View Full Version : Weather School Musing...Can't stop troughing!

12th July 2011, 03:36 PM

Just a quick Musing for you, so that you can see where the bigger cycles within the worlds weather patterns fit in.

Here's a chart for 7pm tonight from Wetterzentrale.de.

It shows isobars (white lines) and also the 500mb heights (that's about 18,000ft). Lower heights are in green, warmer in red. The height of the 500mb 'surface' varies day to day depending on temperatures, hence the lower the heights, to cooler the temperatures at that height in the atmosphere, and vice versa.

A change is about to take place. Look at the heights over the UK; notice the 'n' shape in the heights (the orange colour extending from the Azores high, through Ireland and into the UK mainland). It's this which has brought the relativelym fine weather for today (although it has been raining in the south and southeast).

Now, compare this to the chart below.

This is the forecast chart for midnight Monday. Notice how there is now a trough, extending from a cold pool (green area) over Spitzsbergen, southwards into central parts of Europe?

And, see how low pressure is below it? Well, I don't expect this trough to survive very long, and it is likely to be warmer through as it's cold source air gets cut off. But what it is doing is signalling where the weather is going to go for the rest of the back end of the month and into August.

I suspect that are a couple more unsettled days next week, the trough deepens over Europe, a ridge builds west of Ireland and the UK is under ridges of high pressure. Never hot, but reasonably warm and the chance of showers on eastern coasts.

That probably takes us through to the early part of August, but the rest of August then looks more unsettled as a jet stream attempts to break though.

I've put more online at my Weather School YouTube Channel at http://www.youtube.com/user/weather school

Let me know what you think. Hope that's useful.

Best wishes,