Long range weather forecast for the Western Isles – 19th 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 – Thursday 23d September to Tuesday 28th September

So the EC is suggesting that low pressure moves to the North West of the UK with a wet and windy start to the day on Thursday in the Western Isles. Becoming drier lighter before another band of rain moves in later in they day and winds will be brisk. For the Friday the next area of low pressure moves in bringing further rain heavy at times across the Western Isles with brisk winds. Into the Saturday and low pressure sits to our North West bringing rain and showers along with brisk winds and some sunny spells. Next Sunday and low pressure slowly moves away but we still see further spells of rain and showers across the Western isles with some of these being heavy at times. Some sunny spells and winds easing. For next Monday and Tuesday a slack airflow sets up across the UK with rain and showers moving across the Western Isles winds would be mainly light. Some sunny spells.

GFS – Thursday 23rd September to the Saturday 2nd October

So the GFS is suggesting rain and showers moving across the Western Isles next Thursday as low pressure moves well to the North. Some sunny spells. Winds possibly gusting gale for a time. For Friday an a ridge of high pressure builds across the UK with sunshine and cloud for the Western Isles and brisk winds. The next area of low pressure moves in from the West later in the day which would bring some rain in from the West. For both Saturday and Sunday low pressure sits out to the West of the UK and this would feed in rain and showers to the Western Isles with brisk winds and a few sunny spells. The showers likely heavy at times. For the Monday the low pressure slowly declines away South Eastwards a broad area of low pressure so winds would not be too strong. Some showers and sunny spells. Into the Tuesday and mainly fine and dry with sunshine and cloud along with light winds for us in the Western Isles. For the Wednesday and Thursday sunshine and cloud with rain and showers moving across the islands. Friday and Saturday a long way off as yet with sunshine and cloud. Winds would be light.

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 Cuddy point taken by John J Maclennan

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