Thunderstorms caused heavy rain and flash flooding around the Prescott area.
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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.
Thunderstorms caused heavy rain and flash flooding around the Prescott area.
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 3, 9:59 AM MST, 1 hour 16 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 959 AM MST Thu Aug 3 2017 .SYNOPSIS...Expect one more day of scattered thundertorms across northern Arizona Today. A drier and more stable airmass will bring much less storm coverage this weekend into early next week. && .DISCUSSION...Morning satellite imagery shows cumulus development beginning along the Mogollon Rim with more expansive cloud cover to the south. The 12z RAOB from Bellemont this morning was a bit more moist than yesterday with a precipitable water value of 0.88 inches. The 700-500mb lapse rate was also noticeably steeper than yesterday indicating more CAPE available than the past few days as well. We are expecting the most extensive convective development to occur across the western Mogollon Rim with storms moving generally to the north and northeast. The primary threat will remain flash flooding and gusty outflow winds near thunderstorms. Storm intensity and coverage will decrease after sunset this evening. A significant downward trend in showers and thunderstorms is still on track for later this weekend and into next week as dry southwesterly flow increases across the area. && .PREV DISCUSSION /403 AM MST/...Moisture will be a limiting factor for storm formation through the rest of the week, with drier conditions expected through the weekend and into early next week. Isentropic analysis shows moderate moisture remaining in the region through Thursday evening allowing widespread storm development. Southerly steering flow will allow for storms to develop off the higher terrain such as the White Mountains, Mogollon Rim, and Bradshaw Mountains before moving North- Northeastward. By Friday morning dry air associated with a low pressure system off the California coast will begin to move into the Yavapai county and should limit some storm development over the lower terrain Friday. By Saturday the dry air looks to move into most of the Northern Arizona. While some storms will still be possible with this pattern, these storms are expected to be more widespread and less efficient at producing heavy rainfall rates. The dry air looks to be at its maximum extend Monday before an easterly wave moves across the Four Corners region and re- establishes a wetter monsoonal pattern by the later half of next week. Confidence is not strong over the timing of this return to wetter conditions, however model agreement in a return of moisture does have chances of precipitation increasing in the second half of next week. && .AVIATION...For the 18Z package...Scattered showers and thundertorms forming across the Mogollon Rim after 18z. Mostly VFR conditions with MVFR and local IFR with the stronger storms. Storms clearing after 02z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect scattered showers and thunderstorms today and Friday with areas of moderate to locally heavy rain. Gusty winds will develop near any storms. Saturday through Monday...A general drying trend with daily chances for showers and thunderstorms decreasing across northern Arizona, near average temperatures are expected. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...TPS/Suk AVIATION...ET FIRE WEATHER...MAS For Northern Arizona weather information visit weather.gov/flagstaff
Hazardous Weather Outlook National Weather Service Flagstaff AZ 407 AM MST Thu Aug 3 2017 AZZ004>018-037>040-040430- 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- 407 AM MST Thu Aug 3 2017 This hazardous weather outlook is for Apache...Coconino... Northern Gila...Navajo...and Yavapai Counties in Northern Arizona. .DAY ONE...Today and Tonight The most likely initial development will be over the White Mountains and Mogollon Rim later this morning, with storm motion to the North and Northeast. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Moisture begins to decrease across the area limiting storms to a more isolated pattern through the weekend and into early next week. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
The Flagstaff radar (KFSX), 117 km away, was scanning. The volume nearest the first event began at 18:14 UTC.
1 flash flood, 1 heavy rain. Local standard time, as filed.
The USGS river gauge on Granite Creek in Prescott rose 4.42 feet in 30 minutes (11:15 AM to 11:45 AM MST).
A trained spotter reported ponding and running water in streets near Yavapai College. Pea sized hail (1/4 inch) fell for 15 minutes.
Two inches of rain fell near Yava. West Eastwood Wash was flowing over a low water crossing eight to ten inches deep and 150 feet wide. The heavy rain lasted for two hours.
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, August 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: 720426, 720428.