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Let me just start by saying that Saturday was likely one of the wildest weather days of 2016 across the US, not just here. Saturday was a day that will live in infamy in my mind, mainly because it was just ridiculous. The build up to the event itself was large, and it did not disappoint.
Arctic air had been building across western and central Canada (finally) after a very warm November. This really just set us up for a cold December, as it would only take one system to tap into that cold air. Well, that happened on December 8th, as a cold front marched through and pushed us into well below average temperatures.
Well, the models began to point towards another major cold snap occurring during this timeframe, but they weren’t handling its timing or its strength very well. This was a very active pattern, as well, so it wasn’t gonna be an easy forecast either way. There were a few things that looked to occur:
- Major warm up ahead of the system
- Major temperature fall behind the front
- Wintry precip was possible
- Heavy precip ahead of the front
Where in there do you see “Severe Weather set up,”? You don’t, do you? Yeah, that didn’t happen. One thing is for sure: the system looked to have every bit of the dynamics that it ended up having. In the 5-7 day timeframe, it looked like there was gonna be a threat for severe weather, as the wind energy in the atmosphere was kinda ridiculous. In addition, the forcing was there. A strong cold front; favorable placement in a jet streak? Yup.
This event would have been unique by itself, but the combination of features that it produced created an event that won’t be forgotten (by the weather world, at least). As the days went forward, the severe weather threat rolled to the back burners. Keep that in your mind, though. Wintry weather became the major focus, here and at large. How could it not? The models were forecasting a temperature drop of 30°F to 40°F behind the front. This was forecast to change precipitation from rain to freezing rain to sleet and then to light snow.
No models were forecasting a ridiculous event; only one that could be impactful. And it was important that precipitation kept falling after the frontal passage. This left water on the road, and set up the flash freeze possibility, which was the biggest reason for concern.
By Saturday, this forecast looked in the hand. A major temperature drop was gonna occur, with heavy rain going to a wintry mix and a flash freeze possible. Oh, and that small severe weather risk. Yeah, that thing! Well…that was a bad forecast on my part. Phew, that was a rough one.
That afternoon, temperatures soared into the upper 60s locally, and into the lower 70s in western KY. Dewpoints had shot into the lower 60s region wide, creating a warm and seasonably unstable atmosphere. This set up, along with large scale forcing moving in, created a severe weather risk across the region.
Wind shear was there, instability was there and forcing was definitely there. Additionally, there were some parameters in the lower atmosphere that pointed to tornadoes being a possibility during the afternoon. It was a concerning set up, and one that rose to possibility very quickly.
Luckily, however, most of the major severe weather stayed to our west. You can see by the warnings issued that day, the majority of us missed out on the severe weather event. The thunderstorms developed a bit earlier than expected along the front, and as they developed, they developed a weak cold pool. This was just enough to drive the cold front eastward ahead of the main thunderstorms, and this caused the thunderstorms to become elevated. Thus, we lost our severe weather threat.
h/t Iowa Mesonet
That isn’t the point, though. The severe weather added to an already ridiculous atmospheric set up. We literally rose from 20°F on Friday morning, to 68°F Saturday evening, back to 18°F by this morning. If you were just an outsider looking in, and this was your only experience of Kentucky weather, you would have the worst thoughts about the weather of this place!
Also: I have never ever, ever ever seen the Storm Prediction Center issue severe weather and winter weather mesoscale discussion for our area on the same day. Never. Oh, and we had a Tornado Watch overlaying a Winter Weather Advisory??
h/t SPC
It’s not every day you see a Tornado Watch AND Winter Weather Advisory for the same location. But…Kentucky weather don’t care. pic.twitter.com/hbXSSujIj3
— wxornotBG (@wxornotBG) December 17, 2016
The day was full of meteorological adventures; and, in my mind, is considered to be the running favorite for most ridiculous weather event of the year. As a final point about Saturday, just look at some of these 72 hour temperature graphs from the Kentucky Mesonet.
Absurd. Absolutely absurd.