Just four days in September had measurable rainfall at Tri-Cities Regional Airport, leading to the second-driest September on record for the region.
One of the worst droughts in decades continues, and National Weather Service meteorologist Shawn O’Neill said an immovable high pressure system is to blame.
“That system continues to be stationary on top of us, and all of the tropical systems that could provide us with rain are staying to our south,” O’Neill said Monday.
The rainfall gauge in Blountville received just 0.74 inch of rain in September, which was the second-driest in the 70 years of weather collection by the NWS.
The driest on record was in 1985, when only 0.50 inch of rainfall was collected that September.
“All of the northern stream systems have been drying up before they can penetrate that ridge of the high pressure,” said O’Neill, explaining how ferocious thunderstorms and heavy rains that have soaked the Midwest evaporate before they cross the mountains into Tennessee.
The severe drought conditions begin just south of Tennessee, where O’Neill says the lack of rainfall and destruction of agriculture crops is much worse in Alabama and Georgia and extends up into the Tri-Cities region and northeast into Virginia.
“As that high pressure system expanded in size, the continued drought spread out and the Tri-Cities region continues to worsen,” he said.
“Unfortunately, this is our normal dry season that we are in right now. It would take extraordinary circumstances for us to see any significant relief in the short term, whether it is a tropical system or storm or a stalled frontal boundary from the north.
“Our (precipitation) deficit is so bad at this point, it is going to take a lot of time and several systems to see that (dry) trend change for the better. Until then, the region will continue to experience above-normal temperatures and virtually no rainfall.”
A climate summary generated Monday afternoon using Tri-Cities-based data shows the region is 16.22 inches below normal for the year based on average rainfall.
A 90-day outlook doesn’t provide any measurable rainfall for the Tennessee/Virginia region through January, just continued above-normal temperatures and perhaps some precipitation.
“It won’t be quite as warm as it has been lately, but the temperatures are projected to still be slightly warmer than we’re used to,” O’Neill said about the coming months.
“Some areas to our south and west are starting to project above-normal trends for rainfall for the first half of the winter, which is a sign that things are trending more favorably. But for the next 90 days, I do not see any significant improvements for our region.”