This month has been way warmer than average so far…with our morning lows averaging around 10 degrees above normal! Overall, we expect milder-than-average conditions to continue this month. There will be cooler shots of air but they will be brief. Things are about to change though, with indications that average or cooler-than-average weather could return by early November.
When we look at making long-range forecasts, we examine climate models, what’s happening in the oceans, as well as analog years, which are years in which the atmosphere was in a similar state to what is in right now. That involves examining things like the Polar Vortex and trends with La Nina.
For this fall, we were able to come up with 10 analog years. To narrow it down even further, we picked out years that had a warm to very warm October for our area, and that gave us five years…1971, 1984, 1985, 1996, and 2000. In four out of those five Novembers, temperatures ended up below average, with the core of the cold staying over the northern tier of the country. While we’re expecting near average temperatures locally, there will be periods of chill, more specifically as we head toward the middle of next month.
What raises our confidence even more is a stratospheric warming event that’s expected to take place over the next few weeks. The stratosphere is located 4 to 12 miles above the earth’s surface, above the troposphere, where most of our weather takes place. Warming in the stratosphere usually results in a disruption to the Polar Vortex, allowing cold air to move away from the poles and toward the mid-latitudes. This effect normally takes a few weeks to translate to the surface, hence why we’re not expected major changes until after Halloween.
Overall, drier than normal weather will persist through the end of next month, with plenty of Canadian high pressure and northwest flow days.
-Meteorologist Adis Juklo