Wednesday, February 28, 2018

Water and Weather 2018 so far...

Cuttings montage (January)
Winter 2017/18 (Meteorologically speaking 1st December – 28th February) was bookend by snow. We started off in NE Yorkshire where snow fell on the 30th November, affecting only NE England close to the North Sea coast. At the turn of February-March, there came the Beast from the East.

In between, the weather was more varied than during the previous winter, with more rain; but it was cold at times. January was unsettled and fairly fairly mild, but February was much drier, and colder, especially at the end of the month. It felt much more like winter, and a long one, though my perceptions were coloured by homelife hassles, such as the boiler breaking down in January.


Among the more memorable weather and water incidents:

Named storms (low pressure systems) – by the end of 2017, four low pressure systems had been named by the UK Met. Office and / or the Irish weather service. 2018 began, then with E for Eleanor on 3rd January. Later that  month: Storm David (17th January; breaking the alphabetical sequence because it was named by Meteo France. Then, Fionn (affecting the island of Ireland, but not Britain. On 24th January, the latest of the season so far, Storm Georgina. February quiet; but cold on the coat tails of the Beast from the East, Storm Emma was due to roll in from the southwest, off Iberia on 1st March. Again, out of the alphabetical sequence because it was named by the Portuguese weather service, making landfall in Portugal first. All the storms named more because of the potential for strong winds than precipitation. There were other rain and snow bearing weather fronts emanating from anonymous lows.


High tides, supermoons and blue moons – two full moons in January: on 2nd and 31st. The first known as the Wolf Moon; the second a Blue Moon, being the second in a calendar month. Both were full at / near perigee, the closest point in the Moon’s orbit around the Earth. Shortly after the first one (3rd-4th January), happening just as Storm Eleanor rolled in, some high tides (see notes from our local coast). There was also a fair bit of rain, with coastal and fluvial flood warnings on both sides of the English Channel. River and sea conditions were quieter at the end of January, the pressure being higher, meaning no reprise of the earlier tidal trouble come the Blue Moon.
Pluvial / fluvial turn-around in France for much of 2017, river levels across the Channel in France had been running low all through the autumn, with high pressure in the Atlantic off the Bay of Biscay in charge.  The weather began to turn in December when storms and rain bearing fronts passed over the country and river flows began to improve. Then, in January was very wet. From  Storm / Tempête Eleanor onwards, widespread flood alerts (vigilances) affecting most of the main rivers. According to Eaufrance / Vigicrues, the flow on the Loire at Saumur was below 200 cumecs (cubic metres per second) in early December. Around Christmas is was about 800cumecs. Around the new year, it hit made it into four figures (about normal for winter), then during the week after Tempête Eleanor, it rose more quickly and peaked at around 3100 cumecs on 9th January. The Seine and its larger tributaries, meanwhile were rising slowly but surely. Later in the month, Tempête David brought high winds to NE France, Belgium and southern England. As I grumbled at the perennial winter mud around our way, it was very dull in these areas. “A star has been kidnapped!” said one regional newspaper, La Voix du Nord, meaning the Sun. UK sunshine during January was about average according to the Met. Office, nonetheless, the month had a distinctly wintery feel to it. Whereas France was exceptionally mild and wet – the wettest December-January 2 months period nationally in the record from 1959 -  the track of the jetstream meant it was cold in Scotland. A low of -13.5oC at Dalwhinnie in the eastern Highlands on 21st January. Also snow, with queues along the A82 near Glencoe on that weekend.
Crue de la Seine – with the slow and sure rise, the Seine and it’s larger tributaries, particularly the Marne, were on flood alert for much of January and well into February, even after the weather patterns had shifted and the rain had stopped. Things got particularly high during the last week of January. The flow along the lower Loire exceeded 3000 cumecs again on the last weekend – crues habituelles pour la saison, said Vigicrues.  However, there was more significant flooding affecting the Seine; the Saône and its tributary and sub-tributaries from the Jura area the le Doubs and La Loue; and the Dordogne. On 23rd, there was a vigilance rouge (equivalent to Severe Flood Warning in the UK) on the Loue. A fair bit of footage of the Doubs on Youtube, including an impressive waterfall. Most of the media attention, though was on the Seine, vigilance orange (crue importante) from at the Marne to the Manche (English Channel) by the end of the month. Numerous Youtube footage on Paris from this time, too. A photo of a woman in a rowing boat with a dog amid a flood in a Paris suburb appeared in The Guardian across the Channel on 25th January. The Metro and boat services were also disrupted. Once again, art in the stores of the Louvre had to be shifted somewhere safer. The Seine peaked on the 29th January at Paris Austerlitz at around 1672 cumecs – the peak flow on the Eden through Carlisle (Sheepmount) during Storm Desmond, December 2015, was much the same (1680 cumecs, according to CEH), the Lune and the Tyne both above 1700 cumecs. In contrast to those rivers in northern England, though, the rise was very slow, especially near the peak. It also took considerable time to subside (décrue) afterwards. A combination presumably of lots of water propagating through a large catchment and the lower Seine being very winding, with large meanders (boucles). Throughout the last week of January, the flow into the Channel was around 2200 cumecs (Vernon gauge), thanks to additional inputs from the Oise and other rivers joining downstream of Paris. With so much water coming downstream, there was a vigilance orange in the tidal Seine during the spring tides around the Blue Moon, too. The heights and flows on the lower Seine was about the same as during the June 2016 flood, according to Météo France. In Paris, the peak (5.85m) was a bit lower than in June 2016 (6.1m). There were higher floods in the last century, most notably January 1910, when the flow through Paris was around 2600 cumecs and the level 8.62m.
During that last week, there were flood warnings in England and Wales, including along the Ouse in York and the Severn at Tewkesbury; but there was no major flooding.

