So we are heading into Christmas and as noted in previous posts (1,2,3) as well as everyday observations from this winter to last winter we are in a snow deficit. Obviously there is no snow on the ground at this time and to date we have only picked up 4.1 inches of snow through 16 days in December. On top of that we are seeing temps running above normal, especially over the last week. If you recall, the Climate Prediction Center called for an above normal snowfall and below normal temperature winter season, thanks to us being in a similar La-Nina pattern as we were last year. It has been far from that so far, but the Climate Prediction Center also stated that there was a wild card involved. This wildcard is playing a huge role in our weather right now.
It is know as the Madden-Julian oscillation (MJO). It is a large-scale coupling between atmospheric circulation and tropical deep convection (thunderstorms). Rather than being a standing pattern (like La-Nina or El-Nino) it is a traveling pattern, propagating eastward through the atmosphere above the warm parts of the Indian and Pacific oceans. This was discovered by Roland Madden and Paul Julian.
This atmospheric phenomenon will trump the La-Nina effects and it certainly has. Below are a couple of pictures that illustrate how the propagating thunderstorm activity in the Indian and Pacific oceans translate to out weather in the United States. You will notice that these are listed as phases. As of December 16th, the MJO is currently in PHASE 5. The first chart is temperature, the orange indicates above normal temperatures on average. The right two panels show the percentages of the the temperature anomaly in the left two boxes. Phase 5 is located at the top of the column 2 in both the temperature and precipitation charts.
The same thing goes with the temperature charts below. The brown represents drier than normal conditions. The same PHASE 5 applies to the temperature charts as well.
Now the MJO oscillation typically persists for 30-60 days, an average of 45 days. The MJO has shown some signs of weakening. We may be on the verge of not having a white Christmas coming up but we may be compensated for the lack of snow in sometime in January or February, when La-Nina effects may take over again.
Posted under climate, just cool
This post was written by jkegges on December 16, 2011