Does an El Nino winter mean gloom and doom?

Accuweather.com. and the National Oceanic and Atmospheric Administration better known as NOAA has gone on record predicting that the return of El Nino will affect the 2019 winter weather patterns along the northeast.

What is 'El Nino' and how does it affect our weather? Honestly, I can't seem to decipher the definition but it seems to have something to do with ocean temperatures and currents. Bottom line is that colder weather than we had last year will permeate the northeast in January and February.

Fleetwood Drive, New Fairfield, CT during the winter of 2017 - Ethan Photo

The early part of this winter is predicted to be milder than usual until the cold hits in January and February. Accuweather is also predicting that the northeast will dodge most of the heavy snowstorms.

Not to say the El Nino phenomena is a pile of bunk but over the last couple of weeks, 50 to 60% of Danbury area Accuweather forecasts have been downright incorrect. So explain to me how meteorologists can predict the weather that is still months away when they can't even get the current week's forecast correct?