The present winter storm is jaw dropping from many views. As frigid air continues to plunge into the continental United States, winter storm watches or warnings cowl a lot of the nation. However one thing caught my eye as I scanned the climate radar on the morning of February fifteenth, 2021 – the prevalence of “thunder sleet.” I do know that feels like a superhero or online game icon, however it’s a really a meteorological “thing.” I’ll clarify.
The radar picture above exhibits precipitation depiction. Blue areas are usually thought of to be snow, and pinkish areas are doubtless a mixture of snow and sleet. Many individuals are accustomed to “thundersnow.” If you watch The Weather Channel, my buddy Jim Cantore’s live shot reactions to it are legendary. The American Meteorological Society (AMS) Glossary of Meteorology defines thundersnow as, “a compound of the words ‘thunder’ and ‘snow’ used informally to describe an observation of snow at the surface that occurs with lightning and thunder.” Lightning (which causes thunder) is often related to an environment sufficiently unstable (the air simply will rise) to assist convective cells.
Thundersnow could be very uncommon within the United States. A 2009 paper published in the journal Weather said that thundersnow solely occurs about 0.07% of the time. Thunder snow is uncommon as a result of the combo of raise and instability required for lightning is just extra frequent in heat season months. Additionally, snow is a fluffy and absorbs sound which makes thunder tougher to listen to. However, I think most individuals have heard of thundersnow. The time period “thundersleet” could also be much less acquainted. In reality, I couldn’t discover an entry for it within the AMS Glossary.
Thundersleet (an instance will be heard here) is conceptually just like thundersnow. Convection is inflicting lightning. The important distinction is sleet is falling reasonably than snow. Southerners and other people within the Mid-Atlantic (I-95 hall) are accustomed to blended precipitation occasions. In the U.S., most rainfall begins as snow within the cloud. If the temperature is beneath freezing all the best way right down to the floor, it stays as snow. However, if it falls by means of a area of temperatures above 32 levels F, it melts and falls as rainfall. In some circumstances (like this morning within the Deep South), there are locations with a decrease ambiance chilly sufficient to assist snow. There are different locations the place there may be melting adopted by a refreeze to sleet or ice pellets earlier than hitting the bottom. If the air is above 32 levels F however beneath freezing on the floor, the rain freezes on the floor (freezing rain or glaze).
All of these items are occurring within the South as I write this text. Dr. Brad Johnson is a meteorologist and professor within the Department of Geography at Florida State University. Johnson’s research has explored how hotter city environments can modify the kind of frozen precipitation that falls to the bottom. This weekend Dr. Johnson tweeted the graphic beneath and stated, “Never have I seen the entire state of Texas in a Winter Storm Warning.” I’m not stunned that Johnson, a former doctoral pupil of mine, is monitoring the storm. He is a Weather Geek like me, and he’s from Baton Rouge, Louisiana, a spot presently experiencing blended precipitation. Johnson’s textual content to me this morning sums this storm up properly, “I’ve been scrolling through radar and weather observations for 20 minutes. What a storm this is.”
What’s attention-grabbing (and of concern) is that the forecast fashions and the NOAA Weather Prediction Center name for a number of rounds of this kind of climate within the Deep South over the approaching days. Be cautious.