The University of Tennessee - Forest Resources Research and Education Center

Tilden Meyers of the local NOAA Weather Station provided the following information about the freeze:

Current Impact of April 6-9, 2007 Freeze in the Southeast on the Eastern Hardwood Forest Ecosystems

Sustained freezing and near freezing temperatures and a wind chill in the mid-20s (°F) accompanied with sleet and snow damaged fruit crops and trees as far north as southern Illinois, as far west as Kansas and Texas, and encompassed all the southeastern states, except mid-to-south Florida. Freezing temperatures over the Easter weekend extended into the western states as well as along the upper east coast, but the impact was felt mostly in the southeastern states. Late spring freezes aren't unusual in the south, however the 2007 freeze was longer than usual and caused the most widespread damage since 1996. A mild winter and March temperatures above normal, led to early plant development. The early green up is clearly depicted from insitu observations from two of NOAA's Surface Energy JBalance Network (SEBN) towers located on the Walker Branch Watershed and Chestnut Ridge towers in Oak Ridge, Tennessee. The Normalized Difference Vegetation Index (NDVI) , an indicator of plant canopy green leaf area, clearly shows the early green-up relative to last year and the dramatic impact by the widespread and intense spring freeze on day 98. The NDVI is only 25% above the winter baseline at a time when it should be at a maximum. The graphs below depict the consequent decline of CO2 uptake by the forest ecosystems. Twenty-eight degrees is considered a critical temperature. If it gets below that, young fruit and blossoms can suffer widespread losses. At 25° F, agricultural officials said, farmers can expect to lose about 90 percent of their crop. Average low temperatures over the weekend (6-9 April) across the south were on the average of 24, 20, 16, and 18° F respectively.

The Spring Freeze: Weather