When writing this post, the stats are not in for June 2018 but we can safely say that it was a very warm month and is likely to finish within the top 10 warmest Junes on record in the UK and Ireland. The Central England Temperature (CET) for June 2018 is 16.1°C which would make it comfortably fit in with at least the top 25 warmest Junes on record for the dataset and that is saying something because the CET dataset is the longest in the entire world going all the way back to 1659 for monthly means.
It will be a long season of Winter 2018-19 updates and this is only the beginning. For my first analogue for the Winter, I have decided to look at warm Junes and the Winters which followed these Junes. From the previous year, 2017-18, I knew that warm Junes were a sign historically for colder Decembers though you didn't need to go back far to find a run of warm Junes being followed by mild Decembers - 2003 to 2006 for example. Fortunately, whilst it wasn't an exceptional month at all, December 2017 ended up on the colder than average side and it was preceded by a warm June in 2017. As can be shown by the 500mb height anomaly reanalysis from NOAA below, warm Junes are a clear sign for colder and snowier Winters - at least going by the UK temperature dataset figures. There is very stubborn blocking over Greenland (as noted by the red colours) and even over to Siberia which is a sign of a strong Siberian High whom can be our friend or foe (if you like cold weather that is) when it comes to Winter depending on other factors. This forces the Polar Jet i.e. the jet stream southwards into southern Europe. It just happens that on this reanalysis the trough of below average heights is south enough to the UK and Ireland to cause a very cold and snowy Winter. If it were slightly northwards then it would be a sign for a very mild and disturbed Winter in spite of the blocking up to the north - this last happened in Winter 2013-14. NOAA's composite generator only goes from 1851 to 2014 so I could not put Winter 2017-18 in here but as we've seen, June 2017 was a very warm month and it was followed by a cold (also very snowy) Winter. It's also very worth nothing that the coldest Winter ever recorded in the CET, 1683-84, was preceded by a very warm June (with a CET of 16.0°C) in 1683. The second coldest, 1739-40, was also preceded by a warm June in 1739 (with a CET of 15.2°C). It is reported that temperatures got below -20°C in Ireland in 1739-40 (the Irish record low is -19.1°C in January 1881) and -30°C in the UK (the UK record low is -27.2°C in February 1895, January 1982 and December 1995) during both seasons. These were two examples (and two of the last) of Winters during the Little Ice Age too where Frost Fairs were held on the Thames.
Let's look at the Winters in this reanalysis individually and see how they fared (including 2017-18 since it would be part of the reanalysis if I could put it in).
1976-77: A rather snowy Winter with some decent snowfalls each month. December and January were rather cold whilst February tended to be on the milder side for most and very wet.
2017-18: Very snowy season with snowfalls beginning as early as late November for some. December 10th brought a slider low in from the Atlantic which gave away to heavy snowfalls for midlands of Ireland, England and Wales with accumulations of up to 20-30cm. Other parts of December, January and February had cold zonality giving away to some light snowfalls in the south and east of Ireland whilst quite heavy in Scotland and the north and west of Ireland. The end of February brought a "Beast from the East" event which brought record breaking cold for the time of year with daytime temperatures staying below freezing in the large majority of places of both countries from 28th February to 2nd March. Accumulations from lake-effect snow from 27th February to 1st March ranged from 5-25cm for most and localised, even more. It was the coldest February since 2010 and the coldest March since 2013. Storm Emma which was a result of a displaced jet stream over Iberia brought further heavy snowfalls and combined with the gusty easterly winds gave away to severe blizzards with snow drifts of up to many feet high. Snow depths reached 61cm in Co. Wicklow, Ireland. Another easterly occurred on the weekend of March 17th/18th with snowfall accumulations of 5-20cm and daytime temperatures struggling in the low single figures around freezing point for much of the 18th March.
1940-41: Very cold Winter with some significant snowfalls in January and February. January wasn't as cold as 1940 but still by today's standards, it would be an exceptionally cold month (it'd be on par with January 1987 as a recent example). December was a rather cool month and dry in the south but close to average in Northern Ireland and Scotland.
1970-71: A rather quiet Winter with a dry December and February for many. The last third of December was quite cold with a White Christmas being recorded in the south of England. January tended to be wetter in the south and both January and February were on the milder side with some record warmth at times. Quite a forgettable Winter as many were in the early 70s.
