A disturbance moving through Utah kept thunderstorms active in southern Utah well into the evening. Heavy rain over the Paria River drainage in Utah caused flash flooding that flowed into Arizona and the Colorado River.
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The episode as NWS FGZ wrote it up.
A disturbance moving through Utah kept thunderstorms active in southern Utah well into the evening. Heavy rain over the Paria River drainage in Utah caused flash flooding that flowed into Arizona and the Colorado River.
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 5, 8:52 PM MST, 5 hours 8 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 852 PM MST Sat Aug 5 2017 .SYNOPSIS...A few showers or thunderstorms are possible overnight mainly north of Flagstaff. A drier and more stable airmass will move into the region Sunday and into early next week resulting in much less storm coverage. && .UPDATE...Most shower and thunderstorm activity has diminished across the state tonight, with the exception of some isolated storms in far NW Coconino and Mohave Counties along an outflow boundary from storms in Utah. Some isolated storms remain possible along/north of a Grand Canyon to Kayenta line into the early morning hours of Sunday. Otherwise, a trough moving onto the west coast is pushing a gradually drier air mass into the state, first in the mid/upper levels then even the lower levels will dry out later on Sunday and especially Monday and Tuesday. && .PREV DISCUSSION /322 PM MST/...Drier air will become more entrenched over northern Arizona Sunday and into next week as westerly flow increases. Therefore, shower and thunderstorm development will be minimal each afternoon with the best chance to see an isolated storm or two being near the Utah/Arizona border. The remainder of the area is expected to be dry through at least the middle of next week. Long range models indicate a shift back to southerly flow by late next week which will advect back in moisture-rich air into the region. An increase in shower and thunderstorm activity can be expected when that occurs. && .AVIATION...For the 06Z package...Isolated SHRA/TSRA mainly north of KGCN-KRQE line through around 09Z with otherwise VFR conditions prevailing. A drier air mass will lead to only isolated storms Sunday afternoon mainly north of KFLG-KSOW. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect scattered storm activity to continue through this evening and decrease overnight. Drier conditions will develop Sunday with only isolated storms possible mainly north of the Mogollon Rim. Expect a drying trend with lower humidity and warmer temperatures through the middle of the coming week. The dry period looks to persist through at least Thursday of next week. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...JJ/TPS AVIATION...JJ FIRE WEATHER...MCT For Northern Arizona weather information visit weather.gov/flagstaff
Hazardous Weather Outlook National Weather Service Flagstaff AZ 513 AM MST Sat Aug 5 2017 AZZ004>018-037>040-060400- 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- 513 AM MST Sat Aug 5 2017 This hazardous weather outlook is for Apache...Coconino... Northern Gila...Navajo...and Yavapai Counties in Northern Arizona. .DAY ONE...Today and Tonight Showers and thunderstorms will continue to move east to northeast today as a weather disturbance moves east across far northern Arizona. .DAYS TWO THROUGH SEVEN...Sunday through Friday 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 Cedar City radar (KICX), 138 km away, was scanning. The volume nearest the first event began at 08:58 UTC.
1 flash flood. Local standard time, as filed.
Heavy rain in Utah created a flash flood that flowed through the Paria River from Utah to the Colorado River in Arizona. The stream gauge near the Colorado River indicated a two foot rise in the normally dry river bed.
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: 720458.