Monthly retrospective for December 2015

It was exceptionally mild but very wet in places in the north & west but rather dull too esp in the south. The (Hadley) CET mean temperature was near 9.8C, the highest mean in December recorded since records began, making it warmer than November 2015 (which in itself was very mild) and 5.2C above the normal average. A number of daily maximum temperature records were broken.

December saw temperature anomalies range from about 1-2C above average in the far north to over 6C above on the southern English coast. Hurn (Dorset) was 6.4C above average, and thus was exceptionally mild. The degree of this warmth cannot be overemphasised but it is interesting and quite significant that no weather agency was able to forecast it in advance. It cause may to an extent be due to the extent of the ongoing El Nino event and/or possibly global climate change but there is no definite scientific agreement on this. The warmest places by day were at Gravesend, Heathrow & Northolt with a mean maximum temperature of 13.4C. The coldest mean minimum by night was 2.6C at Aboyne (as in November) in the Highlands. Pressure was 7mb below average in the far northern Isles but 5mb above at Manston (Kent), attesting to the strong pressure gradients at times.

December was a notably wet month and for the UK as a whole it was the second wettest on record. The record breaking rainfall in December also put 2015 in the top ten wettest years in records going back to 1910. It was the wettest December on record for Scotland (333 mm), and for Wales (321 mm) and for Northern Ireland it was the 4th wettest with 208 mm. North west England also saw record breaking rainfall, but central and southern England were much closer to average or even rather dry. Shap Fell in Cumbria saw about 372% of its normal rainfall and Aberdaron in West Wales 304% however as last month parts of the SE were drier, Manston (Kent) & Heathrow in west London saw just 61% of their average & remarkably parts of the far Scottish NE were quite dry as well but mostly amounts were between 125-175% of average rainfall.

Generally, it was rather duller than average right across the UK as a whole away from the far north, Both Eskdalemuir in southern Scotland & Herstmonceux (East Sussex) only saw 24% of their expected average and much of the south of the UK saw figures between 35-65% of average.

Frost was well below average everywhere and many areas saw no frost at all this month. St Catherine's Point (Isle of Wight) never fell below 8.3C all month, and there was little snowfall on the whole, away from the Scottish Highlands. It was a windy month at times and three storms were named by the UKMO, using their new storm naming system: Desmond, Eva and Frank, of which details can be found below.

By the end of December sea temperature anomalies were about 1-2C above average around most UK coasts though nearer 3-4C degrees around the SE coasts, so very mild here compared to average. Soil temperatures were almost uniformly well above average everywhere away from Highland Scotland and soil moisture was generally well above average in most parts, away from the SE & East Anglia and far NE of Scotland with water tables completely saturated in parts of the NW and north of England and west and north of Wales leading to a lot of standing water and localised flooding.

 

Now looking at December in more detail.

The 1st was very mild indeed though sleet and snow affected the far north east & Highlands. Murlough (Co Down) recorded a max of 15.0C and this was just 1C off Northern Ireland's all time December maximum temperature (also set at Murlough in 1994) but is almost certainly one of the highest December temps recorded in Northern Ireland in December. However at midday there was still 5cm of snow at Tulloch Bridge (Highlands). Achnagart (Highlands) recorded 44mm in the 24 hours to 21Z but whilst the wet weather generally eased many river levels continued to rise especially in the south, mid and west Wales and the Welsh borders area. A major search and rescue operation resumed for a woman missing in the River Usk. Witnesses said they saw the 51-year-old in the water near Usk bridge just after 18:30 GMT on Monday in Brecon, Powys. There were many flood warnings in place around Wales due to the bad weather which hit homes and roads. Mid and West Wales Fire and Rescue Service took 50 calls related to floods between 19:00-04:00 overnight. Firefighters used a boat and ladder to rescue two people and a dog from a property under 4ft (1.2m) of water near Welshpool (Mid Wales) Airport. Eight people were rescued from their vehicles in separate incidents by the service's swift water teams. At an incident in Meifod, a helicopter was brought in to rescue a motorist from his car after the current proved too strong for firefighters.Dyfed-Powys Police described road conditions overnight as "treacherous" with roads blocked in Powys on the A483 at Welshpool and Four Crosses, A495 Meifod to Llanymynech, and the Builth Wells area. Cars were left stranded at Buith Wells after the river Wye burst its banks on Monday evening. Roads were also affected at Ceredigion and Gwynedd with the A5/A483 at Chirk, Wrexham, also flooded. Arriva Trains Wales said a replacement bus service was running between Llanrwst and Blaenau Ffestiniog due to flooding as well as between Machynlleth and Newton due to flooding between Machynlleth and Caersws. The area around Shrewsbury and Hereford was also affected by flooding.

