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 10th June until Saturday 19th 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.
Thursday 10th June
Some model agreement for next Thursday. The EC brings in rain across the entire Western isles for most of the day. This rain would be heavy at times and accompanied by brisk winds which could reach gale force for a time. The GFS also has brisk winds with occasional rain and showers. Some sunny spells at times. This is caused by low pressure to our far North West.
Friday 11th June
Some good model agreement for next Friday. The EC builds high pressure across the UK with a day of sunshine and cloud and brisk winds. The GFS has morning rain but this would clear away with a day of sunshine and cloud with brisk winds and high pressure across the UK once again.
Saturday 12th June
Some model differences for next Saturday. The EC brings in further bands of rain across the Western isles and these will be heavy at times. Before clearing late evening. This will also be accompanied by brisk winds. The GFS keeps the rain further to our West. Also introducing brisk winds with a few showers but mainly fine and dry with sunshine and cloud with high pressure across the bulk of the country.
Sunday 13th June
Some further good model agreement for next Sunday. Both the EC and the GFS bring bands of rain across the Western Isles which will be heavy and at times persistant. The EC suggests that rain will occur in the morning hours. The GFS has it later in the day and this is associated with an area of low pressure to our North West whilst high pressure remains in charge the weather across the Southern half of the UK.
Monday 14th June
Some big uncertainties for next Monday. The EC sends a deep and vigorous area of low pressure past North West Scotland. If this was to verify it would bring heavy rain and strong winds across the Western Isles. The GFS on the other hand doesn’t have the area of low pressure. It would be a day of sunshine and cloud across the Western Isles with brisk winds. Scattered showers.
Tuesday 15th June
Again some model differences for next Tuesday. The EC moves that area of low pressure away that is mentioned above. Behind it we see a mixture of sunshine and showers along with brisk winds. The GFS once more builds in high pressure but it would be a rather slack airflow so a mixed bag of sunshine and showers along with breezy conditions for the Western Isles.
16th, 17th, 18th and 19th 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 staying unsettled with further areas of low pressure moving across the Western isles bringing spells of rain and showers and blustery winds across the islands.
our featured photo is Siabost taken by Alasdair Macleod
Western Isles Weather 