Iowans are facing the prospect of a winter defined less by drifting snowbanks and more by steady rain and above-average warmth, kmaland.com reported.
A Historically Strong Pacific Warmth
Justin Glisan points to shifting water temperatures in the eastern Pacific Ocean along the equator as the primary driver behind the forecast. The region is currently experiencing sea surface temperatures approaching four degrees above the 30-year average, a threshold that qualifies the weather phenomenon as a historically strong El Niño.
For an event to earn a strong classification, those temperatures must sit at least two degrees above the 30-year average.
Echoes of the 2023–24 Season
The last strong El Niño event for wintertime was the 2023–24 season. That winter ultimately ranked as the second warmest on record, with temperatures averaging about eight degrees above normal, alongside a designation as the third wettest.
Diminishing Odds for Holiday Snow
Specifically, the odds of Iowans waking up to a white Christmas—defined by Glisan as having at least one inch of snow on the ground on December 25th—face a decline.
Eroding Baselines in Des Moines
According to the National Weather Service, Des Moines has seen at least an inch of snow on the ground for 40 of the past 83 Christmases, just under half.
However, Glisan noted that baseline probability has already eroded by five to ten percent over the last 20 to 30 years independent of El Niño cycles. When combined with a strong El Niño pattern, the likelihood of holiday snow cover diminishes further.
