Long-range winter forecast
It seems like winter is off to a fast start this year with the early cold weather that has persisted in November.
I looked back at recent years with cold Novembers but found most winters that followed had a warmer month or two, with the exception of 2000-01. Early season cold doesn’t necessarily mean a cold or snowy winter will follow.
An El-Nino weather pattern is developing in the tropical Pacific and is expected to continue through the winter. Looking back at recent winters, we had some very cold, but also very warm, ones. Normally a strong El-Nino produces warm winters here such as the winter of 2015-2016. However, other weaker El-Nino years have also produced very cold winters such as 2009-2010. Not only does the strength of the El-Nino come into play but also the type.
This winter a different type of El-Nino called El-Nino Modoki may come into play. A conventional El-Nino is characterized by strong warming in the eastern equatorial Pacific. Whereas El-Nino Modiki is associated with strong warming in the central tropical Pacific and cooling in the eastern and western tropical Pacific. In a conventional El-Nino, the polar and subtropical jet streams generally remain split during winter over the Midwest, limiting cold air intrusions and keeping the heaviest precipitation over the southern U.S. On the other hand, the El-Nino Modoki keeps the ridge far enough west to allow the polar jet to dive into the Midwest. This western shift can also allow the polar and subtropical jets to phase, giving us more potential for snow.
So here is the ABC 17 Stormtrack winter forecast: We expect a colder than normal winter with a lot of variability in temperatures and several notable Arctic intrusions. Snowfall will be higher than the past few years, coming in near normal at 17-20 inches.
