Arizona, 2017Dust Storm and Damaging Winds in Arizona, August 4, 2017
August 4, 2017 · NWS PSR · 3 events in 3 counties and zones
Isolated to scattered thunderstorms developed across portions of south-central Arizona on August 4th, and they brought typical monsoon weather hazards to the area such as damaging outflow winds and dense blowing dust. For the most part, the day was not especially active convectively speaking, but gusty winds did blow down several trees near Deer Valley during the mid morning, and during the…
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- Deaths
- 0
- Injuries
- 0
- Property damage
- $13,000
- Crop damage
- None recorded
- Events
- 3
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.
Isolated to scattered thunderstorms developed across portions of south-central Arizona on August 4th, and they brought typical monsoon weather hazards to the area such as damaging outflow winds and dense blowing dust. For the most part, the day was not especially active convectively speaking, but gusty winds did blow down several trees near Deer Valley during the mid morning, and during the evening hours, strong winds in the Ak-Chin area caused localized dust storm conditions and also damaged a trailer, knocking it off of its foundation.
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 4, 5:10 AM MST, 4 hours 43 minutes earlier.
Area forecast discussion, Aug 4, 5:10 AM MST, 4 hours 43 minutes before
Area Forecast Discussion
National Weather Service Phoenix AZ
510 AM MST Fri Aug 4 2017
.UPDATE...
Updated Aviation and Fire Weather sections.
&&
.SYNOPSIS...
Thunderstorm chances will rapidly dwindle through the weekend and
into early next week as dry air spreads into the region. Any
rainfall will be relegated mainly to high terrain locations through
the middle of next week. As the atmosphere dries, temperatures will
also rebound towards near and slightly above average readings.
&&
.DISCUSSION...
In the mesoscale short term, one prominent MCV was lifting north
towards the Las Vegas area while another probable convectively
enhanced vorticity lobe was exiting Arizona into western New Mexico.
This scenario was present under a shifting synoptic pattern where
more amplified Conus flow was becoming dampened, and elongated
subtropical ridging was becoming re-positioned south of the
international border. The resultant deeper westerly flow will
gradually scour away some of the better moisture while also forming
a more laminar, subsident (and convectively unfriendly) pattern
aloft into at least the beginning of next week.
While Thursday evening regional soundings were starting to show some
of this westerly flow and drying aloft, substantial boundary layer
moisture still lingers to the tune of Pwats hovering in the 1.50-
1.75 inch range. With wet soils and standing water from recent
rainfall, near surface moisture will likely hold during the day (sfc-
H8 mixing ratios 12-13 g/kg) while dry air eats away from above
bringing total column Pwats closer to a 1.25-1.50 inch range.
Satellite imagery was already showing good clearing into central
Arizona and afternoon heating should provide good thermal upslope
flow tapping this abundant sfc moisture.
Forecast soundings indicate minimal inhibition by peak heating this
afternoon, but modeling also suggests neutral to subsident flow with
limited convective coverage. Feel scattered thunderstorm coverage
over high terrain areas is a good bet today with only isolated pop
up showers/storms towards lower terrain communities. The biggest
question is the potential presence and depth of outflow boundaries -
with little inhibition, some stronger boundaries could be sufficient
to force more numerous storms given the high near sfc moisture.
However given the paucity of model support, could not get too
aggressive with POPs today.
More pronounced dry westerly flow will envelop the entire southwest
Conus Saturday and Sunday as positive H5 height anomalies become
stationed over northern Sonora. Once again like Friday, near surface
moisture may linger over parts of the forecast area; however, a more
substantial push of dry air aloft coincident with a warming
midtropospheric profile should effectively shut down deep convection
within the forecast area for several days. In fact, some model
output indicates sfc-H7 mixing ratios falling to 7 g/kg with H5
temperatures increasing to -3C by Sunday (net result = Pwat under 1
inch, zero Cape, and no chance at storms).
