998
FXUS65 KVEF 162302
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
401 PM PDT Fri May 16 2025

.SYNOPSIS...Warm temperatures will continue today with light
afternoon breezes. A stray shower may develop along the Sierra
crest this afternoon with gusty winds and sprinkles in the Owens
Valley. A weather system will drop into the region over the
weekend bringing gusty winds, cooler temperatures, and shower
chances to mainly the Great Basin. Conditions will improve next
week with warm conditions returning.

&&

.SHORT TERM...Tonight through Sunday.

An upper level system will dig into the region on Saturday which
will bring increasing winds to the region. South to southwest winds
increase in response to the increasing pressure gradient with
impactful gusts over 40 MPH in the valleys and gusts up to 60 MPH in
the terrain likely late Saturday morning through Saturday evening
across San Bernardino, far southern Nevada, and Mohave counties. A
wind advisory is in effect for these areas on Saturday where wind
impacts with strong crosswinds, patchy blowing dust, difficult
travel and boating conditions, and easily blown away light weight
items are most likely. No changes were made to the wind headlines at
this time, however a few places were considered:

Looked at adding the Sierra slopes and Owens Valley to the Saturday
wind Advisory as NBM 24hr Max Gust probabilities for over 40 MPH are
70%+. However, looking at the hourly data, probabilities are lower
and isolated. Looked at downsloping set up down Sierra into the
Owens Valley but it didnt look ideal and the stronger winds remained
mostly in the high to mid slopes. There were some instances in hi-
res models and ensemble members that did show higher gust 40 MPH+ in
the Owens Valley, but it`s very short lived. Held off on issuing any
wind headlines for the Sierra and Owens Valley for now, it may still
be needed but the stronger winds would likely be later in the day
compared to the rest of the region so will continue to watch trends
for a better signal and confidence increases.

Also looked at the need to upgrade any of the Wind Advisory to a
High Wind Warning, with the highest potential for this being in the
Western Mojave Desert as well as on the lee side of the Spring
Mountains. In the Western Mojave Desert, the low level jet briefly
increases to 50-60 MPH between 5 PM to 11 PM Saturday evening.
Forecast soundings show these winds struggling to make it to the
surface as we decouple after sunset. There is an increase in
probabilities for gusts over 58 MPH Saturday evening that matches up
with the increasing low level jet, but the highest probabilities
mainly focus on the terrain- valley areas show lower probabilities
and only a brief uptick in the winds. For these reasons, did not
upgrade to a High Wind Warning. On the lee-side of the Spring Mts,
cross sections show a better potential for downsloping that in the
Sierra, however it still is not great and models show max winds of
50-55MPH transitioning down the mountain. While these winds would be
impactful as they would result in strong crosswinds over US-95
between Desert Rock and Indian Springs, winds should be sub-60 MPH
and thus will continue with the wind advisory with wording that
highlights this crosswind impact.

Saturday night and Sunday, winds will become northwest as the main
trough shifts east. A second piece of energy that rides down the
anticyclonic side eof this trough and reinforce these winds Sunday
afternoon. There continues to be model discrepancy about how strong
this reinforcing shortwave will be and thus creates uncertainty in
how strong the winds will be Sunday afternoon. Probabilities for
wind gusts over 40 MPH are highest in northern Inyo County through
Esmeralda and central Nye however it occurs Saturday night and is
confined to the terrain. Winds are not as strong on Sunday, and
while there is some potential for wind impacts Sunday afternoon is
the stronger solution with the shortwave comes to fruition- the
probability for widespread impacts Sunday afternoon is fairly low.
The best chance would be in the Colorado River Valley as north winds
will build waves and could impact boating.

In addition to the winds, the systems this weekend may also bring
precipitation to the Southern Great Basin area. The best chance will
be Saturday afternoon when forcing is highest and weak instability
is able to develop. PWATs will remain around 100%-150%, or about
0.50-0.75 inch, and low levels will struggle to saturate- so
precipitation impacts will be low. There is a low probability
(about 30%) for over 0.25 inches total of rain in Lincoln County,
otherwise precipitation will remain light. Any thunderstorms that
are able to develop could produce lightning and sudden gusty winds
with dry low levels. On Sunday, there is a lingering risk for
showers and isolated thunderstorms in eastern Lincoln and northern
Mohave County, however the probabilities for rain are lower and
more isolated than Saturday.

Temperatures through the weekend will cool each day with each
system. On Saturday, high temperatures will run about 3-5 degrees
below normal, then about 5-8 degrees below normal on Sunday.

.LONG TERM...Monday through Thursday.

Ridging sets up over the region as the trough exits to the east. As
this happens, temperatures will return to above average values. Las
Vegas has a 63 percent probability of reaching its first 100 degree
day on Thursday. By Thursday, expect widespread Moderate (Level 2)
HeatRisk across the desert valleys, a level of heat that affects
anyone sensitive to heat, especially those without adequate cooling
or hydration. There is also the potential for some Major (Level 3)
HeatRisk along the Colorado River, which affects anyone without
effective cooling or hydration. Given the placement under high
pressure, dry conditions and non-impactful winds are forecast
through the long term.

&&

.AVIATION...For Harry Reid...For the 00Z Forecast Package...Breezy
south-southwest winds continue this afternoon with gusts around 20
knots. Winds remain southerly overnight though gusts should cease
and speeds weaken. Strong south-southwest winds tomorrow as gusts
reach 30-40 knots. SCT-BKN clouds at or above 15kft move in today
and persist through tomorrow.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 00Z Forecast Package...Breezy south-southwest
winds continue across most of the area this afternoon. Expecting
gusts in the 15-25 knot range. As the sun sets, winds will weaken
everywhere except DAG where they will remain breezy overnight.
Stronger south-southwest winds forecast tomorrow, except at BIH
where winds will be northwesterly. VFR conditions prevail throughout
the TAF period with SCT-BKN clouds at or above 10kft.

&&

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

&&

$$

SHORT TERM...Nickerson
LONG TERM...Meltzer
AVIATION...Woods

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