OAK RIDGE (AP) - Oak Ridge scientists say they know spring is arriving earlier in the Northern Plains.
The change may be related to the greenhouse effect and global warming.
"Bottom line is we don't know," said T.J. Blasing, a meteorologist on the research staff at Oak Ridge National Laboratory.
Blasing and his colleagues found the timing of winter's last big cold blast in the Upper Midwest changed significantly in the fourth quarter of the 20th century. The cold air masses from Canada stopped pushing into the region after about the 14th or 15th of the month instead of continuing into late February, as was the case in the third quarter (from 1952-75).
During the fourth quarter of the 20th century, the last days of February were about 12 degrees warmer at study sites, Blasing said.