ST. LOUIS — The first half of December has been abnormally warm, a fact significant for scientists tracking climate change.
Meteorological winter begins on Dec. 1. Why do meteorologists use the calendar and not the rotation of the Earth? Because climate scientists follow weather averages and the lowest average temperatures fall in December, January and February.
Even though calendars say December, St. Louis temperatures have not been following suit. We've already had three days with highs in the 70s and temperatures were sitting around 70 degrees close to midnight, which would make today officially day four of 70s.
St. Louis has broken some warm records too. The high of 76 on Dec. 3 was the daily record and tied with an all-time high for December. Just yesterday, St. Louis broke the record for warmest low temperature. Lows only cooled to 60°, the record was 48° set back in 1929.
Climate scientists agree that warmer temperatures put us at greater risk for severe weather events.
"In the winter, a lot of people think it sounds really good to be warm outside, but it never happens in a bubble it comes connected with other consequences," said Climate Central Chief Meteorologist Bernadette Woods Placky. "One of those is how it just really juices our atmosphere for other things to happen."
Heat rises, so when storms come through over warm air, they grow rapidly and larger than if it had been cooler.
"Unfortunately we're seeing it play out in some of this tornado outbreak that we've seen," Woods Placky said. "Just the amount of water that was added to the system, gave a lot of extra energy. I'm not saying that the warmth caused the tornadoes, but it added to the conditions that were out there."
If you've thought this December has been warm, you are right. Temperatures have ranged from the 70s to the 60s, the average for this time of year is in the mid-40s.
"Obviously, this is not normal for us," said Charles Graves, the Chair of St. Louis University's Department of Earth and Atmospheric Sciences.
Professor Graves said, with current warming trends, we need to be prepared for severe weather.
"If you use the excuse, 'all that came out of nowhere,' then you're setting yourself up for a very devastating impact. You need to be aware that we're going to see this, and I think that's an added aspect of this climate change that we need to be concerned about."