From WindsportAtlanta.com: Wiki
While windsurfers generally pay much attention to the wind and weather, Atlanta and the inland Southeast have certain weather characteristics that a windsurfer should know about.
Atlanta, while a pleasant place to live and work, is not a place renown for its wind. A cynic once said of Atlanta, "it's where wind goes after it dies."
The winds we do get are driven primarily by two processes:
Generally, wind is created by either the earth's rotation (trade winds) or differences in air temperature (cold fronts, tropical storms, sea breezes). Because of our location in the Southeast United States, a fair amount of open, surrounding land and irregular geography, especially to the west, and distance from the ocean means that a lot of the factors that make other locations windy (beaches, tropics, Columbia Gorge) simply don't exist here. Many localized weather patterns, like sea breezes, stem from differences in temperature between local features like land and adjacent large bodies of water; again, something Atlanta lacks. Finally, the jet stream, the engine of our cold season weather fronts retreats northward in the warmer months, visiting only occasionally.
That doesn't mean its all bad. It just means that
- windsurfers tend to become students of weather
- windsurfers tend also to have other forms of outdoor recreation, e.g. cycling, kayaking, wake boarding, motor and dirt biking
- windsurfers tend to make pilgrimages to windier locations such as the Outer Banks, Florida, the Gorge, etc.
Once you learn and understand what conditions make wind more likely here, you'll be happier and have more effective time on the water.
The prevailing and upper level winds at Atlanta's latitude are from the west. Weather systems will tend to move from west to east. Even tropical storms at our latitude are heavily influenced by this so tend to "bend right" as they move northward.
Locally, this has a significant impact on days with east wind.
The Jet Stream
Excluding tropical systems, almost all weather systems here are driven by the jet stream. When the jet moves southwards in the fall and winter, we tend to have the common cycle of weather fronts. In the summer, the jet retires northwards and the air becomes very stable in the Southeast, which means light and variable winds. The jet will sometimes venture south in the summer and brings relief in temperatures, but this is uncommon.
Tropical Events and Weather
We can have tropical events - depressions, storms and even hurricanes - during the season that goes from June until the end of November. The wind strength and direction will depend greatly on the proximity of the center of circulation and on which side it passes us. While such winds do provide us with great fun, we are cognizant that the same system may well have wreaked havoc elsewhere.
As the earth cools in the Fall, cold air and the jet stream descend from Canada and encounter warm, moist air moving up from the Gulf of Mexico. The large variations in temperature and air pressure in these convergences generates the familiar cold front pattern. This pattern occurs in three stages:
- Warm, moist air pushes up from the Gulf of Mexico ahead of the front. Temperatures may range from not cold to unseasonably warm. Typically, winds are from the SW. At times, these warm breezes preceding the front are strong enough for an enjoyable day although they tend to be stronger in the spring time.
- Warm air meets cold air as the front moves through Georgia from Mississippi and Alabama. At the convergence, rain and showers form. Depending upon the strength of the systems, these showers can be heavy and accompanied by severe weather - thunderstorms, strong winds and tornadoes. Sometimes, there isn't enough moisture to trigger showers and we'll get a dry front.
- Cold, dry air rushes in behind the front. Temperatures drop. Winds can be from the west to northwest.
When this pattern is active, it may cycle from four to seven days apart, bringing regular windsurfing conditions.
Also common, especially in early fall, are low pressure systems carried by the jet stream which may generate NE and E winds. A variation of this is the wedge where cold air spills down the foot of the Appalachians from a N/NE direction. East and NE winds can be very time dependent because of thermal mixing.
Fall is the end of hurricane season and, occasionally, a system will make its presence felt in Atlanta. The systems tend to be very swift moving, relatively small in scale (although, not necessarily in intensity) and unpredictable.
Many windsurfers in Atlanta sail through the winter with appropriate gear. With the proper suit and even gloves, hood and footwear, one can safely and comfortably sail in mid-winter when air temperatures are in the 30s and water temperature in the 40s. As hypothermia is the biggest risk to a local windsurfer (no known cases of fatal crappie attacks here in Georgia), dressing well is mandatory. Winter conditions can be challenging with strong winds, significant swells and cold temperatures.
Winter weather is primarily
Spring conditions are similar to fall conditions. Warmer southerly flows preceding fronts, however, while bringing fresh SW breezes also make it much more likely that weather fronts will bring severe conditions like tornadoes.
While the air is warmer, the water will remain cool and wetsuits may be necessary until late May or longer depending upon the air temperature and one's tolerance for cold water.
If the air is much warmer than the water, a dome effect may occur, the warm air sliding over the top of surface air cooled by the lake. It may be windy everywhere except at the lake.
Summer means light breezes in Atlanta. With no close by ocean for a sea breeze and the jet stream vacationing for the most part in Canada, there are few means available to create consistent windy weather. Put another way, when it's 95 degrees in Idaho, Atlanta and Florida all at the same time, it's difficult to create wind by cooler air replacing warm, rising air.
The most prevalent ways for temperature induced wind in the summer are a) thunderstorms and b) tropical systems. Once in a long while, you may get a decent breeze drawn by a far away thunderstorm. Remember a couple of things, however:
- lightning can strike up to ten miles from a cloud and there are few things more frightening than holding a 490cm lightning rod in your hands while being the tallest object for hundreds of yards
- the wind can shut down at the most inconvenient of times, leaving you in the middle of the lake in the pouring rain
If your phone has a good radar app, you can keep an eye on how far a system is from you if you get so lucky. However, we urge you to err on the side of caution. You don't want to have one of those "what was I thinking" moments. (We speak from experience.) Also be aware that most apps have a time lag between the radar image you see and real time which may be as long as twenty minutes and storms can move considerably in that time.
We do get the occasional "cold" fronts in the summer but they are the unexpected pleasure and may only happen a handful of times at most between June and August.
Tropical systems (better known as Hurricane Season) can bring strong breezes between June and November. Timing and location are critical as often these systems are fast moving and conditions can vary greatly depending upon how far you are from the center or on what side of the system. Winds flow in to a tropical system (cyclonic) counter clockwise. If you are north and east of the approaching system, the winds will be from the NE to E while if you are west, the winds will be more N to NW. As the center passes, you can get as much as a 180 degree wind shift. The closer you are to the center, the more pronounced the shift. The shifts will clock to the right (clockwise). You may start the day with a NE breeze and then have it go E and finally SE.
Tropical systems, of course, behave erratically. You may well go to the lake expecting a breeze but find nothing as the storm has shifted 50 miles to the east.
- Great elementary explanation of weather systems: Federation of American Scientists