Long range weather forecast for the Western Isles – 3rd December 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 Monday 7th December until Tuesday 15th December.

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.

Monday 7th December

Some good model agreement for next Monday with mainly dry and settled conditions across the Western Isles with some spells of rain at times later in the day. The EC has low pressure moving to the North East of Scotland this low 989 mb and fairly deep. The GFS has a weaker area of low pressure 993 mb with less intense.

Tuesday 8th December

Some model disagreement for next Tuesday with the EC bring the low pressure across the North of Scotland bringing blustery winds and spells of rain for the Western Isles. The GFS bring spells of showery rain with some sunny spells and high pressure building across the UK later in the day. It is expected to be a colder day.

Wednesday 9th December

Further model disagreements with next Wednesday with the EC keeping things dry and settled across the Western Isles with brisk winds. The GFS however develops an area of low pressure to the North of the Western Isles that would sink southward bringing some rain to the islands. Breezy conditions with some snow over higher ground.

Thursday 10th December

Again some significant model differences for next Thursday. The EC brings two areas of low pressure across the UK. These would bring some heavy rain across the islands. Also some strong winds as well. The GFS has low pressure across Shetland but mainly dry for the Western Isles with some scattered showers.

Friday 11th December

Some good model agreement once again with low pressure dominating across the UK with spells of rain. Heavy at times moving across the UK and the Western isles with things becoming drier to the Western Isles later. It would be a windy day across the Islands.

Saturday 12th December

Again both computer models are indicating low pressure systems across the UK which would bring spells of rain which would be heavy at times. Winds would be be brisk across the islands. The EC has low pressure over England a broad area of low pressure. The GFS keeps the low in the Atlantic and this would bring us more rain.

13th,14th, 15th and 16th December

Now this is the really long range. So take it with a large amount of salt and is the silly range. The GFS keeps further areas of low pressure moving across the UK and the Western Isles bringing more outbreaks of rain.

Thanks for reading any feedback is always welcomed.

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