Long range weather forecast for the Western Isles – 25th March 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 coving from Monday 29th March until Wednesday 7th April.

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.

Monday 29th March

Some disagreements for next Monday between the two computer models. The EC has a low pressure system bringing spells of rain which would be heavy at times. Some strong winds as well associated with this weather system. The GFS brings strong winds across the Western Isles gusting 50 to 60 mph. The GFS keeps conditions more settled with some mainly light rain and drizzle. The cloud would dominate with an area of low pressure moving into Ireland.

Tuesday 30th March

Some good model agreement for next Tuesday from both the EC and the GFS. Suggesting that fairly settled conditions across the islands with a mixture of sunshine and cloud. Winds would decrease as well for the first time in the best part of a week. Turning a little milder as well with temps getting into double figures. Also good model agreement with rain across England, Wales and Ireland.

Wednesday 31st March

Some model differences again for next Wednesday. Firstly the EC suggests that some rain will move down from the North and this will be heavy at times. This would be associated with an area of low pressure far to our North. It would also bring in breezy conditions. The GFS builds in an area of high pressure across the UK. Things would settle down across the Western isles with sunshine and cloud along with lighter winds.

Thursday 1st April

Some model differences again for a week on Thursday. Now the EC brings down the area of low pressure from the North down the North Sea. This would bring cold winds with rain sleet and snow showers across the islands. Some strong winds area also possible. The GFS on the other hand keeps high pressure mainly in charge. The low pressure sits over Shetland and would possibly bring some lighter rain to the islands. Winds will be coming down from the North so again colder airflow.

Friday 2nd April

Now some good model agreement between both the GFS and the EC with high pressure to our West and East this would help to drag cold air from the North which would bring some rain sleet and snow showers across the islands. It would be accompanied with some cold air. Winds will be brisk.

Saturday 3rd April

Again some slight model differences for next Saturday. The EC calms the weather down and kills off the cold airflow across the islands. Some wintry showers early in the day. Winds easing. Now the GFS also builds in high pressure but winds coming in from the North East and this would be near galeforce for a time. Rain and wintry showers across the rest of the UK.

4th, 5th, 6th and 7th April.

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 it suggests that we are going to see high pressure building in with fine and dry conditions. Plenty of sunshine and staying fairly breezy at times.

Thanks for reading any feedback is always welcomed.

Featured photo – Eoligarry Jetty by Mairi Mackenzie

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