044
FXUS65 KVEF 012013
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
113 PM PDT Mon Sep 1 2025

* Monsoonal moisture returns tomorrow with scattered thunderstorms
  possible across western and southern portions of the CWA.

* Thunderstorm chances linger into the second half of the week as
  increased moisture levels remain in place over the eastern third
  of the CWA.


.DISCUSSION...This afternoon through Sunday.

A ridge of high pressure building eastward across the area will
maintain above normal temperatures and widespread "Moderate" Heat
Risk levels, with pockets of "High" Heat Risk in the lower desert
valleys, including Death Valley, Pahrump Valley, the southern
portions of the Las Vegas Valley, and the Colorado River Valley. The
one exception to this will be in the higher elevations of Mohave
County, where isolated thunderstorms capable of producing gusty
winds are possible into this evening.  As the ridge shifts further
east into the more traditional Four Corners location tomorrow, an
increase in a southerly moisture influx is expected.  At the same
time, a shortwave will push into the California Coast.  The forcing
from the shortwave, along with PWATs increasing to over 1.00" across
the southern two-thirds of the CWA, will increase storm chances and
coverage tomorrow and Wednesday, with moderate-to-heavy rainfall,
isolated flash flooding, and frequent lightning being the primary
hazards.

By the second half of the week, the ridge will weaken and shift to
the east, scouring the moisture out in a northwest-to-southeast
direction.  Precipitation will generally be confined to our eastern
zones by Friday, but may linger in these areas through the weekend.
Temperatures will also fall to below normal levels by mid-week and
remain cooler than normal into the weekend.

&&

.AVIATION...For Harry Reid...For the 18Z Forecast Package...Light
northeast winds will continue into the early afternoon before
turning to the southeast by 21Z.  Sustained speeds should remain
less than 10 knots, although a few gusts to 15 knots will be
possible.  Speeds will decrease around sunset, and directions should
settle into their typical southwest downslope pattern.  Similar wind
patterns are expected on Tuesday.  VFR conditions will prevail into
tonight.  Model guidance continues to show an area of weak
showers/virga moving across the valley around sunrise, followed by a
better chance of scattered thunderstorms tomorrow afternoon and
evening.  The best chance of convective impacts at the terminal will
be after 21Z, when gusty outflow winds to 30 knots, lightning, and
CIGs down to 10kft AGL will be possible.   Temperatures will top out
around 104F today with readings exceeding 100F between 20Z and 04Z.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 18Z Forecast Package...Smoke from wildfires
burning on the west side of the Sierra has begun to move into the
Owens Valley late this morning.  Visibility has remained 7SM or
greater at KBIH, although brief periods of lower visibility will be
possible through early afternoon.  Once the southeast winds develop
around 20Z, improving conditions are expected.  Elsewhere, generally
good conditions are expected today with winds remaining less than 12
knots.   An isolated thunderstorm is possible over the higher
terrain of northwest Arizona this afternoon, but all other areas are
expected to remain dry.  Scattered thunderstorms are expected to
develop across much of the region tomorrow afternoon as monsoonal
moisture returns to the area.

&&


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

&&

$$

DISCUSSION...Planz
AVIATION...Planz

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