Dust Storm and High Wind in Arizona, August 20, 2023

Name: Dust Storm and High Wind in Arizona, August 20, 2023
Start: 2023-08-20T14:14
End: 2023-08-20T15:30
Location: Arizona

August 20, 2023 · NWS PSR · 6 events in 2 counties and zones

Where it happened

Every event with a place to put it; 6 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: $75,000
Crop damage: None recorded
Events: 6

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS PSR wrote it up.

While the heaviest rainfall and flash flooding remained to the west across southern California, Tropical Storm Hilary did bring very strong winds to parts of southwest Arizona, which also led to areas of dense blowing dust. Hilary brought strong low level winds upwards of 50-60 knots at 850 mb and 925 mb, which mixed to the surface at times. As a result, very strong winds at the surface led to instances of damage along with low visibility due to blowing dust across Yuma County. No injuries were reported.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Phoenix, AZ wrote its last area forecast discussion before the first event at Aug 20, 11:16 AM MST, 2 hours 58 minutes earlier.

Area forecast discussion, Aug 20, 11:16 AM MST, 2 hours 58 minutes before

Area Forecast Discussion
National Weather Service Phoenix AZ
1116 AM MST Sun Aug 20 2023

.UPDATE...Updated 18Z Aviation Discussion.

&&

.SYNOPSIS...
Showers and thunderstorms will become increasingly more widespread
today across southeast California and southwest Arizona as highly
anomalous amounts of moisture associated with tropical cyclone
Hilary pushes into the region. This will lead to extreme rainfall
amounts today across southeast California where
significant and possibly locally catastrophic flooding impacts
could occur. Below normal temperatures this weekend will return
closer to normal by the middle part of next week with drier
weather prevailing.

&&

.DISCUSSION...
Latest satellite imagery shows Hurricane Hilary just off the
coast of the central Baja Peninsula accelerating north-
northwestward. The system continues to weaken as it encounters
cooler water and mountainous terrain. However, significant and in
some areas, historic impacts, are anticipated as the cyclone
marches northward as a Tropical Storm through southern California
this afternoon.

Areas of light rain continue out ahead of Hilary, particularly
across southeastern California early this morning. Latest gauges
have only recorded a few hundredths of an inch over the past 3
hours. Further east across Arizona, conditions are considerably
cooler and more moist than they were 24 hours ago. Latest Phoenix
sounding measured PWATs near 2 inches and this is still further
east from the plume of deeper tropical moisture, where latest
mesoanalysis depicts PWATs as high as 2.5 inches across the Gulf
of California. This tropical moisture will continue to be
transported northward and the general consensus from the HREF
indicates the rain bands from Hilary will develop later this
morning across southeastern California.

Training cells, some containing torrential rain will have the
potential to produce a quick inch or two of rain, which will
quickly run off resulting in areas of flash flooding. Latest ECMWF
QPF EFIs approach 100 percent in some spots, particularly between
the Salton Sea and the adjacent eastern slopes of the Peninsular
Ranges, where catastrophic flash flooding is possible. There is
also a moderate risk of flash flooding across the Imperial Valley,
including New River. Further east across portions of southern and
central Arizona, the models clearly show a well-defined dry slot
and the Flood Watch has been canceled.

As Hilary marches northward, peak winds will decrease but the
wind field will expand outward this afternoon. Latest HREF depicts
this well and still indicates max ensemble wind gusts of 60+ mph
across a large portion of southern California. Further east across
central Arizona, latest wind guidance has trended steadily higher
and the Wind Advisory has been expanded eastward to include the
Phoenix area, where gusts could potentially reach as high as 40-50
mph late this afternoon and this evening. Meanwhile, the multi-
model ensemble track guidance has shown little change over the
past 24 hours, with a track likely through San Diego. This will
place portions of southeastern California in the right front
quadrant, which is historically the most favorable for wind shear
and weak tornadoes to develop.

