619
FXUS65 KVEF 160907
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
207 AM PDT Sun Mar 16 2025

.SYNOPSIS...Calm conditions and seasonal temperatures are expected
across the region today. A low pressure system will bring strong
winds to the region on Monday and Tuesday. These winds will be
accompanied by a large cool down with cooler than normal
temperatures returning on Tuesday. Precipitation will be limited to
the higher terrain of Inyo County and the southern Great Basin.
Afternoon breezes and gradually warming temperatures will be the
defining characteristics during second half of the week.

&&

.DISCUSSION...through Saturday.

Today will literally be the calm before the storm with mild
conditions and seasonal temperatures across the region as we find
ourselves under a transient ridge. Outside of some mid-to-high
clouds pushing into the area, there isn`t much to write home about
concerning today`s weather. Temperatures will peak to a few degrees
above seasonal averages tomorrow thanks to the ridge. However, a low
pressure system will approach and move through the Desert Southwest
tomorrow.

As the region finds itself sandwiched between the exiting ridge to
our east and the approaching trough to our west, surface pressure
gradients increase across the forecast area, which will result in
widespread gusty southwest winds on Monday. Continuing to evaluate
the concern for very strong downslope winds in the lee of the Sierra
Nevada across Highway 395 as well as in western portions of the Las
Vegas Valley off of the Spring Mountains. The latest HREF extends
through 00Z Tuesday and shows between 50 and 60 kts at 700mb in
these areas and between 40 and 50 kts at 850mb - similar trends as
seen in the medium-range deterministic guidance this morning. Gusts
will continue overnight Monday into Tuesday before the trough`s
associated cold front pushes through the forecast area and switches
the wind gust direction from the northwest on Tuesday. GIven the
widespread 70 to 90% chances for 40+ mph wind gusts on Monday and 50
to 70% chances on Tuesday, wind headlines have been issued for much
for the area. Wind Advisories have been issued for the Mojave
Desert, Morongo Basin, southern Nevada, the southern Great Basin,
and Arizona Strip all of which begin on Monday. While we have high
confidence in winds reaching advisory criteria in Inyo County, the
Spring Mountains, the Las Vegas Valley, and northwestern Clark
County/southern Nye County, the potential for higher end downslope
winds exists, which is why High Wind Watches have been issued for
these areas. In these areas there are 60 to 80% chances for
localized downslope winds in excess of 58 mph. In addition to strong
winds, this cold front will also have a strong temperature
component, with afternoon temperatures dropping 8-12 degrees between
Monday and Tuesday.

Minimal changes to precipitation-thinking. Moisture associated with
this trough will increase PWATs over the area to between 120 and
150%, which isn`t impressive when you consider our normal PWAT this
time of year is around 0.30". Regardless, the modest moisture
increase will allow PoPs to increase to 40 to 70% across the
southern Great Basin. Precipitation chances have decreased across
the Mojave Desert, with the primary moisture-related impact being
increased cloud cover. The exception to this is the Spring Mountains
in Clark County, where PoPs continue between 40 and 60%.
Precipitation amounts will generally be low, with Storm Total QPF
ranging from 0.05 to 0.15" in the southern Great Basin - highest
amounts in the mountains. Timing of highest precipitation rates will
start out Sunday night in the Sierra and will shift overnight Monday
into Tuesday across southern Nye and Lincoln counties. Snow levels
will range from 6500 to 7500 feet before dropping to below 5000 feet
on Tuesday, which will allow for a few inches of snow accumulations
in Lincoln County above 5000 feet.

Ridging returns to the region mid-to-late week, which will return
afternoon temperatures to at-or-above seasonal averages.


&&

.AVIATION...For Harry Reid...For the 06Z Forecast Package...The
primary wind direction overnight into early Sunday morning should be
southwesterly, although northwest has about a 40% chance of
occurring. In either case, speeds should remain below 10 knots. By
mid morning, winds should go around to the usual daytime east or
northeast direction, with speeds below 10 knots. In the afternoon,
winds should come around to south or southwest with gusts around 20
knots, although the exact timing of this shift is uncertain. Gusts
should end after sunset. No operationally significant clouds or
weather expected.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 06Z Forecast Package...South to southwest winds
are expected to increase over most of the region Sunday and Sunday
night, with the strongest gusts of 40 to 50 knots over the Sierra
crest. There will be turbulence and possibly rotors downwind of
mountains. Clouds are expected to remain above the terrain.
&&

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

&&

$$

DISCUSSION...Stessman/Soulat
AVIATION...Morgan

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