I’ve been talking about the potential for a cold end to November for a while now. Initially I was expecting this change to begin around the middle of the month but this now looks less likely, instead we see an increase in the Polar Vortex and this in turn will bring further unsettled weather to the United Kingdom. I don’t think it’s going to be particularly mild though with winds generally from the North-West but we could see periods of milder weather ahead of Low Pressure systems.
What we do have is an area of High Pressure developing across Europe, Scandinavia and Russia, this initially is what I was expecting to bring a change to colder weather but latest model outputs keep this High Pressure system a little too far East for this to happen. It does look like we could see a brief spell of more settled weather around the middle of November across the East and South before low pressure returns bringing further wet and windy weather.
Looking towards the end of the month, the models have been very poor recently with changing from a cold outlook to a mild outlook. The reason for this is the conflicting signals we’re seeing at the moment. The models are having to deal with forecasting the increasing Polar Vortex as well as trying to handle the signal for blocking, when this happens the models tend to flip back and fourth in the medium term. We are now starting to perhaps see some slight clarity, however.
The NAO and AO have moved into a more positive state but latest forecasts suggest this isn’t going to last with both returning to a more neutral or weakly negative state through into the second half of November.
We’re also seeing some signs later in the model output of High Pressure developing in the Atlantic, though as I say these outputs are constantly changing with every model run, it does tend to tie in with the above NAO & AO forecast.
So I think over the next 10-15 days things temperatures will return to around the seasonal average, occasionally we will see milder air briefly getting into the mix. We’ll also see periods of settled weather as temporary ridges of high pressure develop particularly across the South and East, further North and West likely to hold onto the unsettled theme.
Moving towards the end of the month the signal for colder than average temperatures remains with the Atlantic becoming increasingly blocked, this of course raises the risk of some snowfall.