There is also a strong signal in the HREF showing scattered
showers and thunderstorms this evening, partially north and east
of Phoenix. These cells will likely train, resulting in torrential
rain, strong wind gusts and areas of flash flooding. For the
Phoenix area, the greater threat of storms will likely arrive
Monday evening, as moisture and instability linger in the wake of
Hilary. A gradual warming and drying trend is then anticipated
through the week as high pressure across the central US builds and
eventually settles back across the Desert Southwest.

&&

.AVIATION...Updated at 1815Z

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Timing of wind shifts and speed increases have responded a little
slower than originally forecast, but gusty southerly winds will
develop by 19-20Z, with gusts up to 20-30 kts. Briefly higher
gusts to around 35 kts will be possible in showers this afternoon
and evening. Strong winds weaken through the evening, subsiding
around 2-3Z, and transition back to the east tonight. SHRA/TSRA
will also be developing and affecting areas to the north and east
of the Phoenix metro, with mainly VCSH across the terminals.
Chances for VCTS remain too low to mention in the TAFs at this
time. VCSH may persist through tonight and not diminish until
14-16Z Monday. BKN-OVC CIGs aoa 10 kft will be common through the
period with FEW-SCT decks around 5-7 kft expected at times.

Southeast California/Southwest Arizona including KIPL and KBLH:
A band of heavy rain will move into Imperial County over the next
few hours. With this band, strong wind gusts in excess of 50 kts
will be possible. There is also a low chance for a brief tornado.
Intermittent light to moderate rain will follow as showers spread
north with visibilities dropping below VFR conditions at times as
intensity increases. Lesser coverage of showers and storms
expected at KBLH before conditions improve heading into the
evening hours. Any thunderstorms that develop will be capable of
producing very strong winds. Winds through the day will
continually veer clockwise with gusts reaching 30-45 kts. SCT-
BKN decks are generally expected to fall to around 3-5 kft, but
could briefly drop lower in any heavier showers/thunderstorms.

&&

.FIRE WEATHER...
Temperatures will cool below normal for this weekend, especially
across southeast California where highs are forecast to mostly stay
in the 80s. This is in response to increasing clouds and
showers/thunderstorms due to tropical cyclone Hilary. Showers and
thunderstorms will become widespread today, primarily near and
west of the Lower Colorado River Valley where very heavy rainfall
is expected to result in extreme rainfall amounts through the
weekend. Can't rule out some strong winds associated with
thunderstorms today, but chances for these winds in excess of 35
mph look to remain low (up to 30%) across southeast California.
Winds will increase out of the southeast Sunday, especially across
the western districts where gusts in excess of 40 mph will be
possible as tropical cyclone Hilary reaches the southwest CONUS.
Drier and warmer conditions are expected to return by the middle
of next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flood Watch through Monday afternoon for AZZ530>533-535-536.

     High Wind Warning until 11 PM MST this evening for AZZ530>533-
     535-536.

     Wind Advisory until 10 PM MST this evening for AZZ534-538-539-
     559.

     Flood Watch through late tonight for AZZ547-556>558-560>563.

     Wind Advisory from 2 PM this afternoon to 7 PM MST this evening
     for AZZ537-540>544-546-548>551.

     Wind Advisory until 7 PM MST this evening for AZZ553>555.

CA...Flood Watch through Monday afternoon for CAZ560>570.

     High Wind Warning until 11 PM PDT this evening for CAZ562>570.

     High Wind Warning from 2 PM this afternoon to 11 PM PDT this
     evening for CAZ560-561.

&&

DISCUSSION...Hirsch
AVIATION...Benedict/Smith/Lojero
FIRE WEATHER...Smith

In the hours before

Local storm report, Aug 20, 1:29 PM MST, 45 minutes before

Preliminary Local Storm Report
National Weather Service Phoenix AZ
129 PM MST Sun Aug 20 2023

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

0119 PM     Non-Tstm Wnd Dmg 2 E Gordon's Well       32.71N 114.93W
08/20/2023                   Imperial           CA   Dept of Highways

            A couple semi trucks have flipped along I-8,
            blocking traffic.

