Tim Troutman, Warning Coordinator meteorologist with the National Weather Service, said just a little over a month ago the region “needs to warm up and stay that way.”
The tornadoes of April 27 which struck Bradley County and the Southeast were caused by instability in temperatures (hot versus cold), moisture and a La Nina system, weather experts say.
Data provided by the National Climatic Data Center showed key storm dates in April leading up to the April 27 storms. Weather warnings began being issued for Bradley County and parts of Tennessee beginning April 4. Each week in April brought new severe storm watches and warnings.
Forecasters believed this was due to daytime heating.
March precipitation totals indicated 11.77 inches of rain fell in the area, coupled with April’s totals of 8.84 inches of water.
Data also indicated 1.49 inches of rain fell on the day of the severe storms.
Today’s potential thunderstorms include the possibility of dangerous lightning and high winds which could topple already loosened or leaning trees affected by the April tornadoes.
Troutman said residents should remain aware and monitor conditions through news sources and NWS as well as other emergency weather warning systems.
As for the next 90 days, Troutman laid out a general observation.
“It’s going to be an interesting outlook for the Tennessee Valley,” Troutman said. “Indications are that we will be below normal temperatures with normal precipitation and the extreme heat we have experienced until this week was short-lived.”
Since the end of May, temperatures have broken or equaled heat records, reaching 98 degrees on occasion and being above the 90-degree daytime high marks until the past few days.
“The indications are the climate patterns will be normal for summer. A slight El Nino pattern is developing for the fall and winter and this could be tricky for our area,” Troutman said.
“We will keep watch on the transition for the upcoming fall weather season,” he added. “Is it going to be much of an effect? That is the question because it is a very active pattern.”
Troutman said this year marks the third year of La Nina/El Nino phenomena which can cause significant changes in U.S. weather.
A La Nina is “cooler than normal water temperatures in the equatorial Pacific Ocean. An El Nino is associated with warmer than normal temperatures,” according to the National Oceanic and Atmospheric Administration.