Long range weather forecast for the Western Isles – 8th 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 Monday 12th April until Thursday 22nd 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 12th April

Some model disagreements for next Monday. The EC has low out to the Western Isles and this would feed in bands of rain across the Western Isles which would be heavy at times with blustery winds and staying on the mild side. The GFS also has low pressure to our West but it keeps the rain further out to sea. A few scattered showers across the islands but plenty of sunshine with brisk winds.

Tuesday 13th April

Again further differences for next Tuesday. The EC builds high pressure to the South West of the UK. Low pressure sits to the North West of the UK. Suggesting we will spells of rain which will be heavy at times with blustery winds. The GFS builds high pressure across the UK and this would bring fine dry and settled weather across the Western Isles with sunshine and cloud with light winds.

Wednesday 14th April

Further uncertainties and differences in the forecast for next Wednesday. The EC sends a low pressure across the UK and this would feed rain across the islands. Heavy rain and rain throughout the day. Strong blustery winds. The GFS on the other hand keeps things settled fine and dry with high pressure across the UK. Dry for the islands and feeling warm.

Thursday 15th April

Again model differences where the EC slowly moves the low pressure away from the Western isles. Spells of rain heavy at times but becoming drier and brighter later with sunshine. High pressure attempts to build in. Then an area of low pressure moves into Ireland later in the day. The GFS has little or no change with high pressure firmly in charge with fine dry and settled weather feeling warm as well.

Friday 17th April

Some good model agreement finally both the GFS and EC have high pressure across the UK with fine dry and sunny weather. Feeling warmer with breezy conditions. Rain and stronger winds moving across Ireland and North West England.

Saturday 18th April

Again good model agreement for next Saturday with the EC suggesting high pressure across the Western Isles. A few patchy showers but mainly staying fine and dry. Light wins. The GFS has low pressure to the South West with high pressure across Scotland. Staying fine dry and settled across the Western Isles with plenty of sunshine.

19th, 20th, 21st and 22 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 high pressure will stay firmly in charge of the weather across the UK. Plenty of blue skies and snshine and light winds. Brisk winds.

Featured photo  – Vatersay Bay taken by Floraidh Macleod

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