News and information

August washout or not

Is the rest of the month a write off?


12/08/2019

Very wet and unsettled period

Much of the UK has had very wet weather recently. It has also been unseasonably windy in the southern half of the UK. Despite the wind and rain it has been quite a warm month to date. Provisional data shows the Central England Temperature (CET) to the 11th August at 18.2C which is 2.3C above the 1961 - 1990 average.

The unsettled pattern is set to continue in the short term with all areas having further showers or longer spells of rain. At times it is expected to become windy again. Are we finished with warm and dry weather this month or is another change likely?

Overcast weather

Beach near Wells-next-the-Sea, photo by TheWeatherOutlook

Are there signs of an improvement?

During the next 7 to 10 days unsettled and rather cool weather is forecast to predominate. The GEFS ensemble graph below shows upper air temperatures on its top half and rain forecasts on its lower half. 

Upper air temperatures are often close to or below the 30 year average. They don't necessarily tell the whole story in the summer months because a strong sun means it can quickly warm up at the surface despite cool air aloft. However, the rain predictions are pointing to quite a wet picture out to about August 23rd. Therefore the combination of cloud, rain and cool upper air suggests disappointing summer weather.

In the longer term there are tentative signs of an improvement. A wide upper air temperature spread develops with some of the GEFS runs bringing back a much warmer air mass. More importantly perhaps is the reduction in the number of rain spikes. In other words most of the GEFS runs are pointing towards drier conditions, at least in the south of the UK. On comparable plots for more northerly locations the general picture is a wetter and more changeable one.

GEFS 06z London 850hPa temperatures and precipitation

GEFS 00z London 850hPa temperatures and rain, photo by TheWeatherOutlook

High pressure building from the south?

If more settled weather returns later this month where will it come from? The most likely scenario is for high pressure to build from the southwest towards the UK. It is a typical pattern and generally brings the driest and warmest conditions to the south and south west.



This morning's GFS 06z model run shows high pressure having more influence during the last third of August. However a westerly flow persists across the northern half of the UK with rain bearing disturbances moving in from the Atlantic. At times they push farther south so even the southern half of the UK doesn't remain completely dry.

GFS 06z 500hPa heights and MSLP

GFS 00z 500hPa and Mean Surface Level Pressure chart

Summary

All parts of the UK have showers or longer spells of rain at times in the next 10 days. Temperatures are expected to be on the low side and it could become quite windy. During the last third of the month there are signs of high pressure having more influence. That suggests a better chance of drier and warmer periods as we head towards the Summer Bank Holiday on August 26th, at least in the southern half of the UK. 

Press and media enquiries

We welcome all press enquiries, whether relating to this news feature, or seeking comment on other weather news.

Contact us

MORE NEWS


LATEST NEWS

Bank holiday weekend promise

NEWSLETTER

Get weather updates by email

Register now

TODAY'S WEATHER

7 day charts

RECENT FEATURES

Summer Bank Holiday

August washout or not

Winter 2019/20 weather

Autumn 2019

Wimbledon fortnight