15 May 2015

Any signs of summer yet?

There’s no doubt that May so far has been a disappointment. While the rain has quenched the thirst of our gardens, it’s washed away any hopes of a barbeque or picnic.

April is renowned for being a mixed month, as the weather makes the transition from winter towards summer, through the season that we call spring.

However, by mid-May, the weather usually shows signs of calming down a little, with less rain and the balance tipping towards sunshine and warmth.


Jet stream not playing ball

Normally during May, the jet stream tends to move north of the UK, diverting low pressure, wind and rain towards Iceland and Scandinavia.

jetstream_midMay_WZ_wpHowever, so far this May, the jet stream hasn’t undertaken this shift northwards and has been sitting over or south of the UK, as well as moving quite quickly.

This has been spawning areas of low pressure and pushing them across us, bringing wind, rain and some chilly temperatures, with rural frosts remaining quite frequent.

Take yesterday for example, much of England and Wales sat beneath a day of rain, with temperatures struggling to reach 10C – a good 8C below where they should be at this time of year.

Any signs of summer warmth?

Well, there’s good news and bad news…

The bad news is that there are no signs of summer warmth for the rest of May from any of the weather computer models.

They all show signs of below average temperatures for most of the time – largely because the wind will generally come from a west to northerly direction.

This means that the air is coming in from a part of the Atlantic ocean where sea surface temperatures are around 1C below normal (blue and green on the map below) – chilling the air that’s moving over it and towards us, making it cooler than it would typically be at this time of year.

sst_anomalies_NOAA_wpOn a positive note, there are signs that the jet stream will slow down a little later next week, meaning that the frequency and intensity of low pressure systems will decrease.

This means that there will be a better chance of longer drier and brighter interludes between any spells of rain that pass through.

When the sun shines, it won’t feel too bad if there is no wind, but clear skies at night will lead to the possibility of rural frosts continuing – farmers and growers beware!

Don’t forget, you can get the latest forecast on the Channel 4 Weather website. I’ll also be posting regular updates on Twitter – @liamdutton

Graphics: Wetterzentrale, NOAA

Tweets by @liamdutton