Tracking the Prestige oil spill: An operational experience in simulation at MeteoGalicia

further ± from the Black Mountains of South Wales. It appears that this particular street propagated (or spread) east-south-eastwards and then developed quite explosively over the hilly West Berkshire Downs area, in a case of topographically enhanced, localised convection. The observer in Hungerford (John Weevers, personal communication) commented on the frequency of lightning, but no hail there (8 km away). The Herstmonceux ascent for 1200GMTon 13 May (not shown) indicated air of Arctic origin, with a low tropopause at 480mbar, and deep instability given the surface temperatures above 10 8C. Unfortunately, there was no midday ascent from Aberporth on the University of Wyoming website, but other southern ascents (e.g. from Camborne) indicate a more usual 250mbar tropopause, as might be expected with polar maritime air. AtWoodlands St. Mary, the temperature fell to 7 8C during the latter stages of the hailfall. No strong gusts were observed, although the wind varied from between south-west and north-west, occasionally becoming near-calm. Much newly emerged foliage was either stripped or holed by the hail.