Severe Storms/Winter Storms

This page is to be used for the Severe Storms topic of the Meteorology event.

Snow Storms/Winter Storms
Snow is less dense than liquid by a factor of a approximately ten when in temperatures just under freezing. This means that 1 inch of rain would be about 10 inches of snow. This can make snow storms very problematic, especially in areas that are not used to getting heavy snow; however more than 6 inches of snow will be a problem anywhere. Some of the key dangers of snow storms include hypothermia, frostbite, car wrecks, or even avalanches if near or on a mountain.

In order for a snow storm to be classified as a "blizzard" it must have the following characteristics: Storms are listed below
 * Visibility reduced to less than 1/4 mile
 * Winds greater than 35 miles per hour
 * Last for a long period of time such as three hours.

Blizzards
A severe snow storm with winds in excess of 35 mph and visibility of less than a 1/4 mile for more than 3 hours. Once these conditions are expected, the NWS will issue a "blizzard warning." When these conditions are expected to not all happen at the same time, but one or two will, a "Winter Storm Warning" or "Heavy Snow Warning" may be issued. Conditions of a blizzard develop on the northwest side of an intense storm system. The lower pressure in the storm and the higher pressure to the west's difference creates a tight pressure gradient. This means a difference in pressure between two locations resulting in very strong winds. The winds can then pick up snow off the ground or blow falling snow creating low visibilities and a chance for significant drifting of snow. Blizzards most often occur in the upper Midwest and Great Plains of the United States because of the flat land. A ground blizzard is a weather condition where snow is not falling but loose snow on the ground is lifted and blown by strong winds. Strong winds/cold temperatures combine to create danger, such as the wind chill factor which can drop to –60F during blizzards in the Midwest. A watch is issued when severe winter weather is probable because of the conditions. A warning is issued when hazardous winter weather is occurring, imminent, or there is a high probability. An advisory is issued when less serious conditions are occurring, imminent, or there is a high probability.

For transportation safety, make sure your car is in good working condition, your gas tank must always be half full, good winter tires, high energy snacks and water is stored in your car, dress warmly, use public transportation if you must go outside, listen to the radio/call state highway patrol, travel during daylight with another person, plan long road trips carefully, and always carry a windshield scraper or broom in your car. At home/work you will want to be concerned about a loss of heat, power, telephone service, and supplies. You should have flashlights, extra batteries, weather/portable radio, extra food/water requiring no cooking/refrigeration, first aid supplies, medicine, baby items, heating fuel, emergency heat source, first aid kit, cold medications, allergy medications, sunscreen, and personal medications. Shoveling too much snow can kill people so make sure a very healthy person does it for short amounts of time.

Hazards
A blizzard's main dangers are its strong winds, freezing temperatures, and deep snow.
 * Find shelter indoors
 * Stay away from windows and doors
 * If you're stuck in a car with the engine running to stay warm, keep the windows open a little bit. This will let poisonous carbon monoxide escape from the inside of the car.
 * Keep extra food and water, a flashlight, a battery-powered radio, and, if possible, a cell phone with you
 * If trudging through deep snow, keep moving. Do not lie down to rest.
 * If caught outdoors, use clothing to cover your face and as much of skin as possible.

Nor'easters
A macro-scale cyclone. A northeaster is a storm that blows from the East Coast of North America. This damage can exceed a billion dollars, which can be economic and transportation-related. During Winter, the polar jet stream moves Arctic air to the east area of the U.S. where warm air is moving upwards. Winds circulate counter-clockwise around a low-pressure center. Some famous nor’easters are the Blizzard of 1888, the “Ash Wednesday” storm of March 1962, the New England Blizzard of February 1978, the March 1933 “Superstorm” and the recent Boston snowstorms of January and February 2015.

Lake-Effect Snow
This is a very common occurrence across the Great Lakes during late fall and winter. It occurs when cold air from Canada moves across the waters of the Great Lakes, moisture transfers to the lowest part of the atmosphere. The warm air rises and leads to cloudiness and snow. It usually takes the form of narrow bands characterized by intense snowfall and limited visibility. Sometimes sunny skies can quickly be replaced by thus blinding and wind-driven snowfall in minutes. It is extremely dangerous to motorists. Lake effect snowstorms occur in only three places in the world: The Great Lakes, the east shore of Hudson Bay and along the west coasts of the Japanese islands of Honshu and Hokkaido.

Freezing Rain
Freezing rain can be extremely dangerous. It occurs when there is a layer of warm air aloft and freezing cold air near the ground. Rain will fall, become supercooled in the cold air layer, and freeze when it strikes the ground or an object on the ground. The result is a layer of ice instead of snow. Even for places that are accustomed to snow storms, as little as 1 cm can completely paralyze a city. Dangers including driving, telephone and electrical wire damage, and entire crops can be destroyed.

