Freezing rain: It will start in the sky as snow, melt as it falls, then freeze on the ground
Freezing rain may hamper the morning commutes of many in Central Indiana on Tuesday with portions of the state predicted to receive nearly a quarter inch of ice cover.
The National Weather Service in Indianapolis says the icy rain will begin Monday evening and finally break mid to late morning on Tuesday. The good news is that NWS predicts ice won’t form on trees and power lines, but roads and sidewalks could become treacherous.
How does freezing rain form?
Greg Melo, a meteorologist with Indy’s NWS, said freezing rain is just normal rain that freezes when it contacts something very cold.
The sky above Indiana will likely be producing snow, but as it falls and meets warmer air above ground-level, it will melt.
What makes this forecast different than normal, Melo explained, is that it’s been so cold in recent days that the temperatures on the ground will cause the falling water to freeze quickly.
“There’s a shallow cold layer at ground level that’s going to freeze the rain on contact,” Melo said. “It might not freeze immediately, but we’re expecting most of the rain to freeze.”
Why are the trees and power lines safe?
Usually freezing rain forecasts spell worry for utility companies shuffling power along aerial lines. But due to warmer air sitting just above ground level, branches and cables are not as cold as the concrete and asphalt below, so Melo said they’ll be spared this time around.
Indiana usually sees two or three freezing rain events each year, so it’s a common enough forecast during winters, but the warm air above the ground is a recipe for something more out of the ordinary.
“This is definitely quite a unique event,” Melo said. “It’s not something we haven’t seen before, but it’s definitely different from typical events.”
Weather in Indianapolis: Freezing rain is on the way. Here's when winter weather will hit today
Karl Schneider is an IndyStar environment reporter. You can reach him at karl.schneider@indystar.com. Follow him on Twitter @karlstartswithk
IndyStar's environmental reporting project is made possible through the generous support of the nonprofit Nina Mason Pulliam Charitable Trust.
This article originally appeared on Indianapolis Star: When does rain freeze and why?
