Long range weather forecast for the Western Isles – 23rd September 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 27th September to Saturday 2nd October

The EC is suggesting for Monday low pressure sits to the North West of the UK. With brisk winds with showers. For us in the Western Isles we are going to see heavy overnight rain clearing away with a ay of sunshine and showers these would be heavy at times with brisk winds possibly reaching gale force for a time. Into Tuesday low pressure moves across the Southern half of the UK and low pressure to the North West. For us in the Western Isles we are going to see brisk winds with frequent showers and some sunny spells. Moving on to the Wednesday low pressure dominates the UK weather with further heavy rain for the start of the day for the Western Isles and then rain and showers. Some sunny spells in between. Brisk winds. For Thursday a ride of high pressure builds in across the UK but still more showers for the Western Isles with some sunshine in between along a brisk wind. For next Friday and a long way off the EC is suggesting that a deep area of low pressure moves to the North West of the UK this would be strong winds and even severe gales to the Western Isles with heavy and persistent rain. A long way off as yet but worth keeping an eye on. Into the final day of this time period the Saturday we are likely to see the area of low pressure hanging around the North West of the UK feeding further showers and blustery winds across Western Isles.

GFS – Monday 27th September to Wednesday 6th October

The GFS is suggesting that low pressure will sit to the far North West and bring rain and showers across the Western isles which will be heavy at times during the Monday. Into the Tuesday we will see rain and showers that will be heavy at times becoming drier later with increasing amounts of sunshine. Winds of 20 to 40 mph. It the Wednesday and ridge of high pressure would build across the UK for us in the Western Isles it would be a mainly fine and dry day with sunshine and cloud. Colder with temps in single figures to start to the day. Some light rain and drizzle. Winds would be light. Into the Thursday and the next area of low pressure moves in. This would bring some rain and showers which again would be heavy at times. Winds would remain mostly light. For both the Saturday and Sunday conditions would be mainly fine and dry with sunshine and cloud. Feeling cooler with some decent and prolonged sunshine as high pressure dominates. However late on Saturday winds would increase with rain moving in and it would become heavy at times. Onto the Sunday and low pressure sits to the North West and would bring rain and showers to the UK. These would be heavy at times across the Western Isles with brisk winds. For the Monday and Tuesday mainly fine and dry with sunshine and cloud light winds before move rain moves in for the Wednesday.

A lot of uncertainty with the long range forecasts due to activity in the tropics.

Thanks for reading any feedback is welcome, our featured photo comes from Gary Ford Benbecula

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