High Wind Watch 4, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
900 AM PDT Wed Jun 15 2022

.SYNOPSIS...Warmer today and tomorrow before a potent low pressure
system brings strong winds, critical fire weather conditions, and
another round of cooler temperatures. A slight chance of
thunderstorms is forecast for Mohave County on Saturday, but
otherwise the area remains dry.
&&

.UPDATE...Seasonably warm conditions expected today with afternoon
highs topping out near mid-June normals, along with light winds.
Main focus of the afternoon package will be wind and fire headlines
in coordination with our regional neighbors. Current forecast looks
good and no update is necessary.

-Outler-

&&

.SHORT TERM...Today.

After a day of below-normal temperatures, seasonal warmth returns to
the area as a shortwave ridge moves into the area. The evolution of
this ridge will have larger implications for the late-week weather
(see Long Term discussion), but for today it will promote warmer
temperatures and light winds. Highs are forecast to be around 5
degrees warmer than yesterday, with values in the mid-to-upper 90s
and 100s across the CWA. Afternoon breezes will be light, around 10-
15 mph.

.LONG TERM...Thursday through the Weekend.

Looking just at the 12Z ECMWF EFI table, significant changes to the
forecast look to be on the horizon come late week and into the
weekend. While temperatures should peak on Thursday due to brief but
fairly high amplitude ridging over the western CONUS, a very strong
low pressure system will be quick to set up over the western
seaboard. The 18Z EC ensemble shows this low axis as a nearly 3
sigma normalized anomaly. Pair this with a high amplitude ridge over
the central US, and a stout H5 gradient looks to set up over the
Great Basin.

This will open the door to several potential impactful situations
from Friday through Sunday, with the highest confidence being
gradient winds across central and northern Nevada. A resultant
surface low pressure anomaly looks to set up east of the Sierra
Nevada range Friday and shift northeast through Saturday. This will
set up a significant surface gradient as well as low and mid level
wind field enhancement setting the stage for high winds across parts
of Esmeralda, Nye, and Lincoln counties, and potentially farther
south depending on the depth of the low. One thing this low doesn't
have coming with it is moisture however. In fact this low will shunt
much opportunity for moisture with a drier fetch from the western
Pacific. At least for the western 2/3 of the CWA...

That being said, a likely named tropical disturbance south of Baja
California will be churning up tropical moisture and advecting much
of it into Arizona through this time. This will lead to Saturday not
only being windy for central and northern Nevada, but thunderstorms
with heavy rainfall potential on tap for much of Arizona, including
Mohave county potentially. This is much less certain as it depends
on several variable such as the low's depth/amplitude, positioning
of the low axis, the resultant upper level dynamics aligning with
focused moisture flux, and peak convective potential.

Right now, the 01Z NBM population seemed to appropriately raise PoPs
and introduced at least measurable QPF into much of Mohave County
for Saturday. Would not be surprised to see the forecast for Mohave
County trend upward in these elements, but even if it doesn't,
believe the range of possibilities Saturday could be either dry
lightning and wildfire potential or thunderstorms with heavy
rainfall pushing into Mohave from central/northern Arizona.
&&

.FIRE WEATHER...Hot and dry conditions to continue for the majority
of the area. Light afternoon breezes today, but winds begin to pick
up on Thursday. Elevated to critical fire weather conditions will
likely begin on Thursday for our Arizona and Nevada zones, lasting
through at least Saturday. The most concerning period will be Friday
and Saturday, where widespread gusts of 40+ mph are possible. Could
even see gusts close to 60 mph in parts of Esmeralda, Nye, and
Lincoln Counties during this time. Afternoon relative humidities are
expected to be around 10% on Friday, with some recovery on Saturday
in eastern Lincoln and eastern Mohave as moisture tries to push into
the area. This moisture may be enough to spark a few thunderstorms
Saturday afternoon, which could produce some dry lightning concerns
in Mohave County. Winds may linger in the eastern portions of the
area on Sunday before tapering off areawide on Monday.
&&

.AVIATION...For Harry Reid...Light and variable winds early this
morning will likely give way to northeast components 7-10 knots
after 16Z through early afternoon then becoming southeast less than
6 knots in mid to late afternoon. Light southwest winds develop
after sunset through the overnight hours. Clear sky through the
period.

For the rest of southern Nevada, northwest Arizona and southeast
California...North-northeast winds 10-15 knots will spread down
through southern Nevada and the Colorado River Valley this morning
then speeds will decrease to less than 10 knots this afternoon
through tonight. Light winds elsewhere and a clear sky through
the period. &&

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

SHORT TERM...Woods
LONG TERM...TB3
AVIATION...Adair

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