July frost

Wierding continues

Morning of 9th July 2015 the Katesbridge Met Office site reported a frost, flat lining air temperature close to 0.0C which arguably means frost was forming on the Stevenson screen. Whether this was an air frost, don’t know. Dew formation produces a less clear flat but is not usually clear in hourly data.

Notoriously cold still air site, convective cooling, no wind. Sun was up by 5AM but there are low hills thereabouts.

Why?

More notably temperatures were widely below 10C (50F) in Northern Ireland, England and Scotland. Where there was a wind, a good example St Bees Head where it was off sea, 11C, Arctic air, reaching right across, Bridlington where the screen is almost on the east coast foreshore was also cool.

The very south was slightly warmer but even the Isles of Silly were cool, bouncing along at 14.1 / 14.2 during the night at the airport, sufficient wind to prevent a serious temperature fall.

Mid afternoon on the 8th the characteristic cloud pattern of a polar air cell is over the ocean and UK. A just off west wind is gently bringing cool air to the west.

By 6am UT the cloud bank has built up more but Katesbridge (Northern Ireland) is just in the polar air, the wind is able to drop and the air is clear.

For now the UK is holding north of the hot band in southern Europe.

For a couple of years now a lot of bad weather has been expressing itself in the eastern Mediterrinin, weather we did not get. We tend to get moderated by the Atlantic. A week ago a brief hot air breakout took place.

Archive of Meteosat immediate images (1MB zip), from here
Thumb plots from Datapoint PDF (1MB)
Datapoint data as CSV to 7hrs 9th. ZIP (69kB)

Images: EUMETSAT or the author. Data: Met Office Datapoint.

Post by Tim