Lecture 15

Question 1

Blizzard

Answer 1

Visibility < 400 m because of wind speeds of >40 km/h
and blowing or falling snow for 4 hours or more
Interaction between upper-level low pressure trough and surface low pressure
Different locations have different classifications

Question 2

Sleet

Answer 2

Rain/snow melts, then refreezes near ground level, forms mostly <1 mm diameter ice particles

Question 3

Freezing rain

Answer 3

Supercooled rain freezes when it contacts ground

Question 4

How do blizzards form?

Answer 4

Interaction between upper-level low pressure trough and surface low pressure

Question 5

Fronts

Answer 5

Boundary between two air masses of different density and temperature

Question 6

Advancing cold front

Answer 6

Forces warm air up

Creates clouds and heavy precipitation

Question 7

Advancing warm frount

Answer 7

Forces warm air over cooler air

Creates clouds and precipitation

Question 8

Special weather statements

Answer 8

Least urgent type of alert

To let you know conditions are unusual and could cause concern

Question 9

Advisories

Answer 9

Issues for specific weather events that are less severe but could still significantly effect Canadians

Question 10

Watches

Answer 10

Alert you about weather conditions where there is potential for a significant storm or severe weather to occur
Can be upgraded as more information becomes known

Question 11

Warnings

Answer 11

Urgent messages that severe weather is either occurring or will occur
Updated regularly

Question 12

Snowfall warning

Answer 12

A snowfall accumulation of 15 cm or more is expected in 12 hours or less

Question 13

Freezing Rain Warning

Answer 13

Freezing rain is expected to last for 2 hours or more, or if slippery or hazardous walking or driving conditions due to freezing precipitation is expected

Question 14

Frost warning

Answer 14

When the air temperature is expected to fall below or near freezing ( 0°C ) during growing season

Question 15

Winter storm warning

Answer 15

When severe and potentially dangerous winter weather conditions are expected, including:
A major snowfall (25 cm or more within a 24 hour period); and
A significant snowfall (snowfall warning criteria amounts) combined with other cold weather precipitation types such as: freezing rain, strong winds, blowing snow and/or extreme cold

Question 16

Alberta clipper

Answer 16

a fast-moving winter weather system originating in the lee of the Canadian Rockies that typically brings snow, high winds, and cold temperatures across the prairies

Question 17

Maritimes Nor’easter

Answer 17

Warm moist air picked up in the tropics moves north up the coast with Gulf Stream; origin often Cape Hatteras, NC
A mass of polar air from Eastern Canada and the North Atlantic moves south
Somewhere in the vicinity of Cape Cod the warm air hits the cold air.
The warm air moves up and over the cold layer.
Low pressure develops, counterclockwise cyclone means that coastal areas get northeasterly winds as the storm approaches

Question 18

Colorado low

Answer 18

Low-pressure area that forms in southeastern Colorado or northeastern New Mexico, typically in the winter. After forming, the system moves across the Great Plains

Question 19

Direct effects of blizzards

Answer 19

Frost bite, hypothermia (death)

Heart attacks during shovelling

Question 20

Indirect effects of blizzards

Answer 20

Loss of electricity
Auto accidents
# of blizzards deaths = or greater than tornado deaths in Canada and US

Question 21

Where are blizzards most common in Canada?

Answer 21

Southern prairies, Atlantic Canada, eastern Arctic

Question 22

Where are blizzards rare in Canada?

Answer 22

Wester NWT, BC and Yukon

Question 23

How may lives do winter storms and excessive cold claim every year in Canada?

Answer 23

100

More than combined toll from hurricanes, tornadoes, flood, extreme heat and lightning

Question 24

White Juan

Answer 24

Halifax, Yarmouth, Charlottetown
1m in 24h
Province wide states of emergency for 4 days
Nightly curfew for 3 days
>5 million in unbudgeted snow removal and wire repair

Question 25

1998 Quebec Ice Storm

Answer 25

January 
Quebec, NB, Ontario, NFLD
80 hours of freezing rain, some sleet
>25 deaths
$7 Bil, US
550, 000 without power
130 major transmission towers
30, 000 utility poles
120, 000 km of power lines and telephone cables

Question 26

Mitigation (6)

Answer 26

1) Better forecasts (not 12 hrs, but 24 hrs)
2) City planning for snow removal from sidewalks
3) Remind seniors at risk of heart failure
4) Dress appropriately
5) Remove trees near electrical wires
6) Consider underground infrastructure