Deep monsoon moisture over northern Arizona and a trough of low pressure passing through Utah made for a rather active day across the area. Thunderstorms produce heavy rain, high winds, and small hail.
Every event with a place to put it. Tap one for its entry below.
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.
The episode as NWS FGZ wrote it up.
Deep monsoon moisture over northern Arizona and a trough of low pressure passing through Utah made for a rather active day across the area. Thunderstorms produce heavy rain, high winds, and small hail.
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 Flagstaff, AZ wrote its last area forecast discussion before the first event at Aug 20, 9:18 PM MST, 2 hours 42 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 918 PM MST Sat Aug 20 2022 .SYNOPSIS...Expect scattered showers and thunderstorms across northern Arizona again on Sunday, with a downturn in activity forecast for early next week. Temperatures will be slightly below average, with generally light winds. && .UPDATE...We currently have an MCS rapidly pulling out of our forecast area to the south, an area stratiform precipitation with embedded heavier showers moving into NW Coconino county, and some scattered storms across Navajo County working to the south. The CAMs (high- resolution models) performed pretty well today with inferring these features, and indicate a slow dissipation of the convective elements remaining across the forecast area tonight. This seems reasonable given the lack of any strong supporting dynamics. The precipitation across N. Coconino appears to be associated with the weak tropospheric wave moving east across UT this evening...and is currently being maintained largey by outflow- enhanced updrafts on it's southwest flank. Given the current environment, this convection could persist for several hours as it works toward the south across western Coconino County. Otherwise, expect most convective elements to decrease as the evening progresses. In any case, scattered thunderstorms are expected again on Sunday, with movement forecast to be to the south once again favoring the areas from the Mogollon Rim to the south with the greatest chances of precipitation. Minor updates were made this evening to account for the evolution of the convection and observed trends. && .PREV DISCUSSION /158 PM MST/...It has been a slow start to thunderstorm activity across our CWA today, but we are beginning to see some storms fire up across northwestern Coconino County and near the White Mountains. Although our 12Z sounding this morning came in lower than what has been seen previously this week, there is still good amounts of moisture in our atmosphere to tap into for the rest of the afternoon/evening hours. Sunday...We'll begin to see the northeasterly flow aloft move in from the high pressure system positioning to our northwest. This wind pattern will shuffle in drier air to the north/northeast portion of our state, limiting the potential for thunderstorm development in these areas. Areas along the Mogollon Rim and south are still forecast to see isolated to scattered showers for the afternoon and evening hours. Monday onward...Storm chances through mid-week will mostly remain for areas along I-40 and south as we continue to have drier air for the north/northeastern portion of our CWA. Around Thursday, model guidance is showing the high pressure system shifting back toward the Four Corners region. If this movement holds true, we could see additional active monsoon days toward the end of next week. && .AVIATION...For the 06Z TAF package...Scatterd -shra and isolated -tsra will continue overnight, with generally light winds across the forecast area. Thunderstorms will develop again on Sunday after 17Z, most numerous along and south of the Mogollon Rim. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered showers and thunderstorms will continue on Sunday, most numerous along and south of the Mogollon Rim, with slightly fewer storms on Monday. Light winds except near storms. Tuesday through Thursday...Expect scattered thunderstorm each day with generally light winds. && .FGZ WATCHES/WARNINGS/ADVISORIES... Flood Watch until 11 PM MST this evening for AZZ008-011-013>018- 037-038-108-111-113>118-137-138. && PUBLIC...BAK/Swenson AVIATION...BAK FIRE WEATHER...BAK For Northern Arizona weather information visit weather.gov/flagstaff
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
608 PM MST SAT AUG 20 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0554 PM HAIL 2 SSE MIDDLE VERDE 34.60N 111.88W
08/20/2022 E0.50 INCH YAVAPAI AZ PUBLIC
TRAINED SPOTTER REPORTS SUSTAINED HALF-INCH
HAIL AND RAIN RATES EXCEEDING 3.5 INCHES PER
HOUR.
&&
BAJSpecial Weather Statement
National Weather Service Flagstaff AZ
625 PM MST Sat Aug 20 2022
AZZ008-037-210215-
Yavapai County Valleys and Basins-Yavapai County Mountains-
625 PM MST Sat Aug 20 2022
...Strong thunderstorms will impact portions of southern Yavapai
County through 715 PM MST...
At 623 PM MST, Doppler radar was tracking strong thunderstorms along
a line extending from near Walnut Grove to near Yarnell to just
southwest of Congress. These storms were moving at 5 to 10 mph to
the south-southeast.
HAZARD...Wind gusts up to 50 mph, up to half inch hail, and heavy
rainfall.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible. Heavy rainfall will reduce visibility.
Locations impacted include...
