Ample monoon moisture and slow moving thunderstorms brought lightning, heavy rain, and flash flooding to a few locations across 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.
Ample monoon moisture and slow moving thunderstorms brought lightning, heavy rain, and flash flooding to a few locations across 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 Aug 12, 10:35 AM MST, 1 hour 25 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 1035 AM MST Mon Aug 12 2024 .SYNOPSIS...Daily chances for showers and thunderstorms continue through Tuesday, before drier conditions set in for the middle of the week. Monsoonal moisture then looks to gradually return by the end of the week. Temperatures will be near-normal, along with generally light winds. && .UPDATE...The morning sounding showed some drying since yesterday morning (0.94 vs 0.79 inches Pwat). Storm motion today will be from the southeast to northwest at 10 to 15 kts...and may become more southwest to northeast later in the day especially over western Yavapai and Coconino counties. Another active day is in store. && .PREV DISCUSSION /402 AM MST/...Today and Tonight...Another round of showers and thunderstorms is expected later this morning and into this afternoon, with ample monsoonal moisture in place. Storms look to initially develop over the higher terrain later this morning and early this afternoon, then gradually pushing northward off the terrain into the lower elevations through the early evening hours. 00Z HREF guidance forecasts around 1000 J/Kg from northwest AZ and eastward along the Mogollon Rim, thus we'll likely see the greatest coverage over these areas. With ample moisture in place (PWATs around 0.90-1.10 inches) and slow moving storms (~5-10 kts), flash flooding will continue to be the main threats with any storms that develop today. A couple strong to severe storms can't be ruled out, but any organized severe weather seems unlikely given a weakly sheared environment with 0-6 km bulk shear < 20 kts. Latest hi-res and U of A WRF guidance do show a complex of storms moving northward from the Lower Deserts later this evening, which may continue showers and storms into the overnight across central AZ. Confidence isn't all that high given that this will be highly dependent upon the progression of today's storms, but we'll maintain a slight chance through the early part of the overnight. Additionally, some guidance suggests the resulting outflow from this complex may make it further north into northeastern AZ by the early morning hours on Tuesday. Tuesday...Showers and thunderstorms look to return on Tuesday, although coverage may be a bit less and mainly focused to areas along and north of the Mogollon Rim. Flash flooding will continue to be the main threat with any storm. Wednesday through Sunday...Global ensembles continue to get into better agreement with a decrease in monsoonal moisture by mid-week as the upper-level jet becomes wavier and high pressure weakens. As flow shifts more northerly, drier air is advected into northern AZ. Thus, any preciptation chances mainly look to be near the White Mountains each afternoon. Slightly warmer, near-normal temperatures return for Wednesday and Thursday as well. This downward trend however looks to be short-lived. Most of the guidance is in agreement with moisture gradually retuning to the High Country as the high shifts into a more typical position, and subsequently a better flow regime. Thus, cooler than normal temperatures and daily chances for showers and thunderstorms look to gradually return by the end of the week. && .AVIATION...Monday 12/18Z through Tuesday 13/18Z...Mostly VFR conditions are expected with SW winds 10-15 kts this afternoon. Scattered TSRA will develop and move northward throughout the day. Brief MVFR to IFR in +RA and strong outflow winds in excess of 40 kts possible with the stronger storm cells. OUTLOOK...Tuesday 13/18Z through Thursday 15/18Z...MVFR conditions possible in SHRA/TSRA on Tuesday 19Z-03Z. VFR conditions are otherwise expected with mostly dry conditions prevailing on Wednesday. Daytime winds W/SW around 10 kts. && .FIRE WEATHER...Today and Tuesday...Scattered to widespread showers and thunderstorms each afternoon and evening. Heavy rainfall and gusty, erratic winds will be the main threats each day. Otherwise, expected west/southwest winds around 10 mph along with slightly below-normal temperatures. Wednesday through Friday...Mainly dry conditions, outside of a few isolated showers in the White Mountains. West/southwest winds 10-15 mph each afternoon and near-normal temperatures. && .FGZ WATCHES/WARNINGS/ADVISORIES...None. && PUBLIC...MAS/Humphreys AVIATION...MCT FIRE WEATHER...Humphreys For Northern Arizona weather information visit weather.gov/flagstaff
Preliminary Local Storm Report
National Weather Service Flagstaff AZ
1129 AM MST Mon Aug 12 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0756 PM Flash Flood Cornville 34.72N 111.91W
08/10/2024 Yavapai AZ Fire Dept/Rescue
Post event report from Saturday 8/10. Fire
department reported flooding along Harmony,
Oak Run Lane, and Page Springs Road.
Flooding of multiple homes along Alvey and
Brooks Lanes.
&&
MCTThe Flagstaff radar (KFSX), 45 km away, was scanning. The volume nearest the first event began at 18:58 UTC.
2 flash flood, 1 heavy rain, 1 lightning. Local standard time, as filed.
The stream gauge on Chevelon Creek showed a rapid rise of around 4 feet between noon and 200 PM MST. The creek return to near normal levels at around 100 AM MST on August 13.
A spotter 4 miles SSW Washington Park reported two inches of rain in about 45 minutes.
Two people were injured by lightning near the Rim Overlook at Horseshoe Bend.
Heavy rain fell over the Pipeline Fire scar in Weatherford Canyon. This sent a flash flood about 1.5 feet deep down Government Tank Wash. The water covered Waterline Road and Switchback Trail. The water then flowed into the first retention basin just west of Landfill Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2024Every state in 2024This day in weather historyWarnings in Arizona, August 2024
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: 1213044, 1213041, 1213229, 1213043.