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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
 

On September 27th, 2014, an EF-0 tornado touched down in the Bradshaw Mountains south of Prescott, AZ. This storm was associated with numerous reports of damage to residential structure and vegetation. An NWS Flagstaff storm survey was conducted in order to assess the Enhanced Fujita scale rating of the tornado. Besides the tornado, reports of flash flooding and heavy rainfall were associated with a variety of storms that impacted much of northern Arizona on this same day.

 
Timeline
Radar Loop of the Groom Creek Tornado

Map showing the the Highline Burn Scar, Ellison Creek, and the Cold Springs swimming hole

Map showing the location of the Groom Creek Tornado

Radar Estimated Storm Total Precipitation on July 15, 2017

  • September 27, 2014 at 1:55 PM MST: Approximate time that the tornado touched down.

  • September 27, 2014 at 2:05 PM MST: Termination of the tornado on the ground.

  • September 28, 2014: NWS Storm Survey crew assessed damage leftover by the Groom Creek Tornado. The tornado was rated as an EF-0, was on the ground for 2.10 miles and had a base width of 700 yards.

  • September 28, 2014: Resident contacted Yavapai County Emergency Management and asked for assistance due to the storm damage.

  • September 29, 2014: Yavapai County Sheriff's Office conducted flyover of damage area.

  • September 30, 2014: Prescott National Forest instituted trail closures for Forest Trails 307 and 377.
Impacts
  • Four homes were assessed as having significant damage.
  • Light damage was labeled for other surrounding houses.
  • Numerous pine trees were snapped off around the trunk or uprooted.
  • Power lines and cables were downed.
  • The downed power lines and tree damage resulted in the temporary closure of Forest Trails 307 and 377 in Prescott National Forest.
Pictures

 

Trees snapped off at the trunk caused damage to the residential structure in the background.

Trees snapped off at the trunk caused damage to the residential structure in the background.

NWS Flagstaff employees assessing tree damage near Groom Creek in the Bradshaw Mountains. The assessment would rate the tornado as an EF-0.

NWS Flagstaff employees assessing tree damage near Groom Creek in the Bradshaw Mountains. The assessment would rate the tornado as an EF-0.

Stand of trees damaged on a hillside. Most of the trees were snapped off at their trunks.

Stand of trees damaged on a hillside. Most of the trees were snapped off at their trunks.

Flash flooding of a roadway in Prescott, AZ on September 27, 2014. Photo Credit: 12 News on Twitter.

Flash flooding of a roadway in Prescott, AZ on September 27, 2014. Photo Credit: 12 News on Twitter.

Meteorology

 

A cold front associated with a strong trough of low pressure moved across California and into Arizona. Southerly winds ahead of the storm brought deep moisture into the area. These conditions created severe thunderstorms and heavy rainfall. An EF-0 tornado formed and traveled over areas near Prescott, AZ.

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

  • Yavapai County Emergency Management at (928) 771-3183 or web.public.works@yavapai.us

  • Prescott National Forest Bradshaw Ranger District at (928) 443-8000