Northern Ireland becomes winter wonderland but severe weather warnings still in place
Northern Ireland is bracing itself for more travel disruption this weekend as the Met Office issued a series of severe weather warnings.
Last night saw a small but vigorous area of low pressure sweeping south through the Irish Sea, bringing gusts of up to 70mph, particularly in exposed areas.
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Meanwhile a cold northwesterly flow was expected to continue feeding heavy showers into Northern Ireland, bringing snowfall of 1-3cm at low levels and 5-10cm on higher ground.
More snow showers are expected across parts of Northern Ireland from tomorrow afternoon and through to Sunday, leading to some locally large accumulations. As these will be associated with strong winds, drifting and temporary blizzard conditions are likely, the Met Office said.
"A very cold airmass will continue to spread southwards from Scotland and Northern Ireland across the remainder of the UK on Sunday accompanied by strong winds," a spokesman said.
"Frequent showers are likely to form in this airmass, primarily affecting northern parts of Scotland and Northern Ireland. With the cold air, snow is likely to accumulate even to low levels wherever showers affect.
"There is the potential for disruption throughout this period due to the accumulating snow and ice but also with temporary blizzard conditions leading to very difficult driving conditions."
Yesterday, 139 schools across Northern Ireland closed because of the challenging conditions.
A number of Translink Metro bus services were affected and some roads in rural areas and on high ground were impassable. The weather disruption was partly caused by "thundersnow storms", where the rain is replaced by snow.
A spokesman for weather company MeteoGroup said the phenomenon of thundersnow was quite rare.
"It is caused in the same way thunder and lightning are triggered during the summer, when a pocket of warm air at ground level rises and collides with the colder air above it," he said.
"Even though temperatures in the UK are, in places, a little over freezing, the air above it is still significantly cooler.
"In the summer, this process creates heavy rain showers and lightning storms. In the cooler winter, the country is pelted with snow instead."
Ideal conditions for thundersnow are a very cold Arctic airmass and relatively warm seas.
"With the strong wind tracking from the north-west, these were the right conditions for thundersnow to occur," the forecaster said.
The snow contained within the thunderstorm acts to dampen the sound of the thunder and while the thunder from a typical storm might be heard many miles away, the thunder during a thundersnow event will only be heard if a person is within two to three miles of the lightning, the Met Office said.
When thundersnow occurs at night, the lightning seems brighter - this is because the lightning reflects off the snowflakes.