Damaging Winds in Nevada, May 20 to 21, 2023

Area Forecast Discussion
National Weather Service Las Vegas NV
146 PM PDT Sat May 20 2023

.SYNOPSIS...Expect another day of scattered afternoon and evening
showers and thunderstorms across much of the region on Sunday
before presistent troughing and dry southwesterly flow slowly
scours out the moisture and brings an end to shower chances by
Thursday. Above normal temperatures will continue until Wednesday
before more seasonal temperatures overspread the area heading into
the weekend.

&&

.DISCUSSION...A shortwave moving into the Pacific Northwest on
Sunday will act to nudge the persistent high pressure ridge east
of us over the Intermountain Range. Although this signals the
beginning a shifting weather pattern, highly anomalous moisture
and weak to moderate instability remains in place resulting in
another day of scattered afternoon and evening thunderstorms.
Storm coverage is expected to be rather widespread with at least a
slight chance in nearly every zone in our forecast area. Primary
concerns will again be gusty winds and dangerous lightning. Based
on the HREF, there should be plenty of sunshine to begin the day
with forecast high temperatures remaining several degrees above
normal.

To begin the work week, the moisture profile is shifting with our
southern areas seeing some drying in the mid-levels but still
above what would be considered normal. The 150-250% of normal
precipitable water values remain over our northern areas and these
areas will continue to be under the threat of afternoon/evening
thunderstorm activity. Some areas including the Western Mojave
Desert and Colorado River Valley are forecast to see afternoon
southerly breezes. By Tuesday, most areas will be dry and windy
but a chance of showers continue across our far northern Nevada
zones.

Temperatures on Monday and Tuesday are forecast to approach the
century mark in Las Vegas but the current probability of reaching
100 degrees at Harry Reid AP on either day is less than 10%.

Wednesday through Saturday...

A much quieter period is anticipated. There is a small but
lingering chance of showers over parts of southcentral Nevada on
Wednesday before dry conditions settle over our entire area
Thursday through Saturday. Troughing influences over the western
states will return temperatures to a more seasonal level late in
the week with afternoon breezes continuing.

&&

AVIATION...For Harry Reid...Very similar setup to yesterday. An
easterly wind less than 10 kts will be favored through much of the
afternoon with storms developing over the mountains north and west
of the valley. Best time for minor to moderate impacts at the
terminal from thunderstorms and resultant strong outflow gusts looks
fall between 00Z-03Z. Gusts up to 35kts could occur, potentially
warranting an AWW if so. Activity should dissipate around 03-04Z
leading to partly cloudy skies and winds less than 10 kts overnight
into Sunday morning. Another day of thunderstorm forecast over the
higher terrain tomorrow which could bring gusty outflow winds to the
valley once again in the late afternoon or early evening
hours.

For the rest of southern Nevada, northwest Arizona and southeast
California...Isolated to scattered TSRA expected across the region
this afternoon and evening, and again Sunday. All regional terminals
can expect at least VCTS after 21Z both days, with possible outflow
impacts as well, with gusts up to 30-35 kts, possibly 40+ kts not
out of the question, but probability for that is low at any
terminal. Coverage should wane significantly by the late evening,
but wind direction confidence is very low due to remnant outflows
expected to be prominent across the region.

&&

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

&&

DISCUSSION...Salmen
AVIATION...Pierce

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