Blizzard Warning: Issued for sustained or gusty winds of 35 mph or more and falling or blowing snow creating visibilities at or below 1/4 mile; these conditions should persist for at least 3 hours.
Wind Chill Advisory: Issued when wind chill temperatures are expected to be a significant inconvenience to life with prolonged exposure, and, if caution is not exercised, could lead to hazardous exposure.
Wind Chill Warning: Issued when wind chill temperatures are expected to be hazardous to life within several minutes of exposure.
Winter Storm Warning: Issued when hazardous winter weather in the form of heavy snow, blizzard conditions, heavy freezing rain, or heavy sleet is imminent or occurring. Winter Storm Warnings are usually issued 12 to 24 hours before the event is expected to begin.
Winter Storm Watch: Alerts the public to the possibility of a blizzard, heavy snow, heavy freezing rain, or heavy sleet. Winter Storm watches are usually issued 12 to 48 hours before the beginning of a Winter Storm.
Winter Weather Advisories: Issued for accumulations of snow, freezing rain, freezing drizzle, and sleet which will cause significant inconveniences and, if caution is not exercised, could lead to life-threatening situations.
Source: National Oceanic and Atmospheric Administration (NOAA)
Snow on the farmstead
Get the deepest snow off a roof as soon as possible
Generally, you will have some time between a large snowfall event and possible structural failure.
Check for danger signs
Before beginning to remove snow or enter a building with excessive snow on the roof, look for signs of building damage and the beginning of failure.
- Look at the sidewalls to see if there are any bulges or indications that knee braces have failed.
- Look at the roof line to see if it is still straight.
- When entering a building with excessive snow, look at the ceiling, open trusses and walls for indications of damage or failure.
- If there are indications of building damage or failure, do not climb onto the roof or enter the building while the snow is on the roof.
Snow removal methods
- Hire a professional if possible.
- Get up on the roof and shovel off the snow. There is a danger of falling off the roof when working on a snow-covered and icy roof. Use ladders and safety ropes and take necessary precautions.
- Use snow rakes or specialty tools that can be used from the ground or portable scaffolding.
- Use extreme caution when working near overhead electrical power lines.
- Avoid excessive scraping on the roof or trying to chip off the ice. These practices can damage the roof and lead to a leaky roof.
- If the weather is not too cold, hot water or some other heat source can be used to melt snow and ice.
- Warm the inside of the building sufficiently with large heaters to melt the ice layer and then wait for the snow and ice to slide off.
- A lot of heat is necessary for even a moderately-sized building, and the building must be an open-trussed structure (no flat ceiling) and have an uninsulated metal roof.
- Be careful to prevent large chunks of ice and snow that slide off the roof from falling on people, animals or equipment.
- Do not put heaters in an attic of buildings with flat ceilings because of the fire and carbon monoxide danger and you could create ice dams along the building's eaves.
It is difficult to say how much snow or ice is safe because it depends on the building design and the snow or ice weight. In most cases, agricultural buildings will have an excessive snow load if there are more than four to six feet of snow on the roof.
Excessive snow and ice followed by cold temperatures can create excessive snow loads. You should monitor the snow load situation on your agricultural buildings and take appropriate action. Check high-risk areas and, if you need to remove snow, please be extremely careful.
Source : umn.edu