Morongo Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

024
FXUS65 KVEF 232302
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
302 PM PST Mon Dec 23 2024

.SYNOPSIS...Quiet and warm conditions today before our next system
moves in tomorrow. Gusty south-southwest winds develop across the
western half of the area tomorrow afternoon while precipitation
chances spread east throughout the day and overnight. Mountain snow
and light valley rains possible during this time, especially for
areas north of Las Vegas. Calmer, more-seasonal conditions resume
Christmas Day. Largely quiet weather beyond that with just some
light precipitation chances over our northeastern zones on
Thursday.

&&

.SHORT TERM...through Christmas Day.

Today will be the last day of completely quiet weather for a few
days as the pattern becomes more active. Thin, high clouds will pass
over the area throughout the day, but temperatures are forecast to
top out well above normal. Highs ranging from the low 60s to mid 70s
will encompass the majority of our CWA, some 10-12 degrees above
typical values. Northerly breezes up to ~20 mph around Laughlin, but
light winds elsewhere.

The pattern shift begins Christmas Eve as a compact, Pacific trough
moves ashore and into our area. This system is a progressive one,
pushing through in ~12 hours. In terms of impacts, expecting mostly
minor impacts from wind and precipitation, though isolated moderate
impacts will be possible in the Spring Mountains.

Starting with the winds, we`ll see an uptick in south-southwesterly
winds beginning Tuesday afternoon as the pressure gradient tightens
ahead of the trough. These will be strongest across our western
zones, where gusts of 40-55 mph are possible. Wind Advisories are in
effect for these locations Tuesday afternoon and night. Late Tuesday
afternoon and evening, winds begin to turn to the west/northwest as
the trough axis and cold front push through. As this happens, there
will be a brief window for locally stronger downslope winds to occur
off the Sierra (Spring Mountains), potentially impacting US-395 (US-
95 and far western Las Vegas). Winds gradually wane into Christmas
morning as the system scoots away.

Now onto the precipitation side. Precipitation chances begin in the
Eastern Sierra Tuesday morning, but don`t really spread east until
the afternoon and evening hours. Based on the progressive and
compact nature of the system, expecting a relatively narrow
band/wave of precipitation to move through any given location in ~6
hours or less. By noontime on Christmas Day, precipitation is
forecast to be out of our area, with PoPs less than 10% across the
CWA. Highest confidence in measurable precipitation is on the high
terrain and locations north of Las Vegas. There may even be some
embedded convection and a few lightning strikes in this regime from
Esmeralda County to Lincoln County. Precipitation potential in the
lower elevations (Las Vegas, Death Valley, Owens Valley, Colorado
River Valley) is much more uncertain. Latest NBM PoPs for these
locations range from 40-80%, including ~75% chances in Las Vegas.
However, the event is now within the range of hi-res guidance, which
is much more skeptical. This morning`s HREF gives these same
locations 10-40% rain chances, with Las Vegas at 10%. Regardless,
precipitation amounts in these valleys is likely to be light, with
only ~25% chances of seeing 0.10". These light amounts may actually
be worse in terms of travel impacts, as the light rain won`t wash
all the oil/grime off the roads and may just mix with it, resulting
in slick conditions. On the wintry side, snow levels predominantly
above 7000` mean that impacts will be limited to the Spring
Mountains and maybe the Aspendell area. Latest NBM gives Kyle/Lee
Canyons 40-60% chances of seeing 4"+ of snow, while Aspendell has
~25% chances. The HREF amounts/probabilities are slightly lower, but
still enough to warrant the Winter Weather Advisory in effect for
the Spring Mountains from 4PM Tuesday to 4AM Wednesday. These totals
may accumulate in short order, with a 50% chance of 1"/hr and 20%
chance of 2"/hr rates Tuesday evening. Combined with gusty winds up
to 55 mph, anyone traveling in Kyle/Lee Canyons Tuesday evening
should be very cautious.

.LONG TERM...Thursday through New Years Eve.

In the wake of our Christmas Eve system, we`ll see a brief period of
shortwave ridging before our a weaker, secondary system skirts our
northeastern area on Thursday. There doesn`t appear to be much of a
wind response with this shortwave, but PoPs do increase to 25-50%
over the Spring Mountains, Lincoln County, and northern Mohave
County. Any amounts will be light, with only a 25% chance of seeing
more than 0.10" QPF in the higher terrain, and only a 10% chance of
seeing 2"+ of snow. Beyond that, the extended forecast looks fairly
quiet as a broad ridge holds through at least Saturday. Towards the
end of the year, forecast uncertainty grows with the EPS maintaining
a progressive storm track to our north while the GEFS has a trough
digging into our area. The latter would obviously be more impactful,
likely bringing increased north winds and maybe some precipitation
chances, but uncertainty remains high this far out.

&&

.AVIATION...For Harry Reid...Light winds will continue into Tuesday
morning before increasing as a storm system moves into the southern
Great Basin.  Wind speeds will remain less than 8 knots through
tonight, with directions following typical diurnal trends.  By
tomorrow afternoon, winds will turn to the southwest as speeds
increase to 15 to 20 knots, and there is a 40 percent chance of
seeing gusts to 20 knots after 00Z tomorrow afternoon.  SCT to BKN
mid and high-level clouds will continue to move across the area with
bases remaining 15kft AGL into tonight. A period of lower clouds
with bases around 10kft AGL is possible tomorrow between 15Z and
20Z. Isolated areas of virga are also possible with these lower
clouds, but the better chance of VCSH will be after 00Z tomorrow
evening.

For the rest of southern Nevada, northwest Arizona and southeast
California...Light winds following normal diurnal trends will
continue at most regional TAF sites into tomorrow morning. By late
Tuesday morning, an approaching storm system dropping into the
southern Great Basin will result in increasing winds along with the
chance of precipitation.  Winds at regional TAF sites will generally
remain below 15 knots through tomorrow afternoon, although higher
gusts will be possible along the eastern Sierra and in the Owens
Valley.  Clouds will also increase with basses falling to 10 to
15kft AGL at most terminals, and scattered showers are possible
after 18Z tomorrow near KBIH, possibly spreading into southern
Nevada by 00Z tomorrow afternoon.

&&

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

&&

$$

DISCUSSION...Woods
AVIATION...Planz

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