Sryan Bruen

Jul 6, 201815 min read

Beast from the East (Late February/early March) 2018 analysis

Updated: Feb 18, 2019

Introduction

The period February 26 to March 3 2018 was an event that brought widespread heavy snowfalls to the UK and Ireland including a 1 in 30 year snowstorm named Storm Emma as well as very low daytime temperatures breaking records for some in a bitter easterly airstream with air originating all the way from Siberia. These were the snowiest conditions in the countries for the majority since January 1982 whilst the coldest since December 2010. The period was dubbed the 'Beast From The East' by people and the media.

The event was primarily caused by a phenomena called sudden stratospheric warming in the second week of February 2018. There's also some signs that suggest it was caused by the solar cycle being close to solar minimum with solar activity plunging and so many spotless days on the sun. Historically, many of our cold events occur around, at or just after solar minimum.

I will guide you through everything to know about this event within this post or article including impacts, science and statistics.

Sudden stratospheric warming

A sudden stratospheric warming is a phenomena where the stratospheric temperatures rise by a very large amount in a short period of time like a couple of days. In a typical Winter, several minor warming events in the stratosphere tend to occur but sometimes, you can get a major warming event here which does not have a pattern or sequence to foretell us when we can expect one. Major warming events have occurred in multiple consecutive years such as 2006 to 2010 but there have been multiple consecutive years without one too such as 1992 to 1998. The contrasts between orography (the study of the formation of mountains) and land sea temperatures cause long Rossby waves in the troposphere (the layer of the atmosphere where weather takes place). The Rossby waves travel upward to the stratosphere and dissipate here which causes the zonal winds to decelerate and warming of the Arctic occurs.

A major warming event within the stratosphere can either displace, split or obliterate the Polar Vortex. Displacing involves the Polar Vortex going to another location where it would not normally be. Usually, the Polar Vortex lies over the Arctic Circle disallowing cold from filtering down into the mid-latitudes. A split involves the Polar Vortex dividing into two or more vortices with each being in a different location. An obliteration involves the Polar Vortex being non-existent in the stratosphere where the layer is just warm all around with little to no colder than average anomalies being seen.

Canadian Warming events can occur too. These involve the dramatic rises in stratospheric temperature to occur over Canada rather than the Arctic itself. These kind of stratospheric events tend to take place within the period from mid November to early December but as seen from 2018, they can take place outside of this period.

It takes minimum 9-14 days (approximately 2 weeks) for a tropospheric response from the stratospheric warming to take place usually but can take up to 2 months. For example, the February 1981 SSW was followed by a cold end to April with a snowstorm across England or the January/February 1963 SSW made the 1962-63 severely cold Winter more prolonged into February. It's difficult to say when this response occurs exactly and it's also difficult to say when the effects run out of power because the effects can happen multiple times through the Winter and early Spring season such as in March 2013 following the January 2013 SSW when a cold spell took place from March 10th to 13th with a brief milder shot on the 15th into the 16th. However, another cold spell happened afterwards lasting to the 7th April. It is therefore very important we look out for changes in our usual zonal pattern following a SSW event.

With all the explanation of what a sudden stratospheric warming event is behind us, let's talk about the February 2018 SSW event or should I say, events because remarkably, two SSW events took place during the month.

On 9 February 2018, two pools of warmer than average temperatures at 10hPa in the stratosphere appeared with one to the southwest of Greenland and the other to the east of Russia. These combined with one another by the latter part of the 10th causing the Polar Vortex to split with one going over the northwest of Canada and the other to the east of Europe. By the 12th and 13th, temperatures in the stratosphere rose by at least +40°C with the pool of warm anomalies to the west of Greenland rising to around -8°C which is very warm for the stratosphere. These anomalies gradually cooled down somewhat for a few days before another rise took place over Canada on the 17th February. The temperatures here rose even further than the previous warming event mentioned above rising up to a balmy -4°C. The first major warming event was a Polar Vortex split which in of itself was unusual because a split has occurred very few times before, two examples of which were January 1985 and January/February 1991. January 1985 was far similar to 2018's one than 1991 and that was followed by a very cold and snowy spell in the middle of the month two weeks after the event had initially occurred. This gave us an indication that something was down the line for our weather after up to that point what had been overall a rather average Winter temperature wise with some cold and mild fluctuations. The second major warming event was a Canadian Warming which has never occurred in February since stratospheric records began in 1951 so was very unusual to see and there was no historical occurrence to base it on what we could expect following it, it had to be nowcasted. As time got closer, it was revealed that the zonal winds reversed a second time which is likely caused by this Canadian Warming but of course with nature, you'll never get a true answer, we can only theorise. The stratosphere took its time for temperatures to go back to average and in fact, we had to wait 'til mid-March for this to happen at 30hPa so the stratosphere was severely disrupted for a very long time meaning the Spring pattern in the Northern Hemisphere was to have a long delay. Zonal wind speeds had reversed to nearly -40 m/s around mid-February and again for a second time near the end of the month. At this time of year, the zonal wind speeds should be around 20 to 30 m/s so this was of huge abnormality. The below chart showing the mean zonal wind speeds at 10hPa in the stratosphere from June 2017 to May 2018 courtesy of Hannah A. Attard reveals just how extreme the zonal wind reversions were - see the huge downward spikes in February. I'd also like to highlight the downward spike in mid-March on the chart. This was followed by the Son of the Beast from 17-19 March which brought more unseasonably cold conditions and heavy snowfalls, especially on the 18th March. However, the spell was not as severe as the Beast From the East because it was shorter and solar radiation was more intense. Therefore, the snow tended to melt quicker.

Forecasting

Near the beginning to mid February, the UK Met Office had forecasted in their 30 day outlook on the chance of easterly winds to occur during the latter part of the month which would give snow and a plunge in temperatures. They stayed consistent throughout with their outlook on this though towards the third week of February started giving some uncertainty on that low pressure could track close to the north and west giving cloudier and milder conditions here. The reason why they showed the chance of easterly winds in the first place was courtesy of the sudden stratospheric warming event that were to occur on 11-13 February. However with the uncertainty above that they added, it's clear that they underestimated the strength of the zonal wind reversion.

In regards to the sudden stratospheric warming, the GFS model started showing it for the second week of February at the end of January with runs differing on timing and strength. At first, the model showed a Polar Vortex displacement than a split with the vortex being displaced over Canada. I had a look through the archives on seeing a similar evolution historically to what the GFS showed here and the example I could find was from February 1982. February and March 1982 were both largely mild months with little cold incursions. However, the ECM soon started to show warming to occur in the stratosphere too but a major warming causing the Polar Vortex to either split or be obliterated. The two models showing different solutions of the warming caused confusion for a bit before the GFS turned more to the side of the ECM and in fact upgraded the split and warming by the early days of February. The GFS started picking up on a second major warming event to occur following the split about a week after it with the warming occurring over Canada, during the first week of February. This was unusual to see given how Canadian Warmings have never occurred in February since stratospheric records began in 1951. As a result, I was unsure of what to expect but the drop off in zonal wind speeds again in mid-March was a sign. I looked through the archives to find a similar evolution to the split in February 2018 and I came across January 1985 which was strikingly similar.

The models started picking up on a significantly cold easterly to occur from the 26th February onwards in around the second week of February well in Fantasy Island. The models stuck to this theme throughout getting closer to the period but there were plenty of wobbles along the way especially on the ECM model. It is likely that these wobbles were caused by the stratospheric warming events because they were unusual and the models don't contain enough numerical data on such events to really know what's going to happen. However, once the first event was over, we started seeing more universal agreement on the beast to take place before the second event took place and caused a huge mess in the model runs. Some model runs were depicting the high pressure up to the north to stay over Ireland and us to be cut off the easterly. This gave Irish model watchers a horrible taste in their mouth and some bad recollections of the February 2012 easterly. However, what they did not take into consideration was the fact that this had a SSW event, or should I say 2 SSW events causing record breaking reversed zonal winds which early 2012 did not have. There was no major warming event throughout the 2011-12 season yet February 2018 alone had 2. The ICON model which is normally not that popular among people stayed the most consistent on the easterly throughout the runs but even it had a few wobbles likely caused by the SSW events. For what they're usually like and in spite of the wobbles, I think the models did extremely well in forecasting the easterly well in advance with it being shown in Fantasy Island all the way back to early to mid-February.

On the 23rd February, Met Éireann issued a weather advisory on the period for unseasonable cold conditions and snowfalls to take place. Usually, Met Éireann don't jump on the train of hype 'til very close to the time so it was something to see a weather advisory from our own meteorological agency!

Weather Advisory for Ireland

Exceptionally cold weather is forecast for next week with significant wind chill and severe frosts. Disruptive snow showers are expected from Tuesday onwards, particularly in the east and southeast.

Issued:Friday 23 February 2018 12:00 Valid:Friday 23 February 2018 12:07 to Friday 02 March 2018 12:00

On the 26th February, Met Éireann issued an orange status warning.

STATUS ORANGE

Snow-ice Warning for Dublin, Carlow, Kildare, Laois, Louth, Wicklow and Meath

Scattered snow showers later Tuesday and Tuesday night will lead to accumulations of 4 to 6 cm by Wednesday morning. Widespread frost and icy conditions also. Updates to follow. Please see Weather Advisory.

Issued:Monday 26 February 2018 11:46 Valid:Tuesday 27 February 2018 15:00 to Wednesday 28 February 2018 11:00

On the morning of the 28th February, Met Éireann upgraded the warning in some counties to a red status so schools were automatically closed in the counties in the warning. This was the first red status weather warning in Ireland since ex-hurricane Ophelia of the previous October.

STATUS RED

Snow-ice warning for Dublin, Kildare, Louth, Wicklow and Meath

Heavy overnight snowfall has led to accumulations of snow between 5 and 10cm. Snow showers will continue to occur during today and again tonight with further accumulations. Total snowfall up to midday Thursday may reach 25cm.

Issued:Wednesday 28 February 2018 05:00 Valid:Wednesday 28 February 2018 05:00 to Thursday 01 March 2018 12:00

On the night of 28th February, Met Éireann issued another red status warning but this time for the entire country. An Taoiseach, Leo Varadkar, urged everybody to stay indoors from 4pm on Thursday 1st March 'til 3pm on Friday 2nd March because this was likely the period when Emma was going to wreak havoc the worst on the Emerald Isle. It is also likely he said 4pm as an early time so that people would have time to take action and arrive home. He did this because there was confusion over whether people should work or remain at home following the issuing of Ophelia's red alert in October 2017. However, as he urged people to stay home at an earlier time than when Emma was most likely to impact the country, it just caused more confusion with a lot of people misunderstanding his plans. This warning was to be edited to include just those severely impacted such as Kildare, Dublin, Wicklow and Wexford following 3pm on the Friday and they would continue to update it until Saturday afternoon. Some schools in Kildare and Wexford would continue to be closed on Monday 5th March due to huge disruption from the snow.

Synoptic pattern and summary

Following the major warming events in the stratosphere, the zonal winds dramatically reversed which led to blocking over Greenland and Scandinavia plunging both the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) into very negative territory. We hadn't seen such negative indexes combined to this level since March 2013. The NAO in particular going negative was remarkable given how not a single day so far in Winter 2017-18 had recorded a negative NAO index. The end of November brought negativity of the index but as soon as the month changed so did the index with a positive NAO being recorded on the 1st December 2017. An easterly began to take place on the 22nd February but pressure was high over Ireland with clear air which led to sunny skies and overnight frosts. At this time, low pressure was out in the Atlantic splitting the Polar Jet or jet stream into two with one heading northwards and the other heading southwards. The winds over Ireland were turning to a southerly direction up to the Arctic which led to warm air advection being sent up there and in turn push cold air out into the mid-latitudes including Siberia. As the easterly continued, this cold air in Siberia gradually filtered through Europe getting closer to Ireland all the while. By the afternoon of the 26th, the -10°C 850hPa temperatures struck the east of Ireland reaching the west by the afternoon of the 27th. These temperatures at 850hPa continued to drop into the 28th with the -12°C isotherm making inroads to the east and even getting down to -14°C for a time. In the UK, upper air temperatures were down to -12 to -18°C widely with the -20°C isotherm not far off. Such temperatures at 850hPa had not be seen in the UK and Ireland since February 1991. This was a definitive Beast From the East alright and something that was very rare with only a certain amount of occurrences in recorded history including February 1956, January 1963, January 1987 and February 1991. Pressure over Greenland and Scandinavia were up to 1061mb and 1056mb respectively with a 974mb low over the Azores. Normally, we have a zonal pattern with an area of high pressure over the Azores called the Azores High and a low pressure over the North Atlantic called the Icelandic Low. However, with the zonal winds completely reversed here, the pattern became the opposite with the low over the Azores and the high up to the north. Like a beast from the east-type event, we very rarely see pressure as high as that over Greenland and Scandinavia as well as pressure as low as that over the Azores. The last time we saw a Greenland high as intense as that was December 2010 (see the chart below). The Scandinavian high was so powerful and intense that it evolved into an anticyclonic storm! It was named Harmut by the Adopt a Vortex program of the Free University of Berlin. A maximum wind gust of 187 km/hr (116 mph) was recorded in Øvre Dividal National Park, Norway close to the centre of the anticyclone. Other hurricane force gusts were recorded across Europe and anticyclonic storms of this intensity are rare events.

As the -10°C uppers appeared on the 26th to the east of Ireland, snow grains started to occur which tended to come in intervals through the day. The snow was heavier to the east of the UK by this stage especially to the southeast in the colder air. However, by the 28th, snow showers had become widespread though less confined to the southeast of England as the winds became more of a straight easterly, with the Irish Sea setup to become a snowmaker machine. The first of big blasts of snow for Ireland occurred on the night of the 27th into the early morning of the 28th with gusty easterly winds producing heavy snow showers of 5-10cm and locally even more to the east of Ireland. This resulted in wind chill temperatures widely below -10°C in both the UK and Ireland. This was called lake-effect snow because a cold airmass passed over the relatively warm Irish Sea with the conditions being met for streamers to take place. Such conditions include the 850hPa temperatures being at least 13°C colder than the sea surface temperature and the long fetch of water (as in there has to be enough distance for the heat of the water to contrast with the cold air and take effect causing the streamers). Further heavy snow showers took place on the 28th across the country continuing into the 1st March before storm Emma started pushing up from the south during the evening. However, some parts did take a while to get a good pasting of snow due to the Anglesey shadow breaking up the fetch. Emma was named by the Portugese Met Service and she was a very complex and unusual storm. Unlike usual winter storms which are formed by a powerful jet stream across the Atlantic, Emma was formed over the Azores courtesy of the Arctic outbreak which in turn was courtesy of the sudden stratospheric warming. The storm brought mild, moist air from the south into the established cold air over top of the country. The storm pushed northwards through the evening of the 1st into the 2nd bringing further heavy snow northwards. As the winds were very gusty coming from an easterly direction, blizzards were widespread with snow drifts up to 7ft. As the snow drifted in the wind, accurate measures of snow depth could not be taken but estimates show that depths would be between 30-60cm widely and even more in very localised spots such as Kildare or Wexford. This made Storm Emma be among the worst blizzards to occur in Ireland along with April 1917, February 1933, February 1947, December 1962 and January 1982.

As the storm pushed northwards and the anticyclonic storm up to the north pushed westwards into North America courtesy of the reversed zonal winds, relatively milder air came along with it melting much of the snow but for some because the snow was so deep, the snow did not fully melt 'til over a week later which given the solar radiation was remarkable. It was good it didn't because flooding didn't become a concern unlike in March 1947 when heavy rain combined with much much milder air from the south produced severe flooding in both countries following the very snowy and cold February which had several snowstorms. However, some freezing rain briefly occurred in England on 2nd/3rd March which gave away to very slippery surfaces and dangerous conditions.

The UK and Ireland on the afternoon of 28th February 2018.

Impacts/stories

For the first time in history on March 2nd 2018, The Late Late Show, which of course is the popular Irish talk show and is the longest running talk show in the world, closed its doors. For safety reasons, their audience and guests couldn't make it so they had to grab random people from the canteen and or off the streets. The show featured comedian Oliver Callan, Joe Duffy, Deirdre O’Kane and country music singer, Cliona Hagan - not to mention stacks of Brennan’s bread.

Dublin nurses give baby Holly a beautiful gesture in Our Lady's Children Hospital, Crumlin. Holly had been waiting 11 months in the hospital for a heart transplant and did not get to enjoy the snow with her family whilst most did. The nurses didn't want Holly to miss out on her chance of building a snowman. They went outside and filled giant buckets with snow. They put the snow on a tray for Holly to play with.

A woman foolishly decided to swim at Sandycove during Storm Emma. She not only put her own life in great danger by doing so but also the lives of others because they had to save her as the waves overcome her.

A man named Frank Price from Tallaght wore his swimming suit and he jumped out of his two-storey window into his garden which was buried in snow. He said he did it for fun and practicing for the next Winter olympics.

86 year old, Eileen Maguire, sled down Sweeney's Hill in Co. Cork with her grandson. This shows you that even old people can have a little fun in the snow!

Statistics

The beast from the east produced the coldest March conditions for some since March 2013 which had been the coldest March since 1962. However, in terms of the temperatures and snowfalls themselves, it was the most significant spell of winter weather since December 2010. 28th February 2018 was the coldest February 28th for the Central England Temperature (CET) region since 1785 with a daily CET of -3.6°C in comparison to 1785's -3.8°C. 1st March 2018 was the coldest March 1st in the daily CET series with a daily CET of -3.8°C beating 1785's -3.5°C. The 28th February was the coldest day in the UK in terms of maximum temperatures since December 1995, even colder than any day in December 2010 (see chart below from the UKMO):

Daily CETs (°C) during the Beast from the East 2018

On 28th February, strangely enough, County Cork recorded the lowest of the temperatures with maximums of -1.1 and -1.7°C at Cork Airport and Roche's Point respectively, both their lowest since January 1987. The air minimum fell to -5.7°C at Gurteen on this day whilst the grass minimum fell to -11.5°C at Markree on the 27th.

Colder temperatures were to be recorded mostly on 1st March with Cork Airport getting down to an air minimum of -7.0°C, its lowest for March on record. Meanwhile, Tredegar in South Wales recorded a maximum temperature of -4.7°C which became the UK's lowest March and Spring maximum temperature on record beating -4.6°C at Cassley, Sutherland on March 2nd 2001.

Here's some snow depth graphs for the period in the UK: