Ivor, Borth and Ynyslas’ Katabatic Wind

Along with the rest of the country we have been enjoying some gorgeous spring weather recently. Clear blue skies all day long and some of the most amazing sunsets and sunrises with spectacular oranges, pinks and purples. It has been quite cold too, especially at night which leads to a local phenomenon of a katabatic wind, affectionately known as Ivor here in Ynyslas and Borth.

It works in a similar fashion to a sea-breeze in the summer, but in the opposite direction and with more force. At night the temperatures in the hills can drop significantly, often reaching minus numbers and maybe even down to minus 8-10ºC. The sea however remains at a fairly constant temperature and is currently around 9ºC. That is a huge temperature difference. The sea warms the air above it which then rises, and cooler air from inland moves in to take its place, creating an offshore wind. As the sun rises in the mornings, it rays reflect off the surface of the sea further raising the temperature of the air above it which drives the wind even faster. This is the exact opposite to the summer sea-breeze effect, but the larger temperature difference increases the effect making the winds stronger.

On top of this, Ivor, the katabatic wind has gravity on its side (unlike the sea-breezes in the summer). The cold air in the hills sinks into the valleys and flows along them just like a river would. Gravity, coupled with topographic funneling in association with winds driven by a temperature gradient can produce some pretty startling effects here, with winds in excess of 20 knots when everywhere else is calm. If this also occurs on a day when there is a general E-NE wind direction then we often gets winds in the 30-40 knot range. More than enough for most people and perfect for those of us who windsurf and Kitesurf.

18 Responses

  1. Thursday, May 8th, 2008

    […] and yesterday I managed a morning windsurf session in the estuary. Ivor was up to his tricks providing perfect conditions and the warmer weather means less neoprene and a […]

  2. Monday, May 19th, 2008

    […] just had another action packed weekend here in rural mid Wales. Thanks to our local katabatic wind I managed to windsurf every day last week and although the wind wasn’t forecast to be great […]

  3. Monday, August 4th, 2008

    […] wind if it swings around and comes from another direction. Not so here. In fact, we have a special katabatic wind (known affectionately as Ivor) that funnels down through the Dovey Valley and blasts us with cold, […]

  4. Saturday, April 18th, 2009

    […] the forecast of lightish winds, the katabatic effect that creates the wind affectionately known as Ivor was in full force this morning, so after a night […]

  5. Thursday, June 25th, 2009

    […] got back from a lovely windsurf session in the estuary at Ynyslas. Its that time of year when Ivor, our local katabatic wind is on top form and with a gentle NE wind forecast and sunny skies he was up to his usual tricks. […]

  6. Sunday, November 22nd, 2009

    […] which can be good when the wind is from the east. This is especially true in the Spring when Ivor, out local katabatic wind, comes howling down the […]

  7. Sunday, February 7th, 2010

    […] just got back from a nice little windsurf session in the estuary here at Ynyslas. Ivor, our local katabatic wind was up to his usual tricks with a decent NE wind funbelling down through the valley at up to 25 […]

  8. Monday, February 22nd, 2010

    […] just got back from a windsurf session the estuary here at Ynyslas. Ivor, our local katabatic wind was up to his tricks so the wind was ballistic at over 40 knots. The water was a seething mass of […]

  9. Friday, March 5th, 2010

    […] next week and there isn’t a single star showing. Oh well, I’ll just have to hope that Ivor out katabatic wind can do something about […]

  10. Wednesday, May 12th, 2010

    […] the exposed nature of the area, with winds that not only blow in off the sea but also our very own katabatic wind called Ivor that funnels down the valley here. Bees don’t really like the wind so this could pose a […]

  11. Monday, October 11th, 2010

    […] now Monday morning and I was hoping for a rest, but Ivor is once again blowing his socks off so it looks as though I shall have to have just one more day […]

  12. Saturday, November 20th, 2010

    […] had a nice early start as Ivor, our local katabatic wind was in full force, so I was on the water at around […]

  13. Friday, April 29th, 2011

    […] This will not only make it pretty hard going on the day, but will also mean that with the help of Ivor, our local katabatic wind, I’m likely to be out on the water beating my body up all day Saturday in an attempt on my […]

  14. Sunday, May 1st, 2011

    […] Ivor kicked in over the weekend as predicted and blew with a vengeance all day long. Despite the fact that I was supposed to be having a rest day on Saturday in preparation for the Dyfi Enduro on Sunday I just had to go for a windsurf. […]

  15. Wednesday, February 8th, 2012

    […] been freezing out there today. The temperature only rose to 2°C, but Ivor our local katabatic wind was blowing his socks off all day long. 30-35 knots in the estuary, making it feel bitterly cold […]

  16. Tuesday, July 23rd, 2013

    […] sun is still out but there are signs of clouds all around and thunder-storms are on the horizon. Ivor, our local katabatic wind was in full-force in the morning so I made us of him by going for an early morning […]

  17. Saturday, July 4th, 2015

    […] the wrong activity though because as I left the house to drive into Aberystwyth Ivor, our local katabatic wind, was blowing his socks off so I could have gone windsurfing. Then, when I got to Aberystwyth the […]

  18. Tuesday, July 19th, 2016

    […] more, Ivor, our katabatic wind seems to be blowing as well… gusting to 30 knots in the estuary at the […]

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Alan Cole

Alan is a Freelance Website Designer, Sports & Exercise Science Lab Technician and full time Dad & husband with far too many hobbies: Triathlete, Swimming, Cycling, Running, MTBing, Surfing, Windsurfing, SUPing, Gardening, Photography.... The list goes on.

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