A strong short wave trough of low pressure swept across northern Arizona with high southwest winds. Timing of the maximum winds aloft coincided with the diurnal heating and allowed for maximum mixing of winds to the surface.
Every event with a place to put it; 5 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.
A strong short wave trough of low pressure swept across northern Arizona with high southwest winds. Timing of the maximum winds aloft coincided with the diurnal heating and allowed for maximum mixing of winds to the surface.
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 Apr 19, 9:43 AM MST, 1 hour 17 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 943 AM MST Thu Apr 19 2018 .SYNOPSIS...A potent cold front will bring another round of strong winds to the area today. Behind the front, there will be increasing chances for rain and snow showers late tonight into Friday. Moderating temperatures and lighter winds can be expected for the weekend and into early next week. && .UPDATE...Northern Arizona is in store for a windy day as a strong cold front approaches the state. Wind Advisory and Warning products as well as a Dust Storm Warning remain in effect with no needed changes this morning. The current forecast is in good shape. We'll be watching a band of high clouds moving through the area that could inhibit some stronger winds from mixing down, but at this time they appear pretty thin and are moving quickly. No updates needed this morning. && .PREV DISCUSSION /326 AM MST/...The next weather maker for northern Arizona is easily discernible on satellite this morning as it moves into central/southern California. The cold front associated with this system will cross the region today and into tonight leading to more strong winds. Model guidance indicates 700 mb wind speeds of 50-60 kts with this system which will translate to widespread advisory/warning level gusts in northern Arizona. The strongest winds are expected to be along the Mogollon Rim and to the north and east. In this area, south-southwesterly gusts of 55-65 mph are anticipated with gusts of 45-55 mph elsewhere. The strong winds are expected to generate areas of blowing dust across northeast Arizona which could reduce visibility to near zero at times. These strong winds combined with very dry relative humidities will lead to critical fire weather conditions across the entire area. Wind products and the Red Flag Warnings all are in effect from 11am this morning until 8pm this evening. Behind the front, cooler air aloft will push into the region with increasing chances for rain and snow showers late tonight into Friday. While an inch or two of snow could fall on the Kaibab Plateau, expect generally light shower activity with liquid amounts of 0.10" or less. The weekend and early next week will feature moderating temperatures and much lighter winds. Long-range models begin to diverge mid next week, but looks like more breezy conditions could be on the way. && .AVIATION...For the 18Z package...Expect very strong south to southwest winds at all levels through 03z Fri due to a cold frontal passage. Surface winds - South to Southwest increasing to 20-35 kts with gusts 40 to 60 kts, fastest speeds across Navajo and Apache counties this afternoon. Aft 03z Fri, wind speeds decreasing to 10- 20 kt gusts to 30 kt, and shifting directions to westerly behind the front. VFR for most of the period, exceptions are areas IFR in blowing dust for the northeast quarter of the state 18z-03z, and aft 06z Friday areas mvfr west across Coconino county as cigs fall to near 3000 feet. Isold to Scattered -SHRA/-SHSN mainly N of a KFLG- K0V7 line after 06Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...A strong cold front will bring very strong winds and widespread critical fire weather conditions to all of the region today. Wind gusts to 65 mph are expected in Navajo and Apache counties this afternoon. Very dry conditions persist through this evening, with increasing humidity and cloud cover for all by Friday morning. Scattered showers are possible Friday. Much less wind is expected on Friday. Saturday through Monday...Drying and warming conditions return starting Saturday, with generally light winds. && .FGZ WATCHES/WARNINGS/ADVISORIES...High Wind Warning until 8 PM MST this evening FOR AZZ012>017-039-040. Red Flag Warning until 8 PM MST this evening FOR AZZ104>118- 137>140. Wind Advisory until 8 PM MST this evening FOR AZZ004>011-037-038. Dust Storm Warning until 8 PM MST this evening FOR AZZ005- 009>014-039-040. && PUBLIC...MCT/TPS AVIATION...JJ FIRE WEATHER...DL For Northern Arizona weather information visit weather.gov/flagstaff
The national radar mosaic for the moment the first event began.
5 high wind. Local standard time, as filed.
The ADOT wind sensor at Two Guns reported a peak wind gust of 62 MPH at 1233 PM MST. The sustained winds were above 40 MPH between 1100 AM and 200 PM MST.
The Springerville Airport reported a peak wind gust of 71 MPH at 1255 PM with wind gusts over 58 MPH between 1140 AM to 210 PM MST. The sustained winds were above 40 MPH between 1120 AM to 210 PM MST. The St Johns Airport reported a peak wind gust of 58 MPH at 337 PM MST. The sustained winds were 40 MPH or higher at times between 300 and 400 PM MST.
The ADOT wind sensor at Jackrabbit (along I-40) recorded a peak wind gust of 58 MPH at 213 PM MST. The Winslow Airport ASOS recorded a peak wind gust of 63 MPH at 105 PM MST. The sustained winds were 40 MPH or higher much of the time between 1250 AM and 240 PM MST. The ADOT wind sensor on Highway 77 near Concho had sustained winds above 40 MPH from 1250 PM until 315 PM. The peak wind gust was 58 MPH at 213 PM.
The Limestone RAWS reported a peak wind gust of 71 MPH at 324 PM MST. The sustained winds were above 40 MPH between around 100 PM MST and 400 PM MST. Mesonet stations around Heber-Overgaard reported wind gusts of 60 and 61 MPH between 1013 AM and 1053 AM.
The Grand Canyon Airport ASOS reported a peak wind gust of 60 MPH at 303 PM MST.
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, April 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: 744373, 744234, 744371, 744372, 744374.