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Revival of the Lavant long-time-no-see. February was notable particularly for the cold, again on both sides of the Channel. At the beginning of the month, as the sun climbed higher in the sky and the days got noticeably lighter and brighter, it began to look springlike, even if it was chilly in the wind. Walking to The Trundle from Chichester on the 3rd, I was pleased to see the Lavant flowing again – long-time-no-see. As far as I’m aware, it didn’t flow at all last year; and even on the 28th December, my other half said the stream was still dry when he walked that way. Autumn 2017 had been another dry one in southern England. Though December was wetter, the rain hadn’t yet percolated through the soil to the the chalk in sufficient quantities to raise the water table. It was January’s rain which really made the difference and got things flowing again. Hints of spring, with snowdrops flowering at West Dean the following weekend and a few daffodils coming out; but I didn’t want spring to be too early or too dry as last year’s was. Thanks very much to January’s rain, the CEH and Environment Agency say in their hydrological summaries for January that the hydrological outlook has improved since the autumn, thanks to the rain in December and January. Most gauged river flows were in their normal range, including those which had been running low at the end of last year, such as the Great Stour in Kent. The nearby well at Little Bucket Farm was no longer dry. The revival of the Lavant was reflected in a sharp increase in the level of groundwater in well at Chilgrove House nearby to the west.


Nextdoor to the east, I saw the Arun was running fairly high when I looked from the train to London Victoria on 15th February. Near Pulborough railway bridge it was overflowing. This was more due to rain falling on the West Sussex Weald from about 10th February. When I went to Littlehampton on the 18th – disappointingly overcast after bright sunshine the day before, the usually sea green water was the colour of weak tea. The tidal current was very strong, as it is here even on regular, moderate tides. Though cloudy, it was one of the milder days of the month; one of the few days of the winter when I could sketch along the coast and not immediately feel cold in the wind.

Then came the really cold bit, dubbed The Beast from the East by the British media, with the coldest weather of this winter and since 2013, and in some areas 1991. Happenings in the upper and lower atmosphere over the Arctic conspired to shift the winds to bitter easterlies and north easterlies, bringing in cold air from northern Scandinavia and Russia. The coldwave was felt throughout the British Isles and northern Europe, with sub-freezing temperatures, snow and bitter wind chill. The cold began setting in during the final week of February as a very  intense anticyclone built over northern Scandinavia and extended southwestwards towards the British Isles. The jetstream diverged; with one arm moving north of the British Isles towards Iceland and the other well south, over north Africa. It continued to loop and wind, with a big tongue of bitterly cold air sticking out from Russia westwards come the end  of the month. Over Scandinavia and just north of the British Isles the normal westerly flow of the stream had reversed to easterly as it looped up into the high Arctic and diverged in mid-Atlantic. The Met. Office issued warnings for snow and ice throughout the UK, particularly eastern areas. The snow began on the night of the 26th. It missed south Hampshire, but there was snow in London, Sussex and Kent; and deeper, drifting snow in NE England and Scotland. North of the Border, they were so concerned that on the 28th, they issued a rare red warning for snow in central Scotland, including Edinburgh. The last time they issued one of those was during the floody havoc wrought by Storm Desmond in northern Britain in December 2015. Down south, meanwhile, the Storm Emma low pressure was deepening in the Atlantic off Iberia and heading northeast across Iberia, western France and towards southern England. With its associated  fronts coming in from the south across the Channel meeting the cold air, the potential, then meant snow, ice and freezing rain round our way to start off March – the beginning of spring meteorologically speaking, even if far from the reality.


