Winter Weather Puzzle: Unstacking the Season's Forecast
Each season meteorologists look at long range signals to gain an edge on how warm, cold, dry, wet or snowy it could be.
You’ve likely heard of El Niño and his sister La Niña, but what exactly are they?
How are the ocean temperature in Pacific, drought in the Philippines and a milder winter in Michiana connected?
In past years I’ve had fun with the winter outlook, a poker game to explain how I use probability to weigh the odds in seasonal forecasting. Then I took to the ice, using the strategy of hockey to explain how often there are only a few quality chances or plays for a big snow.
This year, I already knew I was going to talk about El Niño, but what was the interesting angle that’s not been done before?
Then, it came to me. While listening to the radio, I heard a news report on how the Officials in the Philippines are concerned about worsening drought, due to the strengthening El Niño.
That was it! Ever since my college days, my favorite aspect of weather and climate is the connectivity of it, on large and small scales. Chaos theory or “The Butterfly Effect," speculates how a butterfly flapping its wings on one side of the earth, could propagate to a hurricane somewhere else. It seems a little far-fetched, but the point is the early is a closed system, and everything from butterflies to oceans' temperatures have an impact on the weather.
So how do I explain this kind of connectivity in easy terms, and be entertaining? I texted some colleagues and we spit-balled ideas; rocks in the stream, works of art and a three-ring circus. Then we started to talk board games, Statego? Catan? Jenga? The wheels started turning. It’s something you just have to watch.
El Niño parts of the ENSO (El Niño - South Oscillation) teleconnection. A teleconnection is a linkage between weather changes occurring in widely separated regions of the globe.
There are many teleconnections that can be impactful annually, bi-annually and even every few decades.
ENSO is best described by the Walker Circulation. Named after Sir Gilbert Walker, the British Scientist who connected ocean currents to weather patterns to phases of the monsoon in India, in the early 1900s.
Warmer water near the Philippines, means rising moist air in the atmosphere and more rain in the Western Pacific.
What goes up, must come down. That rising air sinks near Peru and the cycle continues. This is the neutral of base phase of the ENSO cycle.
La Niña is very similar to neutral conditions. Just more extreme, stronger trade wind east to west, and more rain in the western Pacific.
El Niño is just the opposite. The trade winds weaken, the surface wind is more west to east, the warmer water moves from the Philippines to Peru and the Walker Circulation shifts. Heavy rain is closer to South America and the Philippines are in the sinking dry zone.
The change in weather patterns in the tropics is connected to the more northerly latitudes.
The Pacific jet stream strengthens and becomes an amplified west to east storm track across the southern United States.
The Aleutian Low becomes more dominant, which then shifts the polar jet steam, changing storm tracks, changing storm tracks, placing warmer and drier weather across the northern United States.
Which brings us to this year, a strong El Niño is expected to be the major player and tip the balance of winter norms.
Many years, ENSO isn’t a big player, but this year is forecast to be one of the strongest on record. You can’t blame everything on El Niño, but it could be close to textbook. In fact, the NOAA Winter Outlook leans heavily into this.
The ENSO impacts are typically most impactful in the second half of winter. No two El Niños are alike, and the same goes for their impacts.
The snowfall results of the most recent very strong El Niño events for South Bend Winters are as follows. Average winter snowfall (December- January -February) is 51.4 inches.
YEAR | SNOWFALL | AVG TEMP |
1982-83 | 20.1" | 2nd Warmest |
1997-98 | 25.9" | 4th Warmest |
2015-16 | 50.2" | 11th Warmest |
So, my Winter 2024 Outlook calls for a milder and less snowy winter.
Above normal temperatures, no nights below zero and 35 inches of snow.
Last winter was the fifth warmest on record, so it would be very significant if this year tops it.
But last year also had a blizzard before Christmas.
Just a reminder, a mild winter doesn’t mean NO winter.
In fact, last year had more “winter” outside of the winter months. That is another part of the wildcard, however.
If you are interested in El Niño, I encourage you to check out NOAA’s ENSO blog, it’s a fun read that’s updated frequently, and was a source for a lot of the explainer graphics.
Based on past #ElNiños, is your location a snowfall winner or loser? Read our latest ENSO blog to find out! https://t.co/7FJogmivlppic.twitter.com/5ZD7C1BNcn
— NOAA Climate.gov (@NOAAClimate) October 27, 2023