This drier synoptic pattern should hold into at least Tuesday as the
entire flow configuration upstream and north of the region will stay
blocked. In fact, it could be until the end of next week before
moisture seeps back into the region and the stronger deep westerly
flow relinquishes it influence. In the meantime, there is excellent
operational and ensemble support that central H5 heights near 594dm
will build into SE Arizona during the first half of next week. With
the drier airmass, these heights aloft would result in temperatures
rebounding back into a normal or slightly above normal range.
Certainly looking like nothing record breaking or excessive, but a
distinct change from the cooler more humid conditions of late.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:
Southeast California/Southwest Arizona including KIPL and KBLH:
Far less cloudiness and storm activity today compared to past
couple days as drier air begins moving into the region today.
However, a weak disturbance combined with residual moisture will
keep a slight chance of storms going over the lower
deserts (mainly east of the Lower Colorado River Valley). Better
chances north and east of metro Phoenix. Surface winds will tend
to follow familiar diurnal patterns...except for more westerly
winds for the Imperial Valley as compared to recent weeks.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Sunday through Thursday:
Dry conditions prevail Sunday through Tuesday with minimum
humidities in the teens on the lower deserts. Overnight humidities
decline but remain good. Max temperatures increase somewhat but
only slightly above normal values. Storm chances return to the
higher terrain of south-central Arizona Wednesday and Thursday
humidities begin a modest upward trend during this time. Winds
next week will follow familiar warm season patterns.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
Visit us on Facebook, Twitter, and at weather.gov/phoenix
DISCUSSION...MO
AVIATION...AJ
FIRE WEATHER...AJ
In the hours before
Local storm report, Aug 4, 4:49 AM MST, 5 hours 4 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
449 AM MST FRI AUG 4 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0423 PM TSTM WND GST 7 NE DEER VALLEY 33.72N 112.02W
08/03/2017 M54 MPH MARICOPA AZ MESONET
&&Local storm report, Aug 4, 8:04 AM MST, 1 hour 49 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
804 AM MST FRI AUG 4 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0330 PM TSTM WND DMG 1 SW TONOPAH 33.49N 112.94W
08/03/2017 MARICOPA AZ UTILITY COMPANY
DELAYED REPORT: APS REPORTED 6 POWER POLES
KNOCKED DOWN IN TONOPAH.
&&
ADLocal storm report, Aug 4, 9:29 AM MST, 24 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
929 AM MST FRI AUG 4 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0500 PM TSTM WND DMG 5 W DEER VALLEY 33.68N 112.20W
08/03/2017 MARICOPA AZ PUBLIC
DELAYED REPORT: REPORT AND TIME FROM SOCIAL
MEDIA...DOWNED TREES IN PARKING LOT.
CONFIRMED REPORTS WITH THE STORE (SPROUTS).
&&
ADLocal storm report, Aug 4, 9:51 AM MST, 2 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
951 AM MST FRI AUG 4 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0445 PM TSTM WND DMG 6 ESE DEER VALLEY 33.64N 112.02W
08/03/2017 MARICOPA AZ UTILITY COMPANY
DELAYED REPORT: CITY OF PHOENIX STORM DRAIN
DEPARTMENT REPORTED 2 DOWNED TREES BLOCKING
THE ROAD.
&&
ADLocal storm report, Aug 4, 9:52 AM MST, 1 minute before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
952 AM MST FRI AUG 4 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0445 PM TSTM WND DMG 8 S NEW RIVER 33.80N 112.12W
08/03/2017 MARICOPA AZ UTILITY COMPANY
DELAYED REPORT: CITY OF PHOENIX STORM DRAIN
DEPARTMENT REPORTED SEVERAL DOWNED TREES IN
THE AREA.
