Where have the long fetch northerlies gone?

[cheese]

3 hours ago, I remember Atlantic 252 said:

well 90's were very snowy here, upto about '98, then winters changed

I don't remember much snow in the 90s at all. The only event that sticks out to me was in January 1995, but that was mostly a northern event. Leeds had 40cm.

Edited October 27, 2017 by cheese

[stainesbloke]

On 26/10/2017 at 11:09, Sunny76 said:

Even with the post 1987 mild phase, the country had another cold snowy event in Feb 1991, which lasted for quite a few days. It was very cold.

Yes, remember it well. Was -10C first thing in the morning, as the really cold air moved in overnight. Then the snow came and the maximum here was -5C on that first day. 

[Weather-history]

23 hours ago, I remember Atlantic 252 said:

well 90's were very snowy here, upto about '98, then winters changed

How much snow did you see from March 1991 to October 1993? 

[Weather-history]

20 hours ago, cheese said:

I don't remember much snow in the 90s at all. The only event that sticks out to me was in January 1995, but that was mostly a northern event. Leeds had 40cm.

They weren't, from January 1990 to mid November 1993 apart from first half of Fenruary 1991 and December 1990 snow event was virtually snowless. February 1997 to the end of decade was virtually snowless.

[hillbilly]

Maybe it depends where you are from but here in the pennines we always got snow but what does stick in my mind was the late 90s,i think it was either 1997 or 1998 when I could not believe it was almost xmas before we got our first snowfall,now it is almost normal and just a few years ago it was the 3rd week of January.Snowfall during the 90s before 1997 was certainly better than most of the last 20 years except for about 4 of them.One other distinction I have noticed is lack of wind,only March 2013 produced Blizzard like conditions which we got in 1990,1993 and 1995 and almost every year in the decade before 1987.

[Walsall Wood Snow]

1 hour ago, Weather-history said:

How much snow did you see from March 1991 to October 1993? 

As someone who lives regionally close, nothing comes to mind. There could have been a little perhaps at some point, but I vaguely remember a cold and frosty spell in December 92 but there wasn't any snow I think. I believe Winter 1991/92 had a few cold spells, but from clear high pressure. In fact frost seemed to feature more commonly in the 90s I think, and as a kid then, my Mum having to deice the car seemed a common feature during Autumn and Winter (not all the time or every year I'm sure). Decent snow was something I expected maybe one day a year though if that. The Winter of 1990/91 is the earliest decent Winter I have any memories of, but even they are pretty vague and it wasn't until years later I realised when it would have been and how long lasting etc. I've got some photos of me in it though next to a snowman I made. You can tell it's still snowing on them a bit and I look like I'm standing in an arctic wilderness wrapped up in my little parker, as everything even the hedges are thickly plastered in snow.

Another point is why are some people determined to make such a big deal about the fact there were 3 mild Winters following give or take 11 cold Winters in the late 80s. Winter 1990/91 was similar to those previous Winters so nothing much changed at the time did it. They've just become more elusive for a time, but they still come as they did between 2008 and 2013.

[Sunny76]

Maybe the mid July thunderstorms on the 18th of that month, was the start of a shift to cooler weather. Since then, warmer spells have been less frequent, and even the sunny warmer days have been in short supply. 

This could have been the start of a new climate shift, without anyone noticing. Temps have been lower than normal since, despite the slightly warmer October. 

[Relativistic]

1 hour ago, Sunny76 said:

Maybe the mid July thunderstorms on the 18th of that month, was the start of a shift to cooler weather. Since then, warmer spells have been less frequent, and even the sunny warmer days have been in short supply. 

This could have been the start of a new climate shift, without anyone noticing. Temps have been lower than normal since, despite the slightly warmer October. 

* Almost record-warm October.

[Sunny76]

1 hour ago, Relativistic said:

* Almost record-warm October.

I wouldn’t go that far.

Octobers of 1985, 1995 and 2011 had warmer temps.

October 2017 was mediocre at best, for any attempt at an Indian summer. Most of this month has been cloudy and dreary, with very brief warm spells. 

I’m also glad it’s turning colder as fresher now. 

[Weather-history]

On 10/27/2017 at 23:44, Walsall Wood Snow said:

As someone who lives regionally close, nothing comes to mind. There could have been a little perhaps at some point, but I vaguely remember a cold and frosty spell in December 92 but there wasn't any snow I think. I believe Winter 1991/92 had a few cold spells, but from clear high pressure. In fact frost seemed to feature more commonly in the 90s I think, and as a kid then, my Mum having to deice the car seemed a common feature during Autumn and Winter (not all the time or every year I'm sure). Decent snow was something I expected maybe one day a year though if that. The Winter of 1990/91 is the earliest decent Winter I have any memories of, but even they are pretty vague and it wasn't until years later I realised when it would have been and how long lasting etc. I've got some photos of me in it though next to a snowman I made. You can tell it's still snowing on them a bit and I look like I'm standing in an arctic wilderness wrapped up in my little parker, as everything even the hedges are thickly plastered in snow.

