Long range weather forecast for the Western Isles – 4th April 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 Thursday 8th April until Saturday 17th 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.

Thursday 8th April

Some good model agreement for next Thursday. Both the EC and GFS have low pressure move across Orkney and Shetland during the course of the day. Bringing spells of rain heavy at first with blustery winds. Behind it once again we will see cold air feeding across the Western Isles with sleet and snow showers. With gales later in the day.

Friday 9th april

Again solid model agreement. High pressure to the West and East of the UK. A cold airflow will persist bringing sleet and snow showers across the islands. These would be squally at times with some sleet mixed in. This will be carried on a blustery wind and it will be feeling cold.

Saturday 10th April

Model dissagement for next Saturday. The EC is suggesting high pressure builds to the West and a feed of showers would push down across the Western Isles these would be heavy at times and squally with blustery winds. The GFS on the other hand continues the cold air coming down from the North with sleet and snow showers. But becoming milder later with some rain. This would be accompanied by brisk winds.

Sunday 11th April

Some slight model agreement for next Monday. The EC suggests that high pressure builds across the Southern half of the UK with rain and showers moving across the Western Isles from the West it would be mild and wet. The GFS has high pressure West of Ireland but also suggests that we are going to see further spells of rain moving across the islands and mild conditions.

Monday 12th April

Good model agreement again for a week on Monday. Both the EC and GFS suggest that low pressure sits to the far North of the UK and it will bring rounds of rain and showers across the Western Isles with blustery winds. Staying on the mild side but wet.

Tuesday 13th April

Model disagreements for next Tuesday. The EC shows rain and showers for the morning. A chance some of these could be wintry at times. Then builds in high pressure across the Western Isles with some final and dry conditions. The GFS on the other hand brings further spells of rain as the area of low pressure lingers around to the North East of the Western Isles feeding in more rain and shower.

14th, 15th, 16th and 17th 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 low pressure sits to the North of the UK feeding rain and showers across the Western Isles with a chance of it turning more settled toward the end of the time period.

Featured photo – Traigh Iar, Harris, taken by Lyndsay Morrison.

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