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 Monday 14th June until Wednesday 23rd June
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.
Monday 14th June
Some good model agreement for next Monday. High pressure sits across the Southern half of the UK. Both the GFS and EC agree that low pressure moves across the North of Scotland. This would bring brisk winds with rain and showers across the Western Isles with some decent spells of sunshine in the breaks in the cloud.
Tuesday 15th June
Again further good model agreement for next Tuesday. The GFS and EC both show high pressure over the UK with a dry start day across the UK with low pressure moving in from the West. This would bring spells of rain and these will be heavy at times for us in the Western Isles. We will see winds reaching gale force once again gusting 40 to 50 mph.
Wednesday 16th June
Further good model agreement for next Wednesday. High pressure builds across the UK but Scotland effected by a brisk airflow. The above mentioned low pressure system slowly moves away. Rain and showers with sunny spells and brisk winds for the Western Isles. The EC has the low pressure system moving away quicker then the GFS. This would mean the winds ease a little slower.
Thursday 17th June
Some slight model differences for next Thursday. The EC builds high pressure back across Scotland and we would see a day of rain and scattered showers across the Western isles with sunshine and cloud. The winds finally easing. Some sunshine but still plenty of cloud. The GFS keeps the low pressure to our North and this feeds in more rain and showers. A lot less weaker than in previous days and not as strong winds.
Friday 18th June
Further model agreement with the both the GFS and EC suggesting that high pressure will move out into the North Sea and more weather fronts moving in from the West bringing in rain and showers across the Western Isles again. The EC suggests more in the way of cloud then GFS which has more sunshine.
Saturday 19th June
Big model differences for a week on Saturday. The EC brings an area of low pressure into the Western Isles with brisk winds and spells of rain which would be heavy. The GFS builds the low pressure into Ireland and South West england with high pressure building over Scotland and plenty of sunshine and scattered showers.
20th, 21st, 22nd and 23rd June
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 things settled a little across the Western isles with sunshine and cloud. But areas of low pressure move into the UK.
Featured photo from Stornoway by Alison Stewart