DENVER (CBS4) – For the second year in a row, La Niña has formed, and NOAA says it will probably have an impact on both temperature and precipitation across the United States in the months ahead. On Thursday, the agency issued a La Niña advisory for the upcoming winter.

When La Niña forms it typically has the most influence on the winter season in the Northern Hemisphere, which in the field of meteorology, covers the months of December, January and February. Last year we had a moderate La Niña in progress during the winter and it produced just over 80 inches of snow for the season in Denver. The first inch fell in early September.

NOAA forecasters say to expect a similar episode this year in terms of strength, but that doesn’t necessarily mean we’ll see that much snow again in the Mile High City. As of this posting, we have yet to see Denver’s first measurable snow of the season.

Trying to predict what will happen in Colorado during a La Niña winter is difficult because there are so many factors at play, ranging from the very complex terrain to the large distance from oceans. The ultimate outcome will depend on where the jet stream tracks.

More times than not, we see northern Colorado experience a lot of wind during La Niña winters, especially for locations in the foothills along and north of Interstate 70. That wind usually spills out onto the northeast plains and often impacts the I-25 urban corridor between Castle Rock, Denver and Fort Collins.

As far as snowfall, it is usually the most consistent in the north-central and northwest mountains. Places like Steamboat Springs and Winter Park can see a lot of snow during a La Niña winter. The reason for the wind and snow in the northern part of the state is due to the close proximity of the jet stream, which often orients itself somewhere over Wyoming.

Southern and eastern Colorado can be mild and dry during a La Niña winter while the central and western parts of the state don’t usually favor any one particular trend. If the jet stream sits close to the Colorado and Wyoming state line, then the active weather can extend into the central and southern mountain ranges. But if the jet stream stays over central or northern Wyoming, the active weather will usually favor the northern counties.

One cool thing about meteorology is that no two years are ever exactly alike, even if they have similar weather patterns. Add in the complexity of the terrain in Colorado and you can bet that it will be an eventful and memorable season somewhere.

Here’s a list of weak, moderate and strong La Niña episodes in the United States since 1950.

WEAK

1954-55
1964-65
1971-72
1974-75
1983-84
1984-85
2000-01
2005-06
2008-09
2016-17
2017-18

MODERATE

1955-56
1970-71
1995-96
2011-12
2020-21

STRONG

1973-74
1975-76
1988-89
1998-99
1999-2000
2007-08
2010-11