718
FXUS65 KVEF 272106
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
206 PM PDT Sun Sep 27 2026

.KEY MESSAGES...

* Increased chances for showers and thunderstorms arrive Monday
  and Tuesday along with cooler temperatures.

* Stronger storms across the Colorado River Valley and northwest
  Arizona may produce flash flooding, small hail, and strong wind
  gusts.

* Mild weather and warming temperatures are expected during the
  second half of the week.

&&

.DISCUSSION...through next weekend.

Afternoon satellite imagery depicts a deepening West Coast trough
digging southward into northern California. Meanwhile, remnant
mid and high level moisture from Tropical Storm Odalys continue to
stream northward into the Southwestern US, with a broad cloud
shield and some light shower activity developing as far north as
the Las Vegas Valley. These two features will work together over
the coming 48 hours to produce widespread unsettled conditions,
and pockets of heavy rainfall mainly south and east of the I-15
corridor through Tuesday evening. In the meantime, light showers
and localized gusty winds will remain possible through the evening
across southern Nevada associated with increasing moisture above
a dry sub-cloud layer. With DCAPE values of 1000-1500 across the
region, some gusts exceeding 40 mph will be possible, and the KLAS
airport recently gusted to 45 mph as some weak showers moved
overhead.

Moisture will continue to stream northward overnight with light
stratiform precipitation expanding in coverage across Northwest
Arizona and the southern reaches of the Colorado River Valley.
This precip shield will largely be associated with moisture
streaming northward from Tropical Storm Odalys, and will shift
eastward through the day on Monday. Meanwhile, an incoming trough
will approach from northern California through the afternoon
resulting in an increasingly diffluent flow aloft along with
steepening lapse rates as the mid-levels cool. This will result
in expanding instability across the Colorado River Valley and
Northwest Arizona through the afternoon hours. Todays high
resolution guidance continues to struggle on how far west to
initiate convection, but most of the convective allowing models
favor areas near or just east of Las Vegas as the initial storm
development focus area, with activity expanding into the river
valley and northwest AZ through the afternoon and evening hours.
Given the dynamic forcing involved with the incoming low, and
strong southwesterly wind shear, a few severe storms with hail to
quarter size and gusty surface winds will be possible.

Training storms producing pockets of intense rainfall can also be
expected given the deep layer southwesterly shear present ahead
of the incoming low. Given this, the presence of some transient
tropical moisture, and agreement of CAM guidance - expanded the
Flood Watch to include the Colorado River Valley and far southern
Clark County. A few weak showers and storms may also form closer
to the low center across the Sierra and Great Basin, but are not
expected to be of significant impact.

Moisture will wrap around the low as it moves into Arizona on
Tuesday with lingering showers expected across southern Nevada and
northwest Arizona. By Wednesday, the low will shift east with low
amplitude high pressure building back in and a warming trend
commencing.

&&

.AVIATION...For Harry Reid...For the 18Z Forecast Package...
Daily late summer wind pattern expected today for the Las Vegas
Valley including a chance for an isolated shower this evening. Winds
remain fairly light at or under 4 kt this morning, but expect S-SW
winds to increase around and after 19z sustained 10-15 kt with gusts
20-25 kt developing through the rest of the day. An isolated gust 25-
30 kt is possible late afternoon through sunset. Isolated shower
activity is expected this afternoon, with best chances of showers in
the vicinity of the terminal between 22Z and 02Z. Gusts subside
after sunset, but southwesterly winds will remain elevated between 8
and 10 kts overnight. SCT-BKN cigs at or above 15 kft; CIGs down to
10 kft with shower formation overhead. Daily wind pattern expected
again tomorrow, with speeds and gusts slightly lower than today.
Added VCTS after 20z Monday afternoon to account for increasing
confidence in convective development. This threat may persist into
tomorrow night. Any storm will have the capability to produce strong
winds with erratic directions, heavy rain, lightning, and lower
ceilings.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 18Z Forecast Package...Typical daily wind
patterns expected at terminals through the TAF period. Gusty south
winds expected this afternoon across the region around and after
19z, with gusts generally between 20-30 kts. KDAG is the exception
as SW-W winds increase around and after 20z, with elevated winds
continuing into the night. Light shower activity expected around the
Las Vegas Valley and CRV terminals most likely between 20Z and 02Z.
SCT-BKN aoa 15 kft; CIGs down to 10 kft with shower formation
overhead. A stream of steadier rain shifts northward tonight,
impacting KIFP and KEED after 08z...expect lower cigs 10-15kft and
the potential for sporadic gusts with the rain. More widespread
convection expected Monday afternoon and evening for the region,
will update future forecasts accordingly.

&&

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

&&

$$

DISCUSSION...Outler
AVIATION...Moore

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