Long range weather forecast for the Western Isles – 6th May 2021

Good afternoon and welcome to our long range forecast. This is posted either once or twice a week covering from 4 days ahead to 10 days ahead. In this update covering from Monday 10th May until Wednesday 19th May

Please note there is not a lot of accuracy for this kind of time frame. Anything beyond 4/5 days out becomes really difficult and subject to change so we will be looking at trends. Mainly take with a large vat of salt. We will be using the main two computer models for this. The ECMWF ( European Centre for medium range weather forecasts) which is based in Reading and the GFS (Global forecasting system) which is the American based global model.

This comes from the GFS 06z run and ECMWF 00Z run. I will refer to EC to save on typing.

Monday 10th May

Both the EC and the GFS have low pressure over Ireland which will have dominated the weather across the UK over the previous weekend. In the Western Isles we are going to see spells of rain which will be heavy at times. Some sunny spells with brisk winds. It will be cloud dominated and feeling milde then we have seen of late.

Tuesday 11th may

Some model differences for next Tuesday. The EC moves the low pressure away from Ireland into Scotland and away from the West coast. We would see spells of rain which would be heavy at times. Brisk winds. This rain would be expected to clear away as the day goes on. The GFS moves the low pressure southwards across Southern England. We would see morning rain across the islands but this would clear away to mainly fine dry and settled conditions with sunshine as high pressure builds in.

Wednesday 12th May

Again further model differences. The EC brings in low pressure across the UK. We will see brisk winds and spells of rain which would be heavy at times. The GFS keeps conditions much more settled across the UK. A mainly fine and dry weather across the UK. A mixture of sunshine and cloud with light winds. A few scattered showers.

Thursday 13th May

Again further model differences for next Thursday. The EC keeps weather systems across the central half of Scotland. some rain and showers moving into the Western Isles this would be accompanied by brisk winds. The GFS has low pressure over Europe and this moves across England and Wales this would bring in heavy rain however it weakens across the country. For us in the Western Isles we would see fine and dry settled weather conditions with sunshine and cloud it would be breezy.

Friday 14th May

Some good model agreement for next Friday. High pressure builds across the UK and both the EC and GFS have good model agreement with sunshine and cloud. Light winds. Some decent and prolonged sunshine at times. The GFS does suggest some showers building into the late evening.

Saturday 15th May

Some slight model disagreements for next Saturday. The EC has the high pressure breaking down. A day of sunshine and showers these would be heavy at times. Some decent spells of sunshine in between and light winds. The GFS has things mainly fine dry and settled with light winds. But some rain and showers pushing across the islands later in the day.

16th, 17th, 18th and 19th

Now this is the really long range. So take it with a large amount of salt and is the silly range. So with the GFS it suggests that conditions will stay unsettled with further spells of rain and blustery winds.

featured photo – Stenish – Susan O’Briain

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