Congress, Walnut Grove, Wagoner, Yarnell, Peeples Valley, Wilhoit and
Glen Ilah.
This includes the following highways...
State Route 89 between mile markers 258 and 293, and between mile
markers 297 and 298.
State Route 71 between mile markers 100 and 109.
Highway 93 between mile markers 182 and 196.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways. Heavy rainfall will create hazardous driving conditions,
due to reduced visibility and slick roads.
&&
LAT...LON 3422 11245 3400 11275 3400 11305 3415 11297
3435 11277 3444 11253
TIME...MOT...LOC 0123Z 014DEG 4KT 3432 11257 3417 11277 3409 11292
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
JJMSpecial Weather Statement
National Weather Service Flagstaff AZ
713 PM MST Sat Aug 20 2022
AZZ008-037-210300-
Yavapai County Valleys and Basins-Yavapai County Mountains-
713 PM MST Sat Aug 20 2022
...Strong thunderstorms will impact portions of eastern and
southern Yavapai County through 800 PM MST...
At 710 PM MST, Doppler radar was tracking strong thunderstorms along
a line extending from near Yavapai County Fairgrounds to Dewey to
Cordes Lakes to east of Cordes Junction. Movement was south at 5
to 10 mph.
HAZARD...Wind gusts up to 50 mph, up to half inch hail, and heavy
rainfall.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Dewey-Humboldt, Prescott Valley, Cordes Junction, Bumble Bee, Mayer,
and Spring Valley.
This includes the following highways...
Interstate 17 between mile markers 250 and 270.
State Route 89A between mile markers 329 and 330.
State Route 69 between mile markers 263 and 288.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways. Heavy rainfall will create hazardous driving conditions
due to reduced visibility and slick roads.
&&
LAT...LON 3459 11234 3436 11234 3414 11214 3415 11172
3436 11179 3440 11204 3455 11213 3468 11223
TIME...MOT...LOC 0210Z 001DEG 6KT 3464 11224 3447 11227 3432 11209
3429 11191
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
JJMSpecial Weather Statement
National Weather Service Flagstaff AZ
757 PM MST Sat Aug 20 2022
AZZ008-037-210330-
Yavapai County Valleys and Basins-Yavapai County Mountains-
757 PM MST Sat Aug 20 2022
...Strong thunderstorms will impact portions of southern Yavapai
County near Black Canyon City through 830 PM MST...
At 756 PM MST, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles northwest of Horseshoe Reservoir to
Black Canyon City to southwest of Bumble Bee to near Crown King.
Movement was southwest at 15 to 20 mph.
HAZARD...Wind gusts up to 50 mph, up to half inch hail, and heavy
rainfall.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Lake Pleasant, Crown King, Black Canyon City, Rock Springs, Castle
Hot Springs, Horseshoe Reservoir, Turney Gulch Group Campground and
Hazlett Hollow Campground.
This includes Interstate 17 between mile markers 242 and 249.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways. Heavy rainfall will create hazardous driving conditions,
including reduced visibility and slick roads.
&&
LAT...LON 3394 11248 3416 11248 3437 11240 3443 11234
3436 11234 3414 11214 3415 11183 3400 11172
3405 11216 3398 11219 3395 11224 3392 11224
3388 11228
TIME...MOT...LOC 0256Z 055DEG 22KT 3406 11185 3405 11211 3415 11224
3427 11232
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
JJMThe Cedar City radar (KICX), 138 km away, was scanning. The volume nearest the first event began at 07:00 UTC.
6 flash flood, 1 heavy rain, 1 thunderstorm wind. Local standard time, as filed.
Heavy rain in Utah caused a two foot rise on the Paria River just before it joined the Colorado River at Lees Ferry.
Rincon Road at Hassayampa River (normally dry) was close due to flooding. The stream gauge on Martinez Wash at Whickenburg showed a 2 foot rise to 700 CFS rise on this normally dry wash.
Tonto Rreek rose 2.25 feet between 730 AM and 800 AM about 10 miles south of Gisela.
Heavy rain with yard flooding was reported near Dewey-Humboldt. Pea sized hail was also reported.
Cataract Creek/Havasu Creek rose 18 inches at the Supai Gauge.
Agua Fria River rose 8 feet near Humboldt at 515 PM and then rose 4 feet near Cordes Junction rose 4 feet at 815 PM.
The Humbug Creek RAWS reported sustained winds of 36 MPH with gusts to 71 MPH.
Heavy rain caused flash flooding on Big Bug Creek. The water rose to the level of the bridge in Spring Valley. The water almost overtopped South Spring Lane at 635 PM. Photos on social media showed flooding in other areas of the community.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2022Every state in 2022This day in weather historyWarnings in Arizona, August 2022
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: 1055282, 1055279, 1055289, 1055290, 1055293, 1055294, 1055291, 1055292.