419
FXUS65 KVEF 241721
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1021 AM PDT Thu Sep 24 2026

.KEY MESSAGES...

* Warming trend continues through Saturday, with temperatures
  3 to 6 degrees above-normal.

* Isolated-to-scattered thunderstorms expected today in Mohave
  County and portions of San Bernardino County.

* Increasing confidence in clouds, rainfall, and cooler temperatures
  Sunday through Tuesday as tropical moisture surges northward.

&&

.DISCUSSION...Today through Wednesday.

Subtle ridging aloft the next few days will support a warming trend
through Saturday for the southern Great Basin and Mojave Desert. Low
level temperature anomalies slowly increase each day supporting
temperatures about 3-6 degrees above-normal for this time of year.
Expect highs in the 90s to low-100s and lows in the 70s to low-80s
for desert valleys... cooler at higher elevations. A few day period
of cooler temperatures possible Sunday through Tuesday as a trough
approaches the region bringing an increase in clouds and possibly
rain to the region. (More details below on the impacts from this
trough). Highs may struggle to get out of the 80s Sunday through
Tuesday, especially along and south of the I-15 corridor where
better chances exist for rain and thicker cloud cover. Long range
guidance shows ridging building back in for mid-to-late next week
with higher confidence for near to above-normal temperatures
persisting into early October.

Generally dry conditions for the majority of the Mojave Desert and
southern Great Basin the rest of the week, with the exception of
Mohave County and portions of southern San Bernardino County where
isolated storms will be possible this afternoon and evening. Weak
troughing sits off the coast of Southern California while ridging
builds over Texas and the southeast, placing Arizona and the Four
Corners in a modest baroclinic zone with numerous waves riding
northward through it. Short term guidance continues to depict a mid
level wave tracking northward into Central Arizona, working to
advect greater moisture northwestward into the area and providing
lift for afternoon/evening showers and thunderstorms. While moisture
is only marginal with PW at or under 1.00 inch, enough lift from the
aforementioned wave plus orographic lifting from local terrain
should be enough to spark off convection. SBCAPE and MUCAPE are only
marginal as well, mainly under 750 J/kg, but still enough to support
convective development. DCAPE is more substantial around 1500 J/kg
lending to a localized damaging wind threat under the strongest
storms. At this time, expect isolated storms with brief periods of
heavy rain, lightning, and gusty winds. Any convection that develops
will weaken quickly after sunset with the loss of heating and
increasing subsidence in the wake of the departing/weakening wave.

Friday and Saturday look to be the dry days region-wide, then focus
shifts to a deepening trough taking shape over the West Coast Sunday
through Tuesday. Deterministic and ensemble guidance are coming into
better agreement today that tropical moisture from both Hurricane
Odalys and Hurricane Polo will be drawn northward ahead of the
trough as early as Sunday. Despite better agreement today, ECMWF EFI
still shows ensemble agreement only around 50% for significant
rainfall outside of climatology for this time of year for portions
of the region. There are still discrepancies among guidance in the
northward extent of the deeper moisture, exact track of the storms,
and timing of features, which overall affects where potentially
significant impacts will be. Confidence is slowly increasing that
areas along and south of the I-15 corridor could be impacted by
clouds, rain, and cooler temperatures... but lower confidence as to
what extent. It is still too early to tell where the greatest threat
for any prolonged heavy rain or flooding could be; however, this is
a set up to keep a close eye on. Despite the uncertainty, breezy to
gusty southerly and southwesterly winds return over the weekend
ahead of this feature due to a tightening pressure gradient, and as
the trough translates inland, falling heights will result in a
cooling trend starting Sunday that will carry through early next
week. Details will be ironed out in coming days.
&&


.AVIATION...For Harry Reid...For the 18Z Forecast Package...Overall,
winds will generally remain less than 10 knots through Friday
morning and follow typical daily diurnal directional trends. There
is a 20 percent chance of seeing a gust or two to 15 knots out of
the southeast (130 to 170 degrees true) between 22Z and 01Z,
although any gusts should be short lived. Model guidance continues
to indicate a low chance (10 to 20 percent) of breezy southeasterly
outflow winds from convection over Arizona moving into the valley
during the late evening (05Z to 07Z). Winds on Friday are expected
to remain light, with speeds remaining below 8 knots. No
operationally significant cloud cover is expected through the TAF
period.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 18Z Forecast Package...Light winds will persist
at most area terminals through the TAF period. The exception will be
in the northern Owens Valley, including KBIH, where southerly winds
with a few gusts to around 20 knots are possible this afternoon and
early evening. A few thunderstorms are possible this afternoon and
evening, mainly south of I-15, including KDAG, KEED and KIFP. Gusty
outflow winds will be the main concern, with the best chance of
direct impacts at KEED and KIFP. CIGs may also fall below 10kft AGL
near activity. Elsewhere, VFR conditions are expected. All sites
should see diminishing cloud cover overnight and Friday morning. &&


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

&&

$$

DISCUSSION...Moore
AVIATION...Planz

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