BLIZZARDS

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BLIZZARDS
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NWS Blizzard Definition

• Winds gt 30 kts (35 mph)
• Sufficient snow in the air to reduce visibility
  to lt ¼ mile for at least 3 hours
• Note Temperature is NOT a criterion, but its
  usually pretty cold.
• It does not have to be snowing!

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Ground Blizzard

• NO falling snow
• Dry snow that is on the ground gets picked up by
  the wind and blown around
• Usually very localized

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• Blizzard March 19, 2003
• It has been snowing for 2 days straight. We have
  up to 6 feet in some areas. I estimate the snow
  to be around 8ft right at the back of our deck.
  Needless to say we are homebound for at least a
  few days!

The Kloc Family
http//www.w4rmk.com/
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Coal Creek, Colorado 2003

• Visibility reduced by falling snow during a
  blizzard

http//www.coalcreek.com/blizzard2003/ The Jack
Family
Butch
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Coal Creek, Colorado 2003

• Blizzards many times bring lots and LOTS of snow
  with them, nearly burying houses

http//www.coalcreek.com/blizzard2003/ Ruth
Briggs
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Hazards in Blizzards

• Whiteout conditions
• People become disoriented when outside
• Bigger problem in rural/forest areas with fewer
  landmarks
• Usually very cold and hypothermia sets in quickly
• Snow can be very heavy
• Heart attacks while shoveling
• Buildings and trees collapse

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Blizzard Ingredients

• Cold air
• No cold air ? no snow
• Wind
• Need strong winds (i.e. large pressure gradients)
  behind low pressure centers
• Need wind to blow snow around, reduce visibility

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Rocky Mountain Cyclone Blizzard

• Low pressure system develops near front range of
  the Rockies
• Strengthens, drawing cold air from Canada
• Blizzard on back side of Low
• Typically more severe

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Alberta Clipper Blizzard

• Much colder air from Canada that is far from
  moisture sources
• Usually less falling snow, more blowing snow
• Blizzard conditions on the back side of the low
• Storm progresses rapidly

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Set-Up for April 1997 Blizzard
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North Dakota Blizzards of 1996-1997

• 9 blizzard criteria storms
• 4 in January 1997 alone
• Temps well below freezing from Dec-March
• Last storm in April
• 16 to 24 inches of snow
• Rates of 1 to 2 inches/hour
• 210 million in damages

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Blizzard Safety Tips

• Have a winter storm survival kit
• Blankets, sleeping bags, flash light, etc.
• Carry sand and shovel in your car
• Wind shield scraper and flares
• Stay with your vehicle
• Never try to walk home during a blizzard!!
• Carry a cell phone