Strong upper level low pressure is positioned over the California/Nevada border brought strong southwest winds to northern Arizona.
Every event with a place to put it; 7 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
Strong upper level low pressure is positioned over the California/Nevada border brought strong southwest winds to 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 May 21, 4:04 AM MST, 3 hours 26 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 404 AM MST Fri May 21 2021 .SYNOPSIS...A low pressure system will bring strong southwest winds into Saturday, along with areas of critical fire weather. In addition, there will be a chance for showers primarily along and south of the Mogollon Rim today. Temperatures will remain cool through the weekend with warmer temperatures returning next week. && .DISCUSSION...Strong upper level low pressure is positioned over the California/Nevada border this morning with a strong southwest flow over Arizona. A leading shortwave feature has tapped into sufficient moisture to generate an area of showers across central Arizona. Rainfall amounts so far have ranged from a few hundredths to near a tenth of an inch. These showers will favor areas along and south of the Mogollon Rim through the morning hours, before drier air begins to push in from the west this afternoon. We have made adjustments accordingly to the Red Flag Warnings for today based on morning rainfall and expected humidity trends. Strong southerly winds gusting from 40 to 50 mph will continue today and Wind Advisories remain in effect for nearly all of northern Arizona. Drier air overspreads the area from west to east later this afternoon bringing an end to shower chances. The dry southerly flow continues through Saturday leading to additional fire weather and wind concerns. We have issued Fire Weather Watches and Wind Advisories for Saturday for areas from Flagstaff eastward. The greatest uncertainty in the fire weather watch is today's rainfall and how it will affect current fuel moisture. Temperatures will remain cool through the weekend in response to the trough passage. The trough axis finally moves through the area on Sunday leading to much less wind and a chance for temperatures to begin warming. Look for a period of warmer temperatures, dry conditions and lighter winds through much of next week. There is some potential for additional troughing to bring increased winds sometime late next week but confidence is low at this time. && .AVIATION...For the 12Z package...Based on high-res model guidance, light to moderate rain showers look to continue through this morning for KFLG, KPRC, and KSEZ tapering around 18Z. VFR to MVFR conditions can be expected for the aforementioned sites depending on overall shower activity. KINW could see some light spillover sprinkles during this time, however not enough to limit visibility. Winds remain breezy this morning with some gusty outflows from the rain showers. Strong southwest winds at 25-35 kts redevelop after 14Z, with gusts 35-50 kts. Winds are expected to decrease after 03Z Saturday across the region. Areas of low-level wind shear with some minor turbulence are possible along the Mogollon Rim tonight into early Saturday morning. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Winds remain breezy this morning with light to moderate rain showers along and south of the Mogollon Rim. Another round of strong, 40-50 mph southwest gusts develops later this morning, with critical fire weather conditions over much of northwestern Arizona through the early evening hours. Near-critical conditions are expected in eastern Arizona where RH values will be higher. A few thunderstorms and showers are possible in the eastern zones during the afternoon. Expect strong winds again on Saturday with critical fire weather conditions possible in eastern Arizona. Sunday through Tuesday...Lighter winds and gradual warming, with dry conditions to start next week. && .FGZ WATCHES/WARNINGS/ADVISORIES...Red Flag Warning from 11 AM this morning to 8 PM MST this evening FOR AZZ104>109-112-137-138. Wind Advisory until 8 PM MST this evening FOR AZZ004>017-037>040. Fire Weather Watch from Saturday morning through Saturday evening FOR AZZ109>117-139-140. Wind Advisory from 11 AM to 8 PM MST Saturday FOR AZZ009>017-039- 040. && PUBLIC...MCT AVIATION...LaGuardia FIRE WEATHER...LaGuardia For Northern Arizona weather information visit weather.gov/flagstaff
The national radar mosaic for the moment the first event began.
6 high wind, 1 dust storm. Local standard time, as filed.
The Springerville ASOS reported wind gust of 58 MPH or higher at times between 730 and 945 AM. The peak wind gust of 68 MPH was reported at 835 AM.
The Four Springs RAWS recorded peak winds of 58 MPH or higher between 1115 AM and 300 PM. The peak wind gust was 61 MPH at 119 PM.
The ADOT wind sensor at Two Guns reported wind gusts of 58 MPH or higher at times between noon and 5 PM. The peak wind gust of 68 MPH was recorded at 113 PM. The winds lofted sand and dust in the air between Two Guns and Twin Arrows. This restricted the visibility to one-half mile by 1230 PM.
Strong winds (estimated to be 50 MPH) lofted dust and sand into the air between Chinle and Many Farms along Highway 191. The visibility was limited to an estimated 1/2 mile.
The Show Low Airport reported a peak wind gust of 58 MPH at 1255 PM.
The ADOT wind sensor at Highways 277 and 377 reported wind gusts over 58 MPH between 130 and 220. The peak wind gust was 63 MPH at 243 PM.
The Flagstaff Airport measured a few peak wind gusts over 58 MPH between 157 and 215 PM. The peak wind gust was 66 MPH at 157 PM. Bellemont also had a peak wind gust of 66 MPH at 154 PM. A wind sensor at Snowbowl (9379 feet) reported a peak wind gust of 58 MPH at 130 PM. There were multiple reports of uprooted and downed trees as well as broken tree branches throughout the greater Flagstaff from the strong winds. Localized power outages were also reported in the Ponderosa Trails neighborhood.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2021Every state in 2021This day in weather historyWarnings in Arizona, May 2021
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: 952329, 952335, 952322, 952337, 952336, 952332, 952330.