&&

SB

Local storm report, Aug 20, 1:57 PM MST, 17 minutes before

Preliminary Local Storm Report
National Weather Service Phoenix AZ
157 PM MST Sun Aug 20 2023

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

1209 PM     Non-Tstm Wnd Gst 4 S Yuma                32.65N 114.61W
08/20/2023  M62 MPH          Yuma               AZ   ASOS

0115 PM     Non-Tstm Wnd Dmg 1 S Yuma                32.69N 114.63W
08/20/2023                   Yuma               AZ   Emergency Mngr

            Power outages and several trees blown down
            across Yuma. Wind gusts exceeding 60 mph.

0115 PM     Dust Storm       Somerton                32.60N 114.71W
08/20/2023                   Yuma               AZ   Emergency Mngr

            Visibility down to below 1/8 mile in blowing
            dust. Winds gusting to 55 mph.

&&

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

4 high wind, 2 dust storm. Local standard time, as filed.

High Wind, Yuma

When: August 20, 2:14 PM MST
Where: Yuma forecast zone
Measured: 60 kt (69 mph) measured gust
Reported by: ASOS
Coordinates: 32.769, -113.906 (the zone’s center; the record gives no point)

A 69 mph gust was measured at KNYL.

Dust Storm, Yuma

When: August 20, 2:14 PM MST to 2:44 PM MST
Where: Yuma forecast zone
Reported by: ASOS
Coordinates: 32.769, -113.906 (the zone’s center; the record gives no point)

Visibility dropped down to 1/4 mile at KNYL. Nearby in the Somerton area, emergency management reported visibility below 1/8 mile due to dense blowing dust. No accidents or injuries were reported.

Dust Storm, Gila River Valley

When: August 20, 2:40 PM MST to 3:10 PM MST
Where: Gila River Valley forecast zone
Reported by: Trained Spotter
Coordinates: 32.769, -113.906 (the zone’s center; the record gives no point)

Visibility dropped down to as low as 100 feet at times along I-8 near Tacna due to blowing dust. No accidents or injuries were reported.

High Wind, Yuma

When: August 20, 2:45 PM MST
Where: Yuma forecast zone
Measured: 50 kt (58 mph) estimated gust
Property damage: $50,000
Reported by: Amateur Radio
Coordinates: 32.769, -113.906 (the zone’s center; the record gives no point)

Approximately 12 mobile homes sustained severe roof/shingle damage at the Coyote Ranch mobile home park. Nearby along Fortuna Road, a carport awning was destroyed with part of the awning blocking much of the roadway. Timing and wind magnitude estimated based on nearby observations. No injuries were reported.

High Wind, Yuma

When: August 20, 3:00 PM MST
Where: Yuma forecast zone
Measured: 50 kt (58 mph) estimated gust
Property damage: $15,000
Reported by: Public
Coordinates: 32.769, -113.906 (the zone’s center; the record gives no point)

Several downed power poles were reported on Highway 95 between Pacific Avenue and Araby Road. There were additional instances across the Yuma area of down power lines and downed power poles along with downed trees. No injuries were reported.

High Wind, Gila River Valley

When: August 20, 3:00 PM MST to 3:30 PM MST
Where: Gila River Valley forecast zone
Measured: 50 kt (58 mph) estimated gust
Property damage: $10,000
Reported by: COOP Observer
Coordinates: 32.769, -113.906 (the zone’s center; the record gives no point)

Multiple instances of wind damage were reported along several different roads near the Tacna area, including Avenue 16, Avenue 31, Avenue 36, and Avenue 42. Along Avenues 31 and 36, railroad crossing signals were toppled or damaged. Power lines were reported down along Avenues 16 and 42. Awnings were also destroyed on RVs in the Welton area. Timing estimated based on nearby observations. No injuries were reported.

What these are

High Wind: Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.
Dust Storm: Blowing dust that reduced visibility to a quarter mile or less.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Arizona in 2023 Every state in 2023 This day in weather history Warnings in Arizona, August 2023

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1132514, 1132515, 1132513, 1132741, 1132516, 1132517.