Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 210941
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
241 AM PDT Mon Sep 21 2020

.SYNOPSIS...

A general haze should linger for most locations with worse smoke
and degraded air quality expected for portions of northeast
California and the eastern Sierra today. Some degree of smoke and
haze should affect the region through the week, but it will be
dependent on fire activity. High temperatures return to slightly
above average with dry conditions and breezy afternoon winds
expected for this week.

&&

.SHORT TERM...

Real quick...as for smoke and temperatures across the region the
next few days, ditto the synopsis. Expect high temperatures in the
80s for western Nevada and 70s, low 80s for the Sierra and
northeast California with overnight lows around average for this
time of year.

The main highlight for the today through Wednesday will be the
increased afternoon southwest winds and low humidity across the
region generating localized critical fire weather conditions at
times. Today`s winds will be more zephyr-like, mainly surface
pressure gradient driven with gusts generally in the 20-25 mph
range for most locations. Higher gusts are likely for eastern
Lassen and Plumas counties, northern Washoe County, and along the
Sierra Front where those localized critical fire conditions could
take place. Gusts of up to 30-35 mph are possible for these areas.

As we progress into the overnight hours, winds should decouple for
valley locations whereas the Sierra ridges and mid slope areas
continue to be gusty if not increase in intensity thanks to a
passing shortwave trough towards the northwest. With the gusty
winds and overnight humidity recovery looking poor during this
time, this would extend the critical fire conditions for these
locations. By Tuesday afternoon, southwest winds are forecast to
be gusty once again across the region, but slightly stronger
compared to Monday`s thanks to additional upper-level support.
General gusts of 20-25 mph are forecast at this time with more
widespread gusts of up to 35 mph for most of Washoe County,
eastern Lassen and Plumas counties, and western Pershing and
Churchill counties. Another round of localized critical fire
conditions will accompany the gusty winds on Tuesday.

The dry and breezy conditions look to continue for Wednesday, but
not quite as strong as high pressure begins to build in from the
south. The strongest winds for Wednesday could be felt mainly for
locations north of I-80 as a strong 300 mb jet pushes through the
Pacific Northwest region signaling their first significant
atmospheric river of the season. Any precipitation for us you
ask? No. Besides for some possible light showers along the Oregon
border Wednesday night, most of the region will be dry. -LaGuardia

.LONG TERM...Thursday through next Monday...

Forecast confidence is increasing for a Wednesday through Friday
trough passage to track mainly through the Pacific Northwest. This
track would mean that weather impacts south of the Oregon border
would not be very significant. For example, winds aloft increase
Thursday-Friday but surface winds may not see much of an increase
from earlier in the week (expect afternoon breezes with peak gusts
up to 30 mph). Second, afternoon relative humidity across NE
California may trend up by 10-15% while locations from I-80 south may
see little change. Third, the only chances for rain are north of
Susanville on Thursday and even there wetting rains are unlikely.
Fourth, afternoon temperatures Friday and Saturday may be a bit
cooler, but only by a couple of degrees.

Then for Sunday-Monday the forecast calls for high pressure building
aloft along with a warming trend, light winds and little-to-no
chance for rain. Afternoon temperatures on Monday could be 10-15
degrees above average! (The forecast for Monday is for mid-to-
upper 80s for west NV, low-to-mid 80s for NE CA, and upper 70s
for Sierra communities.) JCM

&&

.AVIATION...

Expect breezy southwest winds during the afternoon/evening today
through Thursday with peak gusts up to around 25 kts. These
southwest winds may transport additional smoke downwind of the
Creek and North Complex fires, possibly creating MVFR or IFR
visibilities at times, including at KMMH and KSVE. Elsewhere,
hazy conditions through at least the next couple of days will
continue to obscure terrain and reduce slantwise visibility. JCM

&&

.REV Watches/Warnings/Advisories...

NV...None.
CA...None.

&&

$$

For more information from the National Weather Service visit...
http://weather.gov/reno


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