Severe Thunderstorm Threat From the Central Plains to the Northeast; Extreme HeatRisk for the East Coast

Strong to severe thunderstorms are possible from the central Plains to the Northeast through this evening. Widespread damaging winds are the primary threat but hail and a tornado or two is also possible. Extremely dangerous heat continues across the Eastern U.S. Warm overnight low temperatures will provide little to no relief. Read More >

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Summary

A series of three low pressure systems tracked across Arizona during a six day period from January 18th-23rd, 2010. These systems brought heavy snowfall to the higher elevations of northern Arizona, record flooding to our lower elevation locations, and strong winds area-wide. The third system in the series was (by far) the most intense, with record low pressure readings as it crossed the state on January 21st. Several snow and rainfall records were set throughout this week, with estimates of over 90 inches on the highest peaks of northern Arizona. Liquid precipitation amounts exceeded ten inches in some areas. It was truly a remarkable week of Winter weather.

Snowfall reports from around northern Arizona from January 18th - 23rd, 2010.

Liquid precipitation amounts from central and northern Arizona from January 18th - 23rd, 2010.

Timeline

Storm #1 (early morning January 18th - morning January 19th):
- 8-12 inches of snow fell across the higher elevations of northern Arizona, with up to 1 inch of rain at the lower elevations.
Storm #2 (late evening January 19th - morning January 20th):
- 8-15 inches of snow fell across the higher elevations of northern Arizona, with between 0.50-1.50 inches of rain across the lower elevations.
Storm #3 (early morning January 21st - January 23rd):
- The strongest storm of the three.
- 30-55 inches of additional snow fell above 7,000 feet, with rainfall amounts between 5-10 inches at the lower elevations. The heaviest rain fell along the favored upslope locations just south of the Mogollon Rim.
- Winds of 40-70 mph occurred, in advance of a strong cold front that moved across the state on the evening of January 21st.
- Additionally, several strong to severe thunderstorms occurred as the cold front crossed the area
- It was warm enough that snow changed to rain for several hours over many locations around 7,000 feet (including Flagstaff), which substantially increased the weight and density of the snow.

Impacts

Heavy, wet snow led to significant snow loading on roofs along the Mogollon Rim:
- There were numerous flat roofs in Flagstaff that collapsed including the Bookman's Entertainment Exchange, Jo-Ann Fabrics and Crafts, and the Jay Lively Ice Rink.
- Additionally, the roof of the Pinetop-Lakeside Fire Station Number 2 collapsed.
The weight of the snow also led to widespread power outages for several days along the Eastern Mogollon Rim and White Mountains areas
Services were severely hampered across the Navajo and Hopi reservations
- Due to limited plowing services in these areas, roads remained impassable for days
- Other impacts on the reservations included:
  - Food, medicine, and water shortages
  - Severely disrupted communications
  - Widespread power outages
  - Delayed rescue services
Heavy rainfall, especially during the 3rd storm system resulted in flooding issues below 6,500 feet elevation.
The most significant rises in area creeks and rivers occurred on Tonto Creek and the Agua Fria River:
- The Agua Fria River in Black Canyon City and Rock Springs crested at 28 feet which resulted in widespread flooding of several neighborhoods and mobile home parks.
- Upstream the Agua Fria in Mayer, a flooding death occurred as a young boy was swept away after the vehicle he was riding in became stalled in high water
- Evacuations were required along Tonto Creek in the communities of Tonto Basin and Gisela due to high flood waters
Granite Creek in Prescott crested at 11.0 feet resulting in significant flooding in downtown Prescott.
There were also wind impacts with these systems, especially in the evening of January 21st:
- A portion of a roof was blown off a police substation south of Prescott
- Two homes were damaged in Williams when a large tree fell onto them

Pictures

The roof at Jay Lively Ice rink collapsed due to the weight of the heavy snowfall. Photo Credit: Josh Biggs

The facades of both Bookmans and Joann Fabrics hang off the front of the building after the roof collapsed late in the day on Thursday January 21st, 2010. This was due to the weight of snowfall that had fallen. Photo Credit: Josh Biggs

Heavy snowfall led to deserted streets and closed businesses in downtown Flagstaff. Photo Credit: Deborah Lee Soltesz

Commercial flights out of Flagstaff Pulliam Airport were stopped at 8am Thursday January 21st due to deteriorating weather conditions. Photo Credit: Deborah Olin

The back deck of a Flagstaff resident buried under the storm's snowfall. Photo Credit: Bill Ferris

The aftermath of the storm as seen in Wildwood Hills Mobile Home Park in Flagstaff. Photo Credit: Coral Schooley

Many northern Arizona residents were forced to dig their cars out after the 5-day snowstorm. This photo is from the Heckethorn neighborhood off Lake Mary Road. Photo Credit: Mark Decker

Livestock around northern Arizona had to endure brutal winter weather conditions. Photo Credit: Fireground/Flickr

The Mogollon Rim Visitor Center in Payson received a substantial amount of snow throughout the storm. Photo Credit: Eric S. Neitzel

The National Guard delivered goods to rural areas across northern Arizona in the days following the storm. Photo Credit: Fireground/Flickr

Several feet of snow fell at the Arizona Nordic Village in Flagstaff. Photo Credit: Arizona Nordic Village

Rural areas saw some of the most significant impacts with residents stranded for days in their homes. Photo Credit: Fireground/Flickr

Rural areas saw some of the most significant impacts with residents stranded for days in their homes. Photo Credt: Fireground/Flickr

Meteorology

The first storm in the series of three occurred as a shortwave trough moved west to east across the state of Arizona. The Mogollon Rim provided the major lifting mechanism with this system as strong southwest flow lifted over the terrain. The precipitation was enhanced as the cold front associated with the trough became nearly stationary across the region. Mild southwesterly flow out ahead of a second, stronger trough led to snow levels rising to above 7,000 feet. As this second system and its associated cold front passed, snow levels then lowered again to around 5,000-5,500 feet. The third, and most significant, storm established some all-time record low pressure readings across sites in the Southwest United States, including at Phoenix Sky Harbor International Airport. This system brought with it very heavy precipitation and unusually high winds. The heavy precipitation posed a threat for the lower elevation areas as runoff from the previous two storms led to swollen rivers, creeks, and streams. Air travel was significantly hampered across the region due to a low level jet in excess of 80 knots around 4,500 feet above sea level. These strong winds combined with heavy snowfall brought blizzard conditions to the higher terrain of northern Arizona. A very strong cold front accompanied this system and led to the development of a line of thunderstorms which prompted the issuance of a Tornado Watch for most of southern Arizona. That was the first Tornado Watch issued in Arizona since 1993. Only one tornado was confirmed from the line of storms. Very cold air advected into the state behind the cold front with snow levels falling as low as 3,500 feet by the end of the system.

Progression of the air masses that created the heavy rain and snowfall from Thursday during the day into Friday night.

A very deep cold, low pressure system was centered off the northern California coast during this period with strong southwest flow pulling moisture into northern Arizona from the Pacific Ocean

A very strong jet stream associated with these three storm systems extended from the Central Pacific into the Desert Southwest

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

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Severe Thunderstorm Threat From the Central Plains to the Northeast; Extreme HeatRisk for the East Coast

January 2010 Historic Winter Storm