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Scars from Prairie storms visible from space


Chris Scott
Chief Meteorologist

Friday, July 26, 2013, 10:57 AM -

It’s been a wild few weeks across the Prairies, and the evidence is clear both on the ground and from hundreds of kilometres above the Earth. Recent storms have left visible scars on the landscape due to intense, narrow hail swaths.

Farmers on the ground see the damage that these hail storms have done to crops, but the view from above offers a different perspective on the scale of this destructive weather. NASA’s AQUA and TERRA polar-orbiting satellites provide high-resolution colour images of nearly every corner of the globe once per day and are able to pick out significant hail swaths that have impacted agricultural land.

One of the most dramatic examples is a hail storm that hit just east of Airdrie, AB on July 6th. The picture below taken near Irricana just after the storm could easily be mistaken for a post winter storm scene with deep drifts of ice.

After the July 6th hail storm near Irricana, AB

After the July 6th hail storm near Irricana, AB

Even more amazing was Garry Lockyer’s picture taken the next day from a hot air balloon. Hail still covered the ground in a long swath where the accumulation was deepest.

July 6th hail swath from the vantage of a hot air balloon. Picture taken the day after the storm.

July 6th hail swath from the vantage of a hot air balloon. Picture taken the day after the storm.

The damage to crops resulted in a hail swath scar that will likely be visible from space for the rest of the growing season. High resolution colour satellite images of hail swaths have the appearance of someone taking an eraser to the green farmland, leaving behind a smudged brown streak.

Two other notable hail storms have also left scars on the agricultural landscape of southern Alberta. A hail storm on the same day produced golf ball sized hail near Lethbridge, while a storm the previous day inundated the north end of Taber.

Hail stones near Lethbridge, AB July 6th.

Hail stones near Lethbridge, AB July 6th.

Car trapped in a river of hail after July 5th storm in Taber, AB

Car trapped in a river of hail after July 5th storm in Taber, AB

The view from space shows the scars from these storms on southern Alberta farmland. The July 6th storm which affected Lethbridge had a unique southeasterly track compared to other storms because it was a supercell thunderstorm with strong rotation. If you picture yourself taking a ride on the storm looking ahead, supercells tend to move to the right compared to non-rotating storms. The stronger updrafts in these storms also support larger hail, as is seen in the picture from Lethbridge.

The longest hail swath of the season so far goes to the supercell thunderstorm of July 13th which dropped hail up to grapefruit size in southeastern Saskatchewan before spawning a tornado which did significant damage in Pipestone, MB. The picture below shows a nearly continuous swath of hail-scarred farmland from Ralph, SK to Pipestone, MB a distance of over 200 km. The undulating nature of the path shows how long-lived hail storms tend to ‘pulse’, dropping heavier amounts of hail at various points along the swath as the parent supercell thunderstorm renews its rotating updraft.

Tornado damage at the Pipestone hall.

Tornado damage at the Pipestone hall.

Even longer hail swaths have been documented. Data from the Alberta Hail Project, a world-renowned hail study which ran for 30 years concluding in 1985, suggested that hail swaths in excess of 300 km were by no means exceptional. In fact Pat Boomer, a weather watcher and photographer from Red Deer, documented a nearly 400 km long hail swath from a storm in August 2009.

Hail is to the Prairies as nor’easters are to the Maritimes. It has been a stormy summer thus far, but there is no indication that hail storms are becoming more frequent or more severe. Alberta in particular is one of the most hail prone regions in the world. Our ability to see hail scars from space is a relatively recent development, and offers us a new perspective on the impact of these Prairie beasts.


References:

http://earthdata.nasa.gov/labs/worldview/
http://www.cmos.ca/CB/cb250206.pdf
http://blog.boomerphoto.com/2009/08/10/august-9-hail-track-tour/

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