350
FXUS65 KVEF 111606
AFDVEF

Area Forecast Discussion National Weather Service Las Vegas NV 910
AM PDT Tue Mar 11 2025

.SYNOPSIS...An upper level low bring rain at times to the
southern Mojave Desert and parts of Mohave County today through the
first half of tonight, however any impacts are expected to be minor
today. The next,stronger and colder storm will impact the region
midweek, bringing widespread rainfall and mountain snows to the
region along with gusty winds. Improving conditions are expected
Friday and Saturday but gusty winds and shower chances will return
by Sunday and into early next week.

&&

.UPDATE...Closed low approaching the southern California coastline
will open up and lift eastward today as it pushes inland. Broad
divergence and an influx of precipitable water values in the 100-
150% of normal range will foster the development of light rain
showers mainly along and south of I-40, with activity becoming more
spotty and of the sprinkles variety further north as far as Las
Vegas. This mornings 12z HREF wants to develop a heavier and more
cohesive band of precipitation in the lower Colorado River Valley
south of Blythe after 00z, that then lifts northeast and may clip
far southeastern Mohave County where heavier totals of 0.25"-0.50"
can`t be ruled out. The current forecast has these trends well in
hand with no further update necessary. Will be taking a closer look
at the ongoing winter weather headlines for the midweek storm system
and considering the needs for wind hazards as well.

-Outler-

&&

.SHORT TERM...Today and Tonight.

Satellite imagery early this morning showed an upper level low
spinning off the southern California coast, as evident by the nice
cyclonic rotation of clouds noted on upper level water vapor. Bands
of cloud cover were being pushed out ahead of the low in response to
increasing moisture and strong upper level diffluence. Radar imagery
showed precipitation blossoming along the California coastline
closest to the low itself. Mesoanalysis showed this is where the
highest PWATs over 0.50 inches were located and overlapped strong
forcing from vorticity advection. Further north and east, all the
moisture was mid to upper levels, thus no rain fell from the clouds.
Overall, its been a quiet night in our neck of the woods as winds
remained light out of the south to southwest and temperatures were 5
to 7 degrees warmer than at this time last night.

The upper level low will move inland through southern California
into Arizona today. Moisture will increase due to moist southerly
flow, with PWATs south of the I-15 climbing to 100% of normal and to
150% of normal south of the I-40 in California and Arizona. The low
itself will being to fall part though and become disorganized as it
moves through the region, transitioning from the nice closed low
with organized forcing to an open wave that will be losing its punch
by the time it gets into Arizona. At first, strong upper level
diffluence and a piece of prefrontal forcing will shift through San
Bernardino County into southern Nevada. Some hi-res models really
want to develop an area of scattered showers with this feature that
would push into Clark County after 4 PM PT. This is possible given
the upper level dynamics, and made to to include a low chance for
precipitation this afternoon, however the low levels will struggle
to saturate as the better moisture lags behind this feature and in
general sets up further south. Not expecting rain or snow impacts
with any showers that make it north of about the Baker, CA to
Laughlin, NV area. Probabilities for over 0.l0 inch of total
precipitation through this evening support this as they are 20% or
less.

Further south, better development is expected as moisture and
forcing combine. Of note, the 06Z HRRR shows multiple rounds of
precipitation south of Barstow, CA through Yucca Valley this
afternoon, then more robust precipitation this evening in southern
Mohave County. NBM probabilities show a 50% chance for precipitation
amounts over 0.10 inches through early tonight in these areas, and
a 30% chance for precipitation amounts over 0.25 inches, so isolated
minor rain impacts are possible if someone is driving and encounters
wet roadways. Overall though, rain impacts will be low. Snow levels
will remain around 6500-7000ft as this will be a warmer system, so
snow impacts will also be limited with warm temperatures and light
precipitation keeping accumulations limited.

The low quickly exits to the east after midnight, taking
precipitation chances with it. Dry weather is expected the second
half of the night.Temperatures will be cooler today compared to
yesterday with the system bringing height falls as well as abundant
cloud cover. South to southwest winds could gust 15-25 MPH at times
this afternoon as the system shifts through the region, with gusts
up to 30 MPH possible in southern Mohave County which will see the
best punch of forcing and pressure gradient to help increase winds.

.LONG TERM...Wednesday through Tuesday.

