NOAA’s Winter Forecast features the effects of El Niño
NOAA released the 2018-2019 Winter Outlook Thursday, and it shows some inconclusive ideas for North Alabama and Southern Tennessee! The outlook is given in a statistical chance of being above or below normal; it’s not extremely useful in planning for your milk, bread and sled budget this winter. Wishing for snow yet?
There are a few things of note:
- The El Niño’s strength and position in the Pacific can yield different results from year to year. El Niño does not ‘equal’ weather; El Niño influences weather.
- There’s a large area of unusually warm water in the North Pacific (not mentioned in this report). If it stays there, it promotes a big ridge (warmer weather) over the West Coast through Canada and Alaska, and that usually means a trough – or a dip in the jet stream – over the eastern half of the country. Again, like El Niño, it’s a useful indicator of a pattern, but it does not equal weather.
- The Madden-Julian Oscillation (MJO) mentioned in NOAA’s report is very important to the pattern as well, and it’s very hard to predict to the level that we can with other large-scale pattern drivers like El Niño. If it can line up with the warm northeast Pacific and get stuck in some particular phases for a while (1, 2, 3 and 8 in particular), we could be in for a very cold winter in the East and South. Combine that with an El Niño’s potential storminess, and that could get awfully interesting come January and February (if not sooner).
- The ‘forecast’ for North Alabama and Southern Tennessee is for ‘equal chances’ of below and above average and ‘equal chances’ of drier and wetter than normal. That’s not much of a forecast, but it is useful to other meteorologists who are watching for patterns in the weeks ahead.
- And lastly, we can have a warmer-than-normal winter and still end up with some bitterly cold weather or a major winter storm. The four weeks following Christmas Eve 2017 into January 2018 were the coldest such 4-week period on record in Huntsville. The whole winter ‘period’ from December to February went down in the record books as ‘warmer than normal.’
A mild winter could be in store for much of the United States this winter according to NOAA’s Climate Prediction Center. In the U.S. Winter Outlook for December through February, above-average temperatures are most likely across the northern and western U.S., Alaska and Hawaii.
Additionally, El Nino has a 70 to 75 percent chance of developing. “We expect El Nino to be in place in late fall to early winter,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center. “Although a weak El Nino is expected, it may still influence the winter season by bringing wetter conditions across the southern United States, and warmer, drier conditions to parts of the North.”
El Nino is an ocean-atmosphere climate interaction that is linked to periodic warming in sea surface temperatures in the central and eastern equatorial Pacific. During the winter, typical El Nino conditions in the U.S. can include wetter-than-average precipitation in the South and drier conditions in parts of the North.
Other climate patterns that can affect winter weather are challenging to predict on a seasonal time scale. The Arctic Oscillation influences the number of arctic air masses that penetrate into the South and could result in below-average temperatures in the eastern part of the U.S. The Madden-Julian Oscillation can contribute to heavy precipitation events along the West Coast – which could play a large role in shaping the upcoming winter, especially if El Nino is weak, as forecasters predict.
The 2018 U.S. Winter Outlook (December through February):
Warmer-than-normal conditions are anticipated across much of the northern and western U.S., with the greatest likelihood in Alaska and from the Pacific Northwest to the Northern Plains.
The Southeast, Tennessee Valley, Ohio Valley and Mid-Atlantic all have equal chances for below-, near- or above-average temperatures.
No part of the U.S. is favored to have below-average temperatures.
Wetter-than-average conditions are favored across the southern tier of the U.S., and up into the Mid-Atlantic. Northern Florida and southern Georgia have the greatest odds for above-average precipitation this winter.
Drier-than-average conditions are most likely in parts of the northern Rockies and Northern Plains, as well as in the Great Lakes and northern Ohio Valley.
Drought conditions are likely to persist across portions of the Southwest, Southern California, the central Great Basin, central Rockies, Northern Plains and portions of the interior Pacific Northwest.
Drought conditions are anticipated to improve in areas throughout Arizona and New Mexico, southern sections of Utah and Colorado, the coastal Pacific Northwest and the Central Plains.
NOAA’s seasonal outlooks give the likelihood that temperatures and precipitation will be above-, near- or below-average, and how drought conditions are expected to change, but the outlook does not project seasonal snowfall accumulations. Snow forecasts are generally not predictable more than a week in advance. Even during a warmer-than-average winter, periods of cold temperatures and snowfall are still likely to occur.
NOAA’s Climate Prediction Center updates the three-month outlook each month. The next update will be available on Nov. 15.