Blizzards

• In general, a blizzard is a winter storm during which the winds go up to 40 km/h and visibility is reduced to less than a kilometer due to falling or blowing snow and its lenght is of at least three hours.
• A blizzard is produced by a wave of cold arctic air, snow, bitter cold, high winds and blowing snow that reduces visiblity. These conditions have to go on for at least three hours for it to be a blizzard, but they could go on for several days.
• Low visibility, low temperatures and violent winds create important danger.
• In the USA, blizzards accompanied by violent winds occur more frequently.
• The west coast, zones surrounding the Great Lakes, the south and east of New York and Atlantic states are particularly vulnerable to abundant snowfall.
• There can be freezing rain almost everywhere in the country, but this more frequent in New York, mid-west and Atlantic states.

Hail

• Hailstorms can occur anywhere in the USA, but they occur more frequently in Montana along with the south of the Prairies and Illinois.
• Hailstorms mainly occur from may to october.
• In certain zones of the Prairies, there can be up to 10 hailstorms per year.
• A hailstorm can prove to be a financial disaster for farmers, which cultures are devastated and for people whose houses and cars are damaged.
• Some hailstones are of the size of small peas, while others can be as big as grapefruits.

Heavy rain

• Heavy rains can lead to flooding. It is especially the case when the ground is still frozen or already saturated from past storms.
• Heavy rains can also provoke floods especially when they coincide with spring thaw.

Ice storms

• Freezing rain is tough, clings to all surfaces and is more slippery than snow.
• In small quantities, it is dangerous – in great quantities, it can be disastrous.

Lightning

• Lightning occurs when the air becomes charged with electricity during a thunderstorm.
• Lightning travels at a speed close to 40 000 kilometers per second.

Thunderstorms

• Thunderstorms are often accompanied by violent winds, hail, lightning, heavy rain and tornadoes.
• A thunderstorm generally lasts not more than an hour, but a series of thunderstorm can strike during several hours.