Abundant moisture and forcing from an inverted trough moving across northern Arizona brought strong thunderstorms with heavy rain and strong winds. A flash flood watch was in effect for the eastern portions of northern Arizona.
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.
Abundant moisture and forcing from an inverted trough moving across northern Arizona brought strong thunderstorms with heavy rain and strong winds. A flash flood watch was in effect for the eastern portions of northern Arizona.
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 Jul 24, 9:08 AM MST, 5 hours 22 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 908 AM MST Mon Jul 24 2017 .SYNOPSIS...Widespread showers and thunderstorms are expected across northern Arizona through this evening. Some of the storms could produce heavy rainfall, and a Flash Flood Watch is in effect for areas generally north of I-40. Another round of scattered thunderstorms will develop Tuesday. A decrease in storm coverage is anticipated starting Wednesday, especially across western and central Arizona. && .UPDATE... The flash flood watch for areas generally north of I-40 through midnight looks good. Area radars show strong tstorms around the Phoenix area this morning. Southerly flow aloft is transporting moisture droplets from these storms northward, which has produced a well defined line of steady stratiform rain along a line from William-Sedona then east of I-17. This area should persist for a few more hours, with rainfall rates of .10-.30 per hour. We did see come clearing across southern Apache county earlier, though now convection is starting to develop around Show Low. Scattered showers now north of Hwy 264 will continue northward. && .PREV DISCUSSION /500 AM MST/...Deep monsoon moisture remains entrenched over the state this morning with well above normal precipitable water values. The inverted trough that we have been tracking the past couple days is located over central Arizona and is forecast to move up into northwest Arizona by this afternoon. Widespread mainly light showers with isolated thunderstorms have developed over the past few hours, covering much of northern and central Arizona. As the feature slides north through the day, expect numerous showers to continue, though cloud cover and near moist adiabatic atmospheric profiles are expected to keep instability down for at least the southern half of the forecast area. Could still be a few heavy rainers, but we felt the coverage would be more localized. Farther north, there is a better chance for some breaks in the clouds to allow sfc heating and higher instability. This could lead to higher rainfall rates in the storms generally north of a Flagstaff to Window Rock line. In coordination with NWS offices to our north, we have issued a Flash Flood Watch from 11 AM to Midnight MST for these areas. By Tuesday, the inverted trough feature will be north of the state, but deep moisture will linger. Instability should be higher than today for most areas, so a round of scattered afternoon/evening thunderstorms is likely. Wednesday through Thursday - some drier air enters central and western Arizona with a decrease in storm activity. Moisture lingers along the AZ/NM border with scattered storms. Friday into the weekend - high pressure centered near the four corners will result in a moistening east to southeast flow for northern Arizona. A return to more typical monsoon storm coverage is forecast. && .AVIATION...For the 18Z package...Many areas south of Interstate 40 are expected to see steady rainfall, along with some embedded moderate showers. In this area, persistent MVFR conditions will develop. North of Interstate 40, stronger storms are forecast to develop, with brief periods of MVFR/IFR visibilities in heavy rainfall possible. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect above normal storm activity and high relative humidity through Monday. Slightly drier and more stable conditions arrive Tuesday, bringing activity back down to normal levels. Wednesday through Friday...Chances for showers and thunderstorms will continue, but coverage and frequency should decrease. Slightly drier and warmer conditions near the surface will enhance the threat for gusty outflow winds, associated with thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch through this evening FOR AZZ004>007-009>012- 039-040. && PUBLIC...DL/JJ AVIATION...McCollum FIRE WEATHER...RR For Northern Arizona weather information visit weather.gov/flagstaff
Hazardous Weather Outlook National Weather Service Flagstaff AZ 317 AM MST Mon Jul 24 2017 AZZ004>018-037>040-250300- Kaibab Plateau-Marble and Glen Canyons-Grand Canyon Country- Coconino Plateau-Yavapai County Mountains- Northeast Plateaus and Mesas Hwy 264 Northward-Chinle Valley- Chuska Mountains and Defiance Plateau- Little Colorado River Valley in Coconino County- Little Colorado River Valley in Navajo County- Little Colorado River Valley in Apache County- Western Mogollon Rim-Eastern Mogollon Rim-White Mountains- Northern Gila County-Yavapai County Valleys and Basins- Oak Creek and Sycamore Canyons-Black Mesa Area- Northeast Plateaus and Mesas South of Hwy 264- 317 AM MST Mon Jul 24 2017 This hazardous weather outlook is for Apache...Coconino... Northern Gila...Navajo...and Yavapai Counties in Northern Arizona. .DAY ONE...Today and Tonight Abundant monsoon moisture will combine with a weather disturbance to produce widespread showers and thunderstorms today. Some of the heavier showers will be capable of producing rainfall amounts of one to two inches, leading to localized flash flooding. The highest threat of heavy rain today is generally north of a line from Seligman to Flagstaff to Window Rock. A Flash Flood Watch is in effect for these areas from 11 AM to Midnight MST. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Scattered afternoon and evening thunderstorms are expected Tuesday, some with locally heavy rainfall. A decrease in storm coverage is expected Wednesday before increasing again by Thursday or Friday and continuing through the weekend. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1140 AM MST MON JUL 24 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0230 PM TSTM WND DMG 1 S MIDDLE VERDE 34.60N 111.89W
07/23/2017 YAVAPAI AZ PUBLIC
WIND GUST ESTIMATED AT 50 MPH. AWNING AND
TREE DAMAGE AT RANCHO VERDE RV PARK.
&&
DMThe Flagstaff radar (KFSX), 63 km away, was scanning. The volume nearest the first event began at 21:28 UTC.
2 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Wind gusts from a thunderstorm (estimated at 50 MPH) damaged trees and an awning at an RV park in Camp Verde.
Four or five low water crossings were flooded on Indian Route 15 between Cornfields and Highway 77. All crossings were passable.
Chinle Police received a report of water flowing across a road near Tselani and Cottonwood at 330 PM MST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2017Every state in 2017This day in weather historyWarnings in Arizona, July 2017
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: 718972, 718990, 718996.