Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 220419

Area Forecast Discussion
National Weather Service Las Vegas NV
919 PM PDT Thu Sep 21 2017

.SYNOPSIS...Widespread strong and gusty winds are anticipated this
evening ahead of a potent cold front. This front will bring sharply
cooler conditions to the region tomorrow which will linger into next
week. A few showers or thunderstorms will also be possible with the
front across the southern Great Basin. This cool air may result in
the first freeze of the season near Bishop and parts of central


The Wind Advisory for the Owens Valley has been allowed to expire as
winds have dropped below criteria. The advisory continues for a
short while longer across a majority of the remaining area with a
few marginal gusts still present. Expect these gusts to come down by
06z (11 PM local time) and do not see any reason why the advisory
should not be allowed to expire at that time. Colder air is
currently filtering in behind the frontal boundary which is now
pushing into northern San Bernardino, northwest Clark, and southern
Lincoln counties. Temps have already dropped into the 30s across
Esmeralda and central Nye counties. These areas should continue to
drop to near freezing by late tonight and the Freeze Warning for
these areas seems to be  on track; in addition to the northern Owens
Valley which may take a little longer to get down to freezing
overnight. A few spotty showers are still developing along the front
near the Nevada/Arizona border in Lincoln and northern Mohave
counties. This activity should continue to weaken throughout the
overnight period.


.SHORT TERM...through Sunday night.

As you may have guessed from the blustery conditions outside, a
change in the weather is on the way as a potent cold front slides
across the forecast area. As of 1 pm, the cold front was located
from near Independence, CA stretching northeast up to Ely, NV, and
diving southeastward. Anticipate this front reaching the I-15
corridor by around 11 pm tonight. Behind it, much cooler air will
invade the region with the first freeze of the season looking more
and more probable across the colder pockets of Esmeralda, and
central Nye counties. Also added the Owens Valley to the freeze
warning tonight, mainly for the Bishop area where lows are likely to
fall into the 31 to 36 degree range.  Ahead of the front, gusty
conditions will linger into this evening before subsiding after
sunset. McCarran airport has already gusted up to 44 mph, and
stronger gusts remain possible through late afternoon.

The remainder of the weekend looks quite fine, and very fall-like,
just in time for the Autumn equinox which occurs tomorrow. High
temperatures tomorrow afternoon will average 10 to 20 degrees below
seasonal normals, with the largest departures from normal occuring
across our northern zones. A few additional showers may develop
mainly along the higher terrain of the Sierra and southern Great
Basin Friday and Saturday afternoons as the trough axis lingers
overhead and cold air aloft will fuel instability driven shower
activity. Otherwise, for most of the region, cool and dry conditions
can be expected.

.LONG TERM...Sunday through Thursday.

The aforementioned trough will linger near the four corners through
midweek resulting in a persistent northerly flow aloft across our
area. Gradual increases in heights as the trough weakens will allow
our temperatures to slowly rebound to within a few degrees of
seasonal normals by midweek.  In addition, this flow pattern will be
favorable for daily bouts of gusty north winds down the Colorado
River.  Overall, a dry and seasonable early fall lies week ahead.


.FIRE WEATHER...Windy conditions will persist through this evening
with gusts exceeding 40 mph at times across much of Southern Nevada
and Northwest Arizona, as well as parts of the Mojave Desert in
California. Much cooler conditions will follow this system with
below normal temperatures expected Friday through early next week.
Critical fire weather conditions are not expected due to relatively
high fuel moisture and marginal forecast humidities.

.AVIATION...For McCarran...Strong southwest winds will continue into
the early evening then speeds are expected to decrease and become
west or northwest toward midnight and the overnight hours. A light
north or northeast component can be expected Friday and speeds
should generally be below 10 knots. Mechanical turbulence can be
expected in the terminal area until winds diminish late this

For the rest of southern Nevada, northwest Arizona and southeast
California...A strong cold front sweeping across southern Nevada and
northwest Arizona early this evening will produce scattered showers
and isolated thunderstorms. Marginal VFR conditions with ceilings of
1-3 Kft can be expected with this wide band of showers over Lincoln
County and far northwest Arizona. Elsewhere, widespread gusty
southwest winds over 35 knots and associated hazardous turbulence
across the Mojave Desert Region will gradually diminish by late this
evening. Variable wind speeds less than 15 knots can be expected
Friday across the region.


.SPOTTER INFORMATION STATEMENT...A more fall-like pattern will bring
cooler temperatures and gusty winds to the region. While spotter
activation is not anticipated, reports of wind impacts such as
blowing dust or damage are appreciated.



Short Term/Long Term/Fire Weather...Outler

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