It may seem pretty wild to be talking about winter in July but that’s how the long range forecasters think. While there isn’t a formal prediction right now, there are signs at what we’re potentialy leading up to this fall and winter.
The National Oceanic and Atmospheric Administration, NOAA for short, has issued a La Nina Watch. This means that conditions are favorable for us to slip into a La Nina pattern in the next several months. They’ve given a 50-55% chance of La Nina developing in the Fall and continuing through the Winter. While that’s not necessarily a strong chance, it’s more of a flip of a coin, it wouldn’t be unusual since we see a La Nina pattern on average every 3 to 5 years.
La Nina is when the sea surface temperatures drop to below average along the equatorial Pacific.
That area can change the way pressure systems move across the globe. The La Nina pattern means there is cooler than normal water in this area.
While we don’t see much of a difference with La Nina in fall here in North Dakota. It could impact the hurricane season in the Atlantic and make it more active by creating less shear which would promote storm growth. The Pacific could have a much quieter hurricane season.
We are more impacted by La Nina in the winter. Strong high pressure in the northern Pacific will change how the jet stream lays over the United States, bringing a good chance of colder than normal air. We aren’t impacted as much with snow as we are by the more arctic air outbreaks.
The last La Nina Winter occurred in the winter of 2016 and 17 and was considered weak. The last strong La Nina was the winter of 2010 through 2011.
We still have about a 40-45% chance of staying in the current ENSO Neutral phase – so basically neither La Nina nor El Nino. We have about a 5-10% chance of slipping into an El Nino Pattern, which is highly unlikely. This is when we typically see a warmer than normal Winters.
If we do fall into a La Nina pattern, it’s way too early to tell whether it’ll be a strong or weak pattern this far out.