Darwin, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

358
FXUS65 KVEF 111000
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
200 AM PST Wed Dec 11 2024

.SYNOPSIS...Weak high pressure will briefly build into the region
through today which will result in low impact weather. It will be
dry until a series of shortwaves bring possible showers to the
Sierra through central Nevada on Thursday and again this weekend.
Temperatures will remain near-normal through Thursday before
warming the second half of the week. &&

.SHORT TERM...Today through Friday.

Quiet weather is expect today. A ridge of high pressure currently
sitting over the system will break down through the day as a Pacific
system starts moving towards the region, however the main result
from this system today will be abundant cloud cover. Partly to
mostly cloudy skies can be expected today and tonight but no winds
or precipitation is expected through most of the tonight.
Temperatures today and tonight will be comparable or a few degrees
warmer than yesterday.

The previously mentioned Pacific system will then move through the
region on Thursday. Its been interesting what the models try to
resolve this system, especially in the last 24 hours, as each model
run has been strong than the last. Even this morning, there
continues to be disagreement between models about how strong this
low will be when it moves through, but a majority models have a
strong system compared to the previous run. Such is the nature of
ocean systems where weather data is sparse...

The forcing currently highlighted on many models is actually not bad
at all. A decent mid to low level jet will be associated with the
system, and a few models even close the low off compared to an open
wave on others. Potent vorticity advection will also be associated
as a vort max round the base of the trough, and there is even some
upper level difluence to continue the forcing continuity through the
whole column. This system could have been produced a decent
precipitation event as the forcing is there, but the limiting factor
will be the lack of moisture. While the system does link up with a
modest IVT plume, it quickly dissipates as the system moves inland
and much of the moisture is intercepted by the Sierra. PWATs across
all models are at or a bit below normal through the event across the
region and dry low levels are noted on forecast soundings.

The stronger forcing should be enough lift to create at least
precipitation in areas despite the limited moisture. Precipitation
chances have increased from the previous forecast for most areas.
Low chances for precipitation (20%-30%) now overspread most valley
areas Thursday morning and afternoon, with moderate chances (40%-
50%) in the terrain. The higher chance for precipitation will be in
the Sierra where some moisture should at least make it into the
crest and even overspill into the eastern slopes and thus result in
a 60%-70% probability for any precipitation to make it to the
ground.

Will any of the precipitation that falls be impactful is the
question. With the limited moisture, it is not a high risk for
impactful precipitation. Through 4 PM Thursday afternoon, the
probability for any precipitation (greater than 0.01 inches total
rainfall) is highest (80%+) in the Sierra as well as terrain in
northern Lincoln County. Elsewhere, there is a lower chance across
much of the Southern Great Basin and then little to no chances south
of that. Storm total precipitation over 0.10 inches is highest in at
crest of the Sierra, with low chances (20% or less) in the peaks  of
the Spring Mountains and parts of northern Lincoln County. So all in
all, any precipitation impacts will be confined to the Sierra with
little to no concerns elsewhere as precipitation should be light.
Snow levels will be relatively low through the event, around 4000-
5000ft. and will need to watch for even cooler conditions due to
evaporative cooling which could allow for snow in some valleys.
However with the limited nature of the precipitation in general-
winter impacts are also not expected outside eof the terrain in the
Sierra. The WPC Winter Storm Severity Index keeps minor winter
impact potential confined to the peaks of the Sierra where over 6t
inches of snow accumulation is possible with the better moisture
transport. In the mid slopes below 9000ft, only a couple inches of
snow accumulation are expected with limited to no impacts.

With the stronger system, there is now a response from the winds on
Thursday. Winds in the Sierra as well as in the Western Mojave
Desert show the greatest increase and some potential for impactful
gusts as probabilities for gusts over 40 MPH are now 50% or greater.
Given this is a new trend on the latest model and ensemble runs, as
well as the fact that additional changes including more widespread
potential for impactful gusts if the models continue to bring in
this system stronger, so did not issue any wind headlines at this
time. Would like some more time to look at more trends as well as hi-
res wind data before deciding this new increased wind forecast is
something to jump on and that it will remain in the currently
highlighted areas.

The system will exit Thursday night and Friday, taking any
impacts with it. Temperatures Thursday and Friday will remain
nearly steady at or just above normal.

.LONG TERM...Saturday through next Wednesday.

On Saturday, an extention of a closed low pushing into British
Columbia will bring modest mid-level moisture that will get
intercepted by the Sierra Nevada, resulting in slight PoPs along the
Sierra crest. The bulk of the southern Great Basin and Mojave Desert
will get rain shadowed, resulting in no rain at all. That said,
looking at forecast PWAT, moisture values increase across these
areas from 0.10-0.20" on Wednesday to 0.40-0.50" by Saturday.
Looking at GFS forecast soundings, the moisture is likely to remain
mid-level with the bulk of the moisture entering our desert zones as
increased cloud cover. This lack of rain will continue our current
dry streak of 150 days in Las Vegas.

At-or-slightly above average temperatures will continue through the
weekend and into the next work week with the next shortwave of note
pushing through our forecast area Monday night into Tuesday.
Ensembles still have a bit of a discrepancy regarding timing and
depth of Monday night`s wave, which will determine the level of
impacts seen across our forecast area. Current PoPs highlight the
higher terrain of our northern zones with snow levels between 4500
and 5500 feet, though available moisture isn`t currently anything to
write home about.

&&

.AVIATION...For Harry Reid...Winds follow a diurnal pattern with
speeds under 10 knots through tonight. Southwesterly winds shift to
the south later this morning, then to the northeast in the
afternoon. After sunset, winds shift back to the west/southwest. Mid
and high level cloud cover streams through the area today and
tonight with cloud levels at or above 15kft.

For the rest of southern Nevada, northwest Arizona and eastern
California...Diurnal winds with speeds of less than 10 knots are
expected for most terminals today and tonight. The exception is
KIFP, where gusty northerly winds persist through today with peak
gusts between 20 and 25 knots. Mid and high level clouds stream
through the area today and tonight. Rain and snow showers may begin
to enter the Sierra and Owens Valley tomorrow morning but
confidence in timing is low at this time.

&&

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

&&

$$

SHORT TERM...Nickerson
LONG TERM...Soulat
AVIATION...Meltzer

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