A cold front moved across northern Arizona with strong southwest winds. The strongest winds were downwind from the Mogollon Rim and White Mountains.
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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 cold front moved across northern Arizona with strong southwest winds. The strongest winds were downwind from the Mogollon Rim and White Mountains.
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 Dec 20, 5:35 PM MST, 3 hours 18 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 535 PM MST Wed Dec 20 2017 .SYNOPSIS...A cold front will move into northern Arizona this evening. Expect strong southwest winds tonight into Thursday morning, and light rain and snow showers from late tonight through Thursday afternoon. Chances for showers are forecast for locations along and north of the Mogollon Rim, with the best chances north of Interstate 40. High temperatures Thursday look to be in the low 30s in the mountains to around 50 in the Verde Valley. Warmer temperatures and dry weather are forecast for the weekend. && .DISCUSSION... The cold front at 5 pm along a line from Milford Utah-Las Vegas -Santa Barbara. The wind advisories out for tonight through early Thursday morning look good. We have had several gusts in the 35 to 50 mph range this afternoon. We expect this plus another 5 mph tonight for areas along and just north of the Mogollon rim as a southwesterly low level jet blows across the rim. We have increased and in some cases nearly doubled tonights wind gusts in the wind advisory areas over those sent with the 330 pm Thursday forecast package. The fastest winds for this event are forecast to be from Show low through Springerville, with gusts to 60 possible. Doney Park not to far behind this. Forecast updates have been sent. DL From the 452 am Thursday Discussion... By RR Similarly, the surface cold front will cross the area from the northwest to southeast, first impacting the Kaibab Plateau shortly before midnight tonight and exiting the area by way of the White Mountains Thursday afternoon. Chances for rain and snow showers are forecast along and north of the Mogollon Rim, with the best chances north of Interstate 40. In general, 1 to 2 inches of snow are forecast along the Kaibab Plateau and mountains of far northeast Arizona. Limited QPF and a saturated layer only up to about -12 C should limit snow along the western Mogollon Rim. Around 0.5 inches of snow is forecast in the Flagstaff area. In addition, very cold air behind the front will keep daytime high temperatures on Thursday between 10 to 15 degrees below normal across much of the area. Dry weather and warming conditions are forecast for Friday, with near normal temperatures in place for this Holiday weekend. Models generally agree that a ridge of high pressure will lead to above normal temperatures by Tuesday of next week. && .AVIATION...For the 00Z package...Increasing mid/high level clouds in advance of a cold front moving into the area from northwest to southeast through the evening and overnight. The front will bring a chance for rain and snow showers with localized MVFR conditions to areas along and north of I-40 beginning 04Z-09Z Thu. Shower activity diminishes from northwest to southeast Thu. Southwest sfc winds 15-25 kts with gusts of 30-35 kts. Local gusts of 40-45 kts are possible especially northeast of higher terrain. Winds will shift to the northwest behind the front Thu. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Strong and gusty southwest winds will persist through the evening and overnight hours as a cold front approaches the region. This front will bring a chance of rain and snow showers later this evening and into Thursday mainly north of I-40. Behind the front, winds will shift northerly and usher in the coldest airmass of the season Thursday. Northeasterly winds will persist Friday with daytime temperatures near normal. Saturday through Monday...Above normal daytime temperatures return for the weekend and early next week under dry west-northwest flow. && .FGZ WATCHES/WARNINGS/ADVISORIES...Wind Advisory until 8 PM MST this evening FOR AZZ004-006-007-039. Wind Advisory until 2 AM MST Thursday FOR AZZ012-013-015-016. Wind Advisory from 11 PM this evening to 11 AM MST Thursday FOR AZZ014-017. && PUBLIC...DL / RR AVIATION...TM FIRE WEATHER...TM For Northern Arizona weather information visit weather.gov/flagstaff
Hazardous Weather Outlook National Weather Service Flagstaff AZ 504 PM MST Wed Dec 20 2017 AZZ004>018-037>040-211200- Kaibab Plateau-Marble and Glen Canyons-Grand Canyon Country- Coconino Plateau-Yavapai County Mountains- Northeast Plateaus and Mesas Hwy 264 Northward-Chinle Valley- Chuska Mountains and Defiance Plateau- Little Colorado River Valley in Coconino County- Little Colorado River Valley in Navajo County- Little Colorado River Valley in Apache County- Western Mogollon Rim-Eastern Mogollon Rim-White Mountains- Northern Gila County-Yavapai County Valleys and Basins- Oak Creek and Sycamore Canyons-Black Mesa Area- Northeast Plateaus and Mesas South of Hwy 264- 504 PM MST Wed Dec 20 2017 This hazardous weather outlook is for Apache...Coconino... Northern Gila...Navajo...and Yavapai Counties in Northern Arizona. .DAY ONE...Tonight Wind Advisories have been issued for tonight through Thursday morning due a cold front sweep into the state tonight. Strong winds will occur along and ahead of the front, first impacting the Kaibab Plateau this afternoon and the Mogollon Rim to the White Mountains overnight. Expect southwest winds 25 to 35 mph with gusts from 40 to 55 mph. Localized gusts to 60 mph are possible tonight at locations immediately downstream of the San Fransisco Peaks and White Mountains. In addition, light snow will occur with the front beginning late tonight. In general, 1 to 2 inches of snow are forecast along the Kaibab Plateau and mountains of far northeast Arizona. Around 0.5 inches of snow is forecast in the Flagstaff area, with little to no snow forecast elsewhere. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday Max temperatures Thursday will be between 10 to 15 degrees below normal. Expect mild weather late this week with another drop in temperatures possible by Christmas Eve. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures.
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
The ADOT wind sensor at Two Guns measured a peak wind gust of 62 MPH at 853 PM MST. Wind gusts of 50 MPH or greater were observed from around 815 to around 11 PM MST.
The ASOS at the St Johns Airport measured a peak wind gust of 60 MPH at 240 AM MST. Wind gusts of 40 MPH or higher were observed from around midnight to 500 AM MST. The peak wind gust at the Springerville Airport was 75 MPH at 655 AM MST. The wind gusted over 60 MPH from 1030 PM on the 20th to around 1240 PM MST on the 21st.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2017Every state in 2017This day in weather historyWarnings in Arizona, December 2017
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: 728174, 728138.