058
FXUS65 KVEF 301734
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1031 AM PDT Sun Jun 30 2024

.SYNOPSIS...Hot and breezy conditions will continue across most
of the region today. Monsoonal moisture will move back into
northwest Arizona today, bringing slight chances for thunderstorms
in eastern Mohave County through the middle of the upcoming week. A
strong ridge of high pressure will build Wednesday through the
Independence Day weekend, with temperatures climbing to dangerous
levels for several days.
&&

.UPDATE...The Rest of Today and Tonight.

Mesoanalysis this morning showed very dry air over much of the
region. The 12Z Las Vegas, NV sounding was laughably dry with PWATs
at 0.25in (about 10% of normal). Of note though, a sneaky moisture
pool was noted in southwest Arizona. PWATs over 1.00 inch and
dewpoints over 60F were noted in area observations in the Sororano
Desert. Satelite imagery showed this moisture sneaking into southern
Mohave County as a band of clouds moving north into the area,
however there has been little surface reflection of this moisture
increase.

Will need to watch the moisture pool and how it may influence the
weather in southern Mohave County this afternoon and early tonight,
especially as breezy south to southwest winds develop in the area.
The latest HREF and hi-res models do develop showers and
thunderstorms that might rotate into southeast portions of Mohave
County after 5PM. This is when HREF shows 30%-40% probabilities for
SB CAPE over 500K/Kg and a brief increase of PWATs to 1.0-1.5
inches. The probability for dewpoints over 60F also increases to 80%-
90% this evening and tonight in areas south of I-40 in Mohave
County. Based on this change in the atmosphere since the previous
forecast and ensemble trends, ensured there was a mention of
precipitation tonight through the area. Focused on the far southeast
corner of Mohave County, will monitor trends and model output to see
if precipitation chances need to be brought further west tonight.
Even with all this, chances will be low (30% or less) and impacts
would be limited. Lightning is noted on HRRR models tonight and with
some midlevel instability seen on model soundings in the area,
lightning will be the main threat. Gusty outflow winds and brief
heavy rain will also be possible. Will need to watch for a potential
outflow winds pushing in from convection that develops further
south. A few hi-res wind models do show a south to southeast outflow
moving through southern Mohave County this evening and tonight, but
no impactful winds were noted.

Across the rest of the region, it will remain dry. Increasing south
to southwest winds are expected with gusts 20 to 30 MPH likely this
afternoon as an upper level shortwave moves into central Nevada
today. With dry conditions and breezy winds, a Red Flag Warning is
in effect for today in Lincoln County where fire starts and and
rapid fire growth potential would be likely. Elsewhere, winds wont
be as strong but with breeziness and dry conditions, there is an
elevated fire danger and people should remain careful if
participating in any activities that could easily start fires.
Otherwise, it will remain mostly sunny across the region this
afternoon. High temperatures will be a few degrees warmer than
yesterday, please drink extra water and use precaution if you have
outdoor plans or are sensitive to the heat.

-Nickerson-
&&


.PREVIOUS DISCUSSION...1230 AM PDT Sun Jun 30 2024
.SHORT TERM...through Tuesday night.

Midnight satellite loop showed clear skies areawide. Surface obs
showed hot temperatures and light winds areawide, and higher
dewpoints over Mohave County, although these had rapidly decreased
in the Colorado River Valley in the preceding few hours. The three
primary concerns this period will be fire weather, thunderstorm
chances, and heat. Fire weather concerns will max out today over
northern Lincoln County, where some high resolution models paint a
few hours of gusts over 35 mph this afternoon. See no compelling
reason to change the existing Red Flag Warning there. Farther south,
winds will also pick up over the Spring Mountains, but since fuels
there are not yet critical, having no warning is the correct call.
Thunderstorm chances today through Tuesday should be pretty skimpy,
with small chances being focused in eastern Mohave County today
where the aforementioned higher dewpoints reside. As far as heat
goes, high temperatures should only increase one to three degrees
through Tuesday, with Moderate HeatRisk expanding but Major and
Extreme remaining nearly absent. This will change for the worse as
we get into the long term period.

.LONG TERM...Wednesday through Saturday.

The extended outlook continues to point to an excessively hot period
setting up for a large portion of our area midweek and beyond.
Wednesday looks like the start of an extended period of dangerously
hot conditions with multiple days of near record or record heat
forecast across the Western Mojave Desert including the Barstow
area, across much of Inyo and central and southern Nye counties
including Death Valley National Park, Pahrump, and Beatty, and in
the Las Vegas Valley. Major to extreme Heat Risk is forecast in
these areas through the period where temperatures could approach,
tie, or even break daily heat records. Probably the biggest forecast
challenge will be in deciphering the daily fluctuation in Heat Risk
levels across areas generally south of the I-15 and how this
information will be best relayed to emergency management officials
and to the public. Moderate to major Heat Risk is indicated
throughout the period with Friday standing out as the peak day
featuring widespread high Heat Risk.

This magnitude of heat is dangerous to everyone and proper safety
precautions are recommended including limiting time outdoors and
staying hydrated.
&&

.AVIATION...For Harry Reid...Light southerly winds will begin
picking up around mid-morning before becoming more increasing
further and becoming more southwesterly during the early afternoon
hours. These 20 to 25 knot southerly to southwesterly winds will
continue into the evening hours when gusts will drop off while winds
continue to maintain a more southerly/southwesterly direction
through the overnight hours.

For the rest of southern Nevada, northwest Arizona and southeast
California...15 to 25 knot southerly to southwesterly wind gusts
will pick up around mid-morning for the Las Vegas Valley and
Colorado River Valley TAF sites. These gusty winds will continue
into the evening hours, with winds continuing to favor a southerly
to southwesterly direction once the wind gusts drop off after
sunset. Winds at KDAG will favor a more westerly direction with 20
to 25 knot wind gusts picking up during the afternoon and continuing
through the evening hours. KBIH will follow typical diurnal
directional patterns through mid-day when winds will swing around to
the southwest and pick up with gusts around 20 knots. These breezy
southwesterly winds will decrease and shift to the northwest in a
typical diurnal fashion around sunset.
&&

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

$$

SHORT TERM...Morgan
LONG TERM...Salmen
AVIATION...Stessman

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