&&
ADLocal storm report, Aug 4, 9:53 AM MST, 0 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
953 AM MST FRI AUG 4 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0953 AM TSTM WND DMG 8 N DEER VALLEY 33.78N 112.11W
08/04/2017 MARICOPA AZ UTILITY COMPANY
DELAYED REPORT: CITY OF PHOENIX STORM DRAIN
DEPARTMENT REPORTED SEVERAL DOWNED TREES
ALONG DOVE VALLEY RD.
&&
ADThunderstorm Wind, Maricopa
- When
- August 4, 9:53 AM MST
- Where
- Maricopa County, 7.12 mi NNW of Phoenix Deer Vly Arp
- Measured
- 52 kt (60 mph) estimated gust
- Property damage
- $8,000
- Reported by
- Utility Company
- Coordinates
- 33.780, -112.110
Thunderstorms developed during the morning hours across the northern portion of the greater Phoenix metropolitan area and some of the storms generated gusty and damaging outflow winds. According to the Phoenix storm drain department, at 0953MST gusty winds downed several trees on Dove Valley Road. The downed trees were located about 7 miles north of the Deer Valley Airport. Wind gusts were estimated to be around 60 mph.
Dust Storm, Central Deserts
- When
- August 4, 9:30 PM MST to 10:30 PM MST
- Where
- Central Deserts forecast zone
- Reported by
- Trained Spotter
Isolated thunderstorms developed over the central deserts during the evening hours on August 4th, and some of them produced gusty outflow winds reaching speeds of at least 40 mph. The strong winds picked up dust and dirt and created dense blowing dust, sufficient to briefly cause a dust storm. According to a trained weather spotter located 11 miles southeast of the Ak-Chin village, at 2137MST dense blowing dust briefly lowered visibility below one quarter of a mile. A Dust Storm Warning was not issued however due to the limited areal extent of the dense blowing dust.
Thunderstorm Wind, Pinal
- When
- August 4, 9:37 PM MST
- Where
- Pinal County, 9.92 mi W of Lirim
- Measured
- 61 kt (70 mph) estimated gust
- Property damage
- $5,000
- Reported by
- Trained Spotter
- Coordinates
- 33.026, -112.151
Thunderstorms developed across the far southern portions of the greater Phoenix area during the evening hours and one of the stronger storms generated gusty damaging microburst winds estimated to be as high as 70 mph. According to a trained weather spotter 11 miles southeast of the Ak-Chin Village, around 2130MST gusty winds damaged a trailer in the Hidden Valley area which is to the southwest of the town of Maricopa. The trailer was knocked off of its base by the strong winds. The spotter was passing along the information about the damaged trailer.
- Thunderstorm Wind
- Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
- 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.
- Damaging Winds in Ohio, August 4, 20171 death · $152,000 · 50 kt wind · 10 events
- Flash Flooding in Louisiana, August 4 to 5, 2017$5.0 million · 2 events
- Hail and Damaging Winds in New York, August 4, 2017$286,000 · 1 in hail · 26 events
- Flash Flood and Damaging Winds in Pennsylvania, August 4 to 5, 2017$154,000 · 78 kt wind · 38 events
- Hail and Damaging Winds in Pennsylvania, August 4, 2017$119,000 · 1 in hail · 30 events
- Tornado and Flash Flood in Georgia, August 4, 2017$100,000 · EF1 · 2 events
- Damaging Winds and Lightning Strike in New York, August 4, 2017$56,000 · 65 kt wind · 16 events
- Damaging Winds in Pennsylvania, August 4, 2017$56,000 · 50 kt wind · 7 events
- Hail and Damaging Winds in New York, August 4, 2017$31,000 · 50 kt wind · 14 events
- Hail and Damaging Winds in Ohio, August 4, 2017$33,000 · 1 in hail · 10 events
- Hail and Damaging Winds in West Virginia, August 4, 2017$32,000 · 50 kt wind · 6 events
- Tornado and Flash Flood in New York, August 4, 2017$2,000 · 1 in hail · 29 events
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: 712984, 712985, 712986.