High risk of very cold weather from this weekend
Following on from our update from last Friday the 29th of January when we posted about Ireland been on the Verge of seen a potentially colder period of weather at the end of this week and over the weekend confidence is now growing with all the weather models especially the main forecasting models showing a very cold east to northeasterly airflow across Ireland
The latest updated runs from the weather forecasting models today show a very cold pool of air sitting across Ireland over the early days of next week with the same set up Ireland was under at the end of February 2018. Back then the doors where left open to allow a very cold air to flood out of Siberia something models show again with a disordered polar vortex.
Over the weekend the latest outlook is for frosty weather to return to the forecast with frost for many parts of Ireland with lows of around -4C. Come next week then the coldest of the airmass looks set to extending from the east out of Siberia giving possible night Time lows of -5C to -10C for some parts with day time temperatures struggling to get over freezing. The charts below shows the latest output from the ECMWF, GFS and UK Met Office models showing the 850hPa Temperatures which is around 1.5 Kilometers above the ground with lows of - 8C -12C which would be cold enough for precipitation to fall as snowfall anywhere that receives any.
With the latest models especially the 3 above mentioned showing such strong signals and cold weather the highest risk areas for seen snowfall in this set up would be the eastern half of Ireland with sea streamer working there way in from the Irish sea. With warmer sea temperatures and colder upper air temperatures this will lead to heavy snow showers forming and giving heavy snowfalls across parts of the eastern half of Ireland. If the wind has a more northeasterly directions to it then also parts of Northern Donegal, Derry and Antrim would also be at risk of these showers also known as sea streamers.
WHAT ARE SEA STREAMERS?
Typically sea streamers snow will develop in narrow bands, sometimes called streamers. The streamers tend to align with the wind direction. They are produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water or sea water . The lower layer of air, heated up by the lake water or sea water picks up water vapor from the lake or sea and rises up through the colder air above the vapor then freezes and is deposited on the leeward downwind shores. This also is known as lake effect snow.
Below are different model outputs from 8 different weather models some which run a number of times a day. Around 14 of the 18 model outputs show something much colder next week with the best preforming forecast models also favoring a colder outcome.
If models verify over the week and continue to show such strong signals then parts of the east in particular could see some significant snowfalls next week but at this moment its to early to say if this does end up been the case and the colder weather does arrive the question then will be how long are we likely to see it last for. I do expect some further changes to the different weather model outputs over the coming days with upgrades and downgrades but at this stage the signals are strong for a very cold and possible severe spell of weather to come next week with the weather turning colder from this weekend
I will keep a eye on this over the week and updates on any further changes but the risk of colder easterly/northeasterly airflow later next week is at around 80% but I am only putting a severe colder spell at around 50% at the moment due to the timeframe been still between 120 to 150hrs away.
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Kenneth from the Donegal Weather Channel
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