Flash Flood and Damaging Winds in Nevada, August 11 to 12, 2021

Area Forecast Discussion
National Weather Service Las Vegas NV
154 PM PDT Wed Aug 11 2021

.SYNOPSIS...Northwest Arizona will see scattered afternoon and
evening thunderstorms through Thursday. Elsewhere, storms will be
more isolated over the mountains of southern Nevada and southeast
California. Thunderstorm activity should be minimal Friday through
the weekend followed by increasing monsoonal moisture leading to
an upswing in storms early next week.
&&

.SHORT TERM...through Friday night.

The main area to watch this evening will again be central and
southern Mohave County and the lower Colorado River Valley. Though
the pattern setup is similar to Monday evening, the potential for
organized thunderstorms does not look quite as high. The stalled mid
level circulation over southern Arizona will continue to be a factor
in aiding convection this afternoon, but considerable cloud cover
extending across much of central and southern Mohave County was
limiting surface heating and leading to a later start. Recent runs
of the HRRR indicate thunderstorms developing just east of the
Mohave county border in Coconino and Yavapai counties will work
their way down over Peach Springs toward Kingman and Wikieup late
this afternoon and evening, but may not be able to stay together
west of the Hualapai mountains. Elsewhere over southern Nevada and
southeast California, isolated pulse thunderstorms will be possible
over the mountains this afternoon but should dissipate fairly
quickly in a limited moisture environment as they slowly drift to
the west or northwest off the mountains. Gusty winds will be
possible near any of these storms.

Only very subtle changes in the overall pattern are expected
Thursday with moisture lingering over the same areas. Mohave County
will again see the best potential for scattered afternoon
thunderstorms with a continued tendency to propagate toward the
southwest. Light flow aloft and lingering moisture will remain over
the area Friday and it appears the circulation over southern Arizona
will have moved southward and the limited thunderstorm potential
should be driven by surface heating with isolated storms over the
mountains.

.LONG TERM...Saturday through Wednesday.

While Saturday and Sunday once looked favorable for an upswing in
thunderstorm activity, the latest NBM and model ensembles now
indicate Monday though Wednesday should be the period with
increasing chances for thunderstorms. This is due to a strong area
of high pressure over the northwest states that is forecast to
migrate southward and set up over central Nevada which will shunt
the easterly wave over southern Arizona a little more southward. The
high is then forecast to migrate toward the Four Corners which will
turn the flow more southerly across our region by Monday and the
easterly wave stalls around Yuma then slowly lifts northward and
brings an influx of moisture into our region which begins to
interact with a weak broad trough digging from the Pacific northwest
into northern Californian and Nevada. This pattern would support the
higher chances for thunderstorms indicated by the latest NBM PoP
grids though confidence is fairly low on how the various synoptic
features will come together.
&&

.AVIATION...For McCarran...Light winds will transition to easterly
winds around 8KT this afternoon. After that, continuing to watch the
potential for gusty outflow winds this evening. No significant
change to the previous TAF with continued moderate confidence that
south to southeast winds will push through the terminals between 00Z-
03Z this evening. Gusts will likely be between 20-25KT. If this push
of winds does not make it to the terminals, expect typical south-
southwest winds around 8KT this evening. Otherwise, the chance for
thunderstorms around the LAS terminal is low through this evening.
Storms are likely in western Arizona, similar to yesterday, as well
as north of the Beatty area. A few storms are also possible over the
mountains to the west. Other than the convection, quiet weather is
expected with occasional cloud around 15kft through the TAF period.
Thunderstorms are possible again Thursday afternoon, but there
should be more isolated than what is expected today.

For the rest of southern Nevada, northwest Arizona and southeast
California...Expecting similar conditions today  to what develop
yesterday with a complex of storms developing on the Mogollon Rim
and southern Utah then pushing southwest affecting KIGM, KIFP, KEED,
and KHII late this afternoon and evening. Typical thunderstorm
hazards are expected with these storms as they move through the
area. The highest potential for sudden outflow winds will be in the
EED and IFP TAFs where there is increasing confidence for gusty east
to southeast winds around 03Z this evening.

Elsewhere, isolated thunderstorms are possible through southern
Nevada as well as in the higher terrain of Inyo County. These storms
could also generate gusty outflow winds, but given the isolated
nature of these storms, there is a lower chance for impacts at area
TAF sites. Outside of convection, conditions will be VFR with
typical light diurnal winds.
&&

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

SHORT TERM/LONG TERM...Adair
AVIATION...Nickerson

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

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE LAS VEGAS NV
243 PM PDT WED AUG 11 2021

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

0730 PM     TSTM WND GST     10 SSE ESSEX            34.59N 115.21W
08/10/2021  M64 MPH          SAN BERNARDINO     CA   MESONET

            WIND MEASURED AT OLD WOMAN MOUNTAIN.

