656
FXUS65 KVEF 170436
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
936 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.

&&

.UPDATE...Cloud cover associated with the shortwave will continue to
stream through the area this evening, with a short break overnight
before the next system arrives tomorrow. Winds will begin to
increase out of the southwest in the morning and intensify through
the day. The current Wind Advisories appear to be in good shape,
though some high resolution models continue to suggest wind gusts
over 40 mph reaching Owens Valley. Expect dry conditions to continue
until tomorrow afternoon, when precipitation chances increase in the
southern Great Basin. Totals should generally be light.

&&

.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 06Z Forecast Package...South-
southwest winds continue overnight with speeds generally remaining
below 8 knots. Southwest winds will increase by mid-morning, with
gusts of 30 to 40 knots possible after 19Z.  Winds will remain
elevated through sunset before decreasing to 20 to 30 knots during
the evening.  VFR conditions will prevail with bases remaining AOA
12kft AGL through the TAF period.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 06Z Forecast Package...Conditions at the Las
Vegas area TAF sites will be similar to those described above for
Harry Reid.  Winds at KBIH will remain northerly through late
morning before turning to the west-northwest. Winds will increase
during the afternoon with gusts of 25 to 25 knots expected after
21Z.  Across the western Mojave Desert, including KDAG, westerly
winds will continue through the TAF period with gusts to 40 knots
likely tomorrow afternoon.  Gusty southerly winds are forecast in
the Lower Colorado River Valley tomorrow with gusts to 35 knots
developing by late morning. VFR conditions will prevail in all areas
through the TAF period, with bases remaining AOA 12kft AGL.

&&

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

&&

$$

UPDATE...Meltzer
SHORT TERM...Nickerson
LONG TERM...Meltzer
AVIATION...Planz

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