Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 151606
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
906 AM PDT Mon Oct 15 2018

.UPDATE...

Temperatures are on the rise after the first widespread freeze
over the forecast area this morning. There had been pockets of
freezing prior to this morning...but this looks like all but the
densest population centers received a hard freeze. Winds over the
ridges are still quite stout...but these should decrease slowly
through the day. Winds at Lake Tahoe are also showing some signs
of decreasing. The Lake Wind Advisory will continue for a couple
more hours.

&&

.PREVIOUS DISCUSSION... /Issued 150 AM PDT Mon Oct 15 2018/

SYNOPSIS...

Cold temperatures with a hard freeze will be in place early this
morning. Cool conditions will continue this afternoon with
temperatures warming above average later this week. The forecast
remains dry with no signals for significant storms at least through
the upcoming week.

SHORT TERM...

Post-frontal northeast-east flow continues across western Nevada and
Sierra this morning with strong gusts remaining across the Sierra
crest and west slopes. As the surface gradient weakens through the
morning, winds across valley locations will weaken which will allow
efficient radiational cooling with the very dry air mass in place.
Widespread hard freezes will occur this morning and a Freeze
Warning remains in effect.

Peak wind speeds will continue across the Sierra crest through
sunrise but will weaken through the afternoon. Critical fire
weather conditions are possible in a few areas with stronger
winds. For more information, please refer to the Fire Weather
section.

Tuesday onward the weather looks to remain quiet as a ridge builds
into the western United States. Daytime temperatures will warm to
near season averages with winds remaining light. Fuentes

LONG TERM...Thursday onward...

Upper level ridge expands across much of the west the end of the
week into the weekend, though a meandering weak low pressure center
lingers across the Desert Southwest and southern California. This
will lead to warming temperatures through the weekend with highs
reaching about 4-8 degrees above normal and lows remaining
seasonably cool. With easterly flow in place, mixing will be
limited, though we aren`t expecting stagnant conditions either.

For those eagerly awaiting the first good storm of the season, there
is finally at least something showing up on the horizon starting
around Oct 24-26. The pattern across the Pacific is transitioning
from being highly amplified to more zonal, with a strengthening jet
stream. This could help to usher areas of low pressure into the west
coast and bring wet weather to the region. This overall idea does
have ensemble support as well from the majority of the EC members
and about half the GEFS members. Mind you, longer range outlooks are
inherently lower confidence, especially during transition seasons,
so we would like to see additional model runs with this idea to gain
more confidence. -Dawn

AVIATION...

Strong northeast to east winds continue across the region with gusts
up to 80 mph being reported along the Sierra crest early this
morning. This is causing light to moderate turbulence from the
Sierra downstream into central California. Valley wind speeds are
light this morning for the most part, meaning there is a shear layer
likely present near ridge top level. Winds will remain easterly, but
will weaken in speed through the week.

Otherwise, widespread VFR conditions will continue in a very dry air
mass. -Dawn

FIRE WEATHER...

A very dry post-frontal airmass will provide poor humidity
recoveries (<20%) on mid-slopes and upper elevations this
morning. Areas from Tahoe to Mammoth have the best potential of
seeing areas of critical fire weather conditions for the next few
hours due to stronger east flow aloft across the Sierra. Expecting
Sierra wind gusts to peak now but will subside by late
morning/early afternoon. Widespread strong downslope/drying winds
are expected west of the Sierra crest in this east flow setup.

Valley inversions will also be strong today particularly due to
the cold temperatures developing this morning. As such,
ventilation will be limited through Tuesday with lighter
east/northeast transport winds and limited afternoon mixing. This
may impact prescribed burn plans. Fuentes

&&

.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 11 AM PDT this morning NVZ002.

CA...Lake Wind Advisory until 11 AM PDT this morning CAZ072.

&&

$$

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


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