- Feb 15, 2017

HOW LONG DO WE RIDE THIS TRAIN?

Wow! This winter has been kind and generous and it continues to give in ways you would not expect in the month of February. Temperatures which have been super mild are going to get even warmer. In fact, this weekend record or near record highs are expected over a wide expanse of the Midwest. Look at this meteogram for Cedar Rapids. Some of the forecast lows are warmer than the average highs. Crazy!

Not only are temperatures 25-30 degrees above normal, their's no rain through Monday.

Temperatures in the 60s...on the weekend, with no rain, are you kidding me? Nothing to do but enjoy it.

So how long do we ride this train? Well, that's a good question and to find some answers I switch to the topic of the SOI or Southern Oscillation. Since the middle of December, the SOI which measures differences in pressure between the western and eastern tropical Pacific (Darwin to Tahiti) has been essentially positive.

During the positive period temperatures have frequently averaged above normal. A few days ago I pointed out that if we were going to have any shot at some sort of a winter comeback, the SOI needs to go negative and stay that way (strongly) for at least a 2-3 week period. I also noted that pressures were forecast to rise significantly in Darwin which in turn would help the index spike negative. Sure enough, look at today's value which went from a positive 13.98 yesterday to -1.15 today.

10 days from now the pressure anomalies are still positive (brownish colors) indicating higher than normal pressures in Darwin and Australia.

That indicates to me the SOI should remain negative through that period. If so, the pattern over North America should turn colder in 10 days and perhaps remain that way into early March.

Another teleconnection tied to the SOI is the MJO (Madden Julien Oscillation) At the time the SOI is negative the MJO is forecast to be going through phases 1-3 by the Australian model. Those are known to correlate with colder than average temperatures in February and early March. Phase 3 is not only cold but it's wet as you can see in the phase correlation below.

The way this winter has gone it's problematic to say colder and wetter is a given. However, I do feel there is a good chance we will get back to a much more typical pattern for February somewhere around February 22nd. Even if temperatures are normal, that would be a big change.

I also think the drop in the SOI signifies an energetic pattern coming into the nation early next week. I would think that would result in a stormier period the last week of February. The GFS agrees with a 16 day precipitation total that looks like this.

Here's a closer view of my area.

The potential is also there for dare I say snow. In what location is impossible to pinpoint but the GFS is depicting a snowy trend after 10 days. Again, don't get hung up on any one spot I'm just pointing out there's movement in that direction. I guess we'll know soon enough.