2003-04: December was a rather changeable and mild month with no real notable characteristics to make it stand out. January was generally unsettled and mild though near the end, there was a very cold and snowy interval which led to daytime temperatures being near freezing. February started off record breakingly mild with some unsettled conditions but the month quickly became anticyclonic with a lot of sunny and frosty weather.
2006-07: Very mild and wet Winter - the wettest since 1994/95. It was the wettest December since 1978 with little cold and snowy conditions although there was an anticyclonic interval for about a week ending on Christmas Day. January was very mild (with a phenomenal CET for a Winter month of 7.0°C) and it was the mildest since 1921 though it ended on the somewhat chillier side with a drier spell after an otherwise stormy month. February was another mild and largely wet month but the month contained a notable frontal snow event on the 7th/8th resulting in some of the heaviest snowfall since February 2001 or 1996. March had one potent northerly blast from the 18th-21st with some heavy snowfalls occurring over Scotland and the midlands of England, rather light wintry showers elsewhere.
1992-93: December started off fairly unsettled but as the month went on, it became much colder and even some ice days were recorded. The weather tended to be just quiet and frosty with a lack of snowfall. January in contrast was very zonal with the deepest and most intense storm to be recorded in the North Atlantic ever took place. This storm on the 10th January had a minimum pressure of 914mb leading to blizzards over Scotland in hurricane force winds. February was just very mild, dry and dull with not a lot going on at all.
1960-61: A stormy Winter with a lot of depressions coming in from the Atlantic and is one of the more milder Winters of the 1960s decade. The period July 1960 to February 1961 including this Winter featured some of the wettest ever conditions over England. December and January were a bit on the chilly side in spite of being so changeable and disturbed. Little snow regardless.
1950-51: Very snowy and cold Winter. December in particular was cold with a CET of only 1.2°C (though not as cold as December 1981 or December 2010). January and February tended to be on the wetter side but nevertheless due to the cold air established, these weather systems gave away to a lot of significant snowfall. Every single month from October 1950 to May 1951 featured snow at some stage. It was the snowiest Winter of the 20th century at high levels with 102 days of lying snow at Dalwhinnie in the Highlands of Scotland.
2010-11: A textbook example of a front-loaded Winter. Fantastic cold and snowy start with the second coldest December on record for the CET and one of the coldest months ever recorded in the UK and Ireland with a disappointingly mild and wet end in February whilst January was in the middle with rather cold conditions but not significantly so. Two extreme cold spells took place at the end of November and start of December as well as mid to late December with some of the coldest weather ever recorded. There weren't any blizzards as winds were calm but as a result of this, temperatures plunged on many many days with more than 5 ice days (days where the air temperature did not get above 0°C all day long) for most places. Altnaharra recorded a maximum temperature of -15.8°C on 22nd December, the second lowest on record for any month in the UK. Ireland recorded its all-time lowest temperatures for December with -17.5°C on Christmas Day and Northern Ireland did too with -18.7°C on December 23rd even though it also bet the record for December just 4 days before hand with -18.0°C on December 19th. February was a real disappointing end to what was a fabulous Winter otherwise (similar in some ways to 1981-82). I don't think I need to go on any further, now do I?
2005-06: An odd, frustrating Winter for cold weather enthusiasts in the UK and Ireland. Much of eastern Europe was very cold with the coldest conditions since Winter 1990-91 perhaps. These colder than average temperatures were also over much of central Europe including France. However, the UK and Ireland were on the knife edge a lot of the time close to the Atlantic under an anticyclone which gave away to a very dry season. The end of November brought some snowfall accumulations. December had an easterly near the end of the month which gave some snow showers to eastern locations of the UK. January was snowless largely but it ended very cold with some ice days under severe frost and crisp Winter sun. February ended in an easterly with some snow showers but nothing outstanding. This all changed in March as a cold front pushed southwards on 28th February introducing a very cold northerly airstream resulting in heavy snowfall and even thundersnow in Aberdeen. Northeastern Scotland had up to 50cm of snow in accumulations with the snowiest and coldest March conditions since 2001 everywhere. Birr in Ireland recorded a grass minimum of -16.0°C on March 3rd.
