Has Central Kentucky seen the last of the summer’s heat? When to expect fall weather
The thermometer may have reached 85 degrees Fahrenheit in Lexington Wednesday, but close observers of the forecast will notice an apparent break in the heat later this week, according to the National Weather Service’s seven-day forecast.
In fact, the latest outlooks from the nation’s Climate Prediction Center offer more encouraging news over the next week or so for autumn lovers eager to feel the return of fall weather.
Between Sept. 12-16, most of Kentucky has a 60 to 70% chance of experiencing below-normal temperatures. Those below-normal temperatures have a good chance of sticking around till Sept. 20, according to Climate Prediction Center outlooks.
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So does this mean Lexington and Kentucky more broadly may finally be seeing the last of the summer’s heat? Well…maybe and maybe not. According to Kyle Wilkins, a meteorologist with the NWS in Louisville, long-term forecasting is difficult during this time of year in Kentucky.
Here are several reasons why that is, plus, why more 90-degree days aren’t out of the question for Lexington this month.
What’s the problem with long-term weather forecasting?
Forecasting the weather involves parsing an ever-changing set of variables within a chaotic atmosphere, and recent evidence suggests climate change is shortening the prediction window meteorologists have.
As explained by Wilkins, producing reliable, long-term forecasts beyond a week or so is even trickier. And the influence of Atlantic hurricane season, which is only beginning to reach its peak, muddies the waters further, Wilkins told the Herald-Leader.
“This time of year, remnants of hurricanes can move over our region and dramatically change temperature and precipitation forecasts. These systems can develop and start changing forecasts in a week or less, so they can really mess up longer period forecasts,” Wilkins wrote in an email to the Herald-Leader.
To predict the weather, meteorologists rely on modeling that, while helpful, has limits. After all, a model is only as good as the data it uses to formulate its initial assumptions, Wilkins notes.
“There is no way to capture every aspect of the atmosphere, and the further in time you run a model the more bad data or incomplete data will become bad model guidance,” Wilkins wrote. “When looking at models, they can be all over the place. Sometimes with summer convection we see that one model may be handling current conditions better than others, or maybe, no model is handling current conditions very well.”
As a result, forecasters must adjust accordingly and look for consensus among the models as a weather event draws nearer, Wilkins said.
What should Lexington residents expect from the weather this fall?
According to Wilkins, the presence of a cool spell does not rule out warmer-than-normal temperatures this fall, which is what forecasters are anticipating.
For context, what the NWS considers “normal” is defined as a 30-year average of temperatures.
“It’s possible or even likely that we could see more 90 degree temperatures during September. That’s only 10 degrees warmer than ‘average/normal’. It’s normal for weather to fluctuate above and below normal” this time of year, Wilkins told the Herald-Leader.
As we head into October, the odds of seeing 90-degree days will get longer. The average temperature high in October for our area is 68.6 degrees, Wilkins noted, calling a 20-degree spike above that temperature an “anomaly.”
What’s more, record October highs for Lexington are in the 90s for eight of the first nine days of the month, Wilkins noted.
“Starting on the 10th, the records are in the 80s, so there is a noticeable drop off in high temperatures historically speaking,” he wrote.
The Climate Prediction Center seems to agree with Wilkins. Its outlook for Sept. 16 to Sept. 29 shows a 55 to 60% chance of above-normal temperatures.
Zooming out further to the center’s three-month outlook, covering September through November, the odds are leaning toward above-normal temperatures for Central and Eastern Kentucky.
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