A thunderstorm with heavy rain produced flash flooding in northern Navajo County.
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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.
A thunderstorm with heavy rain produced flash flooding in northern Navajo County.
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 20, 10:20 AM MST, 4 hours 40 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 1020 AM MST Thu Jul 20 2017 .SYNOPSIS...Expect very active monsoon conditions for the next several days. Local heavy rainfall capable of producing flash flooding remains possible from stronger storms. && .DISCUSSION...The morning sounding at FGZ once again showed a very wet atmosphere (0.96" Pwat) and a light east-southeasterly flow. This means that storms will be slow moving and capable of producing heavy rain (over the same area) which could lead to flash flooding. An area of instability and weak rotation (MCV) was moving through southern Navajo County and into northern Gila/southeastern Coconino County this morning. Showers and isolated thunderstorms are already in progress there. Another active day is expected across northern Arizona! && .PREV DISCUSSION /327 AM MST/....Monsoon moisture will remain entrenched across northern Arizona today. The primary change over the past 24 hours is that high pressure in the mid-levels has shifted further to the east. The result over Arizona will be for the steering flow to point from south to north. Such a flow pattern favors an increase in shower thunderstorm activity across northeast Arizona as storms that form in the mountains and along the Mogollon Rim send outflow boundaries across the Little Colorado River Valley, as well as the Navajo and Hopi Nations. The northeast is a bit drier so storms could produce wind gusts in excess of 50 mph. Otherwise, local downpours of up to an inch will be possible. South of the Mogollon Rim, under this steering flow, there likely will be a downturn in activity with storms more isolated and tending to remain over and near the mountains. We have adjusted the forecast grids to account for this tendency. Still saturated soils across the broad area encompassing Prescott and Payson with isolated 2+ inch downpours and flooding possible. From Friday onward...The steering flow remains south to north on Friday with similar results as described above. A center of high pressure then moves in from over the eastern Pacific for Saturday and Sunday with the steering flow becoming northeast to southwest. We will have to see how the moisture hangs in across central Arizona but under this steering flow typically it is quite active from the Mogollon Rim southward (similar pattern to that of the past few days). Beyond the weekend, monsoon moisture remains entrenched across Arizona with daily thunderstorms continuing. && For the 18Z package...Expect scattered to numerous showers and thunderstorms along and north of the Mogollon Rim, with the potential for scattered showers and thunderstorms initiating along outflow boundaries south of the rim by mid afternoon. MVFR/IFR in heavy rain will be possible under the strongest storms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...The active monsoon conditions will continue with scattered to numerous showers and thunderstorms each day. Heavy rain and gusty winds will remain the primary impact. Expect near average temperatures across the area. Saturday through Monday....Expect daily chances for showers and thunderstorms. No significant changes in the weather pattern are anticipated. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...MAS/McCollum AVIATION...RR FIRE WEATHER...SUK For Northern Arizona weather information visit weather.gov/flagstaff
Hazardous Weather Outlook National Weather Service Flagstaff AZ 338 AM MST Thu Jul 20 2017 AZZ004>018-037>040-210415- 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- 338 AM MST Thu Jul 20 2017 This hazardous weather outlook is for Apache...Coconino... Northern Gila...Navajo...and Yavapai Counties in Northern Arizona. .DAY ONE...Today and Tonight Look for scattered to numerous showers and thunderstorms from the Mogollon Rim and White Mountains northward including the Navajo and Hopi nations. Storms across this area will be capable of wind gusts in excess of 50 mph and local downpours of around an inch. South of the Mogollon Rim activity will be isolated to scattered and tend to remain over and near the mountains. A storm or two south of the Rim will be capable of producing 2+ inches of rainfall with flooding still possible as soils remain saturated in many spots. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Daily thunderstorms will continue into early next week with the usual day-to-day variations of coverage and intensity. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1001 AM MST THU JUL 20 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0330 PM FLASH FLOOD 5 S WASHINGTON PARK 34.35N 111.28W
07/15/2017 GILA AZ PARK/FOREST SRVC
*** 10 FATAL ***
FLASH FLOODING REPORTED NEAR THE JUNCTION OF
THE EAST VERDE RIVER AND ELLISON CREEK IN
NORTHERN GILA COUNTY AZ. SWIFT WATER RESCUE
TEAMS RESCUED 4 PEOPLE. 10 PEOPLE ARE
CONFIRMED DEAD.
&&
TMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1103 AM MST THU JUL 20 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1257 PM FLASH FLOOD 2 S PRESCOTT VALLEY 34.58N 112.32W
07/19/2017 YAVAPAI AZ COUNTY OFFICIAL
YAVAPAI COUNTY EM SOCIAL MEDIA PAGE SHOWED
AT LEAST A 2 FEET RISE IN WATER LEVEL OF THE
ALBERSON WASH UPSTREAM FROM FAIN LAKE AND
LYNX CREEK.
&&
TMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1153 AM MST THU JUL 20 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0915 PM FLASH FLOOD 3 ESE CORDES JUNCTION 34.31N 112.06W
07/19/2017 YAVAPAI AZ MESONET
STREAM GAGE AFMA3 (AGUA FRIA NEAR MAYER)
REPORTED A 5.84 FT. RISE IN WATER LEVEL IN A
45-MINUTE PERIOD FROM 8:30PM TO 9:15PM MST.
&&
TMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1209 PM MST THU JUL 20 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0823 PM FLASH FLOOD 1 NW MAYER 34.41N 112.25W
07/19/2017 YAVAPAI AZ PUBLIC
FLASH FLOOD PHOTO POSTED TO YAVAPAI COUNTY
SOCIAL MEDIA PAGE AT INTERSECTION OF CENTRAL
AVE. AND BIG BUG CREEK IN MAYER. TIME IS
APPROXIMATE.
&&
TMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
204 PM MST THU JUL 20 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0900 PM FLASH FLOOD 4 S TEESTO 35.43N 110.41W
07/17/2017 NAVAJO AZ COCORAHS
COCORAHS REPORT OF FLASH FLOODING NEARBY.
TIME IS APPROXIMATE.
&&
TMThe Flagstaff radar (KFSX), 224 km away, was scanning. The volume nearest the first event began at 22:00 UTC.
1 flash flood. Local standard time, as filed.
Heavy rain from a thunderstorm produced an estimated 2-3 foot rise in the Dinnebito Wash at Navajo Route 41. Time is approximate.
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: 718618.