Still Cold but More Bearable

Cold, cold, cold! That's really the only way to describe the past 36 hours here in south-central Kentucky. This evening, most locations are hanging steadily in the 20s, but that is almost a welcome sight compared to the temperatures we endured last night. The WKU farm mesonet site recorded a low of just 2° this morning. Here's a little history for you: the last time Bowling Green saw single digits was Feburary 7 of last year, and last night was the coldest since January 9, 2014. Many areas north of Warren County were sub-zero. Hartford/Beaver Dam in Ohio County was the most bitter in our region, with a low of -4°.

Where in the world did this ice wave come from? The answer is fairly simple (and has nothing to do with that polar vortex nonsense). A few days ago, we were watching the development of an unusually strong high pressure system over Alberta, Canada. Models had forecast this high to push southeastward into the Central US with nearly unprecedented strength. Already around 1050 mb, some models had projected the high to increase to 1063 mb over the Northern Plains states. In other words, that is some very high pressure. Just for comparison, average sea level pressure is 1013.25 mb, and some powerful low pressure systems can fall below 990 mb (or millibars).

Highest barometer readings on record for 80+ United States cities (values in millibars)

While the high didn't quite become that stout, it did break some pressure records around the Badlands with a few locations surpassing 1060 mb. Naturally, frigid air was accompanying this system. The strength of the high contributed to high winds circulating clockwise around it, while the center was completely calm. It's like a tropical storm but not as wet or violent. On approach, these winds contributed to some dangerous wind chills of -5 to -10 degrees below zero, but these subsided for a little while early this morning as the high passed over us at about 1044 mb. Now the high is departing, and we once again find ourselves inside the windy circulation.

Temperatures will only slightly taper tonight with plenty of clouds. Winds will continue to keep wind chills in the teens. Around sometime tomorrow we should see the arrival of a weak cold front. The air mass in place is plenty dry but the front may provide just enough lift to see a few flakes fly during the AM hours. As the day goes on, look for skies to be give way to more sunshine. Another high pressure system will assume reign over the Midwest after the cold front leaves, which will snuff out most of the clouds. This will deliver another shot of bitter air as well, bringing Friday night lows in the single digits once again. Fortunately, winds will decrease to calm levels by Saturday morning.

Tonight: Low around 22° with mostly cloudy skies. Perhaps a few flurries during the early morning hours with winds from the southwest at 10-15 mph (wind chills around 10°).
Friday: A high of 23° with flurries ending early. Northwest winds around 10 mph with skies transitioning from mostly cloudy to mostly sunny.
Friday night: Low near 9° with northwest winds around 10 mph in the evening (wind chills near zero) then becoming calm. Mostly clear skies.

Thanks for reading!
- Caleb Chevalier