Severe Thunderstorm Warning 6, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
1158 AM PDT Sun Jul 17 2022

.SYNOPSIS...Another couple days of monsoonal thunderstorms
expected, favoring the higher terrain. Monsoon moisture retreats
by mid-week reducing rain/thunder chances to below mentionable
levels through the remainder of the week. Temperatures will
remain above-average until next weekend when monsoonal moisture
begins to filter back into the area.

&&

.SHORT TERM...Today and Tomorrow.
This morning's MCV is quite evident spinning over northwestern
Clark County as of 1130AM this morning. This vort max from last
night's convection led to moderate and briefly heavy rainfall
across the county this morning and brought rare rainfall to Death
Valley as well.

Moving into into the afternoon, this MCV will continue to push
northward and wrap around the periphery of the H5 ridge in place.
12Z HRRR takes this and dissipates it moving into north-central NV
as it gets enveloped by the synoptic flow to the north. As it
takes this track, further convection is expected to be enhanced
across Nye and Lincoln counties this afternoon, some of which is
already taking place.

Farther west, another round of Sierra convection is beginning due
to southerly low and mid level flow riding up the Sierra slopes to
the west. While this area isn't as robust from a moisture
standpoint, there is enough instability and minor shearing to
allow some updrafts to grow enough to produce some marginally
severe winds and briefly heavy rainfall. Owens Valley may receive
some 50+ mph thunderstorm outflows or rock/mudslides if these
storms are able to tap into these ingredients this afternoon.

The 12Z HREF again shows a similar pattern to today for tomorrow,
with morning convection in the southern CWA due to another MCS in
Sonora riding up the ridge into the Great Basin. Tomorrow's lacks
a decent inverted trough however so unclear whether this
convection will organize into a MCV or simply push outflow our
direction. HREF members maintain updrafts at least into the lower
CRV for tomorrow morning though so either way, the environment
will continue to be favorable for morning convection again
tomorrow morning which will largely steer the evolution of
convection for the rest of the day.

.LONG TERM...Tuesday through Next Week.
Not much change in the long term expectations. Still expecting
PWAT values to decrease across much of the area and even fall to
below normal for a brief period late week per latest ensemble
meteograms. With the high pressure still in place, heating will
stay above average with subtle vort energy wrapping around the
high. This will set the stage for at least a few days of dry
conditions and confine PoPs to Arizona for the most part. Even
Mohave may have a dry afternoon or two Thursday or Friday, and
rely on convection to the east to kick off outflows for any
precip.

Heading into next weekend, moisture begins to build back into the
Great Basin. A tropical system coming off the coast of Mexico
pushes northwest but out into the Pacific in response to our
entrenched H5 ridge playing blocker. So instead of deep tropical
moisture advecting into the region, the typical northern Mexico
set up should return by next weekend. However, with the ridge
potentially shifted west, much of the upper level features that
lead to more widespread PoP potential may be lacking and high
terrain continues to see the most convection, at least initially.

&&

.AVIATION...For Harry Reid...Light and variable winds should
continue for another hour or two. Once the cloud debris from earlier
storms clears out and stronger heating ensues, winds should favor an
easterly direction, potentially southeasterly. This evening, winds
are expected to turn to the south-southwest persist through the
night. Best chances for thunderstorms outflow will be in the late
afternoon. There could also be a round of thunderstorms tomorrow
morning, similar to what we saw this morning. At the moment,
confidence in this is not overly high, but will be something to
monitor. Erratic and gusty winds will be possible with any storms
that form in the valley. FEW-SCT cumulus this afternoon, with bases
around 12 KFT. SCT-BKN clouds at 12 KFT tomorrow morning as moisture
and potentially precipitation pushes north.

For the rest of southern Nevada, northwest Arizona and southeast
California...Isolated afternoon thunderstorms likely to develop in
northwest Arizona, southern Nevada, eastern San Bernardino County,
and the Sierra crest. Gusty and erratic outflow winds of 30+ mph
will be possible with any nearby storms. Otherwise, generally south
winds are expected to prevail across the area, with KDAG being the
exception. KDAG should see light northeast winds this afternoon
before their typical southwest push this evening. Scattered mid-
level clouds at 10-12 KFT this afternoon. Sites in the Colorado
River Valley could once again see some overnight/early morning
storms, similar to what happened last night.
&&

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

DISCUSSION...TB3
AVIATION...Woods

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