Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 230416 AAA
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
917 PM PDT Fri Sep 22 2017

.SYNOPSIS...Cool fall weather will continue through the
weekend with gradually warming temperatures next week. Occasional
north breezes can be expected, especially down the Colorado River
Valley. A few scattered showers are also possible across Lincoln
county and the Sierra over the weekend.
&&

.UPDATE...An expansive trough covers the entire western CONUS with
dual low centers located in northern Nevada and western Montana. A
cold front is draped across the northwestern portions of the CWA
where satellite imagery shows extensive cloud cover. Not seeing any
radar returns however, left a slight chance over the Sierra and
White Mountains of Inyo County within the densest cloud layer. Gusty
north winds over the southern Great Basin are forecast to push
southward overnight into early Saturday. Except for a 9 PM gust to
39 MPH at Bishop Airport, winds have generally been under 30 MPH.
Grids are updated for the overnight period and the latest forecast
is out. -Salmen
&&

.AVIATION...For McCarran...At 9 PM, winds were generally favoring a
northwest to occasionally north direction but, for the most part,
light and variable. This is expected to continue through the evening
hours before a push of north winds with occasional gusts in the 12-
18 knot range arrives around 9z. However, it`s possible they could
develop as early as 6z. Breezy north winds will continue Saturday
with a transition to lighter northeast winds in the afternoon.

For the rest of southern Nevada, northwest Arizona and southeast
California...Dry and clear conditions expected for most of the
region with broken-overcast clouds expected over the northwest CWA
including KBIH tonight. These clouds will spread across the southern
Great Basin Saturday along with some scattered shower chances in the
same area. Elsewhere, dry conditions with north breezes expected.
&&

.PREVIOUS DISCUSSION...150 PM PDT...

.SHORT TERM...through Sunday night.

The short term period will be primarily influenced a by a strong
early season trough which will slowly traverse across central Nevada
and into Utah over the weekend. This spells cool a continuation of
cool temperatures throughout the weekend, with afternoon highs
averaging 10 to 20 degrees below seasonal normals.  Overnight lows
will be cool as well, with the potential for freezing temperatures
persisting through the weekend in the colder pockets of the southern
Great Basin and the Owens Valley.  While overall, the forecast is
dry, a few showers are possible across the Sierra and Lincoln county
in association with cold temperatures aloft near the base of the
trough on Saturday afternoon.  There may even be enough instability
to generate a few thunderstorms in that region as well.

North winds will be breezy at times, especially down the Colorado
River Valley, but speeds look to stay well below the need for Lake
Wind advisories.

.LONG TERM...Monday through Friday.

Northerly flow will continue behind the trough of low pressure
entrenched across the intermountain west.  Temperatures will slowly
begin to warm up after the cool weekend.  Mid-range models are
indicating the base of the trough will close off leaving a
meandering cut off low beneath a building ridge over the pacific
northwest. That low will help slow the warming trend and keep our
temperatures below normal for a few more days.  Precipitation is
unlikely with this low, but if there is any, it should be very light
and confined to portions of Mohave County.  Confidence is low enough
that I have not mentioned this possibility in the going forecast.
The ridge strengthens by the end of the week when temperatures will
return to near normal for this time of year.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts using standard operating
procedures.
&&

$$

Short Term/Aviation...Outler
Long Term...Berc

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