Long range weather forecast for the Western Isles – 15th November 2020

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 19th November until Saturday 28th November.

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 which is based in Reading and the GFS 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 19th November

As low pressure clears away there is good model agreement that a cold airflow will set up with winds coming down from the North. With this we are likely to see some wintry showers possibly falling as snow. Greatest risk over higher ground. A lot of uncertainty as yet but this has been shown on the computer model runs for a number of days. Things are expected to stay cold but settle as the day goes on with a risk of frost and ice. Something to keep an eye on.

Friday 20th November

Again solid model agreement that after a cold start a weather system will move in off the Atlantic and with it we we will see rain and strong winds. On the leading edge of this we could see some sleet and snow again for a short time but there is a lot of uncertainty about that at this stage.

Saturday 21st November

Once again we see good model agreement that an active airflow from the West will keep things unsettled. We are going to see sunshine and showers. These again heavy and possibly wintry with brisk winds. It will still. feel cold.

Sunday 22nd November

Some model differences for next Sunday as we see a showery airflow continuing across the Western Isles. The GFS is suggesting this lasts throughout the day. However the EC brings heavier rain in later in the day as an area of low pressure moves past to our North West.

Monday 23rd November

Again some model agreement once again we are going to stay in a brisk airflow with winds coming in from the South West. Further spells of rain which would be heavy at times. Staying in the unsettled theme.

Tuesday 24th November

The unsettled theme continues across the Western Isles. The EC builds in high pressure across the Azores and we see weather systems topple around the top bringing us more strong winds and further spells of rain. The GFS keeps the unsettled theme going across the Western Isles as well and does not build in the high pressure system to the same extent.

25th, 26th, 27th and 28th November

Now this is the really long range. So take it with a large amount of salt and is the silly range. A lot of uncertainty as yet but the GFS brings in multiple areas of low pressure which would bring strong winds and rain with the hint of more wintry conditions at the end of the time period.

Thanks for reading any feedback is always welcomed.

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