The Thumb Butte Fire was started by lightning at around 6 AM on July 16 on the South Rim of the Grand Canyon. It eventually burned 8,354 acres before rain stopped the fire from moving.
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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.
The Thumb Butte Fire was started by lightning at around 6 AM on July 16 on the South Rim of the Grand Canyon. It eventually burned 8,354 acres before rain stopped the fire from moving.
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 16, 2:51 AM MST, 3 hours 9 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 251 AM MST Thu Jul 16 2020 .SYNOPSIS...For today, expect a round of scattered showers and thunderstorms across much of the area from the Mogollon Rim northward, with the best chances for storms near the White Mountains. Similar conditions are expected Friday and into the weekend. && .DISCUSSION...For today, satellite and upper-air analysis shows a large ridge of high pressure centered over Texas, with a closed low centered off the coast of SoCAL. Mid and low level water vapor imagery shows a plume of atmospheric moisture and clouds rotating around the high, stretched across New Mexico and eastern Arizona. At the surface, dew points have increased a bit since yesterday, with current observations measuring values in the 40s and 50s. The largest increase has occurred in the Little Colorado River Valley, likely originating from outflow boundaries generated by yesterday's storms. Forecast soundings and HiRes model output predicts another round of weak instability today, generally less than 400 J/kg. However, with the slight increase in moisture comes increasing storm coverage as well. The forecast calls for scattered showers and thunderstorms across much of the area from the Mogollon Rim northward, with more numerous storms in and around the White Mountains. Less coverage is predicted south of the Mogollon Rim, but some isolated storms are possible near Prescott. Similar to yesterday, storm motion will be to the north or northeast at around 10 to 15 mph. We should see storms initiate over higher terrain around 11 am, with the potential for storms and outflow boundaries to drop into valley locations, such as the Little Colorado River Valley, during the early afternoon. Lightning and gusty outflow winds continue to be the primary hazards, although the threat for Flash Flooding is increased today in areas that see training storms. On Sunday and Monday, model forecasts favor the formation of a high pressure center near the Arizona/New Mexico border. At the same time, an easterly wave is forecast to traverse near the mouth of the Gulf of California. With that said, neither of these changes are predicted to initiate a significant low-level moisture surge, but they are worth watching over the coming days as subtle differences in the locations of these features can have significant impacts on the intensity of the monsoon. It's hard to say what the monsoon activity levels will look like during this time. We may end up with extensive mid and high level cloud cover that limits instability and decreases storm coverage. At this point, the current forecast calls for a period of low grade monsoon conditions, but this may change. From Tuesday onward, the general weather pattern becomes less predictable around the middle of next week. Models generally agree that high pressure will remain in place across the area, but it's complicated. Ensemble guidance seems to indicate that dew points will be on the rise during this time indicating the potential for increasing monsoon moisture and thunderstorm activity later in the week. && .AVIATION...For the 12Z package...Expect mostly VFR conditions for the next 24 hours. Surface winds will be light and variable, becoming southwest at 10-15 kts between 17Z today and sunset. Look for scattered showers and thunderstorms producing localized MVFR from 18Z today through 03Z Friday over southern Navajo and Apache counties with isolated storms extending north to the Utah border and west into Coconino county. Aviation discussion not updated for amendments. && .FIRE WEATHER...Expect numerous thunderstorms each afternoon across the southern and central portions of Navajo and Apache Counties and more scattered coverage to the north and over Coconino County. Out flow winds over 40 mph likely with these storms. Saturday through Monday...Expect continued thunderstorm activity over the higher terrain with more coverage to the east in Navajo and Apache Counties and more isolated to the west over Coconino County. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...RR AVIATION...DB FIRE WEATHER...DB For Northern Arizona weather information visit weather.gov/flagstaff
The national radar mosaic for the moment the first event began.
1 wildfire. Local standard time, as filed.
The Thumb Butte Fire was caused by lightning burned 8,354 acres of Havasupai Nation and Grand Canyon National Park Land.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2020Every state in 2020This day in weather historyWarnings in Arizona, July 2020
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: 896893.