As I type this clouds are once more gathering to the west with the promise of yet more rain. It is already my wettest January here in Haytor since I started recording in 2002. As of 1800 GMT 20/1/14 my rainfall total stands at 274.5mm. If you add this to the December total of 407.7mm you get 682.2mm for the winter so far. A whopping 1000mm (1 metre) of rain is certainly possible for the whole winter period. Of course this is the last thing folk on Dartmoor need as the ground is completely saturated, so what of the future?
Well I can see no end in sight to this onslaught. Drier and very cold air is sitting to our east over Scandinavia but has been reluctant to move west and early next week deep Atlantic lows will dive southeast into Britain. Some cold air from the east will be drawn in, so there is a risk of some snow but there is also great uncertainty in the detail. The chart below shows one of many possibilities.
This chart (click on it to enlarge) is from an American numerical weather prediction model and is valid for 0000 GMT next Tuesday, a week ahead forecast. The low pressure system over south Wales will give a lot of rain over Dartmoor as it tracks southeast and the pale blue line indicates that cold air is not far away highlighting the risk of snow. Other models give a different evolution but all of them give rain. Outside chance that once the low moves away south then it could turn dry and frosty for a while, but I’ll believe that when I see it. Interesting times ahead once again for us meteorologists, but not good news for our beautiful landscape and pot-holed roads up here on Dartmoor. Unless it snows of course!
Well we have at last enjoyed a bit of sunshine recently, giving us a bit of a break from the relentless wet weather. With clearer skies we also get colder nights of course, providing the opportunity for some interesting frost formations. These pictures of “hair ice” were recently sent in to me from Ashley in Throwleigh. The photos were taken last Saturday 18th January at the National Trust car park in Postbridge. I must say that I am unsure as to why ice formed on this particular branch, so if anyone has any ideas then please e-mail me!
Well it’s been a while since my last blog, so time to update on the latest weather over Dartmoor.
Last December was my second wettest month at Haytor since I started recording in 2003. I collected 408 mm which was only surpassed in Nov 2009 with 418 mm. The rain has certainly been extremely heavy. Our local river Lemon flooded 3 times in two weeks and on 23rd Dec Postbridge collected 156 mm of rain in 24 hours. Every path coming down from Haytor Rocks that day was a fast flowing stream. Last Sunday I was walking near Hexworthy and just made it over the stepping stones at Week Ford. I was astonished to see a watermark at 8 feet high from when the Dart was in flood!
So, has this stormy wet weather finally come to an end? Well the polar vortex has now split, one half has drifted south into the States giving them severe cold and the other half is making its way down into northern Russia. Incidentally Siberia, Russia and Scandinavia have had an unprecedented mild December. The jetstream is weakening and we have seen the last of the rapidly deepening Atlantic storms. However, we have not seen the end of the rain. In fact later in the weekend, especially on Sunday into Monday, rain systems could well end up over the UK as slow moving features exacerbating the flooding risk. During next week there are now clear signs that the weather is set to turn colder for the second half of January with strengthening easterly winds possible.
So on that potentially snowy note all that remains is for me to say Happy New year!