UK Weather - Winter 2018/19

Simon Culling · Unread post by **Simon Culling** » Tue 04/12/2018 00:04

Winter 2018/19 has started on a very mild note in the south of the UK with the temperature reaching 15.3*C at Westonzoyland (Somerset) on the 1st and 15.9*C at Kew Gardens (London) on the 2nd. Whilst it has remained generally cloudy with outbreaks of rain or showers, the dry spells have given us some hazy sunshine. These mild temperatures are not unprecedented and it is not unusual for a winters day in the UK to see a maximum of 15*C even at the coldest point of the season. The record UK temperature for December and January is 18.3*C for both months and these were recorded at Achnashellach (Highlands) in 1948 for December and at a number of locations and dates for January.

It will remain on the mild side for the rest of the week, although it is a little colder further north and in Scotland, where some snow is likely over the higher ground. The models are struggling beyond Friday, but I think the Atlantic theme will continue with further low pressure systems to the west and north of the UK. Next week might see higher pressure to the south or south east of the UK which will bring drier and cooler weather to the southern half of the UK. No signs of winter yet, though.

Simon Culling · Unread post by **Simon Culling** » Wed 05/12/2018 20:41

There was a general frost over the UK on Tuesday morning, but there was quite a temperature contrast from north to south with the lowest values in the former. The mercury fell to -6.2*C at Redesdale Camp (Northumberland), to -6.1*C at RAF Topcliffe (N Yorks) and to -5.2*C at Eskdalemuir Observatory in the southern Uplands of Scotland. Further south, the low was -1.7*C at Bournemouth Hurn Airport, but +3.2*C on the coast at Swanage. Further south west, in Cornwall, and despite clear skies, Camborne recorded a low of 5*C whilst the Scilly Isle had 8*C. Here in Hythe we had a nip of frost on the grass, but there was a fabulous view of the crescent Moon and Venus very close to one another in the sky to the south at 06:30.

There has been a bit of a shift in the forecast, with the wet and windy weather continuing into the weekend, but then a build of pressure is expected to our NW as the lows move a bit further east and we will see a cooler NW flow bcome established. This will give dry and sunny weather for those of us in the south with frosty nights. Could be a bit of a hooley on Fri/Sat.

Simon Culling · Unread post by **Simon Culling** » Mon 10/12/2018 23:15

The coolest weather remained in the north (especially in Scotland) last week and indeed, the lowest temperature of the season was recorded - a low of -8.8*C was reported from Braemar (in the Scottish Highlands) on the morning of the 5th. The south remained milder with plenty of rain, but we did have the odd frosty night. As the sun reaches its low point in the sky, the days are noticeably darker at the moment, especially when it is cloudy - we need the lights on indoors sometimes at midday!

The forecast shifted a few days ago and we are now seeing a bit of a high pressure block building to the east and it will get progressively colder as the new week progresses as we draw in air from the east, although not that cold that we will see any snow. Current thinking is for the Atlantic to win through next weekend with a return to wet and windy (and mild) weather.

The CET for December was 8.4*C (+3.4*C) up to the 8th reflecting the very mild start to the month. The EWR was 46mm also up to the 8th, which is 48% of the monthly average of 96mm.

Simon Culling · Unread post by **Simon Culling** » Wed 12/12/2018 19:37

It has been a little cooler in the last couple of days, but it will turn much colder from later today (Weds 12th Dec) as we draw in a south easterly feed from the continent. This will usher in a few cold days with a nagging SE breeze, but it is likely to be mostly cloudy and dry - just the odd flurry in the wind on Friday in the far east. The cold spell is likely to be short lived as a vigorous low shunts the high pressure block further to the east at the weekend and we regain an Atlantic influence on our weather. As the associated fronts move into the country on Saturday, the rain will turn to snow for a time over more northern areas and particularly on the hills, but the south is likely to see plenty of wind and rain!

There is increasing talk of a SSW event towards the end of December and plenty of exited chatter about cold weather for NW Europe, but we should remember that a SSW event does not always mean cold weather is guaranteed. If the forecast does materialize, and it is only a forecast, this will make model watching much more interesting into 2019.

Simon Culling · Unread post by **Simon Culling** » Sat 15/12/2018 11:22

It has turned colder over the last few days with a raw easterly breeze yesterday (Thurs 13th) making it feel even colder. The wind died down overnight into Friday allowing a sharp frost to develop inland in more southern parts - the temperature fell to -6.7*C at South Farnborough, -5.7*C at RAF Benson and to -5.6*C at RAF Odiham (Hampshire). Today was bright over much of the UK , but maximum temperatures only ranged between 1-4*C in most parts but at least the wind was light.