Precipitation from Winter Storms

 * HAIL- Updrafts in thunderstorms carry raindrops up into very cold places in the atmosphere and freeze, creating a type of precipitation called hail. It can be dangerous to aircrafts, homes, people, livestock, and cars. The times a hailstone traveled to the top of the cloud can be counted in the layers. The stones can melt and refreeze creating strange shapes. Once the hail can no longer be supported, it begins to fall. Hail swaths are where hail falls a lot, sometimes requiring snow plows. Radar, such as Doppler-radar can detect hail as looking like very, very heavy rainfall. Dual-polarization radar technology also can detect it.
 * FREEZING RAIN- Liquid raindrops in a layer of warm air high above the ground fall into a layer of freezing cold air right above the ground. This forms sleet and freezing rain. When the layer of freezing air is very thin the warm raindrops don't have enough time to freeze and they freeze upon reaching the ground creating freezing rain. Whatever the drops land on gets coated in a layer of ice. Sleet occurs when the layer of cold air is thicker. They are dangerous because they can create slick spots on the roads and put weight on tree branches and power lines which can cause them to snap. Rain that falls as a liquid but freezes into glaze upon contact with the ground.
 * ICE PELLETS- Small, translucent balls of ice. They are rain drops that have frozen before they reached the ground. It is also called sleet and can be accompanied by freezing rain. When a layer of subfreezing air near the ground goes high enough, raindrops freeze into little balls of ice before reaching the ground. Same as Sleet; defined as pellets of ice composed of frozen or mostly frozen raindrops or refrozen partially melted snowflakes. These pellets of ice usually bounce after hitting the ground or other hard surfaces. A Winter Storm Warning is issued for sleet or a combination of sleet and snow based on total accumulation which is locally defined by area.
 * SNOW- Precipitation in the form of ice crystals. It comes from clouds that are below freezing. Water vapor condenses in the atmosphere directly into ice skipping the liquid stage. Once it has developed it latches onto water vapor, freezing and absorbing it. It grows into a snow crystal and falls to Earth. Snowflakes are classified as clusters of ice crystals that fall from a cloud. Graupel, sleet, hail, and snowflakes are all considered forms of snow. It is composed of frozen water, meaning it can be classified as a mineral.
 * RAIN- Liquid drops of water that fall to the ground and don't freeze. Water condensed in clouds must be heavy enough to fall from clouds. Droplets can collide with others or grow as water condense out the air into the droplet to grow bigger. Frontal rain forms when two air masses meet. Warm air cools and condenses. Orographic rain is made because of clouds that form because of topography. High ground forces moist cool air up. It is most likely to occur near mountains with westerly prevailing winds. Precipitation that falls to earth in drops more than 0.5 mm in diameter.

Disaster Supply Kits
For Pets:
 * Water, one gallon of water per person per day, for drinking and sanitation
 * Food, at least a three-day supply of non-perishable food
 * Battery-powered radio and a NOAA Weather Radio with tone alert and extra batteries for both
 * Flashlight and extra batteries
 * First Aid kit
 * Whistle to signal for help
 * Infant formula and diapers, if you have an infant
 * Moist towelettes, garbage bags and plastic ties for personal sanitation
 * Dust mask or cotton t-shirt, to help filter the air
 * Plastic sheeting and duct tape to shelter-in-place
 * Wrench or pliers to turn off utilities
 * Can opener for food (if kit contains canned food)
 * In cold weather, you would also want warm clothes and blankets for each family member
 * Photocopies of medical records and a waterproof container with a two-week supply of any medicine your pet requires (Remember, food and medications need to be rotated out of your emergency kit — otherwise they may go bad or become useless)
 * Pet first-aid kit and guide book (ask your vet what to include, or visit the ASPCA Store to buy one online)
 * 3-7 days-worth of canned (pop-top) or dry food (be sure to rotate every two months)
 * Disposable litter trays (aluminum roasting pans are perfect)
 * Litter or paper toweling
 * Liquid dish soap and disinfectant
 * Disposable garbage bags for clean-up
 * Pet feeding dishes
 * Extra collar or harness as well as an extra leash
 * Bottled water, at least 7 days' worth for each person and pet (store in a cool, dry place and replace every two months)
 * A traveling bag, crate or sturdy carrier, ideally one for each pet
 * Flashlight
 * Blanket (for scooping up a fearful pet)
 * Recent photos of your pets (in case you are separated and need to make "Lost" posters)
 * Especially for cats: Pillowcase, toys, scoopable litter
 * Especially for dogs: Extra leash, toys and chew toys, a week's worth of cage liner

Special Topics for 2017

 * Blizzard 2016: