Wind farms can interfere with forecasts says Met Office as it lodges complaints against planned sites
The Met Office has objected to the construction of a giant wind farm – claiming its turbines could affect the accuracy of its weather forecasts.
It says interference from dozens of giant blades would result in ‘false warnings of severe and hazardous weather being issued’, while heavy rainfall and flood alerts could be missed.
The weather agency has written to planning authorities to register its opposition to the site, which would see more than 20 turbines dotted in the Welsh mountains near one of its weather stations.
The 400ft turbines can reflect the electromagnetic waves emitted by radar, creating ‘clutter’, which prevents accurate readings of atmospheric conditions, the Met Office said.
It has lodged objections to the planned wind farm at Llanllwni, Carmarthenshire, which is currently under appeal, and is set to object to a 28-turbine development at Brechfa, which will go before planners in March.
Both sites are a few miles from a weather radar at Crug-Y-Gorllwyn in Carmarthenshire, which provides coverage for south and west Wales.
Last July, west Wales suffered devastating floods after more than a month’s worth of rain fell in 24 hours, forcing 1,000 people to leave their homes.
A Met Office spokesman said: ‘Weather radar is the only means currently available for monitoring in real time the location and intensity of a range of weather hazards, including rain, hail and snow. Clutter from wind turbines can lead to false warnings of severe and hazardous weather being issued.’
‘Another risk is the potential for missed warnings where either rainfall returns are obscured either by clutter or because more aggressive quality control, developed to try to mitigate wind farm clutter, can have the side effect of deleting real rainfall signals.’
The Met Office failed to lodge a timely objection to the second development in nearby Brechfa due to ‘human errors’, which resulted in them not being consulted.
But in a letter to planning authorities, the agency said: ‘The impact of Brechfa Forest West is significant and we would have made an objection. Both developments in question are in a priority Environment Agency rapid response catchment area, within which accurate rainfall forecasting is a crucial element of the flood management plan.’
The Met Office also warned that the Alltwalis wind-farm, built in 2010 and only 14 miles from their Crug-y-Gorllwyn radar, has already had an impact on their forecasting.
‘Existing impacts from Alltwalis provide good evidence on the likely impacts from Bryn Llywelyn and Brechfa West. The evidence we have largely relates to false alarms of intense precipitation,’ a Met Office report said.
‘This can be and has been presented in the form of both long-term precipitation accumulations and the probability of precipitation. Analysis of significant events, e.g June flooding close to Aberystwyth, provides illustration of impact during severe weather and flooding.’
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