The forecasters are in a bit of a spin at the moment as a big (and deep) low moves NNE to be south of Iceland by midday Saturday (15th) with a smaller low pushing into Eire. As the fronts move into the UK and encounter the resident cold air, they are forecasting not just snow but also freezing rain for northern England and southern Scotland - it is rare for freezing rain to be forecast, and in this case I think it is more likely over the higher ground such as the Pennines, the Peak District and the North York Moors, but it may occur on lower ground in the far NE of England. Further south, we will see strong winds and planty of rain - some private forecasters have bravely forecast a 'sting jet' for the southern Irish Sea (on the SW side of the smaller low) with the very strong winds (suggested up to 100mph) affecting southern Eire and pats of Wales. It will be interesting to see how these brave forecasts pan out.

EDIT: Met Eireann have named the smaller low Deirdre as they expect some severe gusts in southern counties.

Simon Culling · Unread post by **Simon Culling** » Sun 16/12/2018 23:26

The forecast and warnings from the Met Office were justified as quite a large area was affected by freezing rain on Saturday afternoon and evening. It occurred inland from the coast over much of northern England and into southern Scotland and particularly affected the Pennines and Peak District, the Yorkshires and NE England (Durham, Northumberland + Tyneside). It was not restricted to high ground either as places down to 300/400ft amsl appear to have been affected for a time and the precipitation was mixed with some snow and ice pellets - this combined with a 20-30mph wind made it an unpleasant day with plenty of slips/falls and prangs on the roads!

The two tweets below give an idea of the effects:

https://twitter.com/DaveThroupEA/status ... 9754715136

https://twitter.com/thehomefarmer/statu ... 3829437443

The sounding on the following tweet is for Nottingham at 12:00 on Saturday and whilst this was just south of the area affected by the freezing rain it is a classic example nonetheless:

https://twitter.com/danholley_/status/1 ... 9842588672

Here in Hythe, Saturday dawned cold (4*C) and wet and it did not improve much - we had 25mm of rain and a strong SE wind for much of the day. The temperature did rise to 10*C by teatime.

Simon Culling · Unread post by **Simon Culling** » Tue 18/12/2018 01:12

It has warmed up since the cold of Saturday and most of the ice and snow has melted, but the rain and showers continue and will do so for the forthcoming week. The first charts are appearing for Christmas Day and it is looking dry at the moment with perhaps a little frost in the morning, but a lot can change in a week.

There was surprisingly little coverage in the main news media about the freezing rain 'up north' at the weekend, as the southern bias (often referred to as Londoncentric) appears to continue. This was a significant event for quite a large area and restricted transport for over 24 hours. Another couple of Twitter reports with good pictures below - the freezing rain was followed by snow in some places.

https://twitter.com/northnews/status/10 ... 6564921345

https://twitter.com/TRobD14/status/1073992954392559617

As some of you may recall, we also had a freezing rain event in southern England at the beginning of March, so two such occurrences in one year is something of a rarity.

The CET for December was 6.7*C (+1.8*C) up to the 16th and the EWR was 65mm up to the 15th, which is 68% of the monthly average. The latter will rise to near average by the end of this week.

Richard · Unread post by **Richard** » Thu 20/12/2018 19:53

I dont recall if freezing rain has ever happened in NZ

Simon Culling · Unread post by **Simon Culling** » Fri 21/12/2018 23:19

Hello Richard. We discussed this topic in the Spring 2018 thread on UK weather - from post number 13 onwards. Freezing rain is quite rare in the UK and especially over large areas and we need to go back to January 1940 for the worst documented case - there was a Geophysical Memoir (Number 98, I think) published after WW2 on this event, which affected much of the southern half of the UK.

The mild, windy and rather wet weather has continued but there looks to be a change coming in time for Christmas as high pressure exerts more of an influence. It will be a little cooler, but I fear that this may be a cloudy high, so rather dull weather ahead for the very short days. The attached blog entry is from one of the private weather companies here in the UK and also gives a bit more information on the predictions of a SSW event towards the New Year at the end of the entry:

https://www.netweather.tv/weather-forec ... ear-beyond

The positioning of the two lobes is important (assuming the polar vortex does split), so any 'cold weather' for NW Europe is still only a possibility rather than a definite.

