North Georgia Tornadoes and Repeated Weather Patterns
Earlier today on January 30, 2013, northern Georgia experienced an intense squall line associated with a strong cold front sweeping through the Great Plains, upper midwest and southern part of the country.
The region had been experiencing unseasonably warm weather for the past couple of days, and the Atlanta area flirted near 70 degrees Fahrenheit before today’s storms arrived. Considering that it’s the end of January, that kind of a high temperature is quite impressive. It also tells you that something big with the weather is about to occur. You don’t reach high temperatures like that in the winter without “paying” for it. As of right now the storms have passed and we’re dropped twenty degrees in temperature with our low tonight expected to be around freezing. In other words, we went from an early spring back to winter in the course of a few hours.
WSB-TV news footage of the Adairsville, Georgia, tornado
The deadliest part of today’s weather occurred when an estimated EF-2 or possibly EF-3 tornado ripped through the Adairsville, Georgia, area, destroying parts of the town and shutting down interstate 75 for a brief period of time. One person was killed and fourteen others were injured. About 100 cars have been reported to have been tossed around and flipped over by the tornado.
Just north of Adairsville, the outskirts of Calhoun, Georgia, was also hit by a tornado. Eight people were reported to have been injured and local damage includes homes and poultry farm buildings.
As an avid storm watcher, it’s interesting watching the formation and progress of these supercell thunderstorms and how many of the thunderstorm cells tend to hit the same areas of town. Keep in mind what I’m about to discuss is just a theory based on general observations made over the past few years. I don’t have solid facts in front of me right now.
As we know, the general weather pattern over the southeast flows from the west to the east, though at times it flows from the west-southwest to the east-northeast. You get the picture.
When storm systems transit the region they generally move from west to east though the individual thunderstorm cells usually move from southwest to the northeast, sometimes up to 45 degrees off from the system’s general motion. These thunderstorms usually have short lifespans. Once the storm cell “dies,” a new cell often develops on the southwestern quadrant of the previous storm and normally continues in the first storm’s direction.
Anyway, when observing the storm events during the past few years, it’s a little bit alarming seeing the same towns and areas being hit with the severe weather. On the western side of the state, it’s common to hear about towns such as Carrollton, Bremen, Cedartown and Rome. When you factor in the normal weather patterns, you pretty much know if your area will be in danger or not based on the initial reports of the storms’ locations. For example, when you hear storm reports from Cedartown and Rome, you know that you’re pretty much in the clear if you’re living in the northern parts of Cobb and Fulton County.
If you live in northern Cobb or Fulton County, you’re going to pay more attention to the thunderstorms that pass through Bremen and Carrollton near Interstate 20. As the storms generally move from the southwest to the northeast you’ll hear reports of places like Villa Rica, Douglasville and the Dallas area being hit with the warnings. Normally if Dallas gets hit then eastern Marietta, southern Kennesaw and Woodstock are next.
But as the thunderstorms approach the Atlanta area, how often do you hear about anywhere inside of 285 or on the western side of the city being hit with a tornado? Lately it’s been pretty rare.
In the Atlanta metro area, you always hear about Paulding and Bartow County being hit with severe weather. Douglas County follows that along with northwestern Cobb County and then Cherokee County. But as far as southern and eastern Cobb, along with northern Fulton and Gwinnett County, it seems like the severe weather has been avoiding those areas. Yes, those area still get hit with severe storms (such as last spring’s EF-1 tornado in eastern Cobb County), but as a whole those spots don’t experience the frequency of the severe weather that normally strikes just to the west and northwest of the metro area.
My theory about the general lack of tornadoes in east Cobb, Fulton, DeKalb and Gwinnett involves the city of Atlanta. No, we’re not talking about the extremely high crime areas scaring away the thunderstorms. This involves the “urban heat island” of the Atlanta metro area.
An urban heat island occurs when a metropolitan area experiences slightly higher temperatures than the surrounding area. The higher temperatures are from human involvement and urban features such as asphalt, industrial sources, pollutants from cars, trucks and buses, and a general lack of soil, vegetation and bodies of water. Urban heat islands can be measured in both small towns and large cities, though the effect is significantly more noticeable in the cities.
I wonder if the urban heat island of Atlanta has an effect on severe weather and the general lack of tornadoes as you get closer to the city limits. Is it possible for a major city like Atlanta to “shield” the immediate areas to the west and northwest from severe weather? Could this effect also “protect” parts of the metro area to the northwest?
This is just a theory of mine. At some point I’ll do some research and see if there’s more to the pattern of severe weather in northern Georgia.