Red Flag Warning 8, NWS Reno, NV

007 
WWUS85 KREV 030555
RFWREV

URGENT - FIRE WEATHER MESSAGE
National Weather Service Reno NV
1055 PM PDT Tue Sep 2 2025

CAZ270-278-NVZ458-030700-
/O.EXP.KREV.FW.W.0008.000000T0000Z-250903T0600Z/
Surprise Valley California-Eastern Lassen County-
Northern Washoe County-
1055 PM PDT Tue Sep 2 2025

...RED FLAG WARNING WILL EXPIRE AT 11 PM PDT THIS EVENING FOR
THUNDERSTORMS AND STRONG OUTFLOW WINDS FOR THE SURPRISE VALLEY, 
EASTERN LASSEN COUNTRY AND PORTIONS OF NORTHERN WASHOE COUNTY...

* Thunderstorm activity will continue to diminish but isolated 
  lightning strikes will remain possible overnight. 

* The main threat for dry lightning has passed and the Red Flag
  Warning will be allowed to expire as scheduled. 

$$

http://weather.gov/reno

Area Forecast Discussion
National Weather Service Reno NV
134 AM PDT Mon Sep 1 2025

.KEY MESSAGES...

* Above average temperatures with dry conditions 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.

&&

.DISCUSSION...

* A building ridge overhead will allow for above normal
  temperatures for Labor Day. Afternoon highs will end up around 5
  degrees above average. There are minimal chances for showers or
  storms this afternoon in the eastern Sierra (< 10%). We're
  lacking significant moisture as well as any forcing mechanism.
  But a few Cu buildups are possible along the ridges.

* High-resolution HRRR depicts haze areawide with higher chances
  for heavier surface smoke for Mono, Alpine, Mineral, and Lyon
  counties this morning due to the Garnet Fire. Smoke later this
  afternoon and Monday night will depend on how much smoke is
  produced today on the Garnet Fire. As a side note, the HRRR
  assumes a constant source of smoke which is not always the case.

* Storm chances increase Tuesday through the end of the week, with
  the best chances for convection on Tuesday (more on that below).
  But first, Wednesday through next weekend looks to have 10-25%
  chance for showers and storms each afternoon. However, the model
  ensembles start to diverge by Wednesday onward in how much
  moisture remains over the area. For now, we'll keep current
  blended guidance given the uncertainty three plus days out. As
  for the end of the week into next week, there are hints by the
  ensembles for a Pacific low to impact the area, which would
  bring increasing winds.

* As for Tuesday, we have a combination of increasing moisture
  from the south (PWATs >90th percentile) and a negatively tilted
  trough moving through central California. This setup is more of
  a concern for fire weather (see Fire Weather Section below);
  given the upper air support, dry lightning, and faster storm
  motions. But another thing to consider is that these storms
  maybe more of a hybrid variety because of the moisture in place.
  Storms will be capable of strong outflows, small hail, locally
  heavy rain, and dry lightning. -McKellar

&&

.AVIATION...

* Smoke filtering in from the Garnet Fire may bring periods of
  visibility reduction at terminal KMMH. Any other restrictions to
  visibility will be primarily slantwise due to haze aloft.
  Otherwise, VFR conditions will prevail with light winds.

* Mostly dry conditions today across the region today. Storm
  chances increase Tuesday through the remainder of the week.

* High density altitudes may become a problem in western NV today.

-McKellar

&&

.FIRE WEATHER...

Warm and dry conditions along with generally poor overnight
recoveries persist today. There is a very low chance less than 10%
for showers and thunderstorms over Mono, Alpine and Mineral counties
this afternoon.

A wetter pattern returns on Tuesday, but with a twist. Another
plume of monsoonal moisture slips into the region with PWs
generally over 0.75 inches, which matches with the 90th percentile
for this time of the year. However, an upper negatively tilted
trough to our west moving onshore into northern California will
enhance the speed of storms to the north. Surface-based instability
aligns with a mid to upper level jet streak resulting in high
confidence in the development of storms across the Sierra, NE CA
and western NV. Also seen in the agreement of hi-res models. The
main hazards will be dry lightning, small hail, gusty outflow
winds greater than 45 mph and brief periods of moderate to heavy
rain. The gusty outflow winds could exacerbate any new fire
ignitions from lightning, especially over western NV, where there
is a 20-40% of wind gusts exceeding 35 mph per NBM guidance.

The potential for dry lightning remains for much of the week as we
don't totally dry out, but the probabilities drop to 10-25%. However,
this weekend we may have another upper trough, drier, but with
potential for wind gusts exceeding 30 mph, especially for mountain
areas, northwestern NV and northeast CA.

-HC

&&

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