FRIDAY SNOW LATEST as of 12:40pm Thursday: SNOW STARTING EARLIER BUT STAYING LIGHT!
Light snow starting in Reigate around 9 or 10am. Mostly light snow for the rest of the day (Friday <5cm lying snow), but possibly heavier later afternoon & evening. Snow showers on Saturday & Sunday and snow possible Monday & Tuesday with a new LOW developing out west. Temperatures staying low all weekend: at or significantly below freezing throughout: windchill -8°C Friday lunchtime for Reigate.
Predicting the onset of snowfall (or rain) several days ahead is often the least accurate part of weather forecasting. Predicting temperature, wind speed and direction are usually considerably more accurate. The UKMO (UK Met Office) achieve around 70% accuracy for their 3 hourly precipitation forecasts for the current day and over 90% accuracy for temperature forecasts. Pin-pointing exactly WHAT TIME it is going to rain or snow in a particular location several days ahead stretches even the most powerful supercomputers and taxes forecasters. For example… here is a medley of current predictions for snow in Reigate: (no longer a valid forecast but interesting nevertheless!)…
Friday snow starts in Reigate: Meteogroup = 9am; BBC=11am; UKMO = 12:00pm; GFS = 12:00pm. Saturday snowfall rate in Reigate: UKMO = Light snow all day; BBC & GFS = Light snow all day; Meteogroup = none after 6am!
Variations in temperature predictions are less marked but on Sunday there are significant disagreements: the lowest minimum is down to -9°C on Sunday night whilst other models place minimums at -3°C. Thursday evening will bring the most accurate prediction for snow and models should agree more by then. Our own forecast might go something like: Light snow starting after lunch on Friday and going overnight through to Saturday when there will be continued snow showers for most of the day. Snow accumulation: 3-8cm.