Teleconnections, the fascinating phenomenon of interconnected weather patterns across vast distances around the globe, have grown in understanding and prominence in medium-range and long-term weather forecasting over the last several decades.
What are teleconnections?
Teleconnections are significant relationships between weather phenomena at widely separated locations on Earth. They help meteorologists predict weather conditions by analyzing back and forth patterns influenced by the ocean temperatures and currents that impact high and low pressure centers and the long-term position of the jet stream. These atmospheric features drive temperature, precipitation and large storm events.
Some of the teleconnections that influence weather over North America and the United States are El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Pacific Decadal Oscillation (PDO), Pacific-North American Pattern (PNA) and Madden-Julian (MJO) oscillation.
ENSO is a key teleconnection defined by the temperature of the equatorial waters off the west coast of South America. During the El Niño phase, when these waters are warmer than average, Colorado often experiences warmer and wetter winters. In contrast, La Niña, when the Pacific Ocean is cooler than average along the equator off the coast of Columbia, Ecuador, and Peru, typically brings our state colder and drier conditions.
The NAO most directly impacts the North Atlantic region but influences Colorado’s weather indirectly through atmospheric circulation changes. Similar to the NAO is the Arctic Oscillation (AO). For Colorado it is more relevant during the winter months, which can provide a strong signal for for cold air outbreaks.
The PDO, which influences North Pacific sea surface temperatures, also has ramifications for North America. It can lead to prolonged droughts or wetter periods in Colorado and neighboring regions.
For a deeper dive
As you’d expect, the teleconnections are quite complex, but Climate.gov has some great visuals and explanations to help further your knowledge of them.
- ENSO – El Nino-Southern Oscillation
- PDO – Pacific Decadal Oscillation
- MJO – Madden-Julian Oscillation
- NAO – North Atlantic Oscillation
- AO – Arctic Oscillation
- PNA – Pacific-North American Pattern
Understanding these teleconnections and their relationships together is vital for accurate weather forecasting and can bring increased awareness to the likelihood of extreme weather events in Colorado and across North America. I wasn’t exposed to this in my meteorological coursework in the mid 1990s, but this growing area of meteorology and climate science continues to enhance our understanding of the weather ahead.
Local teleconnections expert
Kyle Mozley, forecaster at the National Weather Service office in Pueblo, is the local specialist regarding these teleconnections and their impacts on our weather in the Centennial State, and specifically southern Colorado. In recent email correspondence, Kyle noted that teleconnection signals point to a noticeable weather change by the middle of September.
Mozley says teleconnections support our dry start to the month. “A negative NAO pattern is favored when we’re dry in September and guess what? The NAO is currently around -1.”
Multiple teleconnections pointing to the same outcome, enhances confidence in the forecast or, in this case, ongoing weather pattern. “The MJO is moving through phase 3 into 4,” says Mozely, “and phase 3 has a high skill of dry conditions across Colorado.”
Mozely looks for strong signals in different teleconnections for a wet September in Colorado. He wrote, “ENSO has a high correlation (~60% of mountain sites) of bringing wet weather in an El Nino, but the stronger signal is a positive PNA (~78% of mountain sites).”
If you want wet weather the good news is El Nino continues to hold steady/strengthen off the South American coast. Also, the PNA is forecast to go from its current -3 to around +2 over the next week to week and a half. Both of which point to wetter weather.
“I would expect a flip from our extremely dry conditions currently ongoing, to a wetter pattern on/after Sept 11,” says Mozely. He added that ENSO and PNA projections are likely to have wet weather prevailing through the later half of the month.
To sum it up, Mozely says teleconnections point to “dry conditions through the weekend, before wetter conditions spread across the mountains around Sept 11. The period of Sept 13-21 may see the best chances of wet conditions over the mountains.”
