What’s the difference between freezing rain, sleet and snow? One is most dangerous
Through early morning Wednesday, Dallas-Fort Worth precipitation has been nearly all sleet, which experts at the National Weather Service in Fort Worth say is “quite rare.” Going forward, they expect any precipitation that occurs through Wednesday night to fall in the form of freezing rain.
The National Weather Service has issued an ice storm warning for Tarrant and 13 other North Texas counties up until 9 a.m. Thursday.
The National Weather Service in Fort Worth said the areas affected by the ice storm could see up to half an inch of freezing rain Wednesday night, making the roads extremely treacherous.
For measurement purposes, sleet is considered snowfall. On Tuesday, DFW measured 1.3 inches of snow (sleet), which was a daily record. The previous record for snowfall on Jan. 31 was 1.2 inches, set back in 1985. The Austin metro area, on the other hand, currently has 175,000 customers without power due to almost 1 inch of freezing rain overnight. What is the difference between the two, and why did one type of precipitation cause more damage?
“[Freezing rain] is much more dangerous than sleet, since it freezes on contact with exposed objects (unlike sleet),” said NWS Fort Worth meteorologist Victor Murphy. “The danger here is ice accumulation forming on trees and branches. When the weight becomes too heavy, the branches snap and fall. Often, when they fall, they hit power lines or transformers, resulting in power losses.”
The main difference between snow, sleet and freezing rain is the depth or thickness of the warm layer of air aloft, according to Murphy. If temperatures aloft are below freezing in the atmosphere, between 3,000 and 7,000 feet, then we get all snow. If there is a warm layer between 3,000 and 7,000 feet, the precipitation starts to melt. The thicker or deeper the warm layer, the more rain we get, which turns to freezing rain upon contact with the frozen surface. If the warm layer is thinner, there is partial melting, and the precipitation falls as sleet.
At the NWS office in Ft. Worth this morning, the temperature aloft at 2,500 feet was 20.66 degrees Fahrenheit.
“That is the extent of the cold air associated with this Arctic blast. The lowest 2,500 feet of the atmosphere. From there, temperatures start warming as you go aloft, warming to above freezing at about 4,000 feet,” Murphy said.
That warm layer aloft that is above freezing, at approximately 4,000 to 10,000 feet, causes the precipitation to melt and become liquid. It remains liquid upon reaching the frozen ground, and then freezes on contact. Temperatures warm to nearly 50 degrees at 6,000 feet, then they start cooling again as you ascend into the atmosphere.
