Denver is normally a very dry city. It averages only 14.30" of moisture a year. December is one of its driest months of the year. But Monday December 10 brought a whole new level of dry. Precipitable water is one of the many measurements meteorologists use to determine how much moisture is in the atmosphere. Just like it sounds, it's water able to be precipitated (rained out) if there is a mechanism to do so. It's measured by launching a weather observation balloon twice a day, every day. On December 10, the precipitable water reading in Denver was a measly 0.02".  It set a record for the driest ever reported for Denver in December. Plus, it was only 0.01" away from breaking the all-time driest! On an average December day, it would be closer to 0.2". A surface observation at the same time reported a temperature of 59 degrees. The dewpoint scraped the bottom of the barrel at -23, leaving the humidity at a whopping 3%. https://twitter.com/NWSBoulder/status/1072240649573937152 The National Weather Service in Boulder said the dry air came from high in the atmosphere, which often happens in the cold months as the atmosphere compresses. Our affiliate 9News in Denver spoke to Meteorologist Mike Baker with the National Weather Service about what lead to such a record:

“The entire stratosphere had compressed down, and we were getting this intrusion of stratospheric air right down, almost to the surface on the east side of the mountains,”  “It was just amazing to see that coming down.” Your body probably felt the dryness on the skin, nose, and eyes. Baker compared it to the sickness that tourists get when they come from a more humid sea level and go straight up to the slopes. “First I’m craving oxygen, and the next thing they start craving moisture, and your brain starts to react to that and you get these terrible headaches. That’s Rocky Mountain Sickness,” said Baker.

The extended forecast from the Climate Prediction Center keeps Denver, and much of the country on the warm and dry side through Christmas.