Several changes have been made to the December outlook
, updated Friday by NOAA's Climate Prediction Center
. There has been an expansion of warmer than average temperatures, which are now expected over most of the nation. Below normal temperatures have been added to the forecast in parts of New England and near the Four Corners.
Wetter than normal weather is still anticipated in the Southwest and Southeast, with an area expanded into the central Plains. Below normal precipitation is still expected in the Northeast, with the northern Plains added to the forecast.
With the forecast of above normal precipitation in the West, drought conditions are expected to improve. The most improvement will be seen in California, Arizona, and Nevada.
The outlook was based primarily on model forecasts and long term trends. Atmospheric trends from tropical thunderstorms near the Equator (Madden-Julian Oscillation) and Arctic cold air (North Atlantic Oscillation) were also considered.
Given the current atmospheric state, the onset of El Nino played a minor role in the forecast according to the CPC
. This differs from the winter outlook
, which was updated earlier in November. Even with El Nino already showing signs of development, it's effects on the atmosphere are not expected to be observed until later in the winter.
: Meteorologist Mace Michaels