The 2nd was very wet, at least early on, in parts of the north & west of Wales, Capel Curig (Powys) saw 47mm in the 24 hours to 21Z, it was however very mild with Hereford reaching 14.2C. River flooding was still an issue in places but on the whole receded somewhat from the 1st. On the 3rd a deepening low moved NE across the central northern UK bringing some dull, wet and windy weather to the west. By 21Z it was over N England as a 999mb feature. Ronaldsway saw 48mm of rain in the 24 hours to 21Z but radar returns suggested as much as 100mm+ locally in this period in the Welsh mountains of Snowdonia. A school bus overturned on a bridge which had collapsed due to the rain on the Isle of Man but there were no serious injuries. It was however very mild in the far south west where Bude (Cornwall) reached 14.6C. A chilly start however locally in upland Scotland with a moderate frost and as the rain moved into Scotland it turned to snow in places, esp across mid Lothian with quite substantial falls over higher ground. Strathallen only reached 2.6C before falling back towards freezing. It became windy too in places, Capel Curig (Powys) gusted to 71mph and on the south coast Hurst Castle (Milford, Hants) also reached 73mph unofficially. Incised convection also brought thunder on the cold front in the south locally, in the late evening and overnight as it moved east south east, with some very heavy rain on it and gusty winds too.

The 5th was one of the wettest days across parts of the UK on record, at least in recent decades. This was caused in part by UKMO named storm 'Desmond'. A conveyer belt of warm sub tropical air from below 30N ran across the Atlantic & up across the western & northern UK and embedded into it was a slow moving warm front. This gave huge amounts of orographic rain over high ground, esp Western Scotland, Western Ireland, Cumbria & the Lake District and NW Wales. There was also a strong pressure gradient that developed across the north. This gave very strong winds in places too with gusts to 89mph at Capel Curig (Powys). Aberdaron on the west Wales coast gusted to 77mph. The upland EA gauge at Honister Pass near Seathwaite in Cumbria was one of the wettest with 341.4mm in a 24 hour period, an all time UK record. Another EA gauge at Thirlmere close by recorded 323mm in the same period.

A new 48 hour record of 405mm was also set at Thirlmere in the 48 hours to 8am on 6th December. In the normal recording period from 21-21Z the village of Shap, in Cumbria, received the most rain, with 192mm falling in the 24 hours until 2100 on Saturday, while Keswick was hit with 156mm. It appears from radar returns that many of the highest areas may have seen about 250mm in a 24 hour period. The average rainfall for Cumbria for the month of December is 146mm. There were more than 100 flood warnings issued across N England with several rivers seeing their highest levels on record. Cumbria Police declared a major incident with homes in Appleby and Keswick evacuated and many roads blocked. There were also more than 90 warnings and alerts across Scotland and some main roads were closed due to landslides and flooding. More than 600 homes in North Yorkshire were left without electricity and around 1,000 people were evacuated from their homes in Hawick, in the Scottish Borders after flooding from the River Teviot. In counties Down and Tyrone, in Northern Ireland, roads were closed due to fallen trees. Train companies warned of major disruption across the networks in the affected regions with numerous road restrictions in place.

By the 6th December the effects of the heavy rain on the 5th continued to be felt with a large clean up operation underway. A further 63mm of rain fell at Shap (Cumbria) making a total of 255mm in 48 hours. It remained notably mild for most in the south, Santon Downham (Suffolk) reached 15.1C. About 55,000 homes were left without power after a substation was flooded in Lancaster during the storm. In Carlisle, by the day's end about 2,500 properties remained flooded, & the rail network in Cumbria remained "basically at a standstill" with no trains via Preston . There were still 50 severe flood warning out by the days end in Northern England with 40 schools unlikely to open on the 7th, with eight rescue centres across Cumbria open. Road restrictions were in place on the A66 and other routes.The B5295 bridge at Braithwaite, the Fitz Footbridge in Keswick, and Pooley Bridge in the Eden District were washed away. The heavy rain brought a famous waterfall in the Yorkshire Dales back to life for "the first time in living memory". Water flowed over the top of the white limestone cliffs of Malham Cove on Sunday, footage of the occurrence, was filmed by Stuart Gledhill, who said "The waterfall drop was surveyed earlier this year by cave divers and was found to be 70m (230ft), making it briefly the highest single drop waterfall in England above ground."

