2017-2018 Winter Outlook Issued

It's barely felt like fall and yet we're already looking ahead to the winter season.  NOAA (National Oceanic and Atmospheric Administration) issued their 2017-2018 Winter Outlook for the United States.  It's important to remember when looking at long range outlooks like these, that they should be taken more as a guide, rather than an absolute.

There are many different variables forecasters and climatologists look at to help them put together long range forecasts.  One such factor is the likelihood of La Niña conditions developing late this fall and winter.  La Niña is when sea surface temperatures around the Equatorial Pacific show a cooling trend over a certain period of time - usually 3 months.  The Climate Prediction Center has issued a La Niña Watch for the Northern Hemisphere.  Typically, La Niña patterns tends to favor cooler than normal temperatures over the northern Rockies and far northern Plains, with drier than normal conditions over the south and wetter than normal conditions over the Ohio River Valley.

The 2017 and 2018 Winter Outlook calls for a higher probability for cooler than normal temperatures over the High Plains, with a higher probability of warmer than normal conditions over the south.

There is a higher probability for wetter than normal conditions over the eastern Great Lakes and Ohio Valley, as well as for the northern Rockies.  Drier than normal conditions are possible over the south, and especially over the southeast.


Snow lovers may look at this forecast and think that the 'wetter than normal' probability means more snowfall.  And that's not necessarily the case.  Snow storms, along with the strength and duration of cold spells, depends on individual storm systems as different weather patterns in the atmosphere develop.  Mike Halpert, deputy director of NOAA's Climate Prediction Center says other factors that influence winter weather include the Arctic Oscillation, and the Madden-Julian Oscillation.  The Arctic Oscillation influences how often cold air masses are pushed into the south and are often times difficult to predict more than a couple weeks in advance.  If the Arctic Oscillation locks into a 'negative phase', then the likelihood of colder air into the lower 48 increases.


So while it's interesting to look at these long range outlooks, it also important to understand that they can, and probably will, change.