Subj : Winter Weather 2020 (C) To : All From : Daryl Stout Date : Tue Dec 01 2020 12:01 am Public Information Statement National Weather Service Little Rock AR 600 AM CST Tue Dec 1 2020 November 30th through December 4th is Winter Weather Awareness Week in Arkansas. The purpose of this week is to remind people what winter weather can bring, and how to deal with hazardous winter conditions. Now is the time to prepare for the upcoming winter season. Today's topic is winter precipitation types. Snow -- Snow forms in the clouds and remains as snow all the way to the ground. It most commonly takes the form of snowflakes, which are the familiar six-sided ice crystals. It may also fall in the from of snow pellets or snow grains. Snow flurries are normally seen as a few snowflakes falling, although visibilities can be reduced at times. In Arkansas, the term snow flurries is used to indicate that no accumulation is expected. Snow showers is a term not often used in Arkansas. Given this type of precipitation, snow falls at varying rates, often changing intensities over brief periods. Accumulation may occur, especially during moderate to heavy snow showers. Blowing snow refers to snow that is already on the ground and is lifted into the air by the wind. In Arkansas, heavier snows usually occur when cold air is already in place over the state and a strong upper level low pressure system moves out of the southwestern United States. The low serves to pull moist air from the Gulf of Mexico northward into the cold air. Light snow or snow flurries can also occur in the cold air that follows the passage of an Arctic cold front. Sleet -- Sleet consists of pellets of ice. In fact, for people who have trouble with the difference between sleet and freezing rain, it may be easier to associate sleet with its technical name, which is ice pellets. For sleet to form, snow begins falling from the clouds but then goes through a layer of above-freezing air thousands of feet above the ground. This causes the snow to change to rain. Then, the rain goes through a layer of below-freezing air, usually at least two to three thousand feet thick, and the precipitation turns into pellets of ice. Sleet typically occurs in a fairly narrow band between an area of rain to the south and snow to the north. This band usually moves as the temperature profile changes, but may remain nearly stationary if temperatures fail to fluctuate. This often results in accumulations of sleet. Freezing rain -- This weather phenomenon is sometimes called glaze, because of the glaze of ice that builds up on surfaces near the ground. Freezing rain normally occurs when precipitation falls from the clouds as snow, then goes through an above-freezing layer, which turns the precipitation to rain. Then, the rain reaches the ground where temperatures are below freezing. The rain then freezes as it hits exposed objects. In the worst cases, everything becomes coated with a layer of ice. In Arkansas, freezing rain commonly occurs as an Arctic high pressure system begins to move away from the state. In this situation, cold air is still lingering at the ground, but warmer southerly winds from the Gulf of Mexico begin bringing moisture back over the top of the cold air. Since the air at the ground has not warmed above freezing, the rain that falls freezes on the ground and other objects. Freezing rain, and its cousin freezing drizzle, often develop during the late night hours, creating icy conditions for morning rush hour. Freezing Fog -- While this is not precipitation falling from the clouds, it is another winter weather hazard. Freezing fog typically develops on clear, calm nights when temperatures are below freezing. Fog forms and freezes, usually on bridges, overpasses, and other elevated roadways. The resulting thin layer of ice can create quite a surprise for motorists due to the presence of clear skies overhead. Frost -- Frost describes the formation of thin ice crystals on the ground or other surfaces in the form of scales, needles, feathers, or fans. Frost forms when water vapor in the air turns directly to ice crystals on an object. The temperature of the object must be below freezing for frost to occur. However, frost is sometimes seen on the ground when official temperatures are reported to be above freezing. This is because the official temperature is taken about five feet above the ground, where the air can be a few degrees warmer than the temperature at ground level. && Please visit our web site at https://www.weather.gov/lzk $$ --- SBBSecho 3.11-Win32 * Origin: The Thunderbolt BBS - tbolt.synchro.net (11:1/214) .