Long range weather forecast for the Western Isles – 17th December 2020

Good evening 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 21st December until Wednesday 30th 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 21st December

The EC suggests heavy rain moving across the Western Isles. This will clear away late evening and its wake showers with some of these to be wintry. Low pressure moves across the UK from East to West. The GFS has some showers moving across the Western Isles with some sunny spells and brisk winds.

Tuesday 22nd December

Some good model agreement for next Tuesday with some fine and dry conditions with some sunny spells. A few scattered showers. The EC develops a low pressure in South West of Ireland more strongly with rain away from the Western Isles. The GFS on the other hand has the low pressure in the Irish sea and weaker.

Wednesday 23rd December

Good model agreement sees the area of low pressure moving out towards Europe. In its wake we are going to see colder air move across the Western Isles. A mainly fine and dry day with some scattered showers and plenty of sunshine. Turning colder later with a risk of wintry showers.

Thursday 24th December.

More strong model agreement as High pressure builds across the Atlantic and conditions settle down across the Western Isles. Further cold air filters across the Western Isles. We are going to see a few showers and these will be wintry at times. Some sunny spells.

Friday 25th December

A few wintry showers during the morning on Christmas day as cold air sits across the Islands. We are going to see a band of rain move across the Islands later in the day according to both the GFS and EC. This would initially bring snow before quickly turning to rain and blustery winds.

Saturday 26th December

Again good model agreement for Boxing day with brisk winds across the Western Isles. It will be wet with rain moving across the entire Western Isles. This will be heavy for most. The EC is showing lighter winds then the GFS which will be gale force winds. Still feeling cold in the North Westerly winds.

27th, 28th, 29th and 30th December

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 suggests that we are going to see a cold wintry days for the 27th and 28th December. Turning to rain and showers for 29th and 30th and high pressure builds in for later in the period.

Thanks for reading any feedback is always welcomed.

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