A more active storm track affecting weather patterns in southcentral Kentucky could lead to a slightly enhanced probability of a wetter than normal winter, the director of the Kentucky Climate Center said Tuesday.
That doesn’t necessarily mean more snow, according to state Climatologist Stuart Foster at Western Kentucky University. It could just mean more rain.
Foster said winters in the Bowling Green region generally amount to about 10 inches of snowfall during the season; however, the last two winters have seen more than double that accumulation.
“If we have two snows that cover the grass and last a day, that’s a pretty good winter for us,” Foster said. The average temperature for December was 38 degrees while the average temperature in January 2016 was 34 degrees, according to the National Weather Service in Louisville.
In the short-term, snow is possible for Thursday and Thursday night, with possible accumulation of 1 to 2 inches, the NWS website noted Tuesday.
Moisture content is important in predicting snowfall accumulations, said Josh Durkee, associate professor for meteorology and geography at WKU. Temperature is important, too.
“When winters get warm, they become sensitive to big snows because warmer air has more moisture content,” he said. “You hear warm and you don’t think of snow, but when there is a difference between 20 and 30 degrees, there is also a difference in the volume of water in the air.”
Durkee said while the temperature will dip to the 20s by this weekend, it will rise to the 40s by Monday.
“We are struggling to lock into winter,” Durkee said.
Historically, snowfall amounts don’t show a pattern, but there are seasons of large snow accumulation bunched around seasons when the area barely received any snow. Foster breaks the calendar year in half, looking at snowfall from June 30 of the previous calendar year to July of the following year, with most of the snow accumulating in November, December, January, February and even into March.
The 2015-16 winter saw 24 inches of snow preceded by 23.5 inches in 2014-15.
“It is not uncommon for us to have periods where we had less than 10 inches,” Foster said.
Durkee said weather and the study of the climate are two different things. Climate is a long-term phenomenon, like a personality, he said. Weather is moody, a day-to-day fluctuation of that personality.
For example, January started out in the Bowling Green area with an average temperature in the mid-60s this week and will shift quickly to the 20s within just days, he said.
When a recent six-year period was examined, the results showed that snow builds in accumulation with sporadic lean years. Foster said the winter of 2010-11 saw 21.2 inches followed by a minuscule 1.4 inches in 2011-12 and a slightly less anemic 3.8 inches in 2012-13. The snowfall amount then climbed to 10.4 inches in 2013-14.
Last year’s snow was dominated by two large accumulation months – 14.8 inches in January and 9.2 inches in February. The previous year, though, saw the most snow in February with 12.6 inches and March with 7.2 inches.
How much moisture and whether it turns to rain or snow is affected by weather patterns in the Equator regions, large swirling systems called La Nina or El Nino. Both adjust the jet streams and disrupt traditional weather patterns.
“When you look at the global circulation patterns it is interesting how something in the Pacific Ocean can affect Kentucky,” Foster said.
The Bowling Green region actually sits between major weather patterns – to the north the Great Lakes region down into the Ohio Valley, and to the south.
A La Nina weather system which may hit strong in other parts of the nation has minimal effect here, Foster said.
As the Bowling Green region heads into the winter season, Foster said it is appropriate to take a look back at what he called a “remarkable” weather year of 2016.
“We had a roller-coaster ride of precipitation. This summer – June, July and August – was one of the wetter summers on record and then we just switched off the faucet,” he said. “The fall was one of the driest on record. It is remarkable the degree to which we switched.”
Durkee said while patterns of extreme weather may not be apparent, the weather events are providing precipitation at more extreme levels.
“It is like turning a light switch on and off,” he said.
An extremely dry April, 1.53 inches of rain compared to a normal 4.21, was later followed by a dry June, when 2.47 inches occurred compared to the normal 4.15 inches measured at the Bowling Green-Warren County Regional Airport.
The rain poured in July as 11.12 inches fell, compared to a normal of 4.11, followed by an August that showed 5.16 inches compared to a normal of 3.32, Foster said.
September (1.57 inches), October (0.56) and November (1.91) then hit, dry months nearly 3 inches shy of normal, before things started to stabilize in December, which experienced 4.74 inches of rain, much closer to the December normal of 4.85 inches, the climatologist said.
Some Kentucky counties remain on the U.S. Drought Monitor but are expected to fall off that designation as moisture levels return to normal, the climatologist said.
“In general for Kentucky, an occurrence of 2 inches or more in rainfall in any given day happens about once every four years,” Foster said.
There were some extremes.
During the extremely wet weather, the monitoring station at Draffenville in Marshall County recorded more than 8 inches of rain in five hours.
Foster said snow accumulations are very tricky to predict more than a couple of weeks ahead. In the short-term, Arctic air will move into the area and during January through March there is a possibility of warmer than normal temperatures across the southern tier of the United States.
Average temperatures ranged in the winter months in 2016 from a low of 34 in January to 54 degrees in March, the NWS website noted.
— Real time weather information and historical data is available at kymesonet.org.
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