Long range weather forecast for the Western Isles – 21st October 2021

Welcome to the our long range forecast for the Western Isles. This is our twice weekly update covering up to two ahead. We look at trends and patterns. Usually posted on a Thursday and Sunday.

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.

EC – Monday 25th October – Saturday 30th October

The EC is suggesting low pressure dominates our weather across the UK with rain and showers feeding across the Western Isles heavy at times with winds gusting 20 to 40 mph. Into the Tuesday a developing area of low pressure will past to the North West of the UK bringing bands of rain heavy at times across the Western isles with winds gusting gale force. For the Wednesday low pressure moves across the North West of the UK with high pressure across the South. Further rain will move across the the Western Isles heavy and persistent at times. Winds once again gusting gale force. Thursday will see improve conditions as low pressure clears away according to the EC with rain and scattered showers winds easing and some sunshine. On to the Friday a dry start across the Western Isles but an area of low pressure will form close to Ireland and bring heavy rain across the islands as the day goes on. Winds will also strengthen. Into the Saturday and high pressure builds across Scotland bringing a fine and dry day with sunshine and cloud across the Western Isles but a broad area of low pressure pushes in from South West ireland increasing the cloud later in the day.

GFS – Monday 25th October – Wednesday 3rd November

The GFS is suggesting low pressure dominates on Monday with rain and showers with heavier rain moving across the Western Isles later in the day. Winds gusting to 40 mph. Into the Tuesday further rain and showers heavy with winds gusting gale force as weather systems move past the North West and high pressure builds to the South. Into the Wednesday a deep area of low pressure could bring heavy and persistent rain across the Western isles and strong to gale force winds across the islands. For the Thursday a broad area of low pressure sits to the North West of the UK feeding rain and showers across the Western Isles this will be accompanied by blustery winds. Onto the Friday a developing area of low pressure close to Ireland will bring rain later in the day but the start of the day should be fine and dry with sunshine and cloud and a few scattered showers along with lighter winds. For the Saturday a day of sunshine and scattered showers. Breezy conditions for us in the Western Isles but the GFS shows a deep and vigours area of low pressure moving in England and Wales. The final 4 days of the time period will see low pressure dominate the first few days with strong winds and heavy rain for most of the UK and a risk of things turning colder with wintry showers for the final few days of the time period.

Thanks for reading any feedback is welcome.

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