Everyone who’d rather anthropogenic global heating wasn’t happening, or denying it altogether may this kind of winter chill reassuring, bolstering the deniers’ case. . But it’s a false reassurance. All the time Britain and the continent were under a cold wave, the Arctic was getting worrying warm, thanks to. Analagous to leaving the fridge door open and letting the cold air flow out into the kitchen; the fridge here being the Arctic / North Pole; and Britain / Europe being the kitchen. Bucking the trend of the rest of the British media, The Guardian led with Arctic heatwave triggers climate meltdown fears on 28th. The warming has involved the upper and lower atmosphere over the Arctic. On the 9th February, the Met. Office said in a news release that they were forecasting a Sudden stratospheric warming in the high atmosphere over the Arctic the following week, involving an increase in temperature of as much as 50oC associated with the polar vortex being breaking down as warmer air penetrates from further south (via the north Atlantic jetstream presumably). The following week, they confirmed it had happened. Air was sinking from the stratosphere into the lower atmosphere (troposphere) over the Arctic towards the surface. This subsequently affected the north Atlantic jetstream, slowing it down, prompting it to loop and diverge, even reverse from west to east. That, in turn has affected winds nearer the surface over Britain and Europe. The intense anticyclone built over Scandinavia had a central pressure of 1056 millibars on 28th, but was forecast to decrease rapidly over the next few days. As the polar vortex broke down, warmer air flowed towards the North Pole, in constant darkness at this time of year, the temperature there nudging above freezing at one point, if I remember reading rightly. Certainly temperatures in parts of Siberia have been 35oC above the historical average this February, and a record 61 hours above freezing in Greenland so far this year (The Guardian). 

Links
Weather
UK Met. Office website


https://www.metoffice.gov.uk/guide/weather/symbols
Meteo France - http://www.meteofrance.com/accueil
Meteoalarm (Europe) – weather warnings across Europe, with links to national weather services -  https://www.meteoalarm.eu/
Met. Office News Releases
UK Weather stats (rainfall, temperatures, sunshine hours) for January (01/02/18) - https://www.metoffice.gov.uk/news/releases/2018/january-statistics
February new releases point to a trend to generally drier and much colder weather, especially at the end of the month, and into March, thanks to warming of the stratosphere over the Arctic triggering a slowing of the north Atlantic jetstream and an intense anticyclone building over Scandinavia bringing very dry and bitterly cold northeasterlies from Siberia.
How long will the cold conditions last? (09/02/18) – mention of sudden stratospheric warming possibility prompting marked changes lower in the atmosphere (in the troposphere) to the course of the jetstream and synoptic pattern. https://www.metoffice.gov.uk/news/releases/2018/how-long-will-the-cold-conditions-remain
A mixed week of weather (12th February) – some milder and wetter weather, but confirmation that stratospheric warming over the Arctic has occurred, which could shape subsequent weather - https://www.metoffice.gov.uk/news/releases/2018/a-mixed-week-of-weather-ahead
Freezing conditions to last into spring (March) (23/02/18) – blocking pattern setting in as high pressure settles and intensifies over Scandinavia, winds shift to easterly / north easterly, bringing in bitterly cold air from Siberia. https://www.metoffice.gov.uk/news/releases/2018/freezing-start-to-spring
Bitterly cold with widespread snow (25th February) – the coldest weather of winter 2017/18 so far, and the coldest since 2013, when bitterly cold easterlies set in during the first half of March and persisted until May. No word yet, though as to when this year’s blocked, cold pattern will break.
https://www.metoffice.gov.uk/news/releases/2018/cold-and-snowy-week-ahead
Bitterly cold with snow (27/02/18) – amber and yellow weather warnings around the UK this week (26Feb – 2nd March), bitter cold, especially with wind chill; and snow in the east and southeast on Tuesday. March to begin with the possibility of snow, ice in southern England as fronts come in from the south as low pressure passes over Iberia (Storm Emma, according to the Portuguese weather service).
https://www.metoffice.gov.uk/news/releases/2018/bitterly-cold-weather-continues
Meteo France News Releases
An exceptionally mild but perturbed January with a succession of named storms - http://www.meteofrance.fr/actualites/58919551-janvier-2018-mois-de-tous-les-records
Tempête David affects northern France (and the UK) (18/02/18) - http://www.meteofrance.fr/actualites/58131340-tempete-david-sur-le-nord
http://www.meteofrance.fr/actualites/57448719-retour-sur-la-tempete-eleanor-des-2-et-3-janvier
Snowy and cold start to February - http://www.meteofrance.fr/actualites/59115031-debut-fevrier-froid-et-neigeux . Subsequent snowy episodes during the first week of February.

Shows the cold air forecast to come in from Russia / the NE
BBC News
Snow / weather disruption – BBC, 27/02/18 http://www.bbc.co.uk/news/uk-43207709
Water
CEH hydrology / monthly hydrological summaries for the UK
Environment Agency – River and Sea Levels, England
Environment Agency – Weekly and monthly water situation reports
Similar info’ for Scotland and Wales, at respectively, SEPA and Cymru
Eaufrance
Vigicrues (flood warnings and gauged river flows, France) - https://www.vigicrues.gouv.fr/
Other
The Guardian – online 27/02/18, paper edition 28/02/18: