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.
Our updated December outlook favors warmer and wetter than normal conditions across much of the country. Best chances for a cooler than normal December are across the Central Great Basin and Northern New England. https://t.co/ZojpnS5Ja5 pic.twitter.com/l0HGsidH1j
— NWSCPC (@NWSCPC) November 30, 2018
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.
During December widespread improvement, and potential removal, of #drought conditions is forecast across much of California, the Southwest, and the Great Basin in association with a forecast active southern jet stream. https://t.co/uvDvOR3Qkq pic.twitter.com/T8CdzGxET9
— NWSCPC (@NWSCPC) November 30, 2018
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.
For WeatherNation: Meteorologist Mace Michaels