An area of low pressure of the southern California Coast and a jet streak on the east side of the low produced showers and strong thunderstorms over central 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.
An area of low pressure of the southern California Coast and a jet streak on the east side of the low produced showers and strong thunderstorms over central 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 Sep 23, 4:29 AM MST, 31 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 429 AM MST Mon Sep 23 2019 .SYNOPSIS...Showers and thunderstorms are expected today through Wednesday. A few stronger thunderstorms will be possible this afternoon and evening. An unsettled pattern is forecast into next weekend. && .DISCUSSION...Showers and thunderstorms have initiated across southern portions of the CWA early this morning. A low pressure system continues to dig into the Southwest and is currently situated in northwestern Nevada. The primary precipitation band over northern Arizona currently stretches from south of Payson and northeast towards Show Low, but will continue to expand in coverage through this morning. Dewpoint temperatures have gradually increased this morning, especially along and south of the Mogollon Rim as a much more moist airmass was drawn northward overnight. Mesoanalysis of the 850 mb pressure level displays this moist air well and will be a primary ingredient for expanding coverage of thunderstorms throughout today. CAPE values of around 500 - 1500 Joules per kilogram are providing sufficient instability for current thunderstorms and will likely be higher into the afternoon with some diurnal heating. The above described moisture and instability, aided by dynamics associated with the closed low and trough, will create conditions favorable for a slight chance of severe thunderstorms this afternoon. The greatest chances within the Flagstaff CWA are for Yavapai and Gila counties. These thunderstorms will be capable of producing quarter size hail and wind gusts of around 60 mph, besides heavy rainfall. The slight chance for severe thunderstorms was added into the forecast for a portion of these two counties this afternoon and early evening. Remember to have a way to receive the latest weather information and warnings today. Rainfall rates of up to 1 inch per hour are likely from some of the stronger thunderstorms, while localized storm total rainfall of around 3 inches is possible. These moist conditions, especially seen across eastern Yavapai and western Gila counties, have warranted a Flash Flood Watch to be issued. Never drive across a flooded roadway or wash. The center of the closed low will be over southern California by this evening and continue to bring rainfall into the overnight hours for many locations in the CWA. PoPs are similar to earlier forecasts due to the contiued likely nature of thunderstorms within this early overnight period. As the center of the closed low continues to move south, a more east to northeasterly mid- level flow will begin to cut off access to the deeper moisture that will be over the region today. This will create decreased chances for precipitation beginning early Tuesday morning and through Wednesday for areas north of the Mogollon Rim. Scattered thunderstorms and showers are still forecast within this period. Current guidance is in strong agreement that more southeasterly mid- level flow will bring another round of deeper moisture late Wednesday evening. This is the result of a slight northward shift in the center of the closed low (previously situated over far southwestern Arizona). As the highest available moisture is forecast to be southwest of the Four Corners region, chances of precipitation on Thursday were decreased for that region. The core of the low pressure system will move out of northern Arizona by early Friday morning. This will bring a more west to southwesterly flow for Friday and Saturday out ahead of another advancing deep trough. Guidance continues to be in strong agreement on the presence of this deep Pacific Northwest trough. At least slight chances of precipitation will continue through Sunday, mainly in western and southern portions of the CWA. && .AVIATION...For the 12Z package...Areas of showers and thunderstorm will spread from south to north through the morning with widespread precipitation developing during the afternoon and evening hours. Pockets of MVFR/IFR with the stronger and more persistent precipitation areas. Surface winds remaining light outside of any thunderstorm gusts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Showers and thunderstorms will develop ahead of an approaching low pressure system today and will continue through tonight. Some of these storms may be strong and could produce heavy rainfall. The most likely areas for wetting rains will be along and south of a line from the Grand Canyon to Show Low. Shower and thunderstorm chances decrease on Tuesday, with a wind shift to the northeast. .Wednesday through Friday...Unsettled weather will continue with the best chance for additional rainfall from Wednesday night through Thursday. Look for increasing southwest winds Friday, into next weekend. && .FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch from 11 AM MST this morning until 5 AM MST Tuesday FOR AZZ008-018-037-038. && PUBLIC...NL/ET AVIATION...McCollum FIRE WEATHER...McCollum For Northern Arizona weather information visit weather.gov/flagstaff
The Phoenix radar (KIWA), 97 km away, was scanning. The volume nearest the first event began at 12:00 UTC.
2 flash flood, 1 heavy rain. Local standard time, as filed.
A spotter in Black Canyon City reported 3.50 inches of rain 120 PM (in around 8 hours).
Agua Fria River near Old Black Canyon Highway rose 3 feet by 940 AM and was continuing to rise. Water was flowing across Squaw Valley Road (a low water crossing) in Black Canyon City. A spotter in the area had reported 1.80 inches of rain in around 4 hours by 940 AM.
Tonto Creek rose 5.6 feet at the USGS Gauge near Jakes Corner.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2019Every state in 2019This day in weather historyWarnings in Arizona, September 2019
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: 857085, 857086, 857087.