Another point is why are some people determined to make such a big deal about the fact there were 3 mild Winters following give or take 11 cold Winters in the late 80s. Winter 1990/91 was similar to those previous Winters so nothing much changed at the time did it. They've just become more elusive for a time, but they still come as they did between 2008 and 2013.

Snowiest period for my area from mid January 1997 to end of the 1999 was believe it or not mid April 1998!

Any other snowfalls in that period were tranistory at best. One snowfall and it was gone.

Snowiest periods for my area during the 1990s

First half of February 1991, last third of December 1993, mid February 1994, March 1995, December 1995, late January-February 1996, late December 1996-early January 1997 and mid April 1998.

Second half of February 1991 to late November 1993 was virutally snowless apart for the very end of February and start of March 1993

 

[Relativistic]

15 hours ago, Sunny76 said:

I wouldn’t go that far.

Octobers of 1985, 1995 and 2011 had warmer temps.

October 2017 was mediocre at best, for any attempt at an Indian summer. Most of this month has been cloudy and dreary, with very brief warm spells. 

I’m also glad it’s turning colder as fresher now. 

In terms of maximum temperatures, no records have been set. But the month as a whole has seen average temperatures well above average. The CET is almost certain to finish comfortably above 12C, which will put it amongst the warmest Octobers in over 350 years.

[Thundery wintry showers]

I think the main reason for less UK snow during the winters of 1988-2004 was the synoptic setups, with a greater emphasis on a positive North Atlantic Oscillation, more westerlies, and less northerlies and easterlies.  Rising global temperatures also contributed, but the region of the Arctic from Svalbard into the Russian Arctic, which is where our northerlies often originate from, only warmed slightly.  North Sea areas (e.g. Aberdeen, Newcastle, Norwich) tended to pick up one or two snow events even in mild winters due to snow showers off northerlies, probably the starkest example being the last of those winters, in 2003/04.

Since then, we've still been getting the northerlies but they just haven't been as cold, because our source region of the Arctic has warmed massively, with some winter months seeing widespread anomalies of 10-15C.  There was a straight northerly on New Year's Eve/Day 2016/17 which brought only rain and sleet showers to eastern areas, and another one back on 14/15 February 2016 which gave most areas only wet snow and the odd dusting.   Historically shortwaves in northerly airstrreams sometimes produced frontal snow, and indeed inland areas often relied a lot on them because of the tendency for showers to often be concentrated around coasts, but in recent years it often hasn't been cold enough.

2010 was a very interesting case because although the Arctic was anomalously warm on average, the warmth was strongly concentrated in the Canadian Arctic and our source regions saw much closer to average temperatures (and as one of Reef's graphs showed early in this thread, this area of close to average temperatures extended to the general region north of 80N).  The northerly of 18 December 2010 picked up a scoop of cold air from continental Greenland as well as pulling in air from Svalbard and the Russian Arctic, where temperatures were close to the long-term average, and this led to a northerly of rare potency for recent years.  That combination of relatively low temperatures in our cold air source regions, plus favourable synotics to bring it to the British Isles, and anomalous warmth in the Canadian Arctic, was also a feature of the winters of 1947, 1963 and 1979.

This year, our cold air source regions haven't been as anomalously warm so far as they were last year, although that's not saying much.

Edited October 29, 2017 by Thundery wintry showers

[Singularity]

The retreat of the Arctic Ocean sea ice margins has certainly hurt the potential depth of cold in direct northerlies over the past couple of decades. Last winter it was the worst situation so far, but different wind patterns have allowed the sea ice to recover closer to what was typical a decade or so ago, which is not a big gain but better than nothing. Still - it seems we must indeed look NE to E for our coldest airmass imports these days. One may wonder about looking NW to Greenland, but unfortunately, descent of even extremely cold airmasses down the eastern slopes of the ice sheet results in a lot of adiabatic warming (the airmasses are usually very dry having lost their moisture while ascending the western slopes), which modifies the depth of cold to the point that it's no longe cold enough to be of much use after traversing the northeastern waters of the N. Atlantic.