The 7th was very mild in places in a S'ly flow, Gogerddan (Dyfed) reached 16.4C beating the all time daily date record for the 7th Dec. On the 9th, further fronts & associated rain moved across western parts esp affecting W Scotland and Cumbria. It became windy too in the NW of Wales, NW England & W Scotland with gusts of 80mph at Capel Curig (Conwy) and 74mph at Aboyne (Aberdeenshire). Charterhall (Berwickshire) gusted to 70mph. The village of Glenridding nr Ullswater was once again flooded after the river burst its banks. Glenridding, which had been cut off since Sunday, was flooded again, and police, military officers and the fire service attended the scene. Cumbria Police advised villagers to stay indoors. The 10th continued very wet in the west at least initially. The estimated 24 hr maximum (radar based) rainfall totals to 09Z were about 150mm over mountains around Ft William, 100mm over Snowdonia and 65mm over Cumbria. The 11th was wet but rather cold in the Highlands where Cluanie Inn saw 31mm of rain to 21Z. Cold enough for some snow in parts of the Highlands where Tulloch had 2cm of lying snow.

The 12th was mild for most in the south, colder to the north but very wet in places again as a low pressure area crossed the central UK & the wettest area was around Snowdonia, Capel Curig (Conwy) saw 92mm in the 24 hours to 21Z causing further localised river flooding in places here and on higher ground in the north in an easterly flow the rain fell as snow; by the end of the day there was 6cm of snow at Spadeadam (Cumbria). Dry but quite cold in parts of the Highlands by day, Dalwhinnie only reached -0.9C by day. The 13th saw a cold night in Scotland, Dalwhinnie (Highlands) fell to -8.1C, the lowest UK temperature since last January. A band of rain worked north across central & Northern England during the day and turned to snow across parts of the Highlands & eastern Scotland. At midnight on the 14th Shap had 3cm and Aviemore 4cm but by 6am on the 14th Aviemore had 16cm with a minimum temperature of -5C. The 14th saw a cold start in the Highlands, Kinbrace fell to -7.2C overnight on snow, Dalwhinnie only reached 0.0C by day. By the end of the day there was still 14cm of lying snow at Aviemore as temps dropped away again in the Highlands and N Scotland, in contrast to the very mild weather further south. The 15th saw a cold start in the Highlands on snow covered ground, Aviemore fell to -6.7C. In the far south though very mild and rather wet in places, Bude (Cornwall) rose to 15.3C.

On the 17th in Scotland Achnagart (Highlands) recorded 17.2C at 0500, the highest temp in the UK this month. Perhaps no surprise in such a strange month the highest temperature in the UK should be at 5am in the morning in the far north of Scotland!

The 19th saw the warmest temp ever recorded in UK so late in the year with 17.1C recorded at Graveness (Kent), also a date record. The period from 17th -19th Dec was exceptionally mild and saw a daily CET mean of 12.75C and was probably the second warmest period ever recorded (since 1772) in a winter month. It was wet and locally windy further west though where Whitechurch (Pembrokeshire) saw 55mm in the 24 hours to 21Z and the exposed Capel Curig (Conwy) gusted to 77mph.

On the 20th squally showers ran through the south and west with thunder in places. There was a squall with gust to 66mph at Portland Breakwater unofficially at 2130Z. Emley Moor (Yorks) also reached 62mph. Very wet too in places. The 22nd was a very mild but wet day in the NW. Writtle in Essex reached 16.2C which is a date record. Communities in Cumbria were flooded again (some for the third time in less than a month) following torrential rain and strong winds. The worst affected were the Appleby, Keswick, Kendal and Glenridding areas, where river levels rose quickly. Defences in Appleby were reached when the River Eden burst its banks, flooding 40 properties and prompting several rescues. The Glenridding Hotel flooded for the third time this month. Firefighters used pumping equipment to divert water from an electricity sub station in Appleby. The town's road bridge was closed due to high water levels, as was Keswick's Greta Bridge. Capel Curig (Conwy) saw another 64mm of rain in the 24 hours to 21Z and gusted 71mph & Lerwick to 70mph.

