Long range weather forecast for the Western Isles – 7th March 2021

Good afternoon 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 Thursday 11th March until Saturday 20th March.

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.

Thursday 11th March

Some slight model differences for next Thursday. Both models have a brisk airflow across the Western Isles. The EC has rain and showers moving across the islands. These would be squally and wintry at times. A small area of low pressure sinks across the Western Isles during the middle of the day. This airflow covers most of the UK (see image below). The GFS has the brisk airflow again across the Western Isles with rain and showers. A small area of low pressure moves across North of Scotland which will introduce strong winds gusting 50 to 60 mph. Strongest of this for Uist and Barra.

The midday chat for the EC next Thursday.

Friday 12th March

The EC continues with the strong airflow of rain and wintry showers moving across the islands. These will be heavy at times with some sunny spells. This will maintain brisk winds. The EC also develops a low pressure system to our South West later in the day which will bring some heavier rain to Uist and Barra. The GFS has a brisk North Westerly airflow with rain and squally showers these occasionally heavy at times. Some sunny spells it would feel colder in the wind chill.

The midday chart for the 12th March

Saturday 13th March

The EC for next Saturday brings an area of low pressure across the Western Isles earlier in the day with blustery winds with rain and wintry showers. A slight chance of some snow at this stage but worth keeping an eye on. The GFS has low pressure over Shetland for next Saturday with rain showers moving across the islands. A brief ride of high pressure builds in for the afternoon but the next area of low pressure builds out to the South West this will send a band of rain across the Western Isles bringing heavy rain to Uist and Barra.

6am next Saturday from the EC model

Sunday 14th March

Next Sunday again there are model differences with the EC keeping an area low pressure close to the Western isles with rain and showers to start the day but the low pressure declines away with high pressure building in. The rain and showers ease and the wind starts to calm down. The GFS keeps an area of low pressure close to the Western Isles during the entire day a slow moving area of low pressure. This will bring spells of rain and showers. We will see brisk winds across the Western Isles. A deep area of low pressure is expected to move across the UK during the afternoon bringing rain and blustery winds.

Monday 15th March

Some further model differences for next Monday. The EC has an area of low pressure moving close to the Western Isles which would bring brisk winds. Some heavy morning rain with showers for the afternoon and evening. The GFS has a showery start to the day but high pressure builds in across the UK this introduces drier and more settled weather for the Western Isles with sunshine and cloud. Lighter winds but coming down from the North staying on the cooler side.

The midnight GFS for the 16th March

Tuesday 16th March

Some good model agreement for next Tuesday with high pressure building across the UK. The EC has high pressure sitting across the islands. A cold airflow with some scattered showers. Sunshine and cloud. Winds easing. The GFS has high pressure again across the Western Isles but brings a declining weather front Northwards towards the Western Isles which would bring some rain and showers later into Uist and Barra later in the day before clearing away. sunshine and cloud before the rain arrives.

The middy GFS chart for the 16th March

17th, 18th, 19th and 20th March

Now this is the really long range. So take it with a large amount of salt and is the silly range. So with the GFS it suggests we are going to see a more settled period with high pressure dominating some rain possible for the end of the time period.

Thanks for reading any feedback is always welcomed.

all the charts used in this blog post can be found here https://wxcharts.com/?panel=default&model=ecmwf,ecmwf,ecmwf,ecmwf&region=uk&chart=overview,overview,wind10mmph,snowdepth&run=00&step=132&plottype=10&lat=58.208&lon=-6.388&skewtstep=0

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