These ice crystals stick together as they fall towards the ground, forming snowflakes. If the air near the ground is above freezing temperature, the precipitation will melt to form rain or freezing rain. A snowstorm where there is no accumulation beyond a light dusting of snow is called a snow flurry. A brief snowstorm with snow falling at varying intensity and some accumulation is called a snow shower. If the snow showers are accompanied by strong gusts of wind and accumulation of lots of snow, they are called snow squalls.
A blizzard is considered a severe kind of snowstorm and is described in more detail below. A blizzard is a severe snowstorm defined by the strength of the winds rather than the amount of snow it brings.
With wind speeds at or above 35mph, blizzards create blowing snow conditions, where snow on the ground is picked up by the wind, causing reduced visibility and the accumulation of snowdrifts. A blizzard lasts for three or more hours and often leads to the accumulation of lots of snow, either as new snowfall or as redistribution of previously fallen snow as blowing snow. Most snowstorms form due to low-pressure systems that lift moist air into the atmosphere, but lake effect storms form due to the abundance of moisture from the Great Lakes.
When cold, dry air from the north passes over the Great Lakes area, it picks up large amounts of water, which falls back to the ground as heavy snowstorms in the areas south and east of the lakes.
An ice storm is a winter storm that has an accumulation of at least 0. The ice forms a slick layer on the ground that can make driving and walking conditions dangerous and can cause branches and powerlines to snap due to the weight of the ice. There are different types of icy winter weather , which are determined by the temperature of air masses in the storm. Freezing rain occurred south of the snow area. Ice accumulation from southern Illinois through south central Indiana and into central Ohio ranged from 0.
In extreme southern Missouri, far southern Illinois, southern Indiana and northern Kentucky and far southern Ohio the ice was more than an inch thick, with up to 1. Total precipitation from this storm exceeded three inches for much of southern Kentucky. Tree and power line damage was massive from Missouri to Ohio.
Power outages were widespread from Missouri, where there were more than , homes without power, into Indiana. Ameren Illinois reported more than 7, customers without power at the peak of the storm in southern Illinois. The worst-hit area was western and northern Kentucky into southern Indiana. The Kentucky Public Service Commission reported that at least , homes and business were without power following the storm, the largest power outage on record for the state.
This figure did not include municipal utilities or rural electric cooperatives within the Tennessee Valley Authority system, and estimates put the total number at more than , customers. The power outages affected many public water systems limiting drinking water supplies. On January 31 Kentucky Governor Steve Beshear ordered the activation of all Kentucky Army National Guard units and some Air National Guard units, bringing the total number of guardsmen responding to the storm to 4, On November 30, a strong Arctic cold front was moving through the Midwest.
That morning the front was near the Illinois-Indiana line. West of the front in the cold air rain changed to freezing rain, and west of that heavy snow occurred as a strong upper level disturbance moved over the region.
On the afternoon of December 1, Ameren Energy, which serves a large portion of eastern Missouri and central Illinois, reported more than a half million outages serving 2. Damage to power lines and trees was extensive. Repair crews were hampered by incredible accumulations of ice and sub-freezing weather which prevented any of the ice from melting.
It was a week before most power was restored. This stands as one of the worst ice storms in Wisconsin history. There were widespread accumulations of two inches of ice, with a band of three to four inch accumulations across west-central Wisconsin. FEMA web page on what to do before, during, and after winter storms and extreme cold. This Ready. Urbana, IL Changnon, Stanley A. Frost: Frost describes the formation of thin ice crystals on the ground or other surfaces in the form of scales, needles, feathers, or fans.
As with the term "freeze," this condition is primarily significant during the growing season. If a frost period is sufficiently severe to end the growing season or delay its beginning, it is commonly referred to as a "killing frost.
Please Contact Us. Safety National Program. Ice Storms Weather. Winter Resources. If you see any of the following conditions, do NOT go out on the ice: Cracks, holes or breaks in the ice Flowing water around the edges, just below the surface, or over the top of the ice Ice that appears to have thawed and refrozen If you decide to venture out on the ice, remember the following guidelines: Stay off the ice if it is less than 2 inches thick!
For ice fishing, ice skating and walking, you need 4 inches or more of ice.
0コメント