By Pam Knox, UGA Agricultural Climatologist
Following a very wet 2013, this year has gotten off to a drier than usual start, although generally soil moisture has been very good until recently. In the last few weeks, abnormally dry conditions have started to creep into the mountains in northeast Georgia as well as scattered locations in the west central and southwest parts of the state. However, a major drought is not expected to develop this growing season.
Short-term forecasts out to two weeks indicate that some dryness may continue in southern Georgia but north Georgia is likely to be wetter. In the one to three month period that includes April through June, there are equal chances for below, near, and above normal rainfall, since accurate predictions are very hard in neutral conditions when no El Nino or La Nina are occurring. However, following recent climate trends, temperatures have an increased chance of above normal conditions for the next few months.
NOAA has now issued an El Nino watch for the potential development of an El Nino in the eastern Pacific Ocean by mid to late summer. When an El Nino occurs, we commonly see wet and cool conditions in south Georgia associated with the persistent presence of a subtropical jet stream above the earth’s surface which directs weather systems right across Georgia.
At this time, NOAA is predicting a 50 percent chance of an El Nino developing by mid-summer. If one does occur, then we can expect next winter to be cooler and wetter than normal in 2014-2015. Some scientists believe that this is likely to be a stronger than usual El Nino based on current ocean temperatures. If that happens, the cool and wet conditions will extend throughout Georgia instead of just affecting the southern part of the state.
One impact of El Nino on Georgia’s climate is a reduction in the number of hurricanes in the Atlantic Ocean. However, even in a quiet season, a single direct hit by a hurricane or tropical storm can cause significant damage to the area it passes over. Most other effects of El Nino are seen in the winter when the El Nino is strongest.
Other impacts from El Nino include excessive cloudiness, which reduces solar radiation and increases drying times for hay as well as enhancing the development of fungal diseases. Low-lying areas are likely to be soggy and hard to work due to the persistent rain. Cooler temperatures and high humidity may also affect the development of pecans and Vidalia onions, reducing pecan yields as well as the average size of the onions. In general, El Nino winters are not associated with unusually late frost dates, however. Runoff may also increase, leading to increased erosion or movement of surface applications of manure into streams.
You can find more information about the impacts of El Nino on climate patterns and crop yields at www.agroclimate.org. and winter 2014-2015