018
FXUS65 KVEF 170732
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1232 AM PDT Mon Jun 17 2024

.SYNOPSIS...A transient weather system will bring gusty conditions
and cooling temperatures to the region today and Tuesday, with
afternoon highs dropping below 100 for all but the lowest
elevations Tuesday afternoon. Thereafter, high pressure will
gradually rebuild with increasing potential for major heat impacts
by next weekend for much of the region.

&&

.SHORT TERM...through Wednesday.

Broad trough across the Western US will keep our weather breezy
and dry today and will help drag a weak late-season cold front
through the region late this evening and overnight. This could be
one of the final cold frontal passages we see reaching the Mojave
Desert until the fall months, as we tend to see cold fronts wash
out further north as we head into the summer season. Temperatures
today will remain warm, though should end up pretty close to dally
seasonal normals thanks to slowly declining heights under the
influence of Western US troughing. Temperatures will tumble
further Tuesday thanks to the passage of a weakening cold front,
with triple digit high temperatures limited to the very lowest
elevations of the Colorado River and Death Valley Tuesday
afternoon. Weak troughing will linger into Wednesday but
temperatures will begin to climb again as high pressure starts to
rebuild to our east.

Meanwhile, the other story will be winds which will remain
elevated again today. The strongest winds will remain focused in
Northwest Arizona, where combined with dry fuels will lead to
elevated fire danger in the area. Gusty west winds will also
continue across the Western Mojave Desert near Barstow. Another
focus of gusty winds will be in our northwestern zones associated
with the incoming cold front, where a few gusts of 35 to 40 mph
are likely in eastern Inyo, Esmeralda, and central Nye Counties.
These gusty north winds will filter down the through the Vegas
Valley and Colorado River Valley tonight while gradually losing
their momentum. Breezy north winds will persist down the Colorado
River Valley into Tuesday.

Aside from the temps and winds, the only other note is related to
air quality and visibility, as we have been plagued with smoke and
haze from wildfires in southern California the past couple days.
The shifting wind flow will tend to focus smoke further south
across the southern Mojave Desert today, mainly south of I-40, and possibly
steer things away from our region Tuesday, providing a brief
respite in the haze and smoke seen yesterday.


.LONG TERM...Thursday through next Monday.

A building ridge of high pressure over northern Mexico will allow
for modest height rises and an increase in temperatures across the
Desert Southwest, despite a persistent longwave trough dominating
the synoptic pattern of the western CONUS. Temperatures will
continue to rise through the end of the week and through the
weekend, with temperatures maxing out at around 10 degrees above
seasonal averages by the end of the weekend. As such, expect desert
valleys to return to the `Major` HeatRisk category on Saturday and
Sunday.

Meanwhile, the National Hurricane Center is currently watching a
disturbance in the Gulf of Mexico with a 60% chance of cyclone
formation in the next 48 hours and a 70% chance of tropical cyclone
formation in the next 7 days. Regardless, this warm tropical
moisture is expected to track westward across Mexico before getting
wrapped up into the monsoonal high pressure (which remains situated
over northern Mexico). As such, moisture will funnel up central
Arizona and as far west as the Colorado River Valley, resulting in
slight chances of precipitation in our eastern and southern zones
through the weekend.

The low levels of the atmosphere remain very dry, so showers and
thunderstorms that form are likely to encounter substantial
evaporation before precipitation reaches the ground. The more likely
scenario will be dry lightning, which could increase chances of
wildfire starts in the area. Will continue to monitor this moisture
flux through the week and update the forecast accordingly. To be
clear, this is unlikely to mark the start of the monsoon, as the
high pressure remains too far south for our area to experience
deeper monsoonal convection.

&&

.AVIATION...For Harry Reid...Southwesterly winds decrease and
become variable early this morning. Gusty southwesterly winds return
in the afternoon with peak gusts of around 25 knots. A weak front
will move through the area in the evening, causing winds to shift to
the northwest with gusts over 20 knots possible. Gusty northerly
winds should start to decrease after sunset. FEW to SCT high clouds
pass over the area in the afternoon and evening.

For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty southerly to southwesterly winds pick up this
afternoon in the Las Vegas Valley and Colorado River Valley. Winds
at these locations will shift to the north to northwest this evening
with the passage of a weak front. Gusts accompany the frontal
passage but should subside later in the night. At KDAG, winds remain
gusty out of the west through the evening. Elevated smoke from
wildfires in southern California may spread over KDAG but should
have minimal impact on aviation. In the Owens Valley including KBIH,
winds maintain a northerly direction with an increase in gusts in
the afternoon and evening. Upper level cloud cover will pass over
the forecast area in the afternoon and evening.

&&

.FIRE WEATHER...Very dry conditions will persist today with
minimum relative humidity dropping below 15% for most areas this
afternoon and evening. A Red Flag Warning is in effect for
AZZ101-102 today due to the very dry conditions and persistent
gusty winds resulting in high fire start and spread risk.
Sustained winds in northwest Arizona will likely exceed 20 mph
for much of the day. Elsewhere, it will be dry but winds will
struggle to jump to impactful levels for an extended period of
time and fuels remain marginal. NVZ460 could reach Red Flag
Warning criteria this evening and early overnight; however, it is
uncertain if fuels are sufficient for considerable wild fire risk.

&&

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

&&

$$

SHORT TERM/FIRE WX...Outler
LONG TERM...Soulat
AVIATION...Meltzer

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