Q: Sleet is in the forecast. Is there any difference between sleet and freezing rain?
A: The only real difference is that they are formed a bit differently, explains Brent McRoberts of Texas A&M University. Freezing rain is rain that freezes when it comes into contact with other surfaces, such as pavement or cars. “Freezing rain forms when warm, moist air moves over cold air near the surface,” McRoberts says. “Freezing rain is very dangerous because it tends to coat roads with ice first. If the surface it hits is 32 degrees or lower, it will quickly freeze on contact, and if the ice accumulates, it can shut down an entire city very quickly. Sleet is often confused with freezing rain. Sleet falls to the ground frozen, often forming in advance of a warm front. Sleet falls as ice pellets that make a familiar crackle sound as they hit the ground, trees or cars.”
Q: Can you have freezing rain, snow and sleet at the same time?
A: Yes you can, McRoberts adds. “Winter storm systems frequently contain all three,” he says. “Very often, you can have more than one precipitation type at the same time. All three types of precipitation begin falling from clouds as snow. If a snowflake doesn’t encounter air warmer than 32 degrees as it falls to the surface, you will have snow. If the snowflake encounters a pocket of warmer air beneath the cloud as it falls, it will melt. Sleet occurs when the melted snowflake has a chance to refreeze before reaching the ground, while freezing rain occurs when it doesn’t freeze until contacting the surface. Forecasting the type of precipitation is difficult because just one or two degrees in temperature difference can change whether an area receives rain, snow, freezing rain, sleet, or a mixture.”