La Nina is when the sea surface temperatures in the Pacific along the equator are colder than normal. This impacts the pressure systems in the air above this water which in turn impacts the pressure systems around the globe.
How does it affect North Dakota? It allows for a more variable jet stream. Arctic air outbreaks are more likely during this pattern. Megan Jones is a meteorologist at the National Weather Service in Bismarck as well as a long range forecasting expert. She clears up a common misconception about La Nina winters, “La Nina typically doesn’t have much of an influence on our winter precipiation. a lot of times you think that if we’re favored for more below average temperatures, that must mean we’re favored for more snow but there’s not a lot of research supporting that La Nina itself
will give us more snow.”
And she’s right. When you look at all of the La Nina Winters we’ve had… we’ve gotten anywhere from just over a foot to around 100 inches over an entire season. We are favored to see more snow this year mainly due to the fact that our snowfall has been trending upwards over the last decade.
We also have other long-range and short-range, less predictable circulations around the globe that could impact our snow…El Nino and La Nina are the more widely know circulations but others have an impact here as well and many can only predicted around a few weeks out. I have them labeled on the map below where we typically measure their strength. They can aid in bringing us more or less snow.
But when it comes to forecasting a La Nina winter, it isn’t just the winter season forecasters are considering, but what it could mean for spring. Jones says, “the current forecast does have it a 60% chance of extending into that February through April season. That does raise some concerns for the spring. We are favored to have those below-average temperatures continue. We really want that gradual warm-up going into the spring. and the longer that our winter lasts, the more likely we are the have a sudden warm-up which can be pretty problematic when we’re thinking of springtime flooding.” She reiterates that this isn’t a likely scenario. Just something being monitored.
“[You] really paying attention to the forecast a week maybe two weeks out, depending on what it looks like, that’s what’s gonna be most important for people as we head into the winter,” adds Jones.