Nev · Unread post by **Nev** » Sat 22/12/2018 06:10

Not sure how rare 'freezing rain' is in NZ, but it was mentioned in MS forecasts last year…
https://twitter.com/MetService/status/8 ... 2732665856

There has been the odd report of 'freezing fog' on this forum though…

Simon Culling · Unread post by **Simon Culling** » Mon 24/12/2018 20:53

Thanks for posting that link, Nev. I would suggest that a widespread freezing rain event would be unlikely in New Zealand due to the lack of a continental influence. However, it must occur occasionally in inland areas of the South Island (areas such as central Otago, the Mackenzie Basin + the Canterbury High Country), especially when rain arrives from the SW/W following a very cold spell and the ground temperatures remains below freezing. These would be transient events and more likely to occur overnight and with low wind speeds - so that the low level inversion is not broken down completely.

The weather in the UK has remained mild with rain at times and it is not looking very festive for the Christmas period. The last of the rain will die out today (Monday 24th) and then we can look forward to at least 5 generally cloudy and dry days under the influence of high pressure. This system has plenty of cloud trapped within it, although hopefully there will be some breaks and a little sunshine in favoured places. It will be a little cooler but still on the mild side for the time of year. Even the mountain tops will struggle to see any snow this Christmas.

The forecast SSW event is still in the model output for early in the New Year and the Met Office monthly outlook is still bullish for colder weather in Jan/Feb, but there is nothing exciting yet out to 10 days at the surface. However, if a significant SSW event occurs, changes in the synoptic pattern can occur very quickly.

The CET for December was 6.9*C (+2.1*C) up to the 22nd and the EWR was 103mm up to the 21st, which is 103% of the monthly average.

NZ Thunderstorm Soc · Mon 24/12/2018 23:52

Simon Culling wrote: ↑Mon 24/12/2018 20:53 It will be a little cooler but still on the mild side for the time of year. Even the mountain tops will struggle to see any snow this Christmas.

...so Bing Crosby's song "I'm Dreaming of a White Christmas" is out of the question there, Simon ?

...anyway have a good Christmas and thanks for yor interests in the frosts that we have this year in Raukupaka, Geraldine this year.

Richard · Unread post by **Richard** » Tue 25/12/2018 06:15

Simon- I spent 25 years working throughout the South Island high Country, mostly from May - Oct, I had never heard of freezing rain before learning of it in more recent years, seen lots of big snowfalls during that time but never a freezing rain.

when rain arrives from the SW/W following a very cold spell and the ground temperatures remains below freezing.

In the High Country cold spells are bought about by a anticyclonic periods and cold fronts are always preceded by fohn westerlies especially in those higher region, so any cold air left over from a cold spell is blown out of the valleys. Any freezing that happens is after a shower has past and the sky clears allowing the temps to drop below freezing

Nev · Unread post by **Nev** » Tue 25/12/2018 13:32

Sorry for getting a bit OT here, but thought this informative little snippet might be of interest…

How to Teach Met - CAA/MetService 2015

Freezing rain (pg 186-187)
Freezing rain forms most often in continental climates where a pool of very cold air gets trapped behind a mountain range and…

A warm front brings cloud, precipitation and, most importantly, warm temperatures aloft.

In most cases, the precipitation starts out as snow in the mid-troposphere. It then falls through a warm layer (the warm frontal boundary) and melts.

As rain, it then falls into a shallow layer at temperatures a few degrees colder than 0oC.

Although the droplet cools to a few degrees colder than zero, it doesn’t re-freeze because the aerosols inside it, which were suitable as freezing nuclei in the mid-troposphere, are not suitable freezing nuclei at temperatures only just below 0oC.

Large super-cooled rain droplets are formed. When they fall onto the earth they freeze slowly on contact with any surface colder than zero, including your aircraft.

Freezing rain is extremely rare in New Zealand.

This is because we rarely get classical warm fronts in combination with sub-zero surface temperatures.

Central Otago and Southland however, can display ersatz continental climate characteristics.

Indeed, freezing rain has been reported just twice at ground level in New Zealand – once in Queenstown and once in Invercargill.

Freezing rain.jpg

Hope you have a very Merry Christmas Simon!

...(anticyclonic gloom notwithstanding

)...

Simon Culling · Unread post by **Simon Culling** » Sun 30/12/2018 00:08

Thanks to Richard, Nev + John for their posts concerning freezing rain in NZ. And a belated Merry Christmas + Happy New Year to all Forum members - I have been away for Christmas and without access to a computer - we should all try this as it is quite therapeutic.