About a decade ago, I had hopes that disrupted jet stream and polar vortex patterns would increase blocking incidences close to our NE to such an extent that having to look between NE and E would not seem much of a problem, but alas, other forcing has proved sufficient to deny us much access to those bitter airmasses when even just a couple of the many teleconnections are in states that favour more in the way of westerly flows across our lands. It seems unfair until you consider that we are a small island nation on the eastern edge - so downstream based on typical thermal winds which are westerly - of a large body of open water through which flows a current that originates right down in the tropics.

Well okay - the fact that we can't look to potent northerlies to interrupt this as much as was once the case, well that's largely humankind's fault anyway based on the majority of scientific literature, and it's true that those born into this already-damaged climate are getting a less than fair deal here... unfortunately, no amount of petition signing for example can rectify this - only mitigate, so that'll have to do I'm afraid.

[damianslaw]

Evidence of the warming arctic and effect of warm SST values was very much experienced in February 2005. We had a couple of direct northerly blasts, yet temps maxed out at 6 degrees at that was in Newcastle.

It seems we now need to see 2/3 days of embedded northerly airstreams to produce maxes in the 0-2 degree range, and snow showers to sea level. Trough features always help, but don't always occur in a northerly airstream.

In recent years, we have seen shortwave activity over SE Greenland scupper the longevity of any northerly, they are gone in a flash.

I'm hopeful we will experience a northerly polar low scenario again - its been a long long time since one of those has happened.

Late Oct 2008 was quite unusual delivering snowfall to low levels so early in the year - must have been some cold SST's values to the north and a colder than normal arctic. The summer was cool here, but I would have thought there was alot of high pressure over the Poles reducing sea ice extent.. 

 

[hillbilly]

There seems to be lots of blame on arctic sea ice  on milder winters but is that really the case?Fact is there have been milder spells in history and much of the 20th century was devoid of severe winters up until 1947 also global warming has been happening a long time whereas milder winters really turned up in the late 80s .Personally I think our severs winters mainly come from the east  and it is a question of why don't we get those severe east  spells of weather as often as we have in the past .

[Relativistic]

15 hours ago, hillbilly said:

There seems to be lots of blame on arctic sea ice  on milder winters but is that really the case?Fact is there have been milder spells in history and much of the 20th century was devoid of severe winters up until 1947 also global warming has been happening a long time whereas milder winters really turned up in the late 80s .Personally I think our severs winters mainly come from the east  and it is a question of why don't we get those severe east  spells of weather as often as we have in the past .

I think you raise a fair point here. Perhaps the AMO is playing a part? The beginning of the current positive phase (early to mid-90s) seems to roughly coincide with the decrease in frequency of easterly/north-easterly setups.

[Weather-history]

16 hours ago, damianslaw said:

 

Late Oct 2008 was quite unusual delivering snowfall to low levels so early in the year - must have been some cold SST's values to the north and a colder than normal arctic. The summer was cool here, but I would have thought there was alot of high pressure over the Poles reducing sea ice extent.. 

 

I think it was in part due to the fact that northerly flow happened to pull a very cold pool of air out of  the Greenland area. 

The reason why the start of April 1917 was so cold is the air came from the Spitzbergen area and that recorded -49C, 4 days before and that air was pulled down over the British Isles.

Like with an easterly flow or maybe less so, tap into a very cold pool and bang.

 

Edited November 5, 2017 by Weather-history

[danm]

December 2010 was a classic long-fetch northerly. 

Northerlies often don't deliver down here due to the wishbone effect - we're normally quite sheltered from northerlies and generally get cold, clear sunny days. 

Dec 2010 on the other hand produced the good for everywhere. 

Haven't had a good northerly since then - for this part of the world at least.

[Interitus]

An interesting topic, but the first thing to note is that, contrary to the points made so far, the changes to the Arctic sea ice and temperatures will have probably only meant minor differences to the potency of northerlies for the UK. The reason for this is that research into what are known as cold air outbreaks (CAO) or  marine cold air outbreaks (MCAO) shows that the cold boundary layer over the ice is transformed very rapidly into a modified boundary layer over the sea, within just a few hundred miles.

For example data from plane flights for ARKTIS field experiments showed that -

 observed boundary-layer modifications were very variable ranging from 100 to 300 m thick boundary layers with air temperatures between -32 and -22 °C over the ice to thicknesses between 900 and 2200 m and air temperatures between -15 and -5 °C after 300 km fetch over the open water (Brummer 1996)

and that between 300-1000 km the boundary layer reached a steady state (Brummer 1997).

