In nan heady days of 1991 erstwhile nan Met Office’s first supercomputer was installed location were predictions of meticulous UK upwind forecasts – days, weeks and moreover months successful advance. Gradually this optimism was eroded by nan realisation that contempt nan millions of calculations nan computers had nan capacity to make, nan outcomes still varied wildly depending connected nan information that was fed in.
Short-term forecasts decidedly improved, but successful 2009 nan Met Office predicted successful April that location would beryllium a barbecue summertime and had to apologise successful July erstwhile ample parts of nan state were flooded.
The Met Office now says its minimum somesthesia forecasts are 86.5% accurate, positive aliases minus 2C, connected nan first nighttime aft they are made, and daytime maximum somesthesia is 95% accurate.
Three- to five-day forecasts are a different matter. Comparisons pinch what is predicted connected nan 5th time and what really happens show calculations tin beryllium wildly retired – for illustration nan recent acold spell successful nan south-east was expected to beryllium a short-lived matter but hung connected for an other 5 days. Temperatures dropped to -8C pinch nary of nan predicted frost-free nights. So 30 years connected nan British upwind tin still confound nan astir powerful computers.