It’s been a cold Saturday around the Midwest. Temperatures have actually been below normal and that’s a trend that’s likely to continue into the first half of February. Not to say there won’t be a few mild days in the mix but in general the pattern looks void of that big east coast ridge that’s kept much of the nation toasty the past 2 weeks, at least by January standards.
The warmth is very evident in the 14 day temperature departure below.
Going forward a few markers are showing up that would indicate less warmth and a more seasonal brand of weather. First, the AO (Arctic Oscillation) is projected to go negative.
The reason this holds significance to me is because the AO has only been negative a couple time this winter. The first was early December and the second early January. It’s not coincidence that those are the only 2 periods where decent cold was able to hit and hold for any period of time.
Another marker that should assist in delivering more cold is the WPO (Western Pacific Oscillation). It too has rarely been negative and the two most obvious times were again back in early December and the first part of January. You can see below by early February its shown moving into negative territory.
Here’s the GFS WPO forecast and it’s sharply negative against the base state.
With the AO and WPO in negative conjunction that increases the odds of a colder pattern than we’ve seen in recent weeks. Now I want to emphasize I’m not talking about extreme cold, just more of what’s typical of this time of year. That means lots of highs the next 2 weeks in the range of 28-35 degrees. Not great but far from what it could be at this stage of winter. Roll weather…TS