As Tuesday`s system translates eastward as a dampening open wave
early Wednesday morning, a brief period of low-amplitude ridging
will result in a relative lull between systems for portions of the
area. Deterministic guidance, ensembles, and cluster analyses remain
in very good agreement regarding this system and its evolution, with
its effects expected to first be felt across the eastern Sierra
prior to daybreak Wednesday morning, as heavy snow begins to
overspread the higher terrain. Moisture will spill over the
mountains, first across the Southern Great Basin where rain across
lower elevations and a rain/snow mix across higher elevations is
expected to begin Wednesday morning. Further south, mainly dry
conditions are expected until Wednesday evening and overnight due to
the aforementioned low amplitude ridging, though despite the ridge,
moisture will continue increasing across the region, with an uptick
in gusty southerly winds region-wide Wednesday afternoon onward.
While the greatest probability for gusts in excess of 40 mph exists
across the western Mojave Desert, Inyo County, and the Southern
Great Basin on Wednesday, the higher-end probabilities (60-90%)
through Wednesday evening aren`t as widespread as prior guidance has
suggested. Regardless, these windy conditions will be slow to
diminish, with the wind direction progged to shift to the northwest
with the stronger winds trending southward late Wednesday night into
Thursday as the trough begins pushing through the region. By late
morning Thursday, the strongest winds will be focused along and
south of I-15, with potential for windy conditions to persist across
Mojave Desert zones into Friday.

Widespread precipitation remains the primary focus with this midweek
system, which will maintain as an open wave with an accompanying IVT
plume that will facilitate anomalously high precipitable water
values and the best chance for widespread accumulating precipitation
in some time. The greatest QPF exists across the higher terrain,
especially across the Eastern Sierra where upwards of 1 to 2 feet of
snow are expected, and across the Spring Mountains where 12 to 18
inches of snow are expected. Across lower elevations, guidance
remains consistent in 0.10" to 0.30" of storm total rainfall, and
currently, the most favorable window for substantial precipitation
areawide is from late Wednesday night through Thursday morning, with
precipitation largely exiting to the east by Thursday evening. As
the event ramps up early Wednesday, snow levels begin at roughly
6500-7000 feet, though as colder air filters into the region, snow
levels lower to around 4500-5000 feet coincident with the timing of
the highest PoPs. Thus, greatest snow accumulations in area
mountains are expected above 8000 feet, and Winter Storm Watches
remain in effect for the Eastern Sierra, White Mountains, Spring
Mountains, and Sheep Range. An additional Winter Storm Watch is in
effect for the mountains in the Southern Great Basin above 5500 feet
where confidence is increasing in impactful accumulating snow of 8
to 12 inches. Focus will remain on additional higher terrain across
Mohave County where the Hualapai Mountains could see a brief window
on Thursday for potential substantial snowfall across the highest
elevations as the system exits the region.

Temperatures with this system will be noticeably colder, with highs
10-15 degrees below normal Thursday and Friday. Heading into the
weekend, flow aloft remains weak northwesterly to quasi-zonal,
allowing temperatures to rebound back toward normal, ahead of the
next system early next week. Ensembles  The pattern looks to remain
fairly progressive, with a return to a period of weak ridging for
the upcoming weekend, allowing temperatures to rebound closer to
normal for mid March. Ensembles and cluster analyses are indicating
the next in the series of troughs to take aim on the region early
next week, with potential for another round of precipitation Sunday
night, becoming more widespread through Monday night. However, given
the system early next week is 6 to 7 days out, there remains
substantial uncertainty in the details, thus have maintained the
blended NBM solution for now. Stay tuned.

&&

.AVIATION...For Harry Reid...For the 12Z Forecast Package...Light
winds this morning are expected to turn southeasterly by late
morning, with some gusts over 15 knots possible. A majority of the
model guidance shows a turn to the south or even south southwest
shortly after noon, but the easterly component has been known to
persist longer than expected, so this should be considered. When
winds turn southerly, gusts up to about 20 knots can be expected
into the early evening before speeds decrease. Few to scattered
clouds with bases as low as 6000 feet are expected to arrive in the
early afternoon and persist through the evening; possibly lasting
all night into Wednesday morning on the nearby mountains.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 12Z Forecast Package...A storm system passing
by to the south today and tonight will bring chances of rain
primarily near and south of Interstate 40, beginning in the Barstow
area late this morning and moving east, exiting Mohave County after
midnight tonight. The main concerns will be terrain obscuration and
reduced visibility in and near showers. Lower clouds could cause
concerns as far north as the Las Vegas area, and could even develop
in the southern Great Basin overnight tonight. Winds will also be an
issue today through Wednesday. Gusty southerly winds today are
expected to be strongest in Mohave County, with gusts around 30
knots. After a short lull tonight, southerly winds will increase
areawide Wednesday, with the strongest gusts of 40 to 60 knots
expected over mountains northwest of Interstate 15, likely producing
moderate to severe turbulence.
&&

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

&&

$$

SHORT TERM...Nickerson
LONG TERM...Phillipson
AVIATION...Morgan

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