Looking ahead to this weekend and next week the weather forecasting models now are in good agreement that Ireland will see the flood gates to the east opening with a very cold airmass flowing out of Scandinavia giving very cold temperatures by night and sub zero temperatures also by day in places especially from the early stages of next week onwards.

This is something Donegal Weather Channel warned about back in January when a major (SSW) sudden stratospheric warming event occurred in the Stratosphere with the Polar Vortex been displaced allowing some parts of the world to enter into a very cold period of weather. Some times the response from a SSW can be as quick but sometimes it can also be delayed over the couple of weeks which is why I did say something very cold could develop in February.

The very cold or severe spell of weather we are set to see next week will be the coldest of the season so far and probably the coldest spell of weather we will have seen since late February & early March 2018 when Ireland was effected by a sudden stratospheric warming event at the start of February 2018 that year but back then the response was much quicker from the stratosphere into the troposphere which is the lowest layer of Earth's atmosphere with cold temperatures filtering down much quicker with a reversal of the zonal winds to a easterly flow and colder weather weather developed. The troposphere is the layer of the atmosphere where are weather is made and is the reason why we see impacts at ground level when colder air makes it all the way down to that layer of the atmosphere. The difference between the the cold air in 2018 and next week is were it originates from. The beast from the east at the End of February 2018 the air was colder coming from Siberia but next week colder air will come from Scandinavia which will still be very cold.

You also will see above I mention a very cold spell or Severe cold spell the reason for this is due to the different model outputs with them all going for a very cold spell of weather with some prolonging next weeks spell of weather to a more severe event

Looking at the model outputs now from the ECMWF, GFS, UK MET OFFICE & GEM models the all show very cold upper air temperatures feeding in across Ireland at the end of this weekend.

Charts below are from the models mentioned above which shows the upper air temperatures at 1500 kilometers above the surface at 850hPa.

GFS MODEL ( American model)

This morning GFS run shows very cold upper air temperatures moving down over Ireland over the weekend with upper air temperatures across Ireland on Sunday evening and night as low as -10C to -12C which would be cold enough for any precipitation to fall as snow.

ECMWF MODEL (European model)

The Ecmwf model also brings in them colder upper air temperatures across Ireland on Sunday night into Next week and is in good agreement with the GFS model above up until early next week at least until Wednesday with upper air temperatures of -8C to -10C across Ireland.

THE UKMO MODEL (UK model)

The UK Met Office forecasting model also shows them colder upper air temperatures flooding in across Ireland Sunday night and early next week with upper air temperatures between -8C to -10C. So this model is also in good agreement with the ECMWF & GFS up until midweek next week.

GEM MODEL (Canadian model)

The Canadian model also is in good agreement with the others above the GFS, ECMWF & UKMO bringing in much colder upper temperatures on Sunday and early next week.

From mid week onwards there is some uncertainty on how long this colder spell persists and will it develop into something more severe but my gut tells me that we will at least see this lasting into next weekend with many areas at the risk of big snowfalls near the end of next week.

SIGNIFICANT SNOWFALL RISK

As that very cold air starts to filter down across Ireland on Sunday parts of the east and north of Ireland will start to see snow showers moving in from the Irish sea and north coast giving snow accumulations. In this sort of set up these type of showers are called sea streamers which are created by the warmer sea temperatures and moisture rising into very cold air above creating cloud and in this kind of set up heavy snow showers some which give the big snowfall amounts across the east at the end of February 2018. The chart below is from the ECMWF model for Sunday night 7/02/21 into Monday morning 8/02/21 with the green indicating snowfall. On the chart we see the east of Ireland starting to receive snowfall as well as North Donegal, North Derry and coastal areas of Antrim.

As colder upper air temperatures move down across Ireland on Monday we then see the showers that are been formed across the Irish sea becoming more organized into organized bands of snowfall effecting much of the eastern half of Ireland as well as northern coastal areas of Ulster. Image below is for Monday afternoon and evening shown widespread snowfall across Leinster, east & north Ulster as them bands of snow feed in one after another. This set up looks set to remain for next Tuesday and Wednesday at least with some significant snowfall amounts across Leinster, east & north Ulster.

Some of these showers may work there way into inland areas of east Connacht, east Munster and west Ulster giving some smaller accumulations but much of the western half of Ireland looks set to remain very cold and mostly dry.

SNOWFALL ACCUMULATIONS

From a period of Sunday night into Wednesday some significant snowfall accumulations look possible across the eastern half of Ireland with amount of between 15cm to 25cm building up in this time periods and due to the cold temperatures there will be no thaw. Higher ground areas of the eastern half of Ireland will be no go areas with some higher parts across Wicklow and Dublin receiving up to 40cm.

The latest ECMWF model also show snowfall accumulations across parts of North Donegal, North Derry and Antrim accumulating between 5cm to 15cm.

Chart below shows the accumulations possible by Wednesday morning

**Snowfall accumulations by Wednesday morning 10/02/212**

SURFACE LEVEL TEMPERATURES

Above we looked at the upper air temperatures and now we will look at the surface temperatures which will also be very cold and well below average later this week around 1C to 3C below average and by next week around 5C below average in places.

Temperatures next week by day will range between -1C to 3C with some areas not rising above freezing and frost and icy conditions persisting in places by especially across areas that see snowfall.

Night time lows could fall down to -4C to -9C with the coldest temperatures across the western half of Ireland. Severe frosts and icy conditions nationwide

SEVERE WINDCHILL FACTOR - MODERATE TO STRONG EASTERLY WINDS

A severe Windchill is also expected next week with a Windchill factor possibly as low as -9C to -12C by night and day.

Northeasterly to easterly winds will be Moderate to strong at times also over the week

OUTLOOK FOR LATER NEXT WEEK 10TH FEBRUARY 2021 ONWARDS

The Latest ECMWF model today and yesterday shows the risk of low pressure systems moving northwards across Ireland later in the week and with the very cold upper air temperatures giving the risk of a widespread snowfall event. As a example the latest ECMWF model this morning shows Later Wednesday into Thursday a area of low pressure moving northwards across Ireland with a snow storm like storm Emma back in 2018. Charts below show this.

Other model also show this idea but as I mentioned above at this range from later Wednesday next week its to early to say what will happen but the solution the ECMWF shows could very easily occur giving a more widespread snowfall event.

The Ecmwf model keeps the colder upper air temperatures across Ireland into the weekend with the coldest weather across Ulster, Connacht and Leinster.

By the start of this weekend I think we will have a better idea how long this cold spell will last.

If models keep this trend going over the next 2 days which looks most likely we may see Met Eireann issued a weather advisory as early as Friday for the risk of very cold temperatures and significant snowfalls. From Sunday night into at least mid next week and by Friday we should have a better idea what will happen after the midweek period.

LIVE STOCK DANGERS - FARMERS

I would also like to add one final thing for famers with livestock especially over higher ground areas to be alert and keep a eye on the forecast due to the significant risk of big snowfall accumulations next week over eastern and northern counites. Low temperatures and a added wind chill factor will create very harsh conditions putting animals in danger exposed to such conditions.

Kenneth from the Donegal Weather Channel

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