It does appear to be a very rare event for true freezing rain (with a classic warm nose of air above the ground), but as in the UK, a rainy day followed by a frosty night can give very slippery roads as it all freezes up. In these cases, the ice is often difficult to spot on the roads as it is clear and not always topped with hoar frost.

We have also had plenty of anticyclonic gloom here in the UK Nev, as a high pressure cell has sat over southern Europe giving us light south westerly or westerly winds and predominantly cloudy skies for the last few days. However, the sun did manage to appear on Thursday (27th Dec) to give us a lovely sunny day in Tiverton, Devon, after a nip of frost. It has been a bit colder (especially at night) in Scotland where skies have been clearer, but fog has lingered all day in places and Glasgow had freezing fog all day on Christmas Eve with a maximum of just -1.9*C at the Bishopton site. Such are the vagaries of anticyclones.

The CET for December was 6.9*C (+2.1*C) up to the 27th and the EWR was 114mm also up to the 27th, which is 119% of the monthly average.

spwill · Unread post by **spwill** » Sun 30/12/2018 07:33

I think the closest thing to freezing rain in NZ is a rain shower on a frosty morning, the cold ground freezing the rain drops. I have seen this in Central Otago and Dunedin but rain showers on frosty mornings are far from normal in NZ.

jamie · Unread post by **jamie** » Sun 30/12/2018 08:15

spwill wrote:I think the closest thing to freezing rain in NZ is a rain shower on a frosty morning, the cold ground freezing the rain drops. I have seen this in Central Otago and Dunedin but rain showers on frosty mornings are far from normal in NZ.

We have had this a few times in Waikato that I can recall. End up with big balls of water (rain drops) being frozen. But we are only talking a skiff of a shower. Not even 1mm of rainfall I would think.

Sent from my iPhone using Tapatalk

spwill · Unread post by **spwill** » Sun 30/12/2018 08:23

Yes, just a light shower in my experience.

Simon Culling · Unread post by **Simon Culling** » Mon 31/12/2018 11:21

The anticyclonic gloom has continued through the weekend but at least it has remained mild. However, there will be a subtle change in the atmospheric pattern early in the new week that will shift much of the low cloud to give us some sunshine albeit in a colder airmass. The high pressure will move a little west and build northwards to the west of the UK and this will turn the winds to the north by Tuesday and introduce a much cooler airmass behind a weak south moving cold front. As the high then drifts very slowly east/south eastwards, it will sit over the UK by Wednesday with a central pressure of around 1046mb, but the main thrust of the cold air will be further to the east over Scandinavia and into eastern Europe. We will at least get a few dry and sunnier days with some frost at night.

The Sudden Stratospheric Warming over the North Pole appears to have begun very quickly in the last few days and it will be interesting to see how much higher the temperature at 10hPa will go. The rise at 30hPa is not as pronounced....yet. The graph below is taken from the Tokyo Climate Centre - many of the US sites seem to be closed due to Trump's government shutdown!

Simon Culling · Unread post by **Simon Culling** » Sat 05/01/2019 01:00

The area of high pressure duly strengthened and built over the whole of the UK on the first day of the new year and has remained slap bang over the top of us since. The synoptic map below (courtesy of the Met Office) is for 06:00GMT this morning (Fri 4th Jan) and as you can see, it still has a central pressure over 1040mb. At its height, it seems to have reached at least 1048mb as the highest hourly reported pressure I can find is 1047.7mb which was recorded at Tulloch Bridge (Western Highlands, Scotland) at 09:00 on Weds morning (2nd Jan).

The high has been generally cloudy for most places (including Hythe!!), but western parts and eastern Scotland have seen sunshine and frosty nights. The lowest temperature of the winter (so far) was recorded on Thursday morning at Braemar (in the Scottish Highlands), where the mercury fell to -10.5*C. Nearby Balmoral reported -9.8*C and both sites had a couple of days with their maximums well below freezing - when the air gets trapped in those Scottish glens the sun is not strong enough at this time of the year to provide much warmth.

Simon Culling · Unread post by **Simon Culling** » Tue 08/01/2019 00:25

The high pressure has retreated a little to the SW of the UK (into the Bay of Biscay) but still has a central pressure of 1042mb this morning. This will allow a developing low (986mb) in the northern Atlantic to curve SE to the north of Scotland and head into Denmark by Tuesday morning. This will give the north of Scotland a windy spell and also probably produce a small storm surge in the North Sea - thankfully it should not coincide with high tide for the UK, but I am not sure about the Netherlands where the onshore wind will be a lot stronger tomorrow.

