Long range weather forecast for the Western Isles – 18th July 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 covering from Thursday 22nd July until Saturday 31st July.

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 22nd July

For Thursday the EC keeps high pressure across the UK. A day of sunshine and cloud for us in the Western Isles with a few scattered showers but mainly staying fine and dry with light winds once again. The GFS on the other hand keeps conditions fine dry and settled across the Western Isles with some decent and prolonged sunshine and light winds as high pressure dominates across the UK.

Friday 23rd July

There is solid model agreement for Friday. Both the EC and the GFS have an area of low pressure moving in Ireland bringing rain here. But for us in the Western Isles high pressure sticks around. The EC has more in the way of cloud. Whilst the GFS gives us more sunshine. Both are suggesting that we will see light winds. Still staying mild.

Saturday 24th July

Some slight model differences for Saturday. The EC keeps multiple areas of mainly weak low pressure across the country. This will bring spells of rain heavy at times but for us in the Western isles we are expecting to see fine dry conditions with sunshine and cloud and light winds. The GFS has low pressure system moving across the Southern half of the UK. It will be fine and dry across Northern Scotland with some decent and prolonged sunshine for us in the Western Isles with light winds.

Sunday 25th July

Again further model differences. The EC has low pressure across the UK with rounds of rain and showers moving across England and Wales. For us in the Western Isles it is expected to be fine and dry with sunshine and cloud along with light winds. The GFS suggests a slack pressure pattern with some rain and showers along with brisk winds for much of the UK for us in the Western Isles we would see brisk winds with sunshine and cloud with a few scattered showers.

Monday 26th July

More model differences of next Monday. The EC has showers across most of the UK but for us in the Western Isles the EC keeps us fine and dry with sunshine and cloud. Some decent spells of sunshine at times. Winds would be light and slack. The GFS on the other hand develops two areas of low pressure across the UK one over the Southern half and one over the Northern half this would bring s-ells of rain which would be heavy at times across the Western isles. Winds would be light. Heaver rain still and blustery winds for the Southern half of the UK.

Tuesday 27th July

Further model differences for a week on Tuesday. The EC has a mainly overcast day across the Western Isles with rain and showers. These mainly on the light side. Winds would be mainly be light and temps on the cooler side. The GFS suggest that we will see some morning showers across the Western Isles with brisk winds. But becoming fine and dry with some decent and prolonged sunshine but staying breezy.

28th, 29th, 30th and 31st July

Now this is the really long range. So take it with a large amount of salt and is the silly range. So the GFS is suggesting a few showers for the Wednesday but for the reminder of the week fine dry and sunny weather with high pressure in charge and light winds.

Our featured photo comes from Kirstie Carter with Reef beach.

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