Frost develops when the temperature of the earth's surface falls below 32 degrees Fahrenheit, but because frost is primarily an event that occurs as the result of radiational cooling, it frequently occurs with air temperatures in the middle 30s. The pellets are cloudy or white, not clear like sleet, and often are mistaken for hail. Depending on the region of the USA, this generally means that four or more inches of snow has accumulated in 12 hours, or six or more inches of snow in 24 hours. Significant accumulations of ice are defined as one-quarter inch or greater. This can cause trees, utility and power lines to fall down causing the loss of power and communication.
Rain drops that freeze into ice pellets before reaching the ground.
Sleet usually bounces when hitting a surface and does not stick to objects. However, it can accumulate like snow and cause a hazard to motorists. Heavy sleet occurs when a half of an inch of sleet accumulates. Snow falling at varying intensities for brief periods of time. Some accumulation is possible.