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Summary
 

A cold, strong, intensifying low pressure system spread a blanket of snow over a majority of central and northern Arizona between the evening of February 20th and the night of February 22nd, 2019. Across the Mogollon Rim and other high country regions, reports of two to over three feet of snow were received. Anywhere from a few inches to over a foot of snow fell in the lower deserts and valleys of northern Arizona. For many locations across central and northern Arizona, this storm was among the top 10 greatest recorded. The single-day snowfall record was broken at Flagstaff Airport and in Show Low. As a result of the heavy snowfall, major roadways were closed, trees were downed, and power was lost in local communities.

 
Timeline
 
Radar Loop February 20-22, 2019Radar Loop From 11 AM Wednesday February 20 - 1 AM February 23, 2019. The main snow bands began to impact central and northern Arizona during the evening of February 20th.

 

Observed Storm Total Snow from Wednesday Night to FridayObserved Storm Total Snow from Wednesday Night to Friday. Access all local storm reports throughout Arizona for this storm.

 

 

GOES-17 True Color Satellite Imagery After The StormGOES-17 True Color Satellite Imagery. Images were captured in the morning hours of Saturday, February 23, 2019 and show the expansive snowpack across northern Arizona and much of the desert southwest region.

 

Snowfall RecordsSnowfall records were broken in Flagstaff, Payson and Show Low between February 21 - 22, 2019. Flagstaff Airport and Show Low each experienced a new one-day snowfall record. Payson had its third highest two-day snowfall amount also from this storm.

 

 

 

  • Evening of February 20th:
    • The first snow was recorded at NWS Flagstaff in Bellemont, AZ.
    • Steady snow spread across Yavapai and Coconino counties through the evening hours.
  • Overnight of February 20th:
    • Snow increased in intensity overnight and especially on Thursday morning, February 21st.
  • Morning of February 21st:
    • Between 5am and 11am on February 21st, 14.3 inches of snow fell at the Flagstaff airport.
  • Afternoon of Feburary 21st:
    • Snow began to spread east into Navajo, Gila, and Apache counties through Thursday afternoon and evening.
    • Snowfall rates began to decrease across Coconino and Yavapai counties on Thursday evening as the main moisture plume shifted eastward.
  • Midnight February 22nd:
    • New one-day snowfall record is set at the Flagstaff Airport with 35.9 inches of snow having fallen in the past 24 hours.
  • Morning of February 22nd:
    • Moderate to heavy snow showers linger across Coconino and Yavapai counties with steady heavy snow falling across Navajo, Apache, and Gila counties.
  • Afternoon of February 22nd:
    • Moderate to heavy snow showers gradually diminish across Coconino and Yavapai counties with steady heavy snow slowly tapering off to the east.
  • Overnight of February 22nd:
Impacts
  • Residents in Happy Jack, AZ were without power for a portion of the storm.
  • Power was reported to have been lost in parts of the Pinetop-Lakeside region of Navajo County.
  • School districts throughout northern Arizona, colleges and Northern Arizona University cancelled school on February 21 and 22, 2019.
  • Red Cross Shelters in the high country were opened to take in anyone impacted by the storm.
  • Roads, highways and interstates were shutdown due to the winter weather conditions both during and after the storm.
    • SR-89A was closed between mileposts 387 and 398 due to snow, rockslides and a downed tree. The highway reopened at 6:00 PM MST on February 23.
    • Desert View Drive (SR-64) between Grand Canyon Village and Desert View was closed due to heavy snow and opened at 2:30 PM on February 23.
    • Between the cities of Alpine and Morenci, US-191 was closed through the morning of February 23 due to ice and snowy road conditions.
    • State Route 288 between SR-188 and Young was closed through the morning of February 23 due to ice and snowy road conditions.
    • I-40 was closed between Gallup, NM and Holbrook, AZ in the morning hours of February 23 due to ice on the roads causing hazardous travel conditions.
    • Northbound I-17 was closed between the SR-179 exit to Sedona and Flagstaff.
    • SR-260 was closed between Star Valley and Heber.
    • SR-87 was closed between Payson and Winslow.
  • State of Emergencies were declared by all counties, along with some cities and reservations, in central and northern Arizona.
  • Petrified Forest National Park, Montezuma Castle National Monument and Tuzigoot National Monument were all closed from February 21-22, 2019 due to the forecast storm conditions.
Pictures


 

Time lapse of the snow accumulating between Wednesday night and Friday afternoon outside of the NWS Flagstaff office in Bellemont, AZ.

