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531
FXUS65 KVEF 150927
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
227 AM PDT Sun Sep 15 2024

.SYNOPSIS...
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A large low pressure system dropping down from the
northwest into California and Nevada will bring widespread gusty
south to southwest winds to the region today through Monday along
with a significant cooling trend. A second trough of low pressure
will move across the area midweek bringing a reinforcing shot of
cool air along with scattered showers.
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&&

.SHORT TERM...
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Today through Monday night.

Widespread south-southwest winds gusting 35 to 45 mph will be the
main weather concern across most of our forecast area later today
through Monday as a large closed low digs from the Pacific Northwest
into central California tonight then moves over Nevada Monday and
Monday night. Gusts 30 to 35 mph will be common across the region
this afternoon then a belt of gusts over 40 mph will likely develop
across the western Mojave Desert, Death Valley and Nye County this
evening and persist overnight and Monday. Wind Advisories are in
effect for these zones from 7 PM PDT this evening until 8 PM Monday
evening.

The HREF and NBM indicate occasional gusts over 40 mph will likely
spread across much of northeast San Bernardino, Clark, Lincoln and
Mohave counties Monday morning through early Monday evening. Wind
Advisories are in effect for these zones from 10 AM PDT Monday
morning through 8 PM Monday evening. The slow moving nature of the
system should make this a fairly low-impact event, but it is the
first widespread gradient wind event with gusts over 40 mph of the
fall season. This will usher in a 10-15 degree cooling trend with
temperatures falling into the lower 80s in Las Vegas on Monday and
lows dipping to 55-60 degrees in the Las Vegas Valley Monday night.

A secondary concern is that limited moisture with the system near
the cold pool could also result in a dusting of snow in the Sierra
and White Mountains above 9,000 feet Monday and Monday night.
Scattered light showers and an isolated thunderstorm will also be
possible across northern Inyo, Esmeralda and central Nye counties
Monday.

The latest HREF indicates that moisture that had worked its way up
the lower Colorado River Valley and southern Mohave County will be
too shallow and will be swept east of Mohave County today before
convection has a chance to develop so the chance of showers or
thunderstorms has diminished below 10 percent for that area.

.LONG TERM...Tuesday through Saturday

Lighter winds are expected by Tuesday as the tight pressure gradient
and low level jet moves east along with the trough. However, the
system will leave cold air over the region in its wake. Morning lows
on Tuesday will be 10 to 15 degrees below normal for mid September.
Another deep low will drop down from the Pacific Northwest into the
Great Basin midweek. It should provide some reenforcement for cool
temperatures, keeping highs around 10 degrees below normal through
the end of the workweek. Some guidance is not showing a strong wind
signal with this system, but others highlight the potential for
elevated winds. This will depend on the placement of the trough and
where the tightest pressure gradient will form. Lastly, moisture
advection with the system will bring increased precipitation chances
midweek, particularly in the southern Great Basin. As this system
exits towards the end of the week, Pacific high pressure moves in
behind it and should boost temperatures for next weekend.
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&&

.AVIATION...
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For Harry Reid...Gusty winds will return to the Las
Vegas Valley late this morning into early this afternoon. Wind
direction will vary from 160 to 200 through the afternoon with gust
speeds between 20 and 30 kts (20 percent chance of exceeding 30
kts). Wind direction will become west-southwesterly after sunset
with a high probability (over 70%) of occasional gusts continuing
overnight. Monday will be characterized by gusty southwest winds
through the entire day. No operationally significant cloud cover
through the TAF period.

For the rest of southern Nevada, southeastern California, and
northwestern Arizona...Gusty south winds will pick up across the
region this afternoon with gust speeds between 20 and 30 kts. The
exception is KDAG, which will prevail from the west. Gust speed and
frequency will diminish after sunset, but occasional gusts to 20 kts
should be expected through the overnight period. Hazy skies may
reduce slantwise visibilities in the Daggett and Beatty corridors
from ongoing southern California wildfires. No operationally
significant cloud cover expected through the TAF period.
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&&

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

&&

$$

SHORT TERM...Adair
LONG TERM...Meltzer
AVIATION...Soulat

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