The last couple weeks have been rather unseasonably warm to some extent across the Tennessee Valley – and the country – for Fall (though, if you’ve lived here for any amount of time, you’ll know these seasonal transitions take some time once you get further south than the Mason-Dixon line), and as a result we’ve been getting some comments and messages inquiring about just when the heck our cool season will settle in, and what kind of season we may be looking at both for fall and for the long-term. Luckily, the Climate Prediction Center regularly does long range predictions for their expectations of the season. Let’s take a look at what we’re watching. Today I want to focus in on the coolest portion of our Winter season (roughly from January) as a focal point.
To start, we’ll take a look at temperatures. Through Winter, indications suggest a chance of slightly above average temperatures in the SW and Arctic, with cooler than average temperatures looking more possible in the Pacific Northwest and the central Midwest. In between, in the Tennessee Valley, we’re standing at roughly equal chances either way – that is to say, it will depend on how active the pattern will be, which we can’t tell as astutely just yet. Nevertheless, using pattern recognition, you can get a sense of the jet streams that would cause these temperature trends, which can be a useful proxy for other environmental conditions – for example, high pressure in the southwest and low pressure in the northwest would be the major factors dictating temperatures, and exactly both of those existing would lead to conditions like we’re expecting. This would also potentially indicate an active pattern, if jet stream activity is regular enough of an occurrence to bring the averages down to below-average levels throughout the season in the NW.
Taking a look at the precipitation outlook, the above theories you could have taken away from the temperature map are to some level shown to be reasonable – across some areas in the North and Central Midwest, above average precipitation amounts look possible at times with the Tennessee Valley in relatively close proximity to one of those regions. The Southwest looks drier, which supports the idea of a more dominant high pressure and a rather quiet subtropical jet, which would provide more opportunities for polar jet dominance (this, of course, may lead to some rather dramatic cold snaps if the patterns favor jet intrusions into the continental US). If this is true, we could err on the side of a colder winter, and perhaps with the higher precipitation odds, a winter which could host yet more snow in the area. Of course, this remains to be seen as you can never know a forecast with any sort of real confidence until days – sometimes hours – out, so we’ll keep a very close eye on those trends as we get cooler and cooler.
