Long range weather forecast for the Western Isles – 25th July 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 29th July until Saturday 7th August.

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 29th July

Low pressure dominates the weather on Thursday and there is good model agreement from both the EC and the GFS that areas of low pressure will move across Scotland will bring us blustery winds along with rain which will be heavy at times. Both models have the heaviest of the rain later in the day on Thursday.

Friday 30th July

Further good model support from both the EC and GFS with the low pressure system from Thursday moving into the North Sea and behind it we will see a showery airflow across the Western Isles with sunshine and showers which will be heavy at times and it would be feeling cooler. The showery airflow is expected to ease as the day goes on.

Saturday 31st July

Some slight model differences for next Saturday. The EC has a slack airflow across the UK with high pressure far to the West of the UK. For us in the Western Isles we are going to see a showery day and plenty of clouds with some sunny spells. The GFS has a slack airflow as well but less in the way of showers and more sunshine and cloud with light winds.

Sunday 1st August

Further model agreement for next Sunday with high pressure over the UK or close by to the UK keeping conditions fairly settled with sunshine and light winds for us in the Western Isles with a few scattered showers. The GFS again has more in the way of sunshine then the EC.

Monday 1st August

Some slight model differences for next Monday. The EC has high pressure to the South West of Ireland and we a cloud dominating day across the Western Isles with sunshine and scattered showers with mostly light winds. A weather system awaits to the West of the UK. The GFS has high pressure across the UK with fine dry and settled conditions across the Western Isles with some decent and prolonged sunshine. Winds would be brisk.

Tuesday 2nd August

Model differences for next Tuesday with the EC showing areas of low pressure moving into Scotland which will bring spells of rain heavy at times and increasing winds across the Western Isles. The GFS also has an area of low pressure moving into the Western isles which would bring spells of rain which would be heavy at times along with brisk winds.

3rd, 4th, 5th and 6th August

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 multiple areas of low pressure will move across the Western isles bringing further spells of rain and at times strong winds. Lots can and will change between now and then but worth keeping an eye on.

Thanks for reading todays featured photo is Seilebost taken by Louise Reid.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s