Monsoon moisture over northern Arizona brought scattered thunderstorms to the area. One thunderstorm produced heavy rain and street flooding in Prescott.
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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.
Monsoon moisture over northern Arizona brought scattered thunderstorms to the area. One thunderstorm produced heavy rain and street flooding in Prescott.
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 16, 9:50 AM MST, 1 hour 20 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 950 AM MST Thu Aug 16 2018 .SYNOPSIS...A standard monsoon weather pattern will continue across much of Arizona through Friday. Expect scattered mainly afternoon and evening thunderstorms. A drying trend will develop over the weekend, with only isolated storms expected. && .DISCUSSION...Significant debris cloud this morning and a marginally unstable sounding will delay the onset of convection today. The airmass does support a few heavy rain producing cells later today, mainly due to storm motion, rather than instability profiles. Mesoscale models indicate convection initiating over northern Navajo and Apache counties, with a second area over the Mogollon Rim and White Mountains a few hours later. The higher terrain based convection may move southwest or west into Yavapai county late this afternoon and evening. A similar airmass remains in place on Friday, before drying flow develops over the weekend due to the ridge position shifting west. This drying appears to be short-lived as most longer range data indicates the ridge position moving again early next week, along monsoonal moisture back into the area. && .AVIATION...For the 18Z package...VFR conditions expected for the next 24 hours, outside of showers and thunderstorms. A few isolated -SHRA remain over southern Navajo and Apache counties. Scattered to numerous SHRA/TSRA will develop over the higher terrain after 18Z with storms moving southwest into the evening. Light winds through the day, except near storms. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...High pressure aloft will persist over Arizona through Friday, with scattered to numerous showers and thunderstorms continuing. The greatest concentration of activity is expected along and south of the Mogollon Rim. Saturday through Monday...High pressure is expected to shift to the west of Arizona, bringing a downward trend in storm coverage. Only isolated to widely scattered afternoon showers or thunderstorms are expected, mainly from Payson and Flagstaff south and east to the White Mountains. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...Peterson AVIATION...ET FIRE WEATHER...DB/Peterson For Northern Arizona weather information visit weather.gov/flagstaff
The national radar mosaic for the moment the first event began.
1 heavy rain. Local standard time, as filed.
A thunderstorm brought 2.01 inches of rain (county automated gauge) in just over an hour in Prescott. Street flooding was reported in northwest Prescott.
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, August 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: 786244.