626
FXUS65 KVEF 240015
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
415 PM PST Tue Dec 23 2025

.KEY MESSAGES...

* Widespread rainfall with isolated flash flooding, snow at the high
  elevations, and gusty winds will impact Christmas travel.

* Heavy mountain snow expected in the Sierra and White Mountains
  amounting to several feet of new accumulation in the highest
  elevations by the end of the week.
&&

.DISCUSSION...through next Tuesday. Midday satellite loop showed mid
and high level clouds blanketing our CWA. Area radars showed virga.
Surface obs showed locally gusty south winds and temperatures a few
degrees cooler than 24 hours ago thanks to the opaque cloud cover.

Mid level water vapor loop showed a very striking presentation of
the incoming storm. The mid and high level moisture over our area
today was streaming north from the tropics well ahead of the main
storm, which was located near 30N 137W. In between those two
features were multiple shortwave troughs showing up as comma shapes,
with very strong mesoscale vertical motion shown by deep convection
ahead of the wave axes and sharp drying immediately behind them.

As has been advertised for a while now, this storm and its
associated heavy rain are on the way. High resolution models show
light precip breaking out along and southeast of Interstate 15 as
early as this evening, followed by the main rain band pushing into
Inyo and Esmeralda counties late tonight and sweeping east across
the entire CWA Wednesday and Wednesday night. In general, rain
totals of one half to one and a half inches should be common across
the deserts, with much higher totals of four to six inches on the
south slopes of mountains where orographic lift will be maximized.
All of this supports the Flood Watch which is in effect. Due to the
unseasonably warm nature of this storm system, snow levels will be
extremely high, starting off at 7500 to 9000 feet in the northwest
CWA and over 10,000 feet in the southeast CWA tonight. Cooler air
will begin to push in from the west Wednesday evening, knocking snow
levels down to 6000 to 7000 feet in the western CWA by Christmas
morning. This will allow substantial snow to accumulate in the
Sierra Nevada and White Mountains of Inyo County on Christmas Day,
with multiple feet likely on the Sierra crest. Thus, the Winter
Storm Warnings look good. As snow levels drop on the Spring
Mountains Christmas Day, a few inches of snow will likely bring a
white Christmas to the communities there, but it appears that the
heaviest precip will have exited stage right by then. A weaker
atmospheric river could try to push in from the southwest Friday, so
more winter weather products may be needed after the first wave has
passed. Winds will also be a factor. Southerly winds were already
increasing over the southern Great Basin and should become more
widespread later this evening, so the Wind Advisory there looks
good. One concern is that precipitation drag could tamp down the
wind speeds as the rain moves in, but even if that occurs, stronger
winds could surface both before and after the rain, as well as
during any breaks in the rain. On Wednesday, strong southerly flow
ahead of the rain band should allow gusty winds to surface in Mohave
County and the Colorado River Valley, so the Wind Advisory there
looks good as well. The same caveats about precipitation drag apply.

Models are slowly starting to come into better agreement for the
post-Christmas period, showing lingering low pressure off the West
Coast directing another (weaker) AR toward our area Friday, leading
to chances for more rain and mountain snow before the low weakens,
cuts off, and retrogrades southwestward Saturday onward, allowing
drier air to take over. We will need to watch this closely, as some
of the ensemble members show this low eventually pulling another
slug of moisture back northward toward our area in the middle of
next week.

&&

.AVIATION...For Harry Reid...For the 00Z Forecast Package...Winds
have remained rather light this afternoon, and speeds are expected
to remain light through the night. Areas of virga will persist into
tonight, but the probability of precipitation reaching the ground
before late Wednesday morning remains low. That is expected to
change by Wednesday afternoon as a band of light to moderate rain
moves across the valley. CIGs will likely remain above 8kft AGL into
Wednesday morning; however, as the precipitation moves in, expect
CIGs to fall below 5kft AGL by late afternoon, and possibly below
3kft AGL during the evening in areas of heavier rain. Reduced
surface visibilities of less than 5SM will also be possible by
evening.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 00Z Forecast Package...A complex weather period
is anticipated into Christmas Day as widespread low ceilings and
rain overspread the region from west to east. This will bring bouts
of gusty winds, especially at KBIH, where wind gusts of 20 to 30
knots are expected into Wednesday morning. Elsewhere, winds are
expected to generally remain below 12 to 15 knots outside of any
heavier showers. Low ceilings will become more prevalent with time,
developing overnight into Christmas Eve morning and persisting into
Christmas Day. Broken to overcast skies of 4 to 6kft AGL can be
expected, with at least a low probability of ceilings as low as
1.5kft AGL, along with visibility reductions due to rain and fog.

&&

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

$$

DISCUSSION...Morgan
AVIATION...Austin

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