Deep monsoon moisture was in place over northern Arizona which allowed strong thunderstorms to develop.
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.
Deep monsoon moisture was in place over northern Arizona which allowed strong thunderstorms to develop.
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 15, 9:55 AM MST, 3 hours 50 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 955 AM MST Sun Jul 15 2018 .SYNOPSIS...The monsoon weather pattern will persist over Arizona through next week, with daily rounds of showers and thunderstorms. The main threat with storms today will be heavy rainfall and localized flooding. && .UPDATE... No significant changes this morning to the forecast as convection begins to fire off the higher terrain and close to the center of circulation still apparent on satellite imagery. Main concern will be be the flash flood threat from these efficient storms that do not have much of steering flow and will be slow to move off their initiation point. Wetter conditions near the surface will enhance rainfall efficiency compared to model soundings earlier this morning that showed a decent dry layer near surface. A flash flood watch will remain in effect from 11 am today through 8 pm tonight. && .PREV DISCUSSION /358 AM MST/...At 3 AM it was mostly cloudy across northern Arizona with some breaks in the clouds over Apache County. The ridge axis was located just north of the area with a cyclonic circulation embedded in the flow centered in Gila County and evident in satellite imagery and radar loops. Scattered showers have developed on the north side of the circulation throughout southern Yavapai and NW Gila counties. Deep moisture persists over all of the region with precipitable water values around 1.00" in the mountains and closer to 1.50" for the lower elevations of Yavapai/Gila counties. These values are around 140% of normal for mid July. Later today, areas that clear enough to get some sun and sfc heating should see thunderstorm development. With fairly weak steering flow and deep moisture, localized heavy rainfall and flash flooding will be the primary threat. Much of Yavapai and western Coconino counties have seen heavy rain the past several days which increases the flooding threat there. High resolution models suggest initial storm formation over the higher terrain including the Mogollon Rim & White Mtns by around noon. These storms should then drift west or southwest toward Yavapai and northern Gila. However, with all the morning cloud cover and shower activity, it remains to be seen if these areas will destabilize enough for stronger convection and heavy rainfall. We considered a Flash Flood Watch for these areas but prefer to monitor cloud cover and issue later this morning if clearing occurs. Monday through Wednesday - high pressure begins to strengthen north of the state, placing our region in a bit faster easterly flow of 10-15kt at 500 mb. Moisture remains plentiful with storms expected to develop over the high country each afternoon and move toward the west into lower elevations. There will still be a heavy rain threat but it will be somewhat lower due to the enhanced easterly flow. Thursday through Saturday - high pressure is forecast to strengthen further and become centered over New Mexico. Moisture values remain sufficient for daily rounds of showers and thunderstorms. Warmer temperatures aloft could cause lower storm coverage however, with storms focused more over the higher terrain. Daytime temperatures will also increase to near or above normal levels. && .AVIATION...For the 18Z package... Scattered showers continue to develop south of the Mogollon Rim this morning. Scattered to numerous -SHRA/-TSRA will start up again over higher terrain after 18Z. Local MVFR/IFR conditions with gusty and erratic winds are possible near stronger thunderstorms. Aviation discussion not updated for TAF amendments. Storms will begin to decrease after 03z with isolated showers continuing through the overnight hours. && .FIRE WEATHER...Scattered to numerous thunderstorms with a threat of heavy rain each afternoon/evening will continue through Friday. Light winds will produce slow moving storms with heavy rainfall. Moisture will begin to decrease by the weekend in to next week with thunderstorm coverage becoming more isolated. Gusty and erratic winds may develop near thunderstorms. && .FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch until 8 PM MST this evening FOR AZZ004>008- 012>018-037-038. && PUBLIC...Suk/JJ AVIATION...ET FIRE WEATHER...ET For Northern Arizona weather information visit weather.gov/flagstaff
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
751 AM MST SUN JUL 15 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0645 AM FLASH FLOOD 1 WNW LEES FERRY 36.88N 111.61W
07/15/2018 COCONINO AZ MESONET
PARIA RIVER AT LEES FERRY GAUGE RECORDED A
CREST OF 7.60 FEET, A 3 FOOT RISE FROM BASE
FLOW. AT 6:45 AM MST.