Despite this excitement, the weather has remained benign over the UK in the last few days as the cloudy spell continues - there has hardly been any sunshine in most of the UK this year! As the low moves away we will then be in more of NW flow and this will at last push the cloud away for a while and give us some sunshine and it will be mostly dry - just a few showers in the NW of the UK. However, later in the week (Thurs) the high will push back in from the W/SW and we will be back to the dull and cloudy weather again.

CET for January was 3.9*C (+0.3*C) up to the 6th and the EWR was nil up to the 5th - the monthly average is 91mm for January.

Simon Culling · Unread post by **Simon Culling** » Wed 09/01/2019 01:02

The low duly followed its forecast path and at 06:00 this morning (Tues 8th Jan) it was at 990mb and slap bang over Denmark. It gave a windy afternoon and evening to northern parts of Scotland with some reports of damage on the BBC link below. The video of the drifting sand from the beach at Thurso and the waterfall being blown uphill are the highlights. The highest gusts from Met Office sites were:

78mph at Sule Skerry (a small island off northern Scotland)
76mph at Wick
74mph at Loch Glascarnoch + Fair Isle
72mph at Kirkwall Airport (Orkney)
71mph at Altnaharra

Whilst these wind speeds might not be high for Scotland, the wind direction was more W/NW which is general a less common source of gales in this area. A private station at Sandy Hill (on Orkney) reported gusts up to 96mph with quite a few others were in the 80-90mph range.

https://www.bbc.co.uk/news/uk-scotland- ... s-46781822

Today, a small storm surge has moved down the North Sea to affect the coast of eastern England and East Anglia with tides approx. 1.5m above normal. This will lead to some minor coastal flooding.

https://twitter.com/Netweather/status/1 ... 9176820736

Simon Culling · Unread post by **Simon Culling** » Sat 12/01/2019 00:08

Whilst tidal levels were higher than normal on Tuesday (8th Jan) along the coasts of East Anglia and SE England there were no reports of serious flooding. Huge waves did overtop the defences, but thankfully damage was very limited and localised. The graph below is for the tidal gauge at Cromer (Norfolk) and shows that the first tide of the day on the 8th was about 1.5m above normal.

The weather has been quite a bit cooler since the windy weather on Tuesday with some sharp night-time frosts in places (-6.4*C at RAF Benson yesterday - Thurs), but there has still been quite a lot of cloud at times. Today (Fri 11th) is a little milder and the cloudy mild theme will continue over the weekend and into next week. Whilst the models are trending colder from later next week there is still no evidence yet for a repeat of the 'beast from the east'

The persistent anticyclonic weather has meant that it has been very dry over much of England + Wales for the last few weeks and some sites in southern and eastern parts have not had any measurable rainfall since Christmas Eve, i.e. 18 days. This is something of a rarity for this time of year as one of the most regular weather singularities here in the UK is a return to wet and windy weather between Christmas and the New Year.

Richard · Unread post by **Richard** » Sat 12/01/2019 06:44

Amazing the tidal ranges you get, that 1.5m storm surge is not a lot less than the tidal range on the coast out from here

Simon Culling · Unread post by **Simon Culling** » Tue 15/01/2019 02:15

Richard, the UK has one of the larger tidal ranges in the world - I will try to get two photos of high and low tide at Hythe to illustrate this point. They range between about 2m to 12m (Avonmouth, on the Severn Estuary has the highest) and depend on the local topography. There is a very noticeable difference between low and high tide in most parts of the UK and in the Solent I think the range is about 3-4m.

It has remained mostly dry over the UK (although NW Scotland has seen persistent rain bands off the Atlantic) and generally mild - it was 12*C here in Hythe on Sunday afternoon and we did manage some sunshine. The trend is for colder weather to progressively arrive from midweek, but we are looking at a NW flow rather than one off the continent. The air source will be from a rather cold Canada and this can produce plenty of snow in marginal conditions (so it will be wet snow) as low pressures slide across the UK from the W/NW rather than the more normal SW. Under these circumstances the models get very conflicting and the weather is difficult to predict more than 2 or 3 days ahead. Looks like things will get a lot more interesting than they have been for the last 2-3 weeks, but the devil will be in detail.

CET for January was 5.3*C (+1.8*C) up to the 13th and the EWR was just 2mm up to the 12th.

The final CET for December was 6.9*C (+2.2*C) and the EWR was 116mm - which is 121% of the average.

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