2004-05: A mainly mild Winter overall but not exceptionally so with a notably snowy Christmas Day (which was the highlight of the season really for the majority). It was the Whitest Christmas in the last 50 or so years in terms of the number of stations reporting falling snow. The end of February and start of March brought persistent easterly winds over the countries but accumulations were small and limited leaving enthusiasts in a lot of disappointment. Only parts of the east of the UK including Kent, southeastern Scotland and northeastern England had some significant accumulations.
1933-34: A very cold December - only relatively milder than December 1950 mentioned above but otherwise, this Winter does not stand out. Every month from October to May bar January had some snow at some point in the month but there wasn't really anything significant. I bet some people back then were very thankful for this Winter though not producing much due to the fact that February 1933 had one of the worst blizzards ever in the history of Ireland which produced 10ft drifts.
1966-67: A mild and largely snowless Winter, again one of the few of such of the 1960s decade. January and February started off cold but became very mild and especially in February's case, stormy. December was wet to the south but cold in northern Scotland.
2009-10: The coldest Winter since 1978-79 with the longest cold spell from mid-December to mid-January since 1963. During this period, there were lots of snowfalls, especially in early January with accumulations surpassing 30cm widely. Daytime temperatures did not get above freezing on several days, especially the 7th/8th January when virtually the whole of the UK and Ireland was under severe frost and or deep snow cover. Since records began in 1910, it was the coldest Winter on record in northern Scotland. It was the coldest January since 1987. February was the coldest since 1991 though its snowfalls were rather light and cold wasn't that severe. March was the coldest since 2001 with some blizzards taking place on March 29-31. The month was full of air frost due to an anticyclone giving away to lots of sun during much of March. April and May continued to record some air frost too and it was the longest "Winter" in that case since 1996. It was also a very cold Winter over much of Europe and parts of north America thanks to a record breaking negative North Atlantic Oscillation (NAO).
2007-08: The Winter was a precursor to what was going to happen from 2008-09 to 2010-11 with some little teasers. It was overall quite a mild season but mid-December contained a long spell of anticyclonic weather leading to some frost in places. The 3rd/4th January brought some heavy snow to the UK and Ireland. Peter Duncanson measured a snow depth of 20cm on his lawn just before midnight on the 4th January 2008 in Northern Ireland. February was a very sunny and relatively mild but at times frosty month though wet out to the west of Ireland and parts of Scotland. Both March and April 2008 featured some significant late season snowfalls.
1982-83: Considering what happened during 1981-82, this Winter could be considered very boring and disappointing by weather enthusiasts. It was probably not helped by the fact that this was a very strong El Niño season and one of the strongest on record. December 1982 was average to fairly chilly. January was a very mild and unsettled month but February in contrast was cold and at times snowy. The drop off in the CET from January to February 1983 is the largest on record. As a comparison, February 1983 was just over a degree colder than February 2018 for the CET.
1947-48: In stark contrast to the preceding Winter (1946-47), this was a much much milder Winter with average snowfall accumulations. Most notably, Cornwall recorded 12 inches of snowfall on 12th February 1948 courtesy of a cold pool of air being pushed in from the Atlantic strangely enough whilst some milder air was also attempting to come up from the Bay of Biscay. Christmas Day 1947 recorded a thunderstorm over the south of the UK with marble sized hail.
1930-31: Rather snowy but not overly cold, just fairly chilly. Some notable snowfalls of the season include: 2ft in northern England in early February and two and a half inches falling in London within 90 mins on March 9th making some roads impassable until 4 days later.
1959-60: A stormy December with several gales was followed by a rather cool January with notable snowfalls and a mixed February. Northeastern Scotland recorded 1m drifts in a blizzard on January 18th/19th.
Other Junes that weren't as warm as those in years named above but were still warmer than average and were followed by cold or snowy Winters include 1996, 1995, 1986 and 1984.
So as to be expected there is a mixed bag when you look at the individual Winters but overall when you combine them as the reanalysis shows, you get a cold and snowy signal for Winter 2018-19. Remember that this is only one analogue and we'll be doing many more through the year until I release my Winter 2018-19 forecast on Tuesday, November 27th. I'll also be doing Autumn analogues including an Autumn version of this analogue on warm Junes and the Autumns which followed said Junes.
