Flash Flood Warning 216, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
145 PM PDT Sun Aug 21 2022

.SYNOPSIS...Isolated showers and thunderstorms will be possible in
the eastern portions of the forecast area this afternoon and
evening. High pressure will move into and over the region,
ushering in warmer temperatures along with a brief reprieve from
storms as they become isolated in nature. This brief reprieve is
expected to last through Tuesday. Moisture and convective activity
will return in the middle of the week.

&&

.SHORT TERM...through Tuesday.

Another round of isolated showers and thunderstorms will be possible
again this afternoon and evening. The areas most likely to see these
storms are Mohave, Clark, and Lincoln Counties. The latest 850 mb
analysis shows a sharp dewpoint gradient extending from the western
portions of Clark and Lincoln Counties down across the Mojave
Preserve in San Bernardino County. This gradient is expected to
slowly shift to the east over the course of the afternoon and
evening. The dry air aloft behind this gradient will have the
potential to limit convective activity over the western portions of
Clark and Lincoln Counties this afternoon and evening. For the
storms that do end up developing, the primary hazards will be heavy
rain, frequent lightning, and strong gusty winds.

Persistent northwesterly flow aloft will continue to push moisture
eastward on Monday and Tuesday as an upper-level ridge moves over
the area. With the eastward displacement of the deepest moisture to
our east, we see PoPs decrease through early next week. While PoPs
will decrease, 1" precipitable water values will linger in the
southern portions of the forecast area, resulting in chances for
isolated afternoon showers and thunderstorms in Mohave County and
the higher terrain of Clark and eastern San Bernardino Counties.
While the moisture decreases, we will see temperatures gradually
increase to near seasonal values by Tuesday.

.LONG TERM...Wednesday through Sunday.

By Wednesday the ridge will have moved over the Four-Corners Region,
resulting more southerly flow aloft. This will allow for deep
moisture to return to the region. Long-range models show 1.25"-1.75"
PWats moving up the Colorado River Valley into Mohave County,
southeastern Clark County and eastern San Bernardino County. The
current forecast reflects this increase in moisture with slightly
cooler temperatures and more widespread PoPs on Wednesday and
Thursday.

Forecast uncertainty increases beyond Thursday as we prepare to head
into the weekend. Long term guidance shows a potential trough moving
through along the US-Canadian border resulting in the flattening and
westward displacement of the Four-Corner's ridge. Should this happen
it could potentially result in another brief lull in convective
activity as the deepest moisture is pushed out of the area. However,
since this occurs at the end of the forecast period and there are
discrepancies between ensemble members, confidence in the exact
details is low.

&&

.AVIATION...For Harry Reid...East-southeast winds 5-8KTS will
persist through the afternoon. Isolated thunderstorms developing
over the mountains to the north of Las Vegas will likely move across
Lake Mead early this evening. Outflow will likely reach the terminal
and result in northeast or east winds temporarily gusting to at
least to 20KTS 01Z-04Z. Isolated storms in the Mormon Mesa and Peach
Springs corridors should dissipate by 06Z. Winds are expected to
become light S-SW after 05Z and continue overnight and become light
and variable early Monday morning under a mostly clear sky. Isolated
storms will still possible over the mountains Monday afternoon,
but will not likely create impacts in the terminal area.

For the rest of southern Nevada, northwest Arizona and southeast
California...Isolated thunderstorms will move toward the southeast
over parts of southern Nevada and northwest Arizona this afternoon
and evening with the potential for strong outflow winds which may
impact IFP and EED in the Colorado River Valley 03Z-06Z this
evening. Storms should dissipate after 06Z. Most of southeast
California will be free of storms with winds generally less than
12KTS. Winds will be fairly light under mostly clear skies late
tonight through Monday morning. Thunderstorms will be more isolated
Monday afternoon over southern Nevada and northwest Arizona.

&&

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

&&

DISCUSSION...Stessman
AVIATION...Adair

For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
532 PM PDT SUN AUG 21 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0438 PM     TORNADO          22 SE LITTLEFIELD       36.67N 113.64W
08/21/2022                   MOHAVE             AZ   PUBLIC

            MULTIPLE REPORTS OF A TORNADO OCCURRING
            SOUTHEAST OF LITTLEFIELD IN THE ARIZONA
            STRIP. TIME AND LOCATION ESTIMATED BY RADAR
            AND STORM REPORTS.

&&

MS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
607 PM PDT SUN AUG 21 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0606 PM     TSTM WND GST     4 NNE APEX              36.38N 114.89W
08/21/2022  M70 MPH          CLARK              NV   MESONET

            NEVADA DEPARTMENT OF TRANSPORTATION SITE
            MEASURED A 60 MPH THUNDERSTORM WIND GUST AT
            544PM. GUSTED TO 70 MPH AT 554PM.

&&

MW