The strength of MCAO can be calculated by comparing potential temperatures of the SST and the 700mb level (Kolstad & Bracegirdle 2008 https://link.springer.com/article/10.1007/s00382-007-0331-0) - as typical for forecasting features of MCAO such as polar lows. The 700mb is chosen as being just above the boundary layer depth noted above, whereas the 900mb temperature for example is quickly modified, whilst 500mb, though used sometimes for polar low forecasts, doesn't capture all MCAO.

The charts below show the regions of strong cold air outbreaks, and their change between 1961 and 2000. It is slightly unintuitive, but the first chart shows the most extreme outbreaks at the 95th percentile, which happens on average roughly 18 days per year at any given location. These are clustered though so the assumption is for them to be within the winter half of the year and 3 days in duration so occurring about once a month on average. The highest values (>0 K/bar) indicate strongest MCAO and naturally occur where cold air sources are closest to the much warmer SST, such as the northern fringes of the Atlantic and Pacific, and also further south the Siberian cold air flowing out towards Japan, shown in the first chart.

The other two charts show that large changes have occurred where ice has retreated exposing new areas of open water, but near the UK and even to the north of Norway, the 95th percentile extreme level has only reduced a little over time -

It is thought that changes in NAO for example have been generally as or more important than reduced sea ice for areas away from the ice, such as the slight increase in extreme outbreaks for the western Atlantic, and that may account for differences around our shores also i.e. fewer northerlies, not necessarily weaker.

 

Edited November 9, 2017 by Interitus

[summer blizzard]

On 11/5/2017 at 13:30, Relativistic said:

I think you raise a fair point here. Perhaps the AMO is playing a part? The beginning of the current positive phase (early to mid-90s) seems to roughly coincide with the decrease in frequency of easterly/north-easterly setups.

Although i must admit that a 7 year stretch without a proper northerly is unusual we saw easterlies in Jan 13 and Feb 12 that caused frontal snow. Indeed in terms of easterlies i think we had a very good run from Feb 05 to Jan 13 with only the winters of 07 and 08 not seeing a productive one. 

Our 7 year stretch of no proper northerly in season is similar to the stretch between Jan 97 and Feb 05 in which there was no productive easterly in season but a number of northerlies. It broke and so will this one. 

[Gray-Wolf]

On 04/11/2017 at 22:15, hillbilly said:

There seems to be lots of blame on arctic sea ice  on milder winters but is that really the case?Fact is there have been milder spells in history and much of the 20th century was devoid of severe winters up until 1947 also global warming has been happening a long time whereas milder winters really turned up in the late 80s .Personally I think our severs winters mainly come from the east  and it is a question of why don't we get those severe east  spells of weather as often as we have in the past .

We have expeditions into the Summer Barentsz blocked by 'cathedral like' expanses of ice. Since 2000 there has been no ice in Barentsz over summer and incredibly low amounts over winter. I have only experienced 'beached ice' once in travemunde ,Germany and the impacts on temp were huge with it being freezing close up to the ice but over 70f on the prom. If such a micro climate can be driven by the presence of ice then just think of that over the expanse of the Ocean to our north? The other thing to look at are the SST's across the region. The fact that it is open water tells us that it is 'warm' compared to when that stretch of ocean was sealed by ice? Over ice you can get -25c temps flowing, without such cold air is modified by the waters below? Those waters are also changed since 2000 with open water allowing 'normal Ocean processes' to take place there ans so wash out the Halocline which used to exist there to keep conditions for sea ice present all year. Now we see the north Atlantic drift push ever deeper into the basin at the surface again modifying the airs above.

All of this said we have seen both PMR air from Greenland fetch us snow and deep cold from Russia also leave us open to frontal snow from encroaching Atlantic storms. With storms now carrying ever larger cargoes of potential precipitation the chances of maga snowfalls must also be increased if we have cold established over the UK prior to the arrival of such a storm?

[Lettucing Gutted]

That's very interesting Grey Wolf.  The sight of beached ice combined with the extreme temperature contrasts must have been very surreal, at least for Germany!  Would such ice beachings combined with the temperature extremes, at least in Germany, be exclusively winter and spring phenomena or can they occur in other seasons as well?

Edited November 21, 2017 by Lettucing Gutted

[Snowyowl9]

Well they are showing on the models for this upcoming cold spell.

http://wetterzentrale.de/pics/Rtavn241.html

http://wetterzentrale.de/pics/Rtavn1441.html

 

[Optimus Prime]

It's a long fetch northerly, but it isn't particularly cold; even for November/December.

January 1969, the king of northerlies?  

[damianslaw]

Is it a coincidence I wonder that since I posted this thread, we are now about to see a fourth Saturday in a row with a northerly feed, and the upcoming one will be a direct one, indeed next weekend already looks like delivering another northerly, perhaps more Northeasterly..