John gives us his latest thoughts on likely weather trends on the horizon over the next few weeks. To ensure you are reading the very latest weekly blog, check out Wow and Why
WHAT A WEEK! This will go down as one of the most memorable and impactful cold spells for decades. It’s not always the case that such severe weather can be signposted at long range. But as Sara and I have been hinting for some time, the signs were there that something big was about to hit us.
A key to this cold spell has been the disintegration of the Stratospheric Polar Vortex, and as I suggested last week, this is likely to leave the jet stream – deflected well to our south – ‘punch drunk’ for some time. As a result, don’t expect our normal supply of mild westerly winds to resume in a hurry. There may still be a brake on true spring-like weather resuming.
MONDAY 5TH MARCH – SUNDAY 11TH MARCH
Slowly thawing out
It will be a struggle but, gradually, temperatures will recover. Instead of coming straight from Russia, our air by now will have ‘looped the loop’ around a large block of low pressure, before wafting back across us. In the process, it will have picked up moisture from the Atlantic – and that means rain.
I expect plenty of wet weather through the week. There will still be some snow in the mix, especially across northern areas of the UK. Indeed, parts of Scotland may continue to see further disruptive snowfall well into the week.
It’s very difficult to put timings on individual periods of wet and dry weather through this week, but we will all see some welcome sunshine too, lifting temperatures into double figures in parts of the south at times.
Of course the thaw will bring its own problems. There’s a lot of water locked up in those snow-drifts. Flooding is a distinct possibility.
By the weekend, however, the ‘centre of gravity’ of low pressure may have wafted to our east, allowing more of a northerly feed of air. So, temperatures may dip away again by then, with overnight frosts becoming quite widespread, especially over any lingering snow-cover
Dare I say it? Spring as we used to know it!
MONDAY 12TH MARCH – SUNDAY 18TH MARCH
Damp and chilly
The arrival of northerly winds seems unlikely to mark the return of extreme cold, but another week of below-par temperatures seems likely. Atlantic fronts will try to oust the chill, but most of their attendant milder air will tend to be shunted well to our south by the jet stream.
Those fronts will tend to stall as they approach us, delivering a further mix of rain and some snow. Again the focus for significant snowfall will tend to be across northern parts of the UK and over the higher hills further south.
Frost will continue to be common overnight. But by day, the sun will bring a warmth to our back. It’s getting stronger with every day.
MONDAY 19TH MARCH – SUNDAY 1ST APRIL
Signs of life
The overhead sun is crossing the equator into the northern hemisphere. Of course the weather doesn’t suddenly change as a result – the processes which drive our day to day changes are much more complex. However, I am expecting a trend towards higher temperatures. Dare I say it? Spring as we used to know it!
There are no really strong signals from computer forecast models. But there are faint indications that the jet stream will begin to resume its normal springtime position. It looks as though the northerly bias to our winds will wane, and with higher pressure beginning to push westerlies our way, temperatures will be on the rise. I also expect some lengthier sunny spells to end the month, although inevitably some rain at times too.
We can all agree that March came in like a lion. Perhaps, fittingly, it will go out like a lamb?