0242 PM     FLASH FLOOD      15 NNE DOLAN SPRINGS    35.78N 114.13W
08/10/2021                   MOHAVE             AZ   LAW ENFORCEMENT

            PIERCE FERRY ROAD IS CLOSED BETWEEN MP 13
            AND ANTARES RD DUE TO HIGH WATER.

0246 PM     DUST STORM       10 NE CHLORIDE          35.54N 114.09W
08/10/2021                   MOHAVE             AZ   LAW ENFORCEMENT

            SHERIFFS OFFICE REPORTED A DUST STORM AT MP
            26 ON STOCKTON HILL RD. TRAFFIC HAS STOPPED.

0256 PM     FLASH FLOOD      15 NE DOLAN SPRINGS     35.76N 114.10W
08/10/2021                   MOHAVE             AZ   LAW ENFORCEMENT

            ANTARES RD IS CLOSED BETWEEN HWY 66 AND
            PIERCE FERRY ROAD DUE TO HIGH WATER.

0410 PM     FLASH FLOOD      2 SSW NEW KINGMAN-BUTLE 35.23N 114.03W
08/10/2021                   MOHAVE             AZ   AMATEUR RADIO

            INTERSECTION OF MORROW AND BURBANK FLOODED.

0434 PM     FLASH FLOOD      1 SSE NEW KINGMAN-BUTLE 35.25N 114.01W
08/10/2021                   MOHAVE             AZ   AMATEUR RADIO

            8 INCHES OF WATER FLOWING OVER BANK STREET
            JUST NORTH OF THE HIGH SCHOOL.

0530 PM     FLASH FLOOD      14 NNE WIKIEUP          34.91N 113.56W
08/10/2021                   MOHAVE             AZ   DEPT OF HIGHWAYS

            BOGELES RANCH RD CLOSED FROM UPPER TROUT
            CREEK RD DUE TO FLOODING.

0532 PM     FLASH FLOOD      10 N WIKIEUP            34.85N 113.63W
08/10/2021                   MOHAVE             AZ   DEPT OF HIGHWAYS

            HUFFRITTER CLOSED FROM US 93 TO BACK ROAD
            DUE TO FLOODING.

0532 PM     FLASH FLOOD      3 N WIKIEUP             34.74N 113.61W
08/10/2021                   MOHAVE             AZ   DEPT OF HIGHWAYS

            PUMP STATION RD CLOSED FROM US 93 TO BACK
            ROAD DUE TO FLOODING.

0610 PM     TSTM WND DMG     2 NNW LAKE HAVASU CITY  34.52N 114.33W
08/10/2021                   MOHAVE             AZ   PUBLIC

            SHINGLES BLOWN OFF ROOF NEAR N PALO VERDE
            BLVD AND AVALON AVE.

0615 PM     TSTM WND DMG     1 NNW LAKE HAVASU CITY  34.50N 114.33W
08/10/2021                   MOHAVE             AZ   PUBLIC

            NUMEROUS SHINGLES BLOWN OFF A HOME NEAR
            ALPINE DR. AND HAVASUPAI BLVD.

0615 PM     TSTM WND DMG     1 SW LAKE HAVASU CITY   34.48N 114.33W
08/10/2021                   MOHAVE             AZ   PUBLIC

            SEVERAL LARGE TREES DOWN NEAR SMOKETREE AVE
            AND MCCULLOCH BLVD.

0617 PM     TSTM WND GST     2 WSW LAKE HAVASU CITY  34.47N 114.35W
08/10/2021  M59 MPH          MOHAVE             AZ   MESONET

            WIND MEASURED NEAR LONDON BRIDGE IN LAKE
            HAVASU. DATA COURTESY OF EARTH NETWORKS.

0620 PM     DUST STORM       1 ESE DESERT HILLS      34.54N 114.35W
08/10/2021                   MOHAVE             AZ   PUBLIC

            DUST STORM ALONG HIGHWAY 95. VISIBILITY DOWN
            TO LESS THAT QUARTER MILE.

1000 PM     FLASH FLOOD      9 ENE OATMAN            35.06N 114.23W
08/10/2021                   MOHAVE             AZ   DEPT OF HIGHWAYS

            WEST OATMAN HIGHWAY CLOSED FROM RAMADA RD TO
            COOL SPRINGS DUE TO FLOODING. ROAD REOPENED
            AT 6:56AM ON AUG 11.

&&