Since I’m taking some time off, I thought I would share an interesting read from Stuart Markham at chorleyweather.com on the current situation.

By Stuart Markham

As you are probably aware from the past weeks, we have issued information regarding a major warming in the polar stratosphere, which may lead to a colder pattern at some point in February. The weather models have been hinting at a colder pattern developing from around the 10th but we believe this may not be as result of the stratospheric warming event.

Any change to tropospheric patterns as a result of a warming, change around 3 to 4 weeks after the actual event in most cases. We feel the change we are seeing in the models at the moment, is far to early for a stratospheric response and there is another driver perhaps in play. The MJO (Madden-Julien Oscillation) is a factor we have often written about and we think this is the player at the moment.

Effectively the MJO is an area of tropical convection that can alter weather patterns, for example when the MJO is in the Pacific phase, the Pacific jet can be altered by this activity. More information on the MJO can be found here. The upcoming phases of the MJO favour a blocking Scandinavian high to develop, which is what most weather models are suggesting, in the near future.

Below we have the MJO forecast from both the ECMWF & GEFS models. Both are quite consistent in projecting phases 6, 7, 8 upcoming in the next 2 weeks.

Here are the resulting historical analogues for phases 6, 7, 8 taking into consideration we have no ENSO influence (neither El Nino or La Nina).

Note how phase 6 brings the unsettled theme across the Atlantic, then phase 7 builds in the Scandinavian high, while phase 8 retrogresses this high towards Iceland & Greenland. Both phases 7 and 8 have the potential to bring cold weather across the UK, via an easterly flow.

Now here are 3 snapshots from the GFS model today. Note how we start with low pressure systems flowing in from the Atlantic but as the days progress, a Scandinavian high develops and eventually regresses towards Iceland, much like the analogues above.

Now of course this doesn’t automatically mean a dire cold period ahead with epic record breaking snow. Specifics are miles away as yet. We are just highlighting the potential for a pattern to form that 9 times out of 10, brings much cooler/colder air to our shores. We must also add that the Atlantic yet again looks likely to quieten down again from its usual train like pattern and surely this winter will be the driest winter for quite some time……