Monsoon moisture remained over Arizona which lead to the development of thunderstorms. Some storms produced heavy rain and large 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.
Monsoon moisture remained over Arizona which lead to the development of thunderstorms. Some storms produced heavy rain and large 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, 9:14 AM MST, 3 hours 45 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 914 AM MST SAT AUG 20 2016 .SYNOPSIS...Monsoon moisture will remain in place with the potential for shower and thunderstorm activity continuing through the middle of next week. && .UPDATE...This morning's sounding from Flagstaff shows cooling of about 1 to 2 degrees Celcius in the mid-levels compared to yesterday. This will allow for a bit more instability today, with showers and storms first firing in the White Mountains around 10 to 11 AM MST, and then farther northwest along the Mogollon Rim beginning after 11 AM. The steering flow is northeast to southwest, so we will see storms that develop on the Rim move down into Yavapai and northern Gila Counties this afternoon. We may see an MCS develop this afternoon across Yavapai County as storms move off the Mogollon Rim. The main threat with storms today will be heavy rain, which could lead to localized flash flooding, especially across Yavapai County. There will also be a threat for marginally severe hail and gusty winds with the strongest storms. The PoP forecast was updated to increase storm chances across Yavapai and northern Gila counties this afternoon, otherwise, everything else looks good. && .PREV DISCUSSION /331 AM MST/...A low-level high pressure circulation will remain positioned over south central Arizona through Sunday. The circulation around the high will continue to push moisture residing over the Gulf of California/northwest Mexico into Arizona and across the Mogollon Rim. In addition, a weak trough aloft will provide a cooler than normal mid-level air mass and weak upward motion. As daytime heating progresses expect a decent chance of showers and storms both today and Sunday from the Mogollon Rim south with lower chances in drier air to the north. The main threat the next two days will be isolated heavy rainers. From Monday onward...As westerly flow develops through a deep layer, low-level drying and mid-level warming should start to stabilize the air mass over northern Arizona. However, some model conflicts exist. The European model hangs on to just enough moisture for a decent chance of showers and thunderstorms through the week. The GFS is drier with less convective activity. The development of westerly flow aloft usually brings more stable conditions and favors the less convective GFS solution. As a result, the forecast grids will contain a lower chance of showers and thunderstorms from Monday onward but complete shut off isn't likely due to lingering moisture. && .AVIATION...For the 18Z package...Deeper moisture and greater instability over the southern part of the forecast area will support robust thunderstorm development. Sct SHRA/TSRA will develop along and south of the Mogollon Rim early this afternoon...becoming SCT/NMRS late this afternoon through 03Z as the storms slowly move toward the south and west. Generally ISOLD -TSRA expected north and east of a KGCN-KINW line through tonight. Expect MVFR conditions with the stronger storms. Aviation discussion not updated for amendments. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...Mottice/McCollum AVIATION...BAK For Northern Arizona weather information visit weather.gov/flagstaff
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
924 AM MST SAT AUG 20 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0630 PM TSTM WND DMG CAMERON 35.85N 111.43W
08/19/2016 COCONINO AZ WEB REPORT
PHOTO OF BROKEN 4 INCH DIAMETER TREE BRANCH TAKEN AT
CAMERON TRADING POST... STORMS LASTED FROM 530-7 PM
&&
EVENT NUMBER FGZ1600237
041SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1251 PM MST SAT AUG 20 2016
AZZ015-016-202015-
EASTERN MOGOLLON RIM AZ-WESTERN MOGOLLON RIM AZ-
1251 PM MST SAT AUG 20 2016
...SIGNIFICANT WEATHER ADVISORY FOR COCONINO COUNTY UNTIL 115 PM
MST...
AT 1250 PM MST...DOPPLER RADAR WAS TRACKING STRONG THUNDERSTORMS
NEAR MORMON LAKE...OR 19 MILES EAST OF SEDONA. THESE STORMS WERE
NEARLY STATIONARY.
NICKEL SIZE HAIL WILL BE POSSIBLE WITH THESE STORMS.
LOCATIONS IMPACTED INCLUDE...
MORMON LAKE...
DAIRY SPRINGS CAMPGROUND AND DOUBLE SPRINGS CAMPGROUND.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.
&&
LAT...LON 3479 11147 3492 11159 3501 11149 3495 11138
3485 11136
TIME...MOT...LOC 1950Z 207DEG 5KT 3487 11146
MOTTICEThe Flagstaff radar (KFSX), 44 km away, was scanning. The volume nearest the first event began at 19:59 UTC.
2 hail, 2 flash flood. Local standard time, as filed.
A trained spotter reported 3/4 to one inch diameter hail covering the ground in Mormon Lake.
A trained spotter reported 1 1/4 inch hail in Prescott.
Flash flooding was reported in Gisela with washes running high. A few road crossings were temporarily impassible because of the water and deposited debris on the roads.
Martinez Wash rose 5.7 feet in less than an hour.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2016Every state in 2016This day in weather historyWarnings in Arizona, August 2016
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: 659125, 659123, 659124, 659126.