23 Jun 2012

June Rain Compared to the Average

From our short-term records (only going back to 2006), the average rainfall for June is 38.4mm.

By the 5th of June, we’d just passed the monthly average.

By the 11th of June, we’d had twice the monthly average.

By the 15th of June, we’d had three times the monthly average.

At the time of writing we’ve had 130mm of rain and are expecting heavy overnight rain.

Update 1pm, 24th June: We’ve had another 16mm of rain overnight and this morning bringing the monthly total to 146mm.

Four times the monthly average (153.6mm) seems quite reachable at this time. Especially as Wimbledon is imminent.

18 Jun 2012

Drought Situation – June Update …

A quick update to this post: We’ve now had a total of 116mm rain this June.

A glimmer of hope on the hosepipe ban horizon: One of the three aquifers that our local water company uses has risen from “Exceptionally Low” status to  “Notably Low”. This is an indication that some of the rain is getting through to the underground reservoirs.

See the weekly water situation report here: http://www.environment-agency.gov.uk/static/documents/Research/WE_120612(2).pdf

The Environment Agency are due to publish a new weekly water situation report  in the next day or so. Watch this space.

12 Jun 2012

Record Rainfall for June …

… and it’s not over yet!
June Rain Total
2012 105mm
2011 81mm
2010 22mm
2009 57mm
2008 21mm
2007 11mm
From our records, the monthly average rainfall for June is 38.4mm. As I write this it’s the evening of the 12th of June and in these 12 days we’ve had 105mm of rain so far! That’s over 270% of the average.

Forecasts for the foreseeable future (around 5 days) show more rain is on the way. Longer range forecasts, though far less accurate, predict a continuing grim remainder of June with temperatures below average and still more rain.

End to the Hosepipe Ban?

So is there an end to the hosepipe ban in sight? Not according to our local water company (Veolia Central). Veolia Central take most of their water from unerground water sources and they say that “Following two years of very dry weather before April, our groundwater levels remain very low.”
Veolia Central add: “Unfortunately at present, we cannot relax the temporary use ban further, as we need to conserve our supplies to prepare for the possibility of a third dry autumn and winter.”

They go on to explain that most rainfall from April to September is absorbed by trees and other plants or is lost to evaporation, and that in order to move us out of a drought situation, we need “prolonged and substantial rainfall between October and March“.

So, unless Veolia Central’s measurements show that a lot of the rainfall in recent weeks has not been absorbed or evaporated, and that it has made it down to the underground reservoirs, then it looks like the hospipe ban will remain in place.

It’s not like the garden is suffering too much at the moment!

Increasing Trend

There also appears to be a general trend of increasing rain in June over the last few years. Sadly this corresponds to some theories about what will happen to the UK climate as global warming increases, but this is such a small statistical sample that no credible link can really be made.
June Rainfall from 2007 to 12th June 2012

1 Jun 2012

Potten End Newsletter Article 2

A condensed version of this article originally appeared in a special commemorative edition of the Potten End Newsletter, June 2012. Also, there were some minor mathematical errors in the original article – they have been corrected here.

Potten End Weather

I’ve taken a bit of a departure from my planned series of articles to briefly write about the extraordinarily wet April we’ve just had.

Also, as this is a special commemorative issue of the Newsletter, I’ve been digging around in the weather archives of the Met Office and other sources to find out what the weather was like over 60 years ago.

The Wettest April on Record

The rain it raineth on the just
And also on the unjust fella;
But chiefly on the just, because
The unjust hath the just’s umbrella.
– Lord Bowen
The Met Office declared April 2012 the wettest since records began in 1910. And it certainly felt that way. In fact, our region of the UK received 237% more rain than the average April rainfall from 1971-2000.

How do our Potten End records compare to that? Well, we measured a total of 113mm of rain in April. This is the wettest April we have on record by quite some margin. Here are the rainfall totals for April in previous years:
  • 2011: 8mm
  • 2010: 12mm
  • 2009: 20mm
  • 2008: 45mm
And it rained every day from April 17th to the end of the month. The wettest day being Sunday 29th April with a total of 21mm falling that day.

Surprisingly, the sunshine amounts for April have not been far off the average.
Despite all that rain we’re still in drought conditions with a hosepipe ban because we still haven’t had enough rain in the east and south-east this year.

April has been in stark contrast to March, which was the fifth driest on record for the UK.

The Queen’s Weather

As this is the commemorative edition of the Newsletter, some have been wondering what the weather was like sixty years ago.

In February 1952 when Queen Elizabeth II was proclaimed Queen, the month started out mild and dry, but became grey and a little wet towards the end. It was the driest February compared to the surrounding years with only 11mm of rain that month. In February 1951, 121mm of rain was recorded.

In 1953, the month before the Coronation had been dry and warm with temperatures reaching nearly 32C in the week before the actual event. But the weather turned at the end of May and the day of the Coronation was decidedly cold, grey and wet. Though it did dry out in the afternoon, the high temperature was only 12C.

And This Year?

Because of the lead time in producing articles for the Newsletter, it is not possible to provide meaningful forecasts for the Queen’s Diamond Jubilee bank holiday. All long range forecasts tend to be very vague with a lot of wriggle room. Depending on where you look and how you interpret trends, the weather will always be some combination of hot, windy, wet, cold and dry.

As an example of just how variable long range forecasts can be, here are just some of the forecasts at the time of going to press:

There are indications that a high pressure zone will develop to the north of the UK which could mean a westerly or south-westerly flow will bring changeable conditions resulting in a ridge of high pressure which could bring some pleasant weather. On the other hand that could also mean that low pressure systems will be forced to take a more southerly track resulting in prolonged wet weather.
My favourite prediction is that the high pressure zone extends and moves south causing warm air to be pulled up from Africa or southern Europe. This gives rise to the effect known as the “Spanish Plume” heat wave. OlĂ©!