 7-9 PM convection
scenario from far western NV makes another encore.

One difference compared to previous days is additional mid-upper
level forcing arriving late tonight with the trough`s closest
approach to the Sierra. This will bring a renewed round of showers
and isolated storms, currently favoring the eastern Sierra from
northern Mono county through the Tahoe basin and extending into
far western NV and northeast CA for the overnight into Wednesday
morning. While this activity isn`t likely to be as strong compared
to the afternoon storms, some may be awakened by rumbles of
thunder and/or the sound of rain within this 11 PM-7 AM time
frame.

The main trough passage is on track for Wednesday afternoon, with
coverage even more widespread than today (40-60% chances for most
areas west of US-95). Storm initiation is more favorable from I-80
southward, where cloud cover from overnight convection is more
likely to diminish in time for peak afternoon heating. The best
forcing lifts out to the north and east Wednesday night, so most
of the storms will likely wind down during the evening, except
areas near the OR border could see a more persistent cluster of
cells until around midnight when the ejecting low makes its
closest approach.

From Thursday onward, a drier southwest flow will reduce the risk
of thunderstorms, but residual moisture and daytime heating with
less cloud cover keeps open the possibility for isolated afternoon
showers and storms through Friday. Current projections favor this
potential for northeast CA-northwest NV, with a few sparse cells
also possible into the Basin and Range.

Finally, the whole region looks to be absent from storm chances
for this weekend into early next week. Afternoon west breezes
will prevail most days, although some enhanced wind gusts around
30 mph could occur Sunday afternoon with a weak shortwave brushing
across the northwest US. Temperatures for the upcoming week will
remain slightly below late July/early August averages with highs
mainly around 90 degrees in lower elevations, and upper 70s-near
80 for Sierra communities, with a possible slight warmup toward
the middle of next week. MJD

&&

.AVIATION...

A 20-35% chance of showers and thunderstorms returns after 21Z
this afternoon for KTRK/KTVL and far western NV terminals before
subsiding around 03-04Z. Expect outflow gusts of 30+ kts, small
hail, frequent lightning, and heavy downpours reducing CIGS/VIS to
MVFR conditions at times. Storm chances farther south at KMMH are
less, only around 10% this afternoon.

Isolated thunderstorm activity may redevelop overnight into
Wednesday morning for KTRK/KTVL and far western NV terminals,
mainly between 06-15Z. An increased chance of storms resumes
Wednesday at all terminals (30-50%, except 15-25% at KMMH), with
an earlier onset time as soon as 18Z and similar impacts as
today`s activity.

Outside the storms, light westerly afternoon breezes prevail with
light FL100 winds and partly cloudy skies. Chances for storms
decrease to 10% or less at the main terminals Thursday afternoon.
MJD

&&

.FIRE WEATHER...

The presence of above average daytime RH and good to excellent
overnight recovery, along with mainly wet thunderstorms across
eastern CA-western NV has limited the number of lightning fire
starts during this nearly week-long storm pattern. The few
lightning starts that were reported so far have not shown much
growth. With that being said, we`ll continue to see rounds of
thunderstorms especially today through Wednesday. Rain will be
present with a majority of these storms, although the potential
for lightning strikes outside of precipitation cores remains
present. The potential for growth of any new lightning ignition
remains low (less than 10% chance of becoming large/fast
spreading) due to the above average antecedent moisture
conditions.

Nocturnal elevated convection is also looking more favorable
tonight-Wednesday AM in the eastern Sierra from northern
Mono/Alpine counties into the Tahoe basin, and into far western NV
from 11 PM-7 AM, then extending into parts of northeast CA through
around 10 AM. Lightning activity for the night/morning is
projected to be less frequent compared to the afternoon and
evening today-Wednesday. MJD

&&

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

$$