The weather is turning much more unsettled this week as colder air spreads in across the country, with the potential for some disruptive snow across many parts as well as the additional hazards of ice, strong winds and lightning.
By this afternoon colder air will be in place meaning that showers will turn increasingly wintry, these falling as snow to nearly all levels by the early hours of Tuesday, although perhaps as sleet and hail near the coasts. As the showers will push in from the west they will be more frequent across western and central areas, however the strong winds will still allow quite a few showers to reach eastern areas, with sheltered drier conditions only really offered to eastern Angus and Aberdeenshire which remain out of the warning area.
Due to the showery nature there will be variations in the snow amounts; at low levels accumulations of the order of 2-8cm will be typical through to Wednesday with individual showers tending to run through pretty quickly, however these amounts could build up quickly in places where heavier showers follow in quick succession. The largest accumulations will be above 200m where 10-20cm is likely to build up. The heavier showers will also be accompanied by lightning and hail, particularly across the north and west which bring an increased risk of power disruption here. Although similarly some places could miss the worst of the showers and see fewer accumulations, more likely in the east.
There has been some uncertainty in the level of impacts that the snowfall is expected to bring, and due to the varying snow amounts expected across the UK the previous warning has been split into different areas, however for Scotland the details are as follows:
• A yellow warning for snow and ice is valid from 1500 until 1100 on Wednesday morning across all of Scotland except for eastern Angus and Aberdeenshire. This is a Low likelihood of Medium impacts, however the impacts are likely to be lower this evening as the coldest air does not set in until early Tuesday. Transport routes and services are likely to be affected with longer journey times expected, as well as potential disruption to power supplies from frequent lightning strikes, the combination of strong winds also brings the possibility of temporary blizzard conditions and drifting of lying snow, particularly over higher ground.
• The wintry showers then become slightly less frequent and more confined to western areas during Wednesday afternoon and evening; however it will remain cold with the likelihood of ice continuing, but the lightning risk does slowly reduce.
• Later on Wednesday night and during Thursday a band of rain, sleet and snow will spread from the southwest bringing the risk of a more persistent spell of snow to some areas where this runs up against the colder air, however milder air may reach southern parts to bring a spell of rain and snow melt here. The confidence on the detail of this system is lower with uncertainty on the areas affected and the timings. However a yellow warning for snow will be issued to cover much of Scotland from 1800 on Wednesday until 0900 on Thursday and is assessed as a Low likelihood of Medium impacts to highlight the risk of a further 3-8cm quite widely, with the potential for 20cm over higher ground.
Additionally, during Thursday an area of low pressure will run across the UK to bring much windier spell for some parts, and a yellow wind warning will be issued which is currently assessed as a Low likelihood of Medium impacts. This highlights the potential for gusts of 60-70mph across central and southern Scotland, and a small chance of gusts of 80mph across more exposed coastal areas and higher ground, more especially in the south. The location of the core of the very strongest winds is still uncertain, which will influence the expected impacts. At this stage this is not a named storm but is being monitored very closely and updates will be issued through the week.
As usual, the full details of the warnings can be found at http://www.metoffice.gov.uk/public/weather/warnings/ .
Some indication of the impacts which might be expected can be found at http://www.metoffice.gov.uk/g…/weather/severe-weather-advice .
Health, Safety and Wellbeing Manager
Perth & Kinross Council