Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 010405

Area Forecast Discussion
National Weather Service Las Vegas NV
905 PM PDT FRI SEP 30 2016

.SYNOPSIS...Increasing southwest winds will develop this weekend
ahead of a storm system moving into the region. Following the gusty
winds on Sunday...cooler temperatures will invade the region early
next week with some parts of the Southern Great Basin and higher
terrain of Mohave county seeing their first freeze of the fall

.UPDATE...Isolated showers over central Mohave County dissipated
early this evening and the 00-06Z pop/wx grids were updated
accordingly. The latest NAM and GFS guidance support the forecast
trends detailed in the previous discussion with breezes increasing
Saturday afternoon then wind speeds increasing significantly Sunday.


Moisture and limited instability will continue the threat of isolated
showers or thunderstorms primarily over the terrain of Mohave County
this evening and again Saturday afternoon. Drier air over southeast
California and southern Nevada associated with incoming trough will
eventually scour moisture out of Mohave County on Sunday.

Primary concern on Sunday into Monday will be the wind. Southwest
breezes will increase Saturday afternoon but remain below any
critical thresholds. Stronger/colder low dropping into northern
California will help enhance a stronger surface and thermal
gradient. Downslope event developing late Sunday afternoon in the
lee of the southern Sierra and Spring Mountains at the last hours of
our latest locally run Hi-Res models. Would like to see more data
through Monday morning so held off on the issuance of any public
wind products. Confidence is high that Red Flag thresholds will be
met across Nye County and the Clark County mountains Sunday so Fire
Weather Watch was upgraded to a Red Flag Warning. Less confidence
for Inyo County regarding the Red Flag Warning but based on very low
dewpoints on MOS guidance at Bishop is indicative of downslope wind
potential. Better agreement between operational GFS/ECMWF and GFS
ensembles that incoming trough will not be as deep as yesterday.
Best chance for any showers will be along the Sierra Crest and
Lincoln County Sunday night Monday. Snow levels quickly fall to 7000-
8000 feet following the cold frontal passage. Otherwise warm this
weekend with temperatures at or above normal then plummeting well
below normal Monday.

Concern Monday night into Tuesday morning will be cool temperatures.
We have plenty of time to assess that situation but an early season
Freeze Warning may be justified for some higher valley locations.
Otherwise next week looks dry with temperatures rebounding back to

.AVIATION...For McCarran...Light south-southwest winds are expected
through the night with mostly clear skies.  Breezy southwesterly
winds develop after 17Z Saturday under clear skies.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Light winds favoring diurnal patterns can be expected
tonight under mostly clear skies.  West to southwest wind will
increase Saturday as low pressure approaches the area. Wind of 10 to
15KT gusting over 20KT will be common.

.FIRE WEATHER...Incoming trough will bring an increase
in southwest winds this weekend with the strongest period being
Sunday afternoon through Monday morning. There is a chance of
rain/snow showers for the southern Sierra Nevada and central Nevada
Sunday night and Monday. Upgraded the Fire Weather Watch to a Red
Flag Warning Sunday for southern Nevada and Inyo County. Less
confidence regarding criteria being met in San Bernardino County so
the Fire Weather Watch remains posted. Much cooler on Monday under
northwest flow following the passage a cold front. Dry with a
warming trend beyond Tuesday.

.SPOTTER INFORMATION STATEMENT...Spotter activation will not be
needed. Strong winds are expected to develop Sunday and continue
through Monday. Spotters are encouraged to report according to
standard operating procedures.


Discussion/Fire Weather...Pierce

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