High Wind in California, December 14, 2024

Area Forecast Discussion
National Weather Service Las Vegas NV
745 AM PST Sat Dec 14 2024

.SYNOPSIS...A fast moving storm system will bring another round of
heavy snow to the high Sierra with gusty winds spreading across
the Owens Valley and higher terrain of southern Nevada today.
A strong ridge will then build into the western states with dry
conditions and a slight warming trend through next week.
&&

.UPDATE...Satellite imagery this morning depicts a compact low
moving ashore near the Bay Area in northern California with upslope
precipitation ongoing along the Sierra Crest. SNOTEL data along the
crest suggests snowfall totals of 2-4 inches thus far around the
9500 foot level, with minimal spillover into the Owens Valley. As
the low moves inland this morning, heavier precipitation will spread
down the Sierra with better chances for heavier mountain snow near
Aspendell and rain showers into the Owens Valley. The Winter Weather
Advisory still looks in good shape for the Eastern Sierra Slopes.

The other concern today will be wind, which thus far has been
limited to the higher peaks. However, core of 50-70 knot
southwesterly winds at 700mb will drop south today and intercept the
Sierra and Spring Mountains later this morning through the evening
hours. Downslope winds remain a concern, especially along and west
of US-395 in the Owens Valley and near lower Lee/Kyle Canyons and
Red Rock Canyon in the Spring Mountains.  The wind advisories also
look to be in good shape with no updates necessary.

-Outler-

&&

.SHORT TERM...through Sunday.

A vigorous circulation could be seen on satellite loops off
the central California Coast with a substantial moisture plume
spreading across California and Nevada. Although it may appear
somewhat promising, precipitation in our forecast area will largely
be intercepted by the Southern Sierra again and only 20-40 percent
chances of barely measurable snow are indicated by the NBM across
the mountains of the Southern Great Basin and Southern Nevada this
afternoon. Snowfall totals for the east slopes of the Southern
Sierra still favor generally 4-6 inches between 7000 and 9000 feet
and up to 12 inches near the crest.  A Winter Weather Advisory
remains in effect until 10 PM PST this evening.

The more extensive impact from this system will be strong
southwest or west winds over terrain above 6000 feet across Inyo
County and much of Southern Nevada. High resolution models continue
to indicate the potential for strong downslope winds along east or
northeast facing slopes of the Sierra and Spring Mountains where
gusts of 40 to 55 mph will be possible. Gusts over 60 mph can be
expected over the ridgetops. Wind Advisories remain in effect for
these zones from 9 AM PST until 9 PM PST this evening. Winds will
gradually diminish late this evening and overnight as the axis of
the upper level trough quickly pulls away toward the Rockies
and allows a ridge to quickly build over our region bringing
light winds to most areas and a clear sky by Sunday. The exception
will be north breezes 15-25 mph in the lower Colorado River Valley
from Laughlin-Bullhead City southward.

Temperatures will increase a few degrees today as winds stir up the
boundary layer with highs in the 60s across the deserts zones
followed by little variation Sunday.

.LONG TERM...Monday through next Saturday.

Low amplitude ridge will build in early in the week while incoming
Pacific energy is deflected into the PacNW. An inside slider will
drop around the ridge on Tuesday, but the models continue to flip-
flop on the overall depth of this trough. Both the 12z GFS and EC
showed this trough weakening and remaining more progressive, but the
latest 00z GFS has reverted back to a deeper trough which eventually
cuts off over southwest Arizona. The main impacts would be in the
form of wind, but if the latest runs hold, then we could see some
gusty north winds Tuesday and Wednesday, especially down the
Colorado River Valley. We will need to wait for the latest EC to see
if models remain in agreement, but confidence at this point is low.
Beyond Wednesday, it does look like a strong ridge will build over
the western US keeping us dry. While temperatures will be above
normal, light winds and long nights will promote the development of
valley inversions keeping temperatures in check despite the very
anomalous heights forecast over the region.
&&

.AVIATION...For Harry Reid...Light winds follow typical daily
patterns through mid-afternoon. Chance of seeing 10+ knots during
this time is less than 10%. By late afternoon (22z-00z), breezy
southwest winds are expected to develop, with gusts around 20-25
knots. Probabilities of gusts over 25 knots are ~30%. Southwest
breezes remain elevated through the evening before weakening between
06z-09z. In terms of sky conditions, clouds will be on the increase
throughout the morning hours. CIGs are likely to remain at or above
10 kft, but there is a 30% chance of them falling below 10 kft
between 15z-18z. Sky conditions quickly improve in the late morning,
with 70+ percent chances of CIGs remaining above 20 kft through the
rest of the day.

For the rest of southern Nevada, northwest Arizona and southeast
California...For sites along and south of the I-15 corridor, light
and diurnal winds continue through the early afternoon before breezy
southwest winds kick in by mid or late afternoon. Strongest winds in
these areas will be at KDAG and the Las Vegas Valley where gusts of
20-25 knots are possible. Clouds will be on the increase this
morning, but sky conditions quickly improve in the early afternoon.
CIGs largely remain above 10 kft, but there are 10-30% chances of
them falling below 10 kft in the mid/late morning. For our
northwestern areas, namely the Owens Valley, gusty south winds
develop this morning with downslope westerlies trying to develop in
the afternoon. Confidence in westerly winds reaching KBIH is not
high (maybe 30-40% chances), but if they don't, expect northerly or
possibly even easterly breezes if a strong rotor develops. By 03z,
there is high confidence (80%) that winds will be northerly at KBIH.
Beyond the winds, there will also be light precipitation and lower
CIGs to content with. Precipitation chances will come in 2 waves,
with the first being between 10z-15z this morning (30% odds) and a
second chance between 18z-22z (50-60% odds). Rain will be light and
likely won't reduce visibility, but it will bring CIGs down. Their
lowest values will come during the afternoon where there is a 50%
chance of CIGs below 6500 ft and a 25% chance of CIGs below 3000 ft.
Sky conditions should improve quickly around 00z.

&&

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

&&

SHORT TERM...Adair
LONG TERM...Gorelow
AVIATION...Woods

For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter