Red Flag Warning 8, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
135 AM PDT Fri Aug 16 2024

.SYNOPSIS...

* Stronger winds and low humidity on Saturday lead to critical
  fire weather conditions and choppy lake waters.

* Light showers are possible in northeast California and far
  northwest Nevada on Saturday too. Otherwise, it will remain
  dry.

* Seasonable temperatures continue with early morning frost
  possible for Sierra valleys.

&&

.DISCUSSION...

The forecast hasn't changed much over the last few model runs.
However, confidence has increased about gusty winds expected on
Saturday. Otherwise, it appears that conditions remain dry and breezy
with seasonal to slightly below normal temperatures this weekend and
next week due to an anchored trough offshore of the Pac NW.

Gusty winds are expected to return on Saturday across the region.
Winds increase from the southwest and the south-southwest to 15-25
mph with gusts 25-35 mph. Stronger gusts are possible with a 60-90%
chance of exceeding 35 mph along the Sierra Front, NE CA, the Sierra
and vicinity. The gusty winds bring some choppy lake waters to
area lakes, especially those in the NV basin and range with wave
heights up to 3 ft in Pyramid Lake. Lake Tahoe appears to remain
around 1-2 ft waves at the moment. Therefore, may need lake wind
advisories for Pyramid Lake on Saturday. Furthermore, some light
showers are possible with a 10-15% chance of precipitation across
portions of Lassen and northern Washoe county, near the OR border,
and the Surprise Valley. Otherwise, conditions should be dry
across the rest of the area.

Winds decrease on Sunday, but will still be breezy from the
southwest, especially across portions near the Sierra Front
towards NE CA, and the Eastern Sierra. Next week, winds remain
elevated, but will be lower than over the weekend with the trough
still hanging out in the northern Eastern Pacific Ocean.

Seasonal to slightly below normal temperatures are expected this
weekend and next week. Afternoon highs remain in the upper 80s and
lower 90s for western NV and the lower valleys in NE CA, Mono and
Alpine counties. Highs in the Sierra communities remain in the
70s and upper 60s. Morning lows will be chilly with temperatures
generally in the mid-30s to mid-40s. However, localized areas may
be flirting with freezing temperatures due to clear skies and
light winds. NBM has 30-60% chance of lows around 32F. However,
there is some uncertainty based on winds speeds not been light
enough to allow temperatures to plummet. However, if there are any
stretches of light winds overnight, temps will quickly drop to
near freezing in localized areas in the Sierra valleys on Sunday
and Monday morning.

-Crespo

&&

.AVIATION...

VFR conditions continue through Saturday afternoon with a 10-15% chance
of showers in NE CA and N NV, near the OR border. Otherwise, dry
conditions prevail. Afternoon breeziness continues with west to
southwest winds at 10-15 kts and gusts up to 25 kts. Winds subside
overnight leading to light and VRB winds. Stronger winds along with
LLWS and turbulence return on Saturday.

-Crespo/Giralte

&&

.FIRE WEATHER...

Not a lot of change from the last forecast, although confidence is
increasing towards a critical fire weather day tomorrow, Saturday.
A semi-permanent upper level trough offshore the Pac NW sends
shortwaves our way leading to breezy afternoon winds each day, but
winds will be stronger this weekend as a moderate wave passes the
Pac NW.

On Saturday afternoon, winds increase from the southwest and the
south-southwest to 15-25 mph with gusts 25-35 mph. Stronger gusts
are possible with a 60-90% chance of exceeding 35 mph along the
Sierra Front, NE CA, the Sierra and vicinity. This combined with
minimum relative humidity generally below 15% across most of
western NV, the Eastern Sierra and NE CA will lead to critical
fire conditions for multiple hours on Saturday afternoon. The
strongest winds are expected between 1 PM to 7 PM. So, this is
the period to watch out for. The current watch goes from 11 AM to
11 PM and will be most likely upgraded later this morning. There
is still some uncertainty over the Tahoe Basin due to min RH
flirting with the critical threshold.

Winds slow down on Saturday evening into Sunday. However, winds
will still be breezy with localized areas reaching near critical
conditions for brief periods of time on Sunday afternoon. The
main concern will be on areas surrounding the Surprise Valley,
including northern Washoe and Eastern Lassen, plus the Eastern
Sierra and vicinity. The Sierra near the Tahoe Basin has min RH
values higher than the critical threshold Sunday.

For the rest of the week, periods of breezy southwest winds
during the afternoon hours are expected with localized areas
briefly reaching elevated conditions for fire weather.

-Crespo

&&

.REV Watches/Warnings/Advisories...
NV...Fire Weather Watch from Saturday morning through Saturday
     evening NVZ420-421-458.

CA...Fire Weather Watch from Saturday morning through Saturday
     evening CAZ272-274-278.

&&