On the 23rd, as fronts pushed in from the west, it became wet in parts of the Highlands & north of Scotland, Tyndrum (Highlands) saw 39mm in the 24 hours to 21Z. Windy too, Capel (Conwy) gusted to 81mph and Magilligan (L'Derry, N Ireland) to 78mph & Aberdaron (Gwynedd) to 69mph. The 24th was wet in places and very windy too as UKMO storm 'Eva' affected the north western UK. Capel (Conwy) gusted to 83mph and Aberdaron (Gwynedd) to 70mph. There were isolated thundery showers with hail in parts of the north & west UK in the afternoon too. Cluanie Inn (Highlands) saw 46mm in the 24 hours to 21Z. A squally cold front moved across the south in the mid to late morning bringing some heavy rain and gusty winds, to 61mph at Portland & 60mph at Worthing Pier (unofficially).

Christmas Day, the 25th saw a locally frosty start in places but it became mild with Bude reporting 14.9C but this was not a Christmas Day UK record (which is 15.6C) but it was very wet in the west and NW as fronts became slow moving  Capel Curig (Conwy) gusted to 66mph & reported 71mm of rain in the 24 hours to 21Z. In Conwy county, the A5 was closed in both directions at Betws-y-coed, and between the A4086 at Capel Curig and the B4409 in Bethesda. In Gwynedd, the A55 was closed between junction 11 with the A5 and junction 15 at Llanfairfechan. There were reports of floating cars and some people had to be rescued. Police had also received reports of flooded homes at Talybont. In the Lake District the Army was called in to support efforts to protect parts of Cumbria against further flooding and the government's emergency Cobra committee met to discuss the situation.

The 26th saw a very mild but dull day for most parts away from Scotland, with Hawarden (Yorks) reaching 15.7C, 0.3C off the date record. A front became slow moving across the north of England. Heavy rain caused more flooding in Wales & northern England, and some areas of Snowdonia saw about 200mm of rain in the 24 hours to 21Z. Homes were evacuated in Lancashire and Yorkshire, and rivers overflowed in Manchester and Leeds: the River Irwell and River Roch both overflowed, causing flooding in Salford, Manchester city centre and Rochdale, while roads in central Leeds, where a severe warning was in place on the River Aire, were also under water. In York, people near the River Foss were being advised by the Environment Agency to move valuable belongings upstairs and be prepared to leave their homes. Two Met Office red warnings for rain were issued for parts of Lancashire and Yorkshire,with seven severe flood warnings in Lancashire - (meaning flooding is expected and there is a danger to life) - and 24 in Yorkshire. Houses in Mytholmroyd, West Yorkshire, and in Ribchester and Whalley, Lancashire, were evacuated after rivers burst their banks. Soldiers, who were deployed to Cumbria on Christmas Eve, were helping residents in Lancashire. Several rivers overflowed their banks, including the River Calder and the Rochdale Canal, leaving houses and a bowling club flooded. Every river in Lancashire exceeded record levels, the Environment Agency said. The M62 was closed westbound between junction 20 at Rochdale and junction 19 at Middleton after a large hole appeared in the carriageway as result of rain, with traffic being diverted. A 200-year-old former pub located on a bridge over the River Irwell was destroyed by flooding at Summerseat. Police warned motorists not to drive unless they needed to, with some roads closed. In North Wales homes were evacuated as flooding brought "chaos" to roads, with people rescued from cars and vehicles left stranded. The A55 was closed between junction 11 for the A5 and junction 15 at Llanfairfechan. The A5 was closed near Betws-y-coed, and in Powys, the A487 Dyfi Bridge at Machynlleth was also shut. Coastguard teams were helping people from homes near Beaumaris castle, on Anglesey, after its moat overflowed. There were also evacuations in the villages of Llandwrog and Bontnewydd, near Caernarfon, and people have been taken to stay with friends or neighbours on higher ground.

