Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 250959
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
259 AM PDT Sun Oct 25 2020

.SYNOPSIS...

A strong and mostly dry cold front will bring sharply colder
temperatures today along with gusty north to east winds producing
areas of haze and blowing dust. Stronger winds will persist into
Monday in the Sierra causing fire weather concerns there. All
locations can expect hard freezes Monday and Tuesday mornings.
Milder temperatures return mid to late next week.

&&

.DISCUSSION...

The main forecast change to push back start of lake wind advisory on
Lake Tahoe to 5 PM today.

The long-advertised strong cold front currently runs along a line
from Susanville to Fallon to a bit north of Austin. North winds of
10 to 20 mph behind the front are kicking up dust off of the Humboldt
and Carson Sinks as evidenced by 2.5 mile visibility at the Fallon
Naval Air Station. With continued winds from the north and northeast
today, dust/light haze is expected to spread over many areas of
western and west-central Nevada with some minor reductions in air
quality (perhaps moderate) possible.

Temperatures today will be 15-25 degrees colder than Saturday with
highs mainly in the 40s to near 50 degrees. Precipitation-wise, the
airmass remains moisture-starved; however, upslope flow will bring
a 10-20% chance for dusting of snow this afternoon-early evening
for western Mono County with a few brief sprinkles south of Hwy 50
and east of Yerington/Alt 95. Southwest Mono County should see
the Creek Fire smoke clear out during the afternoon and evening as
winds shift to the north and northeast over the Sierra crest.

The coldest temperatures of the season so far will arrive tonight
with lows down into the teens to lower 20s for most lower elevations
and single digits to mid teens for Sierra valleys. Any areas that
escaped freezing temperatures during the past couple of nights
won`t avoid it tonight. Today is the last chance to finish winter
preparation of irrigation systems to reduce risk of freeze-induced
damage.

Monday and Monday night will remain chilly, with highs struggling
to reach 50 degrees again while lows drop well below freezing. Then,
as high pressure off the CA coast rebuilds inland and shifts to the
Great Basin, temperatures will climb with highs returning to near
average Tuesday and then warm to 4-8 degrees above average
(mainly mid 60s-lower 70s) from Wednesday through the end of the
month. -Snyder/MJD

&&

.AVIATION...

There has been some smoke moving back into the Mammoth Lakes area
this morning, although the airport has been seeing clearer air. We
should see good clearing through the day as a cold front switches
the winds to out of the northeast.

Otherwise, VFR conditions are expected through this week with gusty
winds today and Monday. Blowing dust will be a concern for western
Nevada with minor reductions to visibility. The bigger concern is
actually for the Sierra terminals tonight into Monday as mountain
waves develop over the Sierra Crest creating moderate to severe
turbulence and periods of low level wind shear. -Hoon

&&

.FIRE WEATHER...

* Red Flag Warnings remain in effect for the Tahoe Basin north to
  western Lassen County. A Red Flag Warning has also been issued for
  southern Mono County beginning late this morning through Tuesday
  morning.

Strong north to northeast winds are expected behind a strong dry
cold front moving through the region this morning. Wind gusts
30-40 mph are expected immediately behind the front for most of
the area, but RH will be higher...bottoming out in the 20s later
today.

However, stronger north winds are likely behind the front this
afternoon for portions of southern Mono County where gusts 40-50 mph
are likely. While RH will be high to start, it will drop into the
teens tonight with single digit readings for Monday as very dry
airmass moves in. Given the stronger winds, a Red Flag Warning
remains in effect starting at 11 AM today for southern Mono County.
The winds will continue here through Monday afternoon with some
ensemble members showing it through Tuesday morning.

As for the rest of the area, the forecast looks on track. Winds
become more northeast later tonight. The Sierra Crest will blow
strong with gusts to 100 mph possible. Also, the areas in the Tahoe
Basin and western Lassen County susceptible to northeast winds
will see gusts of 40-50 mph. We still expect these winds to last
into Monday afternoon. RH will drop to the teens where the winds
blow tonight, and would not be surprised to see some areas drop to
the single digits. Widespread single digit RH readings are likely
Monday as well.

For western Nevada, the initial gusts to 40 mph will diminish to 25-
30 mph for much of the area as the stronger pressure gradients will
be over the Sierra and onto the west slopes down into Central
California. With RH falling to near 20% during the day in western
NV, it`s too marginal to issue but localized areas will hit low-
end criteria. -X/Hoon

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory from 5 PM this afternoon to 8 PM PDT Monday
     for Lake Tahoe in NVZ002.

     Lake Wind Advisory from 6 AM this morning to 6 PM PDT this
     evening for Pyramid Lake in NVZ004.

CA...Red Flag Warning from 5 PM this afternoon to 5 PM PDT Monday
     CAZ271-272.

     Red Flag Warning from 11 AM this morning to 5 AM PDT Tuesday
     CAZ274.

     Lake Wind Advisory from 5 PM this afternoon to 8 PM PDT Monday
     for Lake Tahoe in CAZ072.

&&

$$

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



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