Long range weather forecast for the Western Isles – 30th 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 4th October – Saturday 9th October

So the EC is suggesting that an area of low pressure will move across Ireland into the UK. For us in the Western Isles we will see rain and showers. Winds will ease as the day goes on as low pressure clears away Northwards. Into the Tuesday and the low pressure moves across the UK for us in the Western Isles we are going to see rain and showers with some sunny spells. Winds will be brisk. Into the Wednesday we are going to see a brief ridge of high pressure build across the UK. But the next weather system moves into Ireland later in the day. For us in the Western Isles a largely fine and dry day with sunshine and cloud along with a scattering of showers. Into Thursday and a deep area of low pressure runs to the West of the UK that would bring strong winds and heavy rain across the Western Isles. Friday low pressure system moves past the Western Isles with further rain becoming drier later with strong winds. Into the Saturday the next area of low pressure moves in bringing further spells of rain and later in the day strengthening winds.

GFS – Monday 4th October – Wednesday 13th October

The GFS is suggesting that an area of low pressure will move into Ireland and for us in the Western Isles we are going to see rain and showers becoming drier and brighter later. Into the Tuesday the low pressure slowly moves across the UK. For us in the Western Isles we would spells of rain heavy at times with brisk winds gusting to gale force. Into the Wednesday we are going to see an area of low pressure moving across the UK with rain and showers for the Western isles but these will clear away as the day goes on. Thursday low pressure clears away with a ridge of high pressure builds in. For us in the Western Isles we would see fine and dry conditions with sunshine. Winds easing. For the Friday and Saturday high pressure dominates with plenty of sunshine and light winds across the UK with light winds. Including us in the Western Isles. For the final four days of the time period the Sunday, Monday and Tuesday high pressure continues to dominate with sunshine and cloud but an area of low pressure with rain and stronger winds 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. Featured photo taken by Amy Cox.

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