A very strong area of high pressure that brought record heat to northern Arizona in the previous few days started to move eastward. This allowed a southerly flow to develop over the area transporting moisture northward from Mexico.
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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.
A very strong area of high pressure that brought record heat to northern Arizona in the previous few days started to move eastward. This allowed a southerly flow to develop over the area transporting moisture northward from Mexico. This moisture allowed for the development of scattered showers and thunderstorms over parts of 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 Jul 17, 2:05 PM MST, 2 hours 45 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 205 PM MST Mon Jul 17 2023 .SYNOPSIS...A strong area of high pressure will continue to bring very hot conditions for much of Arizona well into next week. This same area of high pressure will begin to stream monsoonal moisture northward as early as today, with chances for showers and thunderstorms expected for the remainder of the week. && .DISCUSSION...Today...Showers and thunderstorms have begun to develop early this afternoon along the Mogollon Rim as moisture increases across Arizona. Surface dewpoints 50-60 deg F along and south of the Rim then falling off to 30-40 deg F near the Utah border. PWATs on the 12Z FGZ sounding however remain a bit low at 0.40", although to the south the PHX sounding has 1.47", so we expect some increase this afternoon as moisture continued to advect northward. Showers and thunderstorms are expected to continue to increase through the afternoon, largely controlled by outflows from the initial convection over the higher terrain along the Mogollon Rim then along and south of the Rim. 12Z HREF guidance and U of A WRF guidance all show the greatest coverage mainly from Flagstaff westward into the Coconino Plateau and the Santa Maria Mountains. Later this evening, the HRRR continues to indicate the potential for storms to be a bit more prolonged over Yavapai County as they move off the high terrain. Model soundings this afternoon still show an inverted-v profile, given the dry air in the lower levels. Thus, gusty winds will be the main threat today. Given the uncertainty in the amount of moisture available, the threat of localized flash flooding can not be ruled out, however the overall risk is minimal. Additionally, the strength of the high directly overhead will be a big factor in coverage today. Over eastern Arizona, closer to the center of the high, strong subsidence will limit upward motion, thus limiting the potential for precipitation development. If this subsidence inversion aloft remains further west, coverage will be more limited across a larger potion of the area. Tuesday...The center of the high pressure will continue to shift eastward through Tuesday. Moisture advection will continue to increase, with more scattered coverage in showers and thunderstorms expected on Tuesday. Based on the latest CAM guidance, the threat for storms should shift to areas along and north of the Mogollon Rim. Debris cloud from remnant overnight convection may limit destabilization over Yavapai and the Coconino Plateau. While the ridge has shifted east, it still remains strong, thus upward motion may be reduced and reduce overall coverage of storms. Wednesday through Sunday...The ridge begins to wobble through the southwest for the second-half of the week. Daily chances for showers and thunderstorms look to remain, however moisture is less plentiful. Thus, the greatest chances look to mainly be along the Mogollon Rim and into the White Mountains. Above normal temperatures also look to continue with the ridge nearly overhead. Thus, Excessive Heat Warnings and Heat Advisories remain across all of northern and central Arizona through at least Friday. However, if the ridge remains in place, these may need to be extended further. && .AVIATION...For the 00Z TAF Package...Scattered TSRA/SHRA will be possible 20Z-03Z mainly south and west of a KPGA-KSOW-KSJN line. Some storms may linger near KPRC through 06Z. MVFR restrictions and gusty, erratic winds will be possible in around around TS. VFR conditions are otherwise expected, with W winds 10-15 kts, gusting 20-25 kts then subsiding to around 5-10 kts after 03Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Today through Wednesday...Showers and thunderstorms will be possible each mainly along and south of the Mogollon Rim today, and along and north of the Rim on Tuesday and Wednesday. Gusty winds, lightning, and brief heavy rainfall will be possible. Mainly light southwest around 10-15 mph each afternoon, with gusts 20-30 mph. Thursday through Saturday...Hot temperatures and drier conditions are expected towards the end of the week. Storm coverage will mainly be limited to the Mogollon Rim and White Mountains. Westerly winds gusting to 20-30 mph expected each afternoon. && .FGZ WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM MST /9 PM MDT/ Friday for AZZ004>018- 037>040. Excessive Heat Warning until 8 PM MST /9 PM MDT/ Friday for AZZ005-018-037. Excessive Heat Warning until 8 PM MST Saturday for AZZ006. && PUBLIC...Humphreys AVIATION...Humphreys FIRE WEATHER...Humphreys For Northern Arizona weather information visit weather.gov/flagstaff
Special Weather Statement
National Weather Service Flagstaff AZ
327 PM MST Mon Jul 17 2023
AZZ008-037-172300-
Yavapai County Valleys and Basins-Yavapai County Mountains-
327 PM MST Mon Jul 17 2023
...A STRONG THUNDERSTORM WILL IMPACT YAVAPAI COUNTY THROUGH 400 PM
MST...
At 327 PM MST, Doppler radar was tracking a strong thunderstorm over
Clarkdale, or 14 miles northwest of Camp Verde, moving east at 5 mph.
HAZARD...Wind gusts up to 40 mph.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Locations impacted include...
Clarkdale, Verde Village, Bridgeport, Cottonwood, Jerome, Dead Horse
Ranch State Park, Mingus Mountain Campground, Playground Group
Campground, Potato Patch Campground, and Tuzigoot National Monument.
This includes the following highways...
State Route 260 between mile markers 207 and 212.
State Route 89A between mile markers 336 and 356.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Heavy rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 3461 11212 3478 11219 3484 11204 3465 11194
TIME...MOT...LOC 2227Z 255DEG 6KT 3473 11206
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH
MASSpecial Weather Statement
National Weather Service Flagstaff AZ
438 PM MST Mon Jul 17 2023
AZZ008-015-037-038-180015-
Yavapai County Valleys and Basins-Western Mogollon Rim-Yavapai County
Mountains-Oak Creek and Sycamore Canyons-
438 PM MST Mon Jul 17 2023
...A STRONG THUNDERSTORM WILL IMPACT COCONINO AND YAVAPAI COUNTIES
THROUGH 515 PM MST...
At 437 PM MST, Doppler radar was tracking a strong thunderstorm over
Munds Park, or 7 miles northeast of Sedona, moving southwest at 10
mph.
HAZARD...Wind gusts up to 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Sedona, Munds Park, Junipine Resort, Village At Oak Creek, Garland's
Oak Creek Lodge, Slide Rock State Park, Cave Springs Campground, and
Manzanita Campground.
This includes the following highways...
Interstate 17 between mile markers 313 and 328.
State Route 179 between mile markers 305 and 313.
State Route 89A between mile markers 370 and 385.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Heavy rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 3503 11164 3487 11153 3472 11174 3495 11191
TIME...MOT...LOC 2337Z 059DEG 7KT 3492 11166
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
MASThe Cedar City radar (KICX), 151 km away, was scanning. The volume nearest the first event began at 23:49 UTC.
1 thunderstorm wind, 1 tornado. Local standard time, as filed.
Strong winds broke large tree limbs, uprooted trees, blew shingles off structures, and caused power outages for much of the city of Page.
A short lived-landspout tornado video was relayed to the NWS.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2023Every state in 2023This day in weather historyThe tornado archive for Arizona, 2023Warnings in Arizona, July 2023
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: 1126494, 1126495.