The weather is one of the choice topics of discussion among people of good Southern stock. A forecast for rain is a great conversation starter, and a decent snowfall can produce enough war stories to keep people chatting for days.
So far, 2011 has given the people of Chattanooga, the Tennessee Valley and Northwest Georgia plenty of grist for the conversation mill. From snow in January, to tornadoes in February, to 80-degree temperatures in March, Mother Nature has provided a Whitman’s Sampler of weather conditions, leading to rampant speculation about what this spring will bring. The consensus is that area residents are in for a bumpy ride.
But since 99.9 percent of the people in Chattanooga have no meteorological training, how accurate is that assessment? Moreover, what kind of weather can local residents expect over the next two months? And how should they prepare?
Since 100 percent of the staff at the Hamilton County Herald has no meteorological training, either, the newspaper turned to a local authority on the matter: David Glenn, chief meteorologist at WTVC News Channel 9. He unravels the mystery of what this spring holds: “This winter, two factors worked together. The La Niña pattern is the periodic cooling of the eastern Pacific waters, which tends to cause ocean and air current changes across the globe. La Niña is the opposite of El Niño, which is the periodic warming of the same Pacific waters.
“Historically, La Niña winters have exhibited cold starts in December, only to have milder conditions prevail in January and February. We did have the cold December and February, but what about January? La Niña was there, but a polar jet stream blocked that pattern.
“Something known as the Pacific Decadal Oscillation could have caused this. We are currently in a cooler period of the PDO, which can lead to blocking patterns that last for weeks. We saw such a pattern from December through late January, which resulted in cold arctic air moving in. Plus, the storm systems moving in from the Pacific crossed the Rockies and then dropped south over the Plains, which pulled in the colder air.
“The end result was several periods of snow and below normal temperatures for December and January. The blocking pattern subsided in February, and we warmed up as true La Niña conditions settled in.”
The end result, Glenn says, was 13 inches of snow for the season, which is well above the normal range of 4.8 inches per year.
“Even though we had a lot of snow, rain was lacking during the time the blocking pattern dominated our pattern. We began February with a huge rainfall deficit. La Niña patterns historically are drier for the Southeast, but here in the Tennessee Valley, it can bring near to slightly above normal rainfall. So, since the La Niña pattern took over in February, we’ve had above normal temperatures and above normal rainfall,” he says.
Glenn says the ongoing La Niña is also responsible for the rumblings about a rough spring.
“Historically, La Niña patterns across the Southeast can enhance the development of strong storm systems racing through the Plain states and then into the Tennessee and Ohio River Valley. That usually puts us in a favorable area for severe weather. This can be most active in March and April.”
To prepare for whatever lies ahead, people should have a severe weather plan in place, Glenn says.
“Have a safe place planned so everyone in your home knows where to go for safety. For severe thunderstorms and tornadoes, that would be the lowest level of your home away from windows, such as a bathroom, closet or hallway. A storm shelter or belowground basement is even better. Mobile homes are not safe, so you must get to a safer structure when tornado and severe thunderstorm watches are issued,” he says.
In regard to water over a road, Glenn wants drivers to be aware that just six inches of water can move a car. To avoid trouble, he recommends people remember this simple rhyme: “Turn around; don’t drown.”
He also wants people tuned in to a local weather source when conditions begin to worsen.
“I’ve worked in this industry for almost 20 years. In that time, I’ve seen technology change drastically. The result has been much more accurate forecasts. Doppler radar improvements have increased the warning times for tornadoes and severe thunderstorm development,” he says.
Above all, Glenn says to respect the weather, even if you’re among the 0.1 percent of people in Chattanooga who have meteorological training.
“I’m a humble forecaster with a huge amount of respect for local and regional weather patterns. I always tell folks the weather is gonna do what it wants to do, and it’s up to us to figure out when and where.”
Visit www.newschannel9.com for immediate weather and radar in Chattanooga, the Tennessee Valley and North Georgia.