From NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

It’s not often I am lost for words!

Porthmadog Weather Station

You will recall my post a few weeks ago, querying the siting of the Met Office’s weather station at Porthmadog, which often appears in the “hottest of the day” listings. As Ray Sanders pointed out, the Stevenson Screen is extremely close to that line of trees/bushes, which are located to the north and east, creating a very nice sun trap.

The Met Office’s own rules are quite clear – that there should be no trees  nearby that might influence the measurements.

I FOI’d the Met Office asking them what they knew about Porthmadog, and was astonished by their reply:

In short, they are happy to use a Class 4 site for climatological purposes, even though that class is next to junk status.

Class 4 makes no restrictions over vegetation, unlike the first three Classes; Class 1 for instance stipulates that vegetation should not exceed 10 cm:

https://library.wmo.int/doc_num.php?explnum_id=11612

According to the station notes the Met Office also sent me, 20% of the surface area within 10m exceeded 30 cm in height.

Class 4 sites certainly are not acceptable sites for climatology, nor for that matter are Class 3 ones. As the WMO notes, they can have up to 2C of uncertainty.

It is bad enough that the Met Office is using this site. But it is even worse that they know about the issues, but still plan to carry on doing so.

How many other weather stations are of such poor quality?