Developing strong El-Nino and winter weather
Decreasing daylight and falling temperatures as we head into fall may have you thinking about the upcoming winter in Mid-Missouri. Last winter’s temperature came in at 31.5 degrees which is slightly below the 32 degree average for December through February. We only had 12 inches of snow for the 2014-15 winter season which is 6 inches short of the 30 year average.
This winter could be influenced by a developing El-Nino pattern which occurs as ocean water temperatures rise above normal across the central and eastern Pacific, near the equator. Long-term climate models are forecasting a strong El-Nino in the next few months, possibly one of the strongest in 50 years. El-Nino usually reaches it’s peak during the winter months.
During a strong El-Nino, the polar jet stream is typically farther north than usual, while the subtropical jet stream remains across the southern United States.This usually produces a warmer winter across much of the Missouri River Basin region and a wet winter across the southern states. This can lead to drier weather in Missouri as the storm tracks stay mainly north or south of our area.
However, not all El-Ninos are the same and there are other climate phenomenon which can also interact with the El-Nino pattern, resulting in a variation of seasonal impacts.
I looked back at strong El-Nino winters with an Oceanic Nino Index of 1.5 or higher and noted the winter temperature (December through February) and seasonal snowfall during those years using official climate data from the Columbia Regional Airport since the 1950s.
During the last strong El-Nino of 1997-98 we had a warm winter with below average snowfall. The winters of 82-83 and 86-87 were also warm but had different snowfall results with only 4 inches in 82-83. You’ll notice that during the strong El-Nino events during the 50s through 70s we had colder winters with more snowfall, possibly due to a negative Pacific Decadal Oscillation Index during those years. The PDO is a long-lived El-Nino like pattern which can also influence seasonal weather.
The Stormtrack weather team will monitor the weather patterns in the upcoming weeks and release our winter forecast in November. Watch for updates to the developing El-Nino as we head into fall.
