Electricity North West weather watch – December

Tomorrow (5^th December) marks the two year anniversary of Storm Desmond which caused widespread damage and disruption and the loss of power to 55,000 people in Lancaster and Morecambe and more than 13,000 homes and businesses in Cumbria. 

Since Storm Desmond we have invested more than £270m in the network which will benefit more than five million customers from rural Cumbria to urban Manchester, including almost 1,000 miles of trees cut, £14m in upgrading and replacing overhead power lines and £14m in upgrading underground electricity cables.

The financial boost also includes a further £5.4m investment to help protect key substations of which £4.6m has been invested at our main substations at Lancaster, Carlisle and Rochdale. The extra defences, which include raising key equipment over 10ft high, new flood doors and CCTV which help monitor any activity in the substation.

Despite significant investment we still monitor the weather closely, so let’s find out what the weather has in store for the region for this festive period, with MeteoGroup senior meteorologist, Matthew Dobson.

Look back: November and the role of La Nina

After a mild and blustery October, with a couple of potent wind storms passing across the UK, November has on the whole been a quieter month, with a lack of strong wind events and no further UK Met Office named storms. The reason for this has been a large area of high pressure which has steadily intensified just to the west of the UK during November, expanding northwards towards Iceland in the last ten days. It has acted as a barrier to approaching Atlantic low pressure areas, diverting many of them well away to the north and east. Meteorologists call these persistent high pressure ridges, 'blocks'. They can disrupt the normal westerly motion of weather systems from the Atlantic and into Europe.

An interesting aspect of the UK's weather through November has been a curiously repetitive cycle. We ended up seeing short-lived cold snaps, with chilly north-westerly winds, mainly sunny skies and local night frost during the weekends and start of each week. But then spells of cloudier, damp and milder weather pushed through during the Tuesday to Friday periods. This has happened, almost like clockwork, during every week of the month! Such cycles do occasionally develop and can make things easier for long range weather forecasting, if we can be confident no other global weather pattern will upset the balance. In this case, we saw an alternating cycle of fairly weak low pressure areas and their fronts pushing eastwards for a few days, followed by transient ridges of high pressure toppling south-east, leading to the brighter, drier and colder snaps.

An explanation for the persistent high pressure area to the west of the UK can be attributed to a developing 'La Nina' in the tropical Pacific. La Nina is Spanish for the 'The Girl Child'. It is the reverse of the more widely quoted phenomenon, El Nino or 'The Boy Child'. La Nina is simply when the normally cool sea waters periodically become even cooler.  The 'see-saw' of El Nino - La Nina is truly a global weather pattern, as scientific research confirms that both La Nina and El Nino do have some influence on the UK's weather. When La Nina is developing in autumn, more often than not the UK will see a greater frequency of calm, dry and often chilly conditions in November, with winds from the North West.

Look forward: December and how may La Nina affect the UK's weather this month

November ended on distinctly cold note, with raw northerly winds, and heavy snow showers affecting northern and eastern Scotland and eastern coastal counties of England. Early December will see some moderation of this cold, as winds flip back to a less cold west or north-westerly direction and cloud and patchy rain will reduce the frost risk. The Atlantic jet stream should become stronger as we head through the first half of December and this brings the threat of some deeper low pressure areas tracking close to the UK.

For instance, we are keeping a close eye on a spell of strong to gale force south-westerly winds and heavy and prolonged rainfall, expected to sweep the Electricity North West region on Wednesday night and Thursday. A squall line of briefly torrential rain and very gusty winds (50-60mph gusts even inland) is predicted to sweep the region from west to east during Thursday daytime, followed by much, colder, windy and showery weather for Friday and Saturday.

The temperature change between Thursday and Friday will be impressive, with highs hitting a very mild 12-14C on Thursday morning, crashing to close to zero on Thursday night and then highs of only 3-6C on Friday daytime!  Watch out for wintry weather hazards of snow, frost and ice on Friday and through this weekend. Plenty of heavy and squally showers, falling as snow and bringing the chance of a covering to some areas, perhaps even to low levels.

With La Nina still intensifying, it is likely that low pressure areas will still be steered south-eastwards across the UK for much of the time, maintaining the threat of some cold northerlies at times.

In the event of an unexpected power cut you can contact Electricity North West 24/7 on the new free national number 105 or call 0800 195 4141 or let us know on Twitter @ElectricityNW.

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