Weak La Niña influencing Georgia's weather
Mar 12, 2009 9:18 AM,
By David Stooksbury
University of Georgia
Spring will likely be drier than normal for most of Georgia. March will have wide swings in temperature. A late freeze or even a snow or an ice storm isn’t out of the question. Severe thunderstorms and tornadoes are common this time of year.
Through most of this winter, Georgia’s climate was primarily a response to a neutral climate pattern. The neutral pattern is one of three climate patterns that have major influences on Georgia’s climate. The other two and better-known patterns are El Niño and La Niña.
This past winter, Georgians have experienced a classic neutral winter with periods of very cold and very warm weather. Rainfall in neutral winters can be very dry, near normal or very wet. This winter has been a very dry one.
Since the beginning of the year, the climate pattern has gradually shifted to a weak La Niña. This change is expected to have a major influence on the state’s spring climate.
It is important to realize that knowing which climate pattern we are in gives us only the probabilities of what to expect. It can tell us how we might want to hedge our bets, so to speak. It isn’t a guarantee.
Because the climate pattern is now in a weak La Niña, there is a very high chance that the Coastal Plain will experience a very dry spring. The chances of a very dry spring decrease into the Northern Piedmont. In the Piedmont north of a Carrollton-to-Elberton line, near normal rainfall is the most likely outcome.
In the mountains of north Georgia, there are no clear indications of what to expect rainfall-wise over the next three months. If a consistent storm track occurs over the mountains, then the spring may be wet. However, if the storm track is just 50 to 100 miles north of Georgia, then the mountains will experience a dry spring.
The good news is that typically under a weak La Niña — like we have now — the storm track has a tendency to be farther south, which means the mountains might receive some beneficial rains.
As far as temperatures are concerned, we can expect a continuation of a wide range, especially through the middle of April.
The date of the last killing freeze, or 28 F or below, or the last frost has no relationship with the climate pattern. Knowing that Georgia is currently under the influence of a weak La Niña tells us nothing about when the last freeze will occur.
Just as important, a warm March does not tell us anything about the likelihood of a late freeze. The 2007 Easter freeze is a prime example. March 2007 had been very warm and most plants had broken their dormancy. Then a devastating freeze hit in early April.
Snow and ice storms are not unusual in Georgia during March. Additionally, March through May is a time when severe thunderstorms and tornadoes are common. Because tornadoes can occur at anytime, day or night, all Georgians are encouraged to have a National Oceanic and Atmospheric Administration, or NOAA, weather radio at home. NOAA weather radios can be purchased at most electronic stores, large discount stores and many grocery stores.
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