Argus, California Weather Forecast Discussion

765
FXUS65 KVEF 262145
AFDVEF
Area Forecast Discussion
National Weather Service Las Vegas NV
245 PM PDT Fri Sep 26 2025
.KEY MESSAGES...
* Chances of showers and thunderstorms are in this weekend`s
  forecast for southern Nevada, southeastern California, and
  northwestern Arizona.
* Moisture gradually scours out of the region through the work week,
  with a fall-like pattern bringing below-normal temperatures and
  breezy afternoons.
&&
.DISCUSSION...Through Thursday
A cutoff upper level low, currently centered north of Twentynine
Palms, will be the main driver of weather this weekend. Plentiful
moisture along with forcing from the low has already set off
thunderstorm activity early this morning over northwestern Arizona.
One storm produced a gust of 67 mph at 6 AM PDT in Nye County. This
activity should ramp up this afternoon with the introduction of
surface heating, particularly in regions along and south of
Interstate 15. However, this early morning activity may hinder
development later today due to leftover cloud cover and exhausted
atmospheric instability. CAMs have also backed off, pushing the more
active period into the early afternoon rather than late morning.
Heavy rainfall, gusty outflow winds, and small hail are all
possibilities with the strongest storms. The position of the low
becomes favorable for moisture advection on Saturday, sending PWATs
into the 0.75 to 1.50 inch range. The result will be more widespread
POPs and an increased concern for heavy rainfall and flash flooding.
The primary areas to watch for flash flooding are southern San
Bernardino and southern Mohave counties.
The upper level low will track east through Arizona on Sunday,
leading to a reduction in moisture and precipitation potential. The
greatest chances appear to be in northwestern Arizona and far
eastern Nevada, where forcing from the weakening low and lingering
moisture may kick off storms in the afternoon. Dry southwesterly
flow will take its place through the workweek as an upper level
trough moves into the Pacific Northwest. There is some uncertainty
in whether remnant moisture from Hurricane Narda will make it into
the flow, but if it does, POPs linger into Monday and Tuesday.
Outside of precipitation, lower heights aloft allow for below
average temperatures through most of the week.
&&
.AVIATION...For Harry Reid...For the 00Z Forecast
Package...Thunderstorms are expected to track west through Clark
County through at least 01Z this evening. These storms have
produced downpours, small hail, and gusty winds between 40 and 50
mph so far today. They are also expected to bring lower ceilings
down to around 8kft. Outside of any convective influence, winds
will remain relatively light, 10 knots or less, and will follow
typical diurnal directional trends. Additional thunderstorm
development in the Las Vegas area is likely tomorrow afternoon and
evening, but confidence in placement relative to the terminal is
low at this time.
For the rest of southern Nevada, northwest Arizona and southeast
California...For the 00Z Forecast Package...Thunderstorm activity
will continue through the afternoon and early evening across areas
along and south of Interstate 15. These have produced gusty outflow
winds, heavy rain, and low ceilings capable of terrain obscuration.
Away from storms, winds follow diurnal trends with speeds of less
than 12 knots. Another round of storms will begin tomorrow
afternoon, lasting into the evening, at all TAF sites except KBIH.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION/AVIATION...Meltzer
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NWS VEF Office Area Forecast Discussion