I have been struck over the last few days by the huge difference between snow cover at the top of Hampstead Heath (380 feet ASL) and nearby but slightly lower locations such as Swiss Cottage. Although the top of the Heath is generally a little snowier than nearby lower spots, for the recent snow event the difference has been remarkable. At the top of the Heath near the car park behind Jack Straw's Castle, the snow depth has been a consistent 5-8cm since Monday morning (11th) with trees and shrubs plastered in snow even until this morning. It is a true winter scene. Only a few hundreds yard away where we live at a height of about 250 feet, the snow has been 2-3 cm in depth with the trees losing their cover from Tuesday. Down in Swiss Cottage, no more than 1.5 miles from the top of the heath at a height of about 180 feet, there is now scarcely any snow to be seen. Other parts of London are now similarly snowless. I presume the difference is attributable to a combination of the lapse rate, orographic uplift and fewer buildings. Still, it is rather remarkable given the relatively small altitude differences involved.