The MJO teleconnection is something that is often referred to when predicting the medium range weather outlook. For those not in the know, it is effectively a measure of where there is enhanced convection in the tropics, the theory being, if you have anomalous ascending air in one part of the world - you would expect there to be corresponding descending air elsewhere and thus a knock on effect on a variety of global weather patterns including the weather experienced over Europe.
The MJO was brought to the fore-front of sub-seasonal weather forecasting in part due to a Paper from Cassou (2008) that linked the 8 Phases of the MJO to general weather patterns over the European region (NAO-, NAO+, ATL Ridge and Scandi blocking) seen below:
This is still in use to this day as a leading paper in MJO Correlation to European Weather patterns.
The trouble is, these 4 patterns are too broad to look at the specifics of what this would mean for a number of applications, Energy Production/Demand being an example - as NAO- could mean warm southerly or cold northerly.
I was recently involved in a MSc Project that looked at linking the MJO to the GWL (Grosswetterlangen) patterns in association with the MetSet Tool that I have developed. Joshua Lee wrote the paper, with Dr Robert Lee and Professor Steve Woolnough being the other supervisors from the University of Reading.
It yielded some interesting results - rather than just a flare up in NAO+ regime as we cycle through Phase 3 to 5 it seems there is more detail to it, firstly we get an increase risk in Southerly patterns/South-Westerly patterns first and then Westerly Anticyclonic (WA) before moving onto Westerly Cyclonic (WZ). It also gives insights into what paterns are most favoured for the different phases - Please see the full charts for each of the 29 patterns below:
