
Have to admit, it is being an unusually cold March.
But, why is it being so cold for so long? Time to do one of my famed explanations, along with an image.
The reason why this cold air over the UK (whether is it snowing or not) is refusing to let go is because of a large area of high pressure sitting over North or East Europe, and how that high pressure often kept "ridging" south to cover more of Eastern Europe, as this image shows.
But because that high pressure system is refusing to budge or die out, it then becomes a "blocking" high. That has the effect of deflecting or killing off nearby low pressure systems. As in this case, keeping the usual Atlantic "train" well at bay to the west of the UK
That high pressure system also has deep cold surface air trapped within it (shown in light blue), and because winds go around in a clock-wise direction around a high pressure, it has a habit of dragging some of that cold air westwards towards the UK.
Usually, once such a "blocking" high pressure is set in, it would take a lot of shifting to get it to move on as low pressure systems keep punching at and failing in doing so. It is also right now where the sea surface in the Northern Hemisphere is at it's coldest (there is a lag effect where the sea takes longer to cool down than land, but just as longer to warm up so it becomes at it's warmest in early Autumn), so there are no competing contrasting airmasses to produce powerful jet streams anyway.
I've also put in an additional mention of a "col", something I mention in my forecast. That's the "dead" area between low pressure and high pressure systems, it's often slack and calm but cloudy and foggy under such a set up.
A blocking high in the same area in the summer season can even have the effect of keeping it cool and cloudy as winds keep coming in from the east or north, as well as pushing high altitude jet streams to the south of the UK, thus keeping us on the "cold side".
So, if we really want a hot summer, then we need to see a complete reversal of the weather system to what is shown in this map and have high pressure "ridging" in from the south. That way, we would often have winds coming in from the south west or the south.
However, having said all that, March is still essentially a "winter" month anyway so it is a bit too early to start pining for warm weather despite the lengthening daylight. It's when we are still experiencing snowfalls and sub zero temperatures in June that we really should be worried!
And there you have it.
Mind you, I'm more bored of this "Groundhog Day" style weather where it has been yet another dry and cloudy day here at Folkestone. Yet, this time last week we were recovering from a snowstorm!