UK Met Office vs others

May 1, 2009 at 9:14 am | Posted in Weather | Leave a comment
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Yesterday the UK Met office put out their long range waether forecast for the summer.  Overall prognosis Warm, Dry and Sunny.

I have a couple of problems with that, first, I think the UK Met Office is heavily biased towards the south of the country, specifically southern England.  Secondly it seems to be somewhat different to other forecasts I’ve seen.

The various forecasting groups, UK Met Office, European and US all use models that try to match previous weather with trends to predict what will happen months down the line. The variations that happen in a chaotic system, which is what the atmosphere is, mean that very small changes that happen today may have a huge effect further on in time, or conversly a competing change may cancel it totally.  This means that, past a time limit of just 3 days, variations mean that a standard weather forecast is, unless there are very strong trends, just a guess.  So here we are looking at 3 months!!

So let’s rewind a little and assume that the forecast models can manage to predict what will happen, it becomes obvious that there are significant differences because below is a graphic from the excellent Netweather web site

augusttemp

Now admitted, the temperature difference for Aug are small, but the graphic says that the average temperature for the whole country will be below average, whereas rain for august, from the same site is forecast to vary between a low of 80% for Northern Scotland to a high of in excess of 120% for Southern England.  Doesn’t look like too many BBQ’s for me

August Rain

August Rain

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