Severe Weather
Living in Alaska makes residents familiar with severe weather of all types.
In the Juneau area, common severe weather events include snow, high winds,
dense fog, and coastal storms. Less common, but still occasionally observed
are thunderstorms, hail, waterspouts, extreme cold, and blizzards. Extreme
weather events in Juneau may be accompanied by secondary effects such as flooding,
landslides, and avalanches. Still, severe weather rarely comes as a
surprise in Alaska, so it's certainly possible to protect your home and property
from Alaskan weather.
Types of Severe Weather
The following severe weather events occur with some regularity in the Juneau
area:
Heavy Snow:
Heavy snow (6 inches or more in 12 hours or a foot or more in 24 hours) can
immobilize a community by bringing transportation to a virtual halt.
Air and ground transportation systems can be severely hampered and may even
close until snow removal can be completed. Accumulations of snow can
cause roofs to collapse and can topple trees and power lines. An accumulation
of heavy snow can also damage light aircraft and can sink small boats. On
mountainsides and slopes, heavy snow can lead to avalanches. A quick thaw
after heavy snow can cause substantial flooding, especially along small streams
and in urban areas. The cost of snow removal, repairing damages, and the loss
of business can have severe economic impacts on cities and towns.
Injuries and deaths related to heavy snow usually occur as a result of vehicle
accidents. Casualties also occur due to overexertion while shoveling
snow and hypothermia caused by overexposure to cold weather.
Extreme cold
Extreme cold interferes with a community's infrastructure. It causes
fuel to congeal in storage tanks and supply lines, stopping electric generation.
Extreme cold can cause water and sewer pipes to freeze and rupture, and can
interfere with the operation of motor vehicles. If extreme cold conditions
are combined with little or no snow cover, the ground's frost depth can increase,
affecting buried pipes.
What is considered an excessively cold temperature varies according to the
normal climate of a region. The all time record low temperature in Juneau
is -22 degrees Farenheit, so extreme cold is a rarity in the Juneau area.
Still, wind chill temperatures as low as -50 degrees Farenheit are possible.
The greatest danger from extreme cold is to people. Prolonged exposure
to the cold can cause forstbite or hypothermia and can become life-threatening.
Ice Storms
The term ice storm is used to describe occasions when ice accumulates to
1/4 inch or more on exposed surfaces such as trees, homes, power lines, and
vehicles. Ice storms can be the most devastating of winter weather
phenomena and often cause power outages, sometimes of extended length.
Ice storms result from the accumulation of freezing rain, which is rain the
becomes supercooled and freezes upon impact with cold surfaces.
High Winds
High winds are the most common extreme weather event in Southeast Alaska.
In the downtown Juneau and Douglas areas, the mountainous terrain induces
what are known locally as Taku winds. These winds occur an average of
four times a year from October through April. Hurricane force wind gusts
(72 mph or greater) occur roughly once every two years during these Taku wind
events. Taku winds produce strong wind shear and turbulence that can affect
the operation of air transportation in the area. Taku winds can also
cause dangerous marine weather conditions.
Storm Surge
When high winds are combined with high tides and coastal storms, they can
generate what is known as a storm surge. Storm surges are a leading
cause of property damage in Alaska. Storm surges occur when 
the
sea is driven inland above the high-tide level onto land that is normally
dry. Often, heavy surf conditions driven by high winds accompany a storm
surge, adding to the destructive force of the flooding waters. The conditions
that cause coastal floods can cause significant shoreline erosion as the flood
waters undercut roads and other structures. The picture at right shows the
storm surge that occured on Thanksgiving Day in 1984. Because of their potential
for heavy damage, storm surges can be the most dangerous and devastating aspect
of coastal storms.
Dense Fog
Dense fog is fog that reduces visibilities to 1/4 mile or less for an hour
or longer. Fog usually forms under clearing skies after several days of rain.
Dense fog occurs in Juneau fairly often and can last up to a week at
a time. Most dense fog events happen in November and December, and can
interrupt aviation service as well as make driving and boating hazardous.
Dense fog can also significantly affect air travel. The Juneau International
Airport is adjacent to mud flats on the Gastineau Channel, an area favorable
for fog formation.
Severe Weather Warnings
The National Weather Service Forecast Office in Juneau monitors for severe
weather in Southeast Alaska. It coordinates weather forecasts and warnings
with local emergency managers, the media, and other government agencies.
What You Can Do
Before and during a storm:
- Get a NOAA Weather Radio to monitor severe weather
- Keep cars and other vehicles fueled and in good repair, with a winter
emergency kit in each.
- Store drinking water, first aid kits, canned food, manual can opener,
radio, flashlight and extra batteries where you can get to them easily,
even in the dark.
- Winterize your home, barn, shed, garage, or other structure that may provide
shelter for your family, neighbors, livestock, or equipment. Install
storm shutters on doors and windows, repair roof leaks, and check the structural
ability of the roof to resist wind damage and sustain unusually heavy loads.
- If you must go outside during a severe storm, dress for the worst possible
conditions.
- When driving or outdoors, carry with you enough spare clothing to protect
you from the weather.
- Report downed power lines and broken gas lines immediately.
- Check on neighbors, especially those who might need help.
The leading cause of death in winter storms is transportation accidents.
During the winter season, keep these tips in mind to stay safe:
- Keep your car fueled and in good repair.
- Install good winter tires.
- Be aware of road conditions. If you are concerned that you will not have
the ability to drive safely on bad roads, get someone else to drive you
or stay home if possible.
- Carry food, water, and extra clothing.
