Thickness lines

[MINESAPINT]

We all know heat causes expansion and cold causes contraction. This is no different with air, so if air is warm it will take up a larger space than if it is cold (dense). The thickness lines can be found on some synoptic charts and indicate the thickness (height) of 50% of our atmosphere between 500mb and 1000mb. I have just been on findafishingboat web site where there are some free synoptic charts which do have thickness lines, they are fine dotted lines with numbers along their length such as 528 and 510. Do not mistake them for isobars. The numbers indicate the thickness of 50% of the atmosphere in decametres so you will note 528 equates to 5.28Km and 510 equates to 5.1Km. You will see from the charts the 528 line arrives in UK on Monday and the 510 is still over the north sea but by Wednesday the 510 line covers most of the southern half of the country. By Thursday the 510 line is still present and you will note the isobars are pretty tightly spaced indicating a very strong easterly wind. It is very rare for the 510 line to visit our shores but whenever it does it brings with it extremely cold conditions and on this occasion it is venturing further south than I have noticed it previously. But of course we know the true judge as to whether it is cold is whether your postman is still in shorts - ours still is but it remains to be seen whether he is on Thursday!!!!!!!!!!!!!

On some synoptic charts thickness lines are indicated in 6 decametre steps 510, 516, 522, 528, 534 etc

MINESAPINT

[Green Aura]

That's quite interesting - the Met Office has issued a yellow snow warning (don't go there!) on a pretty much straight east/west split from Monday. I assume that's your easterly front coming in. It doesn't mention anything about a north/south difference though.

Anyway, keep warm everyone and enjoy the sunshine today, or I will for you if you don't have any.

[MKG]

I'm actually looking forward to this. We (it seems) have an EXTREMELY localised climate pattern (halve all extremes then halve again in winter) and, apart from occasional breakthroughs, that seems to be the norm.
I shouldn't have said that, should I?