Winter Outlook 2015-2016: Cold, Wet South and Warm, Dry North, Says NOAA
By the Weather Channel
NOAA issued its winter 2015-2016 outlook Thursday, and the strong El Niño's fingerprints are all over it.
"A strong El Niño is in place and should exert a strong influence over our weather this winter," said Mike Halpert, deputy director, NOAA's Climate Prediction Center. "While temperature and precipitation impacts associated with El Niño are favored, El Niño is not the only player. Cold-air outbreaks and snowstorms will likely occur at times this winter. However, the frequency, number and intensity of these events cannot be predicted on a seasonal timescale."
Other influences that may play a role this winter are the Arctic Oscillation and the Madden-Julian Oscillation.
It is important to remember that this forecast is for the winter season as a whole and does not project when and where storms may occur.
Below we take a closer look at the forecasts from NOAA for temperature and precipitation across the U.S. this winter.
Winter Temperature Outlook From NOAA:
Shaded areas indicate regions where NOAA believes there is a greater-than-average chance that the average temperature from Dec. 1, 2015, through Feb. 29, 2016, will rank among the upper or lower one-third of all winters in the 1981-2010 climatological reference period.
For the core winter months of December through February, NOAA says the southern tier of the nation is likely to be colder than average, particularly in Texas and the Gulf Coast states.
Meanwhile, a large swath of the western and northern United States from California into the Pacific Northwest eastward into the Midwest, Great Lakes and Northeast is expected to be warmer than average, overall.
Above-average temperatures are also likely in Alaska and most of Hawaii.
Keep in mind, these outlooks are overall trends over a three-month period.
An individual cold front or an upper ridge of high pressure can lead to a brief period of colder or warmer weather, respectively, that bucks the overall three-month trend. The same front or area of high pressure can bring a brief period of enhanced precipitation or dry spell that may or may not be indicative of the overall trend that is forecast.
Winter Precipitation Outlook From NOAA:
Shaded areas indicate regions where NOAA believes there is a greater-than-average chance that the total precipitation from Dec. 1, 2015, through Feb. 29, 2016, will rank among the upper or lower one-third of all winters in the 1981-2010 climatological reference period.
NOAA also expects winter 2015-2016 to trend wetter than average over much of the southern tier of the nation, from California into the Desert Southwest and into the southern and central Plains, as well as into much of the Deep South and Gulf Coast. The East Coast, from the Southeast into portions of the Mid-Atlantic and into southern New England, may also see a wetter than average winter.
Conversely, a drier-than-average winter is expected over parts of the Pacific Northwest, northern Rockies and into the far northern Plains and parts of the Great Lakes and Midwest.
Much of central and western Alaska, as well as Hawaii, will likely see drier-than-average conditions this winter.
Drought improvement is likely in California this winter, and the Southwest and southern Plains will likely see drought removal.
However, Halpert noted, "California would need close to twice its normal rainfall to get out of the drought and that's unlikely."
On the other hand, drought development is expected in parts of the northern Plains, the northern Great Lakes, as well as in Hawaii. The Pacific Northwest and the northern Rockies will continue to see drought conditions.
El Niño Not the Only Variable
A strong El Niño is expected to persist through the winter, influencing the overall temperature and precipitation impacts. However, other factors indicate that there is a risk for colder temperatures in parts of the East. Two variables, in addition to El Niño, that could play an important role this winter are the Madden-Julian Oscillation and the Arctic Oscillation.
The Arctic Oscillation is a climate pattern characterized by the strength of counterclockwise winds around the Arctic. Its positive phase confines cold air to the polar regions, while its negative phase is associated with cold air penetrating farther south, as well as an increased chance of nor'easters.
The Madden-Julian Oscillation is associated with variations in tropical thunderstorm activity (convection) and is characterized by an eastward-moving pulse of atmospheric features affecting cloud formation, precipitation and pressure patterns. This pulse circles the globe roughly once every one to two months. In turn, the jet streams over the North Pacific and South Pacific can be impacted during the winter due to large-scale changes in tropical convection. This can contribute to blocking activity, which impacts the amount of precipitation across the Pacific Northwest.