Long range weather forecast for the Western Isles – 18th October 2020

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 coving from Thursday 22nd October until Saturday 31st October.

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 which is based in Reading and the GFS 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 22nd October

Good model agreement with regards to Thursday. After a wet start to the week Thursday is expected to be a more settled. High pressure in charge. Rain moving in much later in the day. Overcast day with mainly light winds with stronger winds into the late evening. Its expected to be a cooler day.

Friday 23rd October

Again good model agreement with showers and blustery winds. Brisk winds with a strong South Westerly airflow. Some sunshine. Temps in low double figures and an area of low pressure building out West.

Saturday 24th October

There is some computer model agreement about a deep area of low pressure moving to the North West of Scotland. The GFS brings the low pressure closer to the Western Isles then the EC and would see strong winds gusting 40 to 50 mph with some hints of 60 to 70 mph for the Uists and Barra. This is a LONG way off yet and worth keeping an eye on at this stage. The EC suggests the low would be further West and thus reducing this risk of us seeing stronger winds. So at this stage we are again looking at trends and to see if computer models continue to show this area of low pressure forming and bringing it close to us. I will keep an eye on it closely and keep you updated if required.

Sunday 25th October

Good model agreement that would suggest that the area of low pressure would move away. The GFS suggests that we would see more in the way of rain and breezy conditions. The EC suggests less in the way of rain. Mainly high pressure across the UK.

Monday 26th October

Some model disagreement for the 26th October. The GFS suggests strong winds with heavy rain moving into the Western Isles. Winds gusting above 40 mph. The EC suggests brisk winds with high pressure across the UK but keeping things dry across the Western Isles.

Tuesday 27th October

Again more model disagreement the GFS suggests more of an unsettled airflow with brisk winds and more in the way of rain. The EC again suggest brisk winds and dry conditions with high pressure across the UK.

28th, 29th, 30th and 31st October

Now this really the long range. So really is take it with a large amount of salt and is the silly range. At this long range the GFS suggests an unsettled theme for the Western Isles. It also shows a deep area of low pressure across Ireland and into England and then South East Scotland. Again a long way off yet.

Thanks for reading any feedback is always welcomed.

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