SR 89A from Flagstaff to Sedona

SR-89A from Flagstaff to Sedona was closed for nearly 2 days during the storm due to heavy snow and icy conditions

Milton Rd in Flagstaff

Near whiteout conditions were observed in Flagstaff throughout the storm

SR 260 in Heber

SR-260 was closed in Heber for much of the storm due to heavy snowfall and difficult to impossible travel conditions

I-17 Whiteout Conditions Near Flagstaff

Whiteout conditions were observed along I-17 near Flagstaff on February 21st

I-40 Eastbound near Winslow

Heavy snow and ice led to slick roadways along all of I-40 with several accidents reported throughout the storm

Heavy Snow in Payson

Two to three feet of snow in Payson created difficult to near impossible travel conditions throughout the storm

SR 89A Treefall

Heavy snow led to a treefall across SR-89A in Oak Creek Canyon

Flagstaff Police Patrol

Police patrolling in the snow around Flagstaff during the early morning hours of February 21.

Buried State Patrol Vehicle

Payson received upwards of 30 inches of snow and buried an Arizona State Trooper vehicle.

US 191 near Hannigan Meadow

A semi was stuck on US Highway 191 near Hannigan Meadow and a local law enforcement officer is on the scene.

I-40 Westbound RV Wreck

Heavy snow and poor visibility led to very hazardous driving conditions in Flagstaff throughout the storm. An RV turned over on the morning of February 21st leading to a short closure of the roadway.

Meteorology
 

Three primary ingredients are needed for heavy snow: cold air, moisture, and lift. Cold air was already in place over Arizona prior to the onset of the Feb 21-22 heavy snow event thanks to the presence of a deep trough at 500 mb which had brought several inches of snow to northern portions of the state earlier in the week. Another very cold mid-level trough moved from the Gulf of Alaska over an eastern Pacific ridge, with a strong jet streak forming from the Gulf of Alaska toward the Washington coast by Tuesday evening. This strong jet streak served to not only reinforce the trough of cold air over Arizona as it progressed southward, but also provided a mechanism for sustained lift over a broad area. Substantial precipitation was observed at low-elevation locations which don’t typically see much precipitation in events where uplift resulting from winds impacting terrain is the major source of rising motion.

Moisture was transported from the central Pacific, over the top of the eastern Pacific ridge across the Gulf of Alaska, and southward just off the U.S. west coast in association with the jet streak. Strong southwest winds aloft began transporting this moisture into Arizona around the base of the trough on Wednesday afternoon, with the most significant period of moisture transport being from early Thursday morning through Friday morning. With the very cold air in place, snow-to-liquid ratios were quite high throughout the event. This resulted in snow of a light and fluffy consistency, increasing observed snowfall amounts over what they would have been had the snow been heavy and dense.

Upper Air chart from 5 AM MST on February 21, 2019 showing 500 mb heights, wind barbs and temperatures.Upper Air chart from 5 AM MST on February 21, 2019 showing 500 mb heights (solid black lines), wind barbs (showing wind speed and direction) and temperatures.

 

Upper Air chart from 5 AM MST on February 22, 2019 showing 500 mb heights, wind barbs and temperatures.Upper Air chart from 5 AM MST on February 22, 2019 showing 500 mb heights (solid black lines), wind barbs (showing wind speed and direction) and temperatures.

 

 
Points of Contact
 

For more information on impacts and general inquiries about this event, please reference the contacts below:

  • National Weather Service:
    • Brian Klimowski, Meteorologist-in-Charge at (928) 556-9161 ext. 222 or brian.klimowski@noaa.gov
    • Tony Merriman, Warning Coordination Meteorologist at (928) 556-9161 ext. 223 or tony.merriman@noaa.gov
  • Arizona Department of Transportation: at info@azdot.gov