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000
FXUS65 KVEF 251710
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1010 AM PDT Sun Jun 25 2017

.SYNOPSIS...The prolonged heat wave over the region will finally
break by Tuesday as a weak weather system moves across the western
states. This system will result in enhanced winds Monday and will
increase the fire danger over portions of southern Nevada and
northwest Arizona. Limited moisture will lead to possible isolated
thunderstorms over the southern Sierra and northwest Arizona today
before drier air moves in by Monday.
&&

.UPDATE...Quick update this morning account for the latest trends
and short term guidance. Clouds and light virga showers continue to
drift north across southern Nevada and northwest Arizona. These are
associated with an axis of higher moisture that could result in very
isolated showers over the higher elevations of Lincoln, Clark, and
Mohave county this afternoon. Showers/isolated thunderstorms will
also be possible across the Sierra again this afternoon. The main
threat with any storms will be outflow winds.

The forecast focus for today will be the increasing winds across the
region and any areas of critical fire conditions associated with
them.
&&

.AVIATION...For McCarran...Light winds generally out of the east
will veer southwest  and increase this afternoon. Winds over 10kts
are anticipated by 23Z today. Expect gusty west-southwest winds to
continue through much of the night, with gusts over 20kts possible
after 03Z. There with a chance that winds will drop off for a brief
time between 10Z and 15Z and go light, however confidence is too low
at this time and did not include it in the current TAF forecast.
Gusty southwest winds will continue tomorrow, with stronger winds
anticipated after 18Z Monday than what we should see today.
Otherwise, virga concerns in the McCarran airspace will be minimal
through the afternoon, and VFR scattered clouds should move away by
tonight.

For the rest of southern Nevada, northwest Arizona and southeast
California...Winds will increase out of the west or southwest this
evening and overnight, with the strongest winds expected in San
Bernardino county on the downslope side of the Spring Mountains.
After a brief lull Monday morning, west winds will pick back up
Monday late morning, and will be stronger than today. Otherwise,
isolated showers or virga are possible in the higher terrain this
afternoon, but widespread ceiling/precip issues are not anticipated.
&&

.PREV DISCUSSION...
333 AM PDT Sun Jun 25 2017

.SHORT TERM...Today through Tuesday.

The ridge remains centered over Arizona and Nevada today and the
continued Excessive Heat Warning is a given with similar
temperatures to Saturday. The difference this morning is that there
is a band of considerable mid level moisture extending from Arizona
across southern Nevada and up toward northwest Nevada. This has been
keeping temperatures elevated a few degrees from 24 hours ago. Light
radar returns were noted, but primarily virga is expected. This band
of moisture will continue to lift toward the northeast today as the
eastern Pacific trough begins to nudge inland. This is the feature
that will bring the main weather pattern change Monday and Tuesday,
finally breaking the prolonged heat wave over the region. Increasing
southwest winds will accompany the incoming trough Monday and gusts
around 35 mph can be expected across portions of San Bernardino,
Clark, Lincoln and Mohave counties. Temperatures will lower a few
degrees also, but relief from the excessive heat will be noticeable
by Tuesday as temperatures lower a few more degrees.

.LONG TERM...Wednesday through Saturday.

By Wednesday, the ridge over the southwest will continue to be
suppressed a bit as the tail end of a trough drapes over much of the
western CONUS through the work week. Models are now indicating that
a impulse/shortwave will develop off the coast of northern
California by Friday. The strength and impacts of this feature are
uncertain at this time as model variance is high for Fri and Sat.

Temperatures will be approaching normals by Wed and remaining near
normal through the forecast period. Breezy southwest winds are
expected each afternoon with wind speeds 10 to 15 mph and gusts
around 20 to 25 mph. Wednesday afternoon, both the GFS and ECMWF are
showing a tight gradient over much of central Mohave County. This
will cause some gusty southwest winds up to 30 mph Wed afternoon.
Otherwise, dry and mostly clear conditions through the rest of the
work week and into the weekend.
&&

.FIRE WEATHER...The prolonged heat wave over the region will finally
break Monday and Tuesday as a trough moves inland from the eastern
Pacific. This will result in enhanced southwest winds gusting over
35 mph for portions of southern Nevada and northwest Arizona Monday
afternoon and evening leading to critical fire conditions. Isolated
thunderstorms will be possible over the Sierra and northwest Arizona
today then a dry and stable air mass will spread over the region
with the incoming trough.
&&

.CLIMATE...Near record to record high temperatures will be
possible today and Sunday. The current record of consecutive
days above 110 degrees in Las Vegas is 10 days (1961), and for 115
degrees, 4 days (2005).

Las Vegas, NV Climate

           Forecast High Temps (F)       Daily Record Max Temps (F)
SUN (6/25):  113                          115 (1970)

          Forecast low Temps (F)       Daily Record High Min Temps (F)
SUN (6/25):           89                           86 (1974)
&&

.HYDROLOGY...Observed flows on unregulated creeks, specifically
Independence Creek, Big Pine Creek and Rock Creek indicated flows
have decreased slightly since their peak flows occurred earlier this
week. Creeks, streams and rivers along the eastern Sierra slopes of
Inyo County as well as the Owens Valley will be flowing high and
fast through into at least early next week. Minor flooding could
occur near creeks as well as a few low water crossings on some
roadways. Remember, never drive through flooded roadways or around
barricades. Also, pastureland or farmland adjacent to creeks,
streams or rivers could experience areas of standing water.
&&

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

$$

UPDATE...WOLCOTT
AVIATION...ALLEN
SHORT TERM/FIRE WEATHER...Adair
LONG TERM....Kryston
HYDROLOGY...Pierce

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