by Aurelia Baca
Following a mild November, December 2015 was also warm and wet across the region. The entire Southeast experienced above average temperatures and precipitation totals during December. In fact, many states set new temperature records. Specifically, nine states set December records for their statewide average temperature, maximum temperature, and minimum temperature.
|Location||Average Temperature (degrees F)||Temperature Departure (degrees F)||Total Precipitation (inches)||Precipitation Departure (inches)|
|Baton Rouge, LA||61.4||+7.8||6.33||+0.73|
|Little Rock, AR||52.0||+9.0||8.38||+3.41|
December temperatures were much above average with some locations reaching the 70s and 80s. Many weather stations observed record-breaking temperatures throughout the month. Virginia, Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Florida, Alabama, and Mississippi experienced their hottest December on record (Fig. 1). Most of the region was 9°F to 14°F above their mean temperature norm, while southern Florida was 6°F to 9°F above their mean. The warmest part of December was the 24th through the 27th as maximum temperatures reached the 70°F’s and minimum temperatures remained in the 60°F’s. The coolest part of the month was the 19th and 20th as minimum temperatures fell below 30°F over most of the Southeast.
Most of the region observed above average precipitation totals by the end of December. In total, eight states (Alabama, Arkansas, Georgia, Kentucky, North Carolina, South Carolina, Virginia) observed well above average precipitation totals (Fig. 2). Stations in Alabama, Georgia (except the southeastern quadrant), the Florida Panhandle, southern Florida, northern South Carolina, North Carolina, and south-central Virginia recorded precipitation totals 200 to 600 percent of normal. Stations across central and northern Florida and southeastern Georgia recorded precipitation totals 5 to 50 percent of normal.
Drought and Climate Impacts on Agriculture
There were no drought conditions (class D1 or greater) present during December. There were some damaged agriculture reports across the region. Heavy rainfall events caused flooding over southeastern Florida and damaged winter yellow squash, zucchini, and green beans. In Georgia, farmers were unable to harvest a significant amount of their pecan groves due to saturation. Lastly, lack of cold temperatures (specifically between 32°F and 45°F) in Georgia reduced the necessary winter dormancy for peach trees and blueberry bushes, which will likely negatively affect the yield in 2016.
A couple of contributing factors to the abnormal December climate are the El Nino and Arctic Oscillation. El Nino tends to enhance the subtropical jet stream, which directs storm tracks along the southern states. An El Nino normally causes above normal precipitation totals across the southern states during the winter months. For temperature, the Arctic Oscillation was positive for the majority of December. This means that the Arctic air is trapped in the polar region. Consequently, arctic air masses remained north while southerly flow directed warm air in the region causing above normal temperature conditions.
Reference: NOAA National Centers for Environmental Information, State of the Climate: National Overview for December 2015, published online January 2016, retrieved on January 13, 2016 from http://www.ncdc.noaa.gov/sotc/national/201512.