The 27th was another mild day with Chivenor (Devon) reaching 15.9C, just short of the all time date record. The effects of the very wet weather continued in the northern England though the worst of the rain had moved away southwards. More than 7,500 customers in Greater Manchester and Lancashire remained without power, Electricity North West said, including 5,500 homes and businesses in Rochdale. Officials said pumps at the Foss Barrier - where the River Foss joins the River Ouse - had been overwhelmed and flood barriers had to be lifted, meaning areas in York that would usually be protected were now vulnerable to flooding. York City Council said the River Ouse was expected to peak at more than 5m - close to its highest recorded level of 5.40m. Residents of the Windsor House residential home, in York, were moved to other care homes after the basement flooded. North Yorkshire Police ran out of "road closed" signs and Northern Rail advised passengers not to travel in Cumbria, East Lancashire and West Yorkshire. Resident Brian Marshall said flood waters in Hebden Bridge, West Yorkshire, had been running with such force on Saturday night that sandbags had been "ripped up". He said: "It was just impossible to do anything." In Wales homes were evacuated after flooding with Red Cross volunteers using 4x4s to transport doctors and nurses to Bangor Hospital due to flooding on the A55.

The 30th was another wet and windy day as UKMO named deep low pressure 'Frank' moved NW of Scotland and its fronts and winds affected many parts of the UK leaving further flooding in its wake. In the far north Fair Isle gusted to 75mph whilst in the far south west the Scilly Isles gusted to 75mph. Scotland bore the brunt of the bad weather, Tyndrum (Highlands) seeing 82mm in the 25 hours to 21Z, with hundreds of homes evacuated in the Borders towns of Dumfries, Hawick and Peebles. In Dumfries and Galloway, the River Nith burst its banks causing flooding in the town of Dumfries. A severe flood warning, indicating danger to life, was issued for the Whitesands area. The villages of Moffat and Carsphairn were cut off and fire crews rescued people from properties by boat. The River Tweed in Peebles also had a severe flood warning in place with more than 300 homes evacuated in Hawick. Emergency services responded to reports of a missing kayaker on the River Findhorn in Moray, while in south Ayrshire 12 passengers had to be airlifted from a bus stuck in flood water near to Dailly Cemetery. National Rail reopened lines in Scotland following flooding on the Scottish railway network by the evening but a landslip closed the A83 in Argyll & flooding closed the M74 in South Lanarkshire for a time. More than 100 people were evacuated from their homes in Ballater in Aberdeen. In North Yorkshire, soldiers evacuated homes near a bridge in Tadcaster after it collapsed, prompting fears of flooding and a possible gas explosion. In Northern Ireland, about 20,000 homes and businesses in Northern Ireland lost power overnight. In Wales, more than 1,400 properties in Carmarthenshire, Pembrokeshire, Swansea and a handful in Ceredigion lost power and the weather caused three separate crashes on the M4 where there was standing water on both sides of the motorway between junctions 35 at Pencoed and 36 at Sarn. Further south part of the Victorian Birnbeck Pier in Weston-super-Mare collapsed into the Bristol Channel due to high winds. In Devon, a delivery driver smashed through the window of a car to save the lives of two elderly people trapped in rising floodwater in Sparkwell, Devon.

On the 31st it was a windy night along the south coast esp as squally showers with hail ran east, The Needles (Isle of Wight) reported 92mph, the highest gust in the UK this December, Prawle Point (S Devon) unofficially gusted to 78mph, St Catherines Point (Isle of Wight) gusted to 73mph and unofficially so did Portland Breakwater & Worthing Pier (W Sussex). Portland (Dorset) gusted to 68mph. Thunder was also reported in several locations. Another occluded front which ran east along southern counties in the late afternoon also gave strong winds and some hail and thunder (76mph unofficially at Hurst Castle, Milford, Hants).

 

David Wiseman disclaimer – Issued as a non commercial  ‘Not for profit’ forecast. The user assumes the entire risk related to its use of this data. I am providing this data "as is" and disclaim any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will I, David Wiseman, or any related contactors be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data . Climate stats have been compiled with the partial use and help of UKMO news page data , with thanks. Other news data was compiled from many sources including UKww reports, news papers & some BBC local news reports.