What are some typical and extreme values of thickness?
(see also Q/A 2A.5 above: thanks to Jon O’Rourke for looking up the extreme values we hold in the NMC at Bracknell) A. As already noted elsewhere, the values of the (total) thickness between levels at 500hPa and 1000hPa give a useful measure of the mean temperature of that layer. In summer, values might range from 546dam (cool, showery northwesterly) to 560dam (warm, settled anticyclonic spell); in winter from 530dam( brisk, chilly, showery flow, with inland night frosts) to 550dam (mild, open-warm sector type). (The values are given for comparitive analysis only, and the weather types of course don’t necessarily follow from the values); Values below 528dam in winter would herald the arrival of potentially wintry conditions, and in summer, thickness values above 564dam might be a precursor to some notably high temperatures. As to extremes, for the UK mainland land-mass only, the highest Jon could find came out around 576dam in July over southeast Kent (SE England), and the lowest aroun