&&
JDSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
755 AM MST SUN JUL 15 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0330 AM FLASH FLOOD 12 NW LEES FERRY 36.96N 111.76W
07/15/2018 COCONINO AZ PUBLIC
INFERED FROM PARIA RIVER AT LEES FERRY GAUGE
RECORDING A CREST OF 7.60 FEET, A 3 FOOT
RISE FROM BASE FLOW. AT 6:45 AM MST.
&&
JDSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1050 AM MST SUN JUL 15 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0515 PM FLASH FLOOD 7 NE K'AI'BII'TO 36.66N 110.97W
07/14/2018 COCONINO AZ DEPT OF HIGHWAYS
FLASH FLOODING CAUSED A BRIDGE TO WASHOUT
LIKELY NORTH OF AZ HWY 98 ALONG INDIAN ROUTE
6330 FROM A SEVERE THUNDERSTORM THAT PASSED
TO THE WEST OF THE WASHOUT LOCATION. THE
PICTURES AND REPORT WERE PROVIDED BY A
MEMBER OF THE ROADS DEPARTMENT OF NAVAJO
NATION.
&&
NLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1115 AM MST SUN JUL 15 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0300 AM HEAVY RAIN 10 SSW SECOND MESA 35.66N 110.57W
07/15/2018 E1.60 INCH NAVAJO AZ OFFICIAL NWS OBS
HEAVY RAIN CAUSED WATER IN THE POLACCA WASH
(GAUGE POLA3) NEAR SECOND MESA TO RISE BY
1.61 FEET BETWEEN 1000 Z (AT 5.81 FEET) ON
AND 1025 Z (AT 7.42 FEET). BY 1730 Z, WATER
BEGAN TO RECEDE AT POLA3, TO A RECORDED
LEVEL OF 6.91 FEET.
&&
NLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
118 PM MST SUN JUL 15 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0115 PM HEAVY RAIN 1 SW FLAGSTAFF MALL 35.21N 111.60W
07/15/2018 E2.50 INCH COCONINO AZ PUBLIC
HEAVY RAINS LEADING TO REPORTS OF URBAN AND
SMALL STREAM FLOODING FOR THE EAST FLAGSTAFF
AREA. THE DURATION OF THE HEAVY RAIN EVENT
WAS 45 MINUTES.
&&
NLPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
131 PM MST SUN JUL 15 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0127 PM FLASH FLOOD 2 E DOWNTOWN FLAGSTAFF 35.19N 111.61W
07/15/2018 COCONINO AZ PUBLIC
FLOODED URBAN ROADWAYS AND LOW-LYING AREAS
IN MUCH OF EAST FLAGSTAFF. VIDEO
DOCUMENTATION OF A FLASH FLOOD AT THE
INTERSECTION OF BUTLER AVE AND FOURTH
STREET.
&&
NLThe Flagstaff radar (KFSX), 174 km away, was scanning. The volume nearest the first event began at 20:47 UTC.
2 heavy rain, 1 flash flood, 1 hail. Local standard time, as filed.
Arizona Department of Transportation reported flooding on State Route 264 in several locations between Steamboat (mile marker 430) and Burnside (mile marker 438). The road was closed for several hours as a preventative measure. ADOT was clearing debris off the road.
Heavy rain from thunderstorms caused flash flooding in the northern drainages of the Schultz Fire scar. The impacts were along Copeland Avenue northward to Wupatki Trails. Water was flowing over roads and drainage ditches were overtopped.
A public rain gauge reported 1.80 inches of rain in less than 3 hours ending at 0400 PM MST.
Radar and other rain gauges estimated between 3 and 5.90 inches of rain over parts of the area. This represents between a 100 year and a 1000 year rainfall event.
Three homes had flood damage inside, other structures and outbuildings suffered flood damage, and 2 residences requested debris removal. Coconino County road crews spent up to 2 weeks removing debris, mud, and rocks from water channels and roads.
Hail damaged approximately 1000 cars in shopping centers and car dealerships.
Heavy rain was reported on Highway 89 with water running across the roadway. Cars could still make it through the flooded section of highway.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2018Every state in 2018This day in weather historyWarnings in Arizona, July 2018
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: 778684, 778673, 778697, 778685.