ST. LOUIS - “Polar Vortex” is a trendy phrase with meteorologists and people who make small talk about the weather, but what does it mean?
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For people in the Riverbend this week, it means falling temperatures over the next few days – starting this afternoon. Meteorologist Ben Herzog from the St. Louis Office of the National Weather Service (NWS) said temperatures will fall throughout the day Monday – from almost balmy morning highs of around 40 (hence why rain came instead of snow) to below 20 degrees by Monday afternoon. Temperatures will continue to fall through Thursday morning, with dangerous lows Wednesday and Thursday mornings of around zero degrees. Wind chills are expected to be negative 20 Wednesday morning and negative 10 Thursday morning.
But what does this have to do with the Polar Vortex? Well, the Polar Vortex is a weather system usually hovering around the North Pole – hence its name. When the jet stream switches from a west-to-east into a north-to-south flow, as it currently has, weather systems from that area of the world tend to dip a little further south than usual, which includes the Riverbend with this juncture.
Because of this polar vortex, a cold front is sweeping through the area Monday. It will be reinforced by a second cold front Tuesday afternoon, which will take temperatures from cold to downright bone-chilling. That cold front may be accompanied by two possible bands of light snow. While Herzog said forecasts were unsure of where that snow may fall at this time, precipitation is not expected to exceed an inch, and all the snow will be fluffy and light.
To rescue the Midwest from this Polar Vortex, Herzog said warm air will move through the area Thursday afternoon, which may mean some snow. Where and how much are still up in the air, as precipitation is expected to come from a low pressure system forming over the Great Plains. This will drive winds from the south to come to the area, bringing warmer air.
In typical Midwestern winter fashion, temperatures are expected to reach the 40s on Friday and as high as 50 degrees Saturday following the passing of this unsettled air from out west on Thursday afternoon.
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