Winter 2009-10 part 2 - January freeze-up: worst since 1986!


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It's January 11th 2010 and we are now into the fourth week of the cold spell - now the most prolonged since the fierce winter of 1985-6. Overnight temperatures have dropped as low as -14C during the past week, giving ice on the insides of my windows and allowing the Dyfi Estuary to freeze over in places as it did in January 2009 - so two cold winters in a row. This has created excitement in the tabloids who confidently cited the cold weather as proof that global warming is a scam/con/hoax. However, most science is best found in the scientific literature and not in the tabloids - put it another way, if you had the misfortune to be diagnosed with cancer, who would you prefer to go and see - an oncologist or a tabloid op-ed writer?

Climate models do not rule out cold winters for the time being and the extent of the wintry weather this past week is beautifully illustrated from this image taken by NASA's TERRA satellite on Thursday 7th January, showing all but some coastal areas of Wales blanketed in snow:

satellite image snow extent wales

Machynlleth only had a few falls of snow, resulting in a covering of no more than 3cm, but up in the hills above 7-10cm was more widely seen, and in the higher mountains who knows how much? The deep drifts photographed for my last post will not have changed a lot and more snow will have accumulated on top of them, but the problem has been that one of the snowfalls melted to slush and then froze again, making all minor roads treacherously icy. So this week I have stayed closer to base, apart from a quick look at the Estuary (see further down), and gone about on foot.

This is the view from Y Wylfa, a 150m high hill that overlooks Machynlleth, across the Dyfi Valley to Tarrenhendre, late in the day on the 6th:

y wylfa above machynlleth

Zoom-in showing unusual small S-facing corries on Tarrenhendre....

Tarrenhendre from Y Wylfa

On the way down that evening the gritters were busy keeping the main road safe, but the ice and snow remained on the lanes:

untreated road, Machynlleth

No accident observed here - perhaps it was just a hint?

road closed

From the dark recesses of my spare room I dug out my crampons for a walk with friends on the 7th, finding them a very useful aid to making progress across the frozen and in places horribly slippery surfaces!

crampons on ice

So on the 7th we set out to do a 5 or 6-mile round of the hills immediately above Machynlleth. It was a beautiful day of sparkling snow and deep-blue skies, although the Northerly airflow had allowed the North Channel Effect to occur over the Irish Sea, with convective cells shooting up along a N-S line out in Cardigan Bay - here captured in the morning with a telephoto:

pembrokeshire dangler from above Machynlleth

And here, zoomed-out, at lunchtime. The distant thunderheads can clearly be seen, and isolated lightning strikes occurred within the line of storms according to the Met Office sferics-plotter. Because this N-S line of convective activity tends to cross Pembrokeshire, meteorologists have given it the slang-term "the Pembrokeshire Dangler", as I explained to my companions, commenting afterwards that it would probably be the first and last time that phrase cropped up in a conversation with them!

pembrokeshire dangler from above Machynlleth

The surface-hoar was everywhere, and on the frozen Llyn Glanmerin it was especially impressive, refracting the sunlight to create myriad rainbow points of illumination:

surface hoar on snow

On the nearby snow, a closer inspection revealed leaflike ice crystals to nearly a centimetre:

surface hoar on snow

Views were clear and superb in the cold Polar air:

Tarrenhendre from above Machynlleth

Here's the view up the Dyfi Valley, with Mynydd Cemmaes and the windfarm forming the horizon:

Mynydd Cemmaes windfarm from above Machynlleth

Continuing on our way, we passed above Rhiwlwyfen, where I lived for a few years. This is the view inland towards Foel Fadian. It used to take me less than two minutes to get to this viewpoint from my home!

Moel Fadian from Rhiwlwyfen

We continued on down to Forge via forest tracks, and had an icy walk along the road back into Machynlleth, where the crampons proved useful again, and I picked up a blister on my right foot having not worn my Alpine climbing boots for rather a long time!

On the 8th, I had an email from Alex at Roustabout, a business located right on the Estuary at Frongoch Boatyard, to let me know that ice-floes had appeared (I had asked him if he'd mind keeping tabs for me) - thanks Alex!

The 9th dawned cold and fairly clear so I set off down to the Estuary. The first stop was at Gogarth, where mud of the the salt-marshes was covered in some of the largest hoar-frost ice crystals I have seen:

Ice crystals

Contorted and broken sheets of ice littered the Estuary sandbanks:

Ice flows on the Dyfi Estuary

Here's the view upstream, with the steep-sided Llyfnant Valley in the background:

Ice flows on the Dyfi Estuary

By the time I got over to Frongoch, the tide was flooding in earnest. Immediately I could hear strange clunks and booms. On investigation, it turned out to be ice-sheets coming up-river on the tide and coming up against the chains from the mooring-buoys....

Ice flows on the Dyfi Estuary

I stopped awhile, watching this chaotic interaction going on, before the fireside at the White Lion in Machynlleth became too much of a temptation!

In the time it's taken to write this early on a Monday morning, another period of snow has occurred and everything is white over again. And tomorrow, a frontal system attempting to push in from the Atlantic creates an airmass "Battleground" - where we could see rain, sleet or snow - and if the latter, a major fall is possible, but there are enough variables involved to create a little uncertainty in forecasting it - a forecasting nightmare in other words! I suspect quite a few people will be quite glad by now, if the milder air out West wins the battle!


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