Long range weather forecast for the Western Isles – 22 September 2020.

Good morning 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 Saturday 26th September until Monday 5th October.

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. We will be using the main two computer models for this. The ECMWF which is based in Reading and the GFS which is the American based global model.

This comes from the GFS 00z run and ECMWF 00Z run. I will refer to EC to save on typing.

Saturday 26th September

There is good model agreement that suggests that Saturday will be a mainly fine dry and settled day with a mixture of sunshine and cloud with light winds and a few scattered showers. A fairly chilly day with winds from the North East.

Sunday 27th September

Some difference in the model agreement with the EC suggesting rain moving in during the evening. But most of the day is likely to be fine dry and settled with a mixture of sunshine and cloud. A chilly start to the day with a risk of frost for Lewis and Harris things can change between now and then.

Monday 28th September

Fair bit of disagreement with Monday. EC bringing in some showery rain and breezy conditions. The GFS bringings in an area of low pressure with spells of rain that will be heavy at times. Not suggested to be a deep area of low pressure.

Tuesday 29th September

Seems to be some model agreement with a day of sunshine and showers and brisk winds. Staying on the cool side.

Wednesday 30th September

Both models spin up an area of low pressure. The EC brings the area of low pressure closer to us bringing rain and windy conditions. The GFS suggests a deeper area of low pressure to our North West which would keep the worst of the winds away from us but would bring some rain.

Thursday 1st October

Again fairly good model agreement on spells of rain. Heavy at times and carrying on the unsettled theme.

2nd, 3rd, 4th and 5th October

This is well into the silly timeframe. EC doesn’t even go this far out so just the solo use of the GFS. This time frame shows a strong North Westerly flow with low pressure in the North Sea. At the end of the time frame low pressure moves in a fairly deep one but at this time range its pointless to speculate.

I will do another long range update towards the weekend.

I hope you have enjoyed.

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