The pattern that got established early in October has, over the past 2-3 weeks, gone through an enormous change. I "think" it can be tied to several major occurrences. The first was what is called a Sudden Stratospheric Warming event. There is a pretty good write-up about SSW's on Wikipedia (click here). This SSW event may have occurred because of the exceptionally strong MJO that developed that in turn triggered a chain of events to the upper level wind field. It could be also that the SSW was the culprit and not the MJO. That is up for debate. If you recall there was a brief "warm" event at the North Pole (not unprecedented) where temperatures got close to freezing and even now a very early Hurricane near the Azores has formed in the Atlantic. So, it's been rather unusual lately.
BTW, here is the latest MJO phase space composite chart.
The indices of this MJO are 3 standard deviations above normal! Plus with the AO and NAO so deeply negative, it is extremely surprising that the Arctic air has only briefly made it into the western high plains. Another surge will briefly make it this weekend. Normally with these types of contributions for January, the Arctic air would have made it well into Texas.
Ok, so what the heck is going on? Could the El Nino influences be in control at this point? It doesn't appear so as I can demonstrate on the satellite image.
First, as of early this afternoon there was a disturbance (small scale storm) near the Four Corners that was moving southeast. Typically this would bring a swath of snow into the plains this time of year. But this time the atmosphere is just too dry to support much into the plains. I would say there should be a inch of two of snow possible into the Oklahoma Panhandle. The system will likely intensify and tap into moisture as it approaches the east coast late this weekend.
There was a large polar low circulating across eastern Canada. But it was elongated into northwest Canada and this has prevented a big dump of cold air into the states. More importantly on the map was the huge storm over the Gulf of Alaska. It will move into the far northwest U.S. and southwest Canada bringing copious rain and snow to that region. A second system (the X on the far left) will bring additional heavy precipitation to that region. Look at the predicted precipitation!
Just like earlier this fall and winter, this area getting that much precipitation IS NOT a signal of an El Nino event! It's too far north! On the other hand, the precipitation expected across south Texas and into Florida can be tied to the ENSO event.
Also on the satellite map above, I've drawn in a dotted blue line. In most El Nino events, the jet stream across the Pacific would be aimed at northwest Mexico or at least southern California. Currently though it is slamming into the Pacific Northwest.
So what does this all mean for the high plains? It is so complicated, my confidence has tanked. I'm going to hold on to a slim thought for a storm forming next week (and it was actually hinted at in the European computer models) but at this point I would not count on it, i.e., don't take any mitigation measures.
I do think the pattern may be returning to it's former self. What that means is that the chance of several impacting storms will be increasing towards the end of January and into the first few days of February. Overall the month of February should end up normal to below normal on temperatures and most likely above normal precipitation. This would be valid for especially the central and southern parts of the plains.
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