Freeze Warning 1, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
837 AM PDT Sat Sep 28 2019

.SYNOPSIS...A strong weather system will bring widespread gusty
winds to the area today and bring much cooler conditions will
Sunday and into early next week. The biggest impact over the next
7 days will be the winds this weekend and potential for a first
freeze across parts of Inyo, Esmeralda, and Nye counties early
next week.

&&

.UPDATE...Near advisory levels gusts already being observed across
the western Mojave Desert of San Bernardino County. Elsewhere,
observed gusts approaching 30 mph. Wind speeds will peak this
afternoon and evening before diminishing in the early morning hours
of Sunday. Wind Advisory now in effect.

As for our Freeze Watch for a few or our northern zones. Will make
final decision this afternoon once I have looked at all the latest
guidance.

&&

.SHORT TERM...Through Sunday Night.
The short term focus is likely obvious this package due to the
already issued Wind Advisory that spans nearly the entire CWA
beginning this morning and persisting through late tonight. While
overall, latest NBM wind guidance is lower than the previous
forecast, hi-resolution outcomes continue to show the potential
for this strong low to produce gusts to the mid to upper 50 mph
range at or around 21Z this afternoon for the higher terrain areas
of Lincoln, Clark, and Inyo counties. Even with the NBM lower
numbers, everywhere in the wind advisory will easily meet advisory
criteria. There was some consideration in extending the advisory
beyond 06Z tonight, as some of the higher terrain areas of Mohave
and Lincoln counties could linger to about 08Z or so according to
some model outcomes but these areas should stay confined to higher
terrain with little impacts so didn't opt to extend for an
isolated lingering wind concern.

Secondarily, the other impact of note is the prospect of first
freeze for Inyo and Esmeralda counties Sunday morning. Taking a
close look at top performing guidance as of late as well as
multiple ensembles numbers for these regions, there is still a
fairly large spread in low temperatures possibilities, which
unfortunately span about 2-3 degrees on either side of freezing.
Indeed, the forecast calls for 32 or lower for locations such as
Bishop and higher terrain of Esmeralda and the Tonopah area, but
can't say that confidence is high just yet. Would like to continue
to see a decreasing low temp trend and less temperature spread in
the ensemble members before opting for the upgrade to a warning.
Thus will let the watch ride for now and let the day shift assess,
hoping higher confidence will be present.

&&

.LONG TERM...Monday through Friday.
The main upper low across the northwest that will be responsible
for this weekend's wind will also be responsible for much cooler
temperatures early next week. As the short term discussion
mentioned, there is some potential for first freezing temperatures
as early as Sunday morning but higher confidence looks to be
Monday and possibly Tuesday mornings as the low continues to push
reinforcing cold fronts down into central and southern Nevada. 850
mb temperatures drop to the single digits with weaker overnight
winds that should allow for temperatures to drop efficiently both
nights. Even parts of extreme northwest Clark county could see
upper 30s come Monday and Tuesday morning.

By mid-week, the aforementioned low will be forced eastward as a
brief ridge builds over the western US allowing temperatures to
recover back into the low to mid 80s. By late week, long range
outcomes begin to diverge substantially so will opt to address
this in later discussions.

&&

.FIRE WEATHER...A strong upper level system will bring windy
conditions across the region today and especially this afternoon
and evening. Sustained winds of 25 to 35 mph and gust potential as
high as 60 mph will be possible. This area of high winds will
extend from San Bernardino County, through southeastern Nye, much
of Clark, Lincoln, and Mohave counties. The higher terrain areas
of these counties could see even higher winds.

Min RH values this afternoon should for the most part stay above
critical values with the exception of parts of Esmeralda and Inyo
counties. Winds in these areas won't be as high as the
aforementioned locations and additionally, fire partner guidance
indicates these areas as low risk or lower. Thus, not expectation
for a RFW, however, the winds alone should discourage any burning
today and will keep fire weather concerns elevated.
&&

.AVIATION...For McCarran...Gusty southwest winds along with mountain
wave and turbulence hazards today. Winds will be quick to pick up
this morning, peak in the late afternoon/early evening, then
gradually tail off between sunset and midnight. Sunday morning will
bring lighter winds with lesser southwest breezes returning for the
afternoon.

For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty southwest winds expected across the region today.
Expect strong surface wind and clear air turbulence hazards as well
as mountain wave activity from the Sierra Nevada and White
Mountains. Winds gradually subside tonight as a cold front sinks
south across the area with winds shifting to the north or northwest
for much of the area north and west of I-15.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any impacts associated with the high winds expected this weekend.
Any damage, power outages, or measured wind reports over 50 mph
are greatly appreciated.

&&

UPDATE...Pierce

SYNOPSIS/SHORT/LONG/FIRE...TB3
AVIATION...Steele

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