Welcome to the our long range forecast for the Western Isles. This is our twice weekly update covering up to two ahead. We look at trends and patterns. Usually posted on a Thursday and Sunday.
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.
EC – Monday 18th October – Saturday 23rd October
So the EC is suggesting an area of low pressure will move past the UK on Monday feeding rain and showers into the Western Isles which will be heavy at times. Winds would be brisk. Into the Tuesday and again another day of sunshine and showers these would be heavy at times. A smaller and shallower area of low pressure would sit to the West of the UK. Moving onto Wednesday low pressure dominating the weather across the UK feeding further rain and showers across the Western Isles which will be heavy at times. Some sunny spells and brisk winds. More of the same for Thursday with further rain and showers feeding into the Western Isles heavy at times as low pressure stays close to the UK. Into Friday and the low pressure moves across Scotland feeds further rain and showers across the Western Isles. Some sunny spells and brisk winds. Changes happen on the Saturday with one area of low pressure moves away and showery start to the day for the Western Isles. Becoming drier and sunnier as the low pressure clears but the next area of low moves into Ireland bringing heavy rain later in the day.
GFS – Monday 18th to Wednesday 27th October
So the GFS suggests that on the Monday low pressure scoots past the Western Isles bringing bands of rain across the Western Isles heavy at times along with brisk winds. Moving into Tuesday and Wednesday and areas of low pressure will move past the UK feeding rain and showers across the Western Isles these will be heavy at times with brisk winds. Into the Thursday and the area of low pressure moves Southwards bringing rain and showers to the Western Isles and feeding colder air in from the North with showers for the Western Isles and brisk winds. A change for the Friday with high pressure building in. It would result in a fine and dry day across the Western Isles with sunshine and cloud. Winds would be light. High pressure again for the Saturday before heavy rain moves across the UK from the West later in the day pushing into the Western Isles later in the day. The final four days of the time period and the GFS is suggesting for the Sunday to Wednesday that bands of rain and showers along with brisk winds across the Western Isles with a risk of gales at times. Some dry conditions in the breaks in the rain.
Thanks for reading any feedback is welcome. Featured photo taken by Carolyn Prosser of Reef