Long range weather forecast for the Western Isles – 22nd August 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 Thursday 26th August until Saturday 4th September.

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.

Thursday 26th August

Solid model agreement for next Thursday with high pressure in charge across the UK. A day of sunshine and cloud with light winds. Some mist and low cloud would be possible in the early hours.

Friday 27th August

Again solid model agreement for next Friday with both the GFS and EC showing high pressure across the UK. A day of sunshine and cloud. Some decent and prolonged sunshine. Possible wall to wall sunshine with light winds. Early morning mist and fog will be possible.

Saturday 28th August

Little change for next Saturday. The EC again has high pressure dominating across the UK. Sunshine and cloud for us in the Western Isles with some rain and showers moving into England and Wales. The GFS on the other hand keeps the UK dry with sunshine and cloud. For us in the Western Isles once again some decent and prolonged sunshine and light winds.

Sunday 29th August

Little change again for next Sunday. High pressure dominates across the UK. Light winds with sunshine and cloud for the Western Isles. Some decent and prolonged sunshine. Both the GFS and EC are in agreement on this. The EC does develop an area of low pressure far to our West but will bring increased cloud in later.

Monday 30th August

Further model agreement for a week on Monday. High pressure dominates across the UK according to the GFS and EC. The EC has a little in the more of slack conditions. So a mixture of sunshine and cloud with a risk of showers. The GFS keeps the sunshine and cloud with light winds.

Tuesday 31st August

Some model differences for a week on Tuesday. An area of low pressure moves across Northern Ireland according to the EC. For us in the Western Isles a mixture of sunshine and cloud with a few scattered showers. No change for the GFS which keeps sunshine and cloud. Some decent and prolonged sunshine with light winds.

1st, 2nd, 3rd and 4th September

Now this is the really long range. So take it with a large amount of salt and is the silly range. So the GFS is suggesting that high pressure dominates with sunshine and cloud. Light winds. Before an area of low pressure moves to the far North West which would bring increased winds and rain for the Saturday.

Thanks for reading any feedback is welcome, our featured photo comes from Barra island on Twitter.

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