Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 270422 CCA

Area Forecast Discussion...Corrected
National Weather Service Las Vegas NV
920 PM PDT Wed Apr 26 2017

.SYNOPSIS...A northwest flow will give way to a stronger disturbance
clipping the region from the north on Friday. This will result in a
period of north or northwest winds for much of the region, and
potentially strong winds down the Colorado River Valley. Conditions
through early next week will remain generally dry with a cool down
Friday and Saturday. A warming trend will commence Sunday as the
disturbance pushes east.

.UPDATE...The latest surface observations and radar velocity data
showed a considerable increase in southwest to west winds around
southern Nevada in the past hour or so with gusts of 25-30 mph. This
is in response to the approaching cold front and the associated
surface pressure gradient increase. The front was just northwest of
Indian Springs at 04Z, and will push across central Clark County
around midnight. This will usher in a prolonged period of gusty
north winds as a deep upper low slides over Nevada, Utah and Arizona
Friday into Saturday. Minor adjustments were made to the wind grids
tonight. The rest of the forecast trends look good. -Adair

.SHORT TERM...through Friday Night.

Biggest concerns through the short term continue to be the winds, as
well as the potential for damaging winds along the Colorado River
Thursday night into Saturday.  Northwest flow aloft dominates the
weather pattern currently with a weak frontal passage progged to
slide south across the region this evening. This will result in some
strong winds mainly across the western Mojave Desert and parts of
the southern Great Basin where gusts over 40 mph will be possible.
Elsewhere, a switch to north or northwest winds will be noticed
tonight with a brief period of gustiness possible overnight along
the Colorado River as the front moves through.

Tomorrow...north winds will linger but the strength of the winds
will decrease through the morning hours for most locations.
Meanwhile...a reinforcing shot of north winds arrives Thursday
evening in association with a trough beginning to slide across the
Great Basin and into the four corners.

This is traditionally a windy set up for the Colorado River Valley,
and this event takes no exception.  MOS guidance suggests sustained
winds exceeding 40 mph at times near Laughlin/Bullhead city, and
perhaps getting close along other river locations as well (Needles,
Havasu, etc).  While high resolution guidance is not yet as bullish,
pattern recognition and MOS guidance, as well as fairly substantial
pressure gradient have led me to issue a high wind watch for this
area. The next couple shifts can continue to evaluate the potential.
Regardless of the exact wind speeds which unfold, it will be very
windy from Cottonwood Cove southward Friday and Saturday, and those
planning events or outdoor recreation should be well prepared for
the expected wind impacts.

Temperatures Thursday will be fairly similar to those observed
today, with a cool down commencing Friday as heights fall in
response to the developing trough.

.LONG TERM...Saturday through Tuesday. North winds will continue on
Saturday as noted in the short term discussion, then subside
Saturday night as the low moves away to the east. The next feature
of interest is high pressure building off the West Coast, and
whether/when it will move inland. The operational GFS and ECMWF have
both backed away from previous runs which showed another trough
diving down the front side of the ridge and amplifying into the
Desert Southwest, and now show the ridge working its way inland with
rising heights and warming temperatures. However, only about half of
the ensemble members agree with this idea, with some holding on to
the trough. With the uncertainty in mind, nudged temperatures
halfway toward the new model guidance. This puts KLAS into the upper
80s early next week, where new model guidance suggests 90 or higher.
If future model runs continue to trend toward the ridging solution,
temperatures will need to be bumped up accordingly. Stay tuned.

.AVIATION...For McCarran...A frontal passage will arrive around
06Z-07Z with the winds shifting to the northwest with occasional
gusts of 20-25 knots. Breezy north winds will persist most of the
day Thursday with gusts to 25 knots possible and occasional
variances between northwest and Northeast directions.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Breezy conditions will exist across most of the region
through the period. West winds with gusts over 35 knots can be
expected near KDAG and KNXP this afternoon through early Thursday
morning with some improvement midmorning before the west winds
return Thursday evening. South winds of 10-15 knots will give way to
north winds tonight down the Colorado River with gusts of 20-25
knots expected near KIFP and KEED.  Much stronger north winds
possible Friday and Saturday. Meanwhile...periods of northwest winds
expected near KBIH with gusts to 20 knots possible.  Skies should
generally consist of only scattered high clouds.

.FIRE WEATHER...Dry and breezy conditions expected the next several
days with windy conditions expected along the Colorado River. Strong
winds combined with low relative humidities will result in a period
of critical fire weather Friday and Saturday along the Colorado
River Valley and a Fire Weather Watch has been posted for this
potential. Improving conditions are expected Sunday as wind speeds
decrease but conditions will remain dry. &&

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


LONG TERM....Morgan

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