Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 240338
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
838 PM PDT Sat Mar 23 2024

.SYNOPSIS...Strong southwest winds will gradually diminish
overnight, but linger through Sunday in San Bernardino County.
Expect scattered showers and possibly a rumble of thunder through
Sunday, with light rain amounts in the valleys and light snow
accumulations in the mountains. Sunday will be the coolest day for
most of the region, with temperatures warming back to late March
averages by the middle of the upcoming week. As March comes to a
close next weekend, a deep area of low pressure will usher in more
unsettled weather.
&&

.UPDATE...Recent radar loops showed numerous showers with isolated
brief thunderstorms over much of Mohave County early this evening.
The latest HRRR/HREF indicated these will move out of the county
before midnight. Winds speeds have decreased slightly across the
region after sunset and will continue to diminish overnight across
all but San Bernardino County as the axis of the upper level trough
transitions across our area by Sunday morning resulting in winds
becoming northwest generally 15-25 mph over Inyo County and most of
southern Nevada and far northwest Arizona. Scattered instability
showers under the cold pool of the upper low will develop during the
afternoon as indicated by the latest HRRR and HREF. The forecast was
updated through Sunday afternoon to blend CAM PoPs with the latest
NBM to increase coverage of showers a little more across the valleys
and deserts of southern Nevada and northwest Arizona. -Adair
&&

.PREV DISCUSSION...
152 PM PDT Sat Mar 23 2024

.SHORT TERM...through Sunday night. Wind event was well underway as
of midday, with gusts over 40 mph occurring at quite a few stations,
mostly in Nye and Clark counties. Winds should slowly decrease from
north to south tonight, and strong winds tomorrow should be limited
to the Barstow and Morongo Basin regions. Area radars showed
scattered light returns. One area over far southwest Clark County
was slowly increasing, where visible satellite loop suggested that a
northeastward-propagating trapped lee wave had intersected a
standing wave. Surface dewpoint depressions were still around 30F in
this area, so any rain reaching the ground should be light. Farther
north, lightning detection sensors had noted a handful of flashes
and strikes within about a 50 mile radius of Tonopah. Overnight,
heights will continue to fall as the trough draws closer, allowing
lifted indices to hover around zero, supporting scattered showers
and perhaps even a thunderstorm or two. There will be conflicting
factors on Sunday as the trough axis passes by, but cold temps aloft
keep lifted indices neutral to slightly negative and cyclonically
curved flow remains overhead. Thunder chances would most likely be
limited to Mohave County and adjacent areas of Lincoln and Clark
counties, with shower chances primarily on the higher terrain
elsewhere. High temperatures came down several degrees today from
yesterday, and should come down another five to ten degrees Sunday.

.LONG TERM...Monday through Saturday.

Active pattern expected through the long term period as a series of
weather systems move through the region, bringing cooler than normal
conditions along with periods of gusty winds and mainly mountain
rain and snow showers.  As the weekends trough shifts east on
Monday, a northwesterly flow aloft will take hold Monday and Tuesday
with dry conditions for most of the lower elevations, though some
low chances for showers will persist across the southern Great Basin
and Northwest Arizona with some residual moisture and instability
present.  In the post frontal environment temperatures will remain
cooler than normal both days as well.

By Wednesday, low amplitude shortwave ridge will begin to shift into
the Southwestern states allowing for a brief increase in regional
heights and allowing surface temperatures to climb close to seasonal
normals, though it will likely remain just a touch on the cool side.
Meanwhile, a deepening trough will take shape off the Pacific
Northwest Coast that will bring increasingly gusty winds to the area
for the later half of the week along with cooling temperatures.
Ensemble guidance is struggling with the details of this second
trough, with some members keeping the trough more progressive while
others develop a stronger and deeper trough that digs into the
Southwestern US over the weekend. Regardless of the exact evolution,
confidence is fairly high in a continuation of cool and unsettled
weather for the second half of the week, which may last into the
weekend. Depending on how far south the trough digs into the region,
some shower activity will be a possibility as well. Stay tuned.
&&

.AVIATION...For Harry Reid...Winds will diminish some overnight,
but there is now only a 30% chance of speeds falling below 10kts.
Northwest winds of less than 20kts should develop by late morning
tomorrow and continue through the remainder of the day.

For the rest of southern Nevada, northwest Arizona and southeast
California...Winds will gradually decrease to less than 20kts
overnight and Sunday for most areas except the western Mojave
Desert, including KDAG, where gusty west winds to 35kts will
continue into Sunday afternoon. CIGs should generally remain above
10kft AGL at most terminals, although lower bases are possible near
showers, resulting in mountain obscuration along the Sierra and
higher elevations in southern Nevada.
&&

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

$$

SHORT TERM...Morgan
LONG TERM...Outler
AVIATION...Planz

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