Winter 20/21 - General Discussion

Dazler97

Northern England today, my step dads sister sent me the picture

nacho libre

Dazler97 wrote: »

Northern England today, my step dads sister sent me the picture

Nice. I'd take one decent snowfall like that at this stage.

Dazler97

nacho libre wrote: »

Nice. I'd take one decent snowfall like that at this stage.

Same here to be honest, Scotland got up to a ft of snow

ZX7R

Where I was born in dunlavin in wicklow there Is hill fort .
,couple of times as a child I was brought up to it by both my father and or brother.
If the weather conditions were perfect you could just make out part of wales with the naked eye.

Nqp15hhu

From altitude I can see Mull and slightly further from the north coast in my fathers plane.

Reckless Abandonment

That horizon chart is great GL . Never knew it increased so much at a few meters . Cheers

Oneiric 3

That photo is perfectly possible. Where I live, NE Galway, you can regularly see the hills of north and west Mayo and all the more so if they are snowcapped. Climb above 50m, which is considered Himalayan around these parts, and it is perfectly possible to see the hills of Tipperary and north Kerry when the air is dry and cloud base is high.

I recall looking up a superzoom 'Canon' lens years ago, and its zoom capacity was breathtaking. Saw one image where a photographer on the south coast of England took zoomed shots of actual buildings on the north coast of France using this particular lens (which I can't recall the name of right now)

Oneiric 3

sryanbruen wrote: »

If you feel that way then fair enough. However, I will continue to post about the stratosphere ‘til the end of time or as long as I’m a weather enthusiast anyway as I find its variability and dynamic nature quite interesting irregardless of what happens at a tropospheric level. How it can vary from a very strong SPV to a very weak SPV in a matter of days via stratospheric warmings. It’s just all fascinating to me. It’s a continuously researched phenomena too so there’s always something new to learn and nothing is concrete. The stratosphere never “promised” anything, I think it’s people’s expectations getting the best of them (and I have done that before too *sigh*).

It’s unfortunate it is now used as another source that the media can “justify” their nonsense on that they pull out of their arse because of events like 2018. I do find that quite frustrating knowing that was the extreme end of tropospheric impacts and will highly unlikely see again anytime soon.

Is there any historic strat data available Syran to allow us to to maybe run a few correlation tests with SSW events and potentially colder weather down the line? I see much talk on Twitter about this but I always find explanations about SSW vague at best, which just increases my apathy towards it.

Is there a way of predicting when a SSW might occur? From what little I know, they nearly always seem to triggered around the far west of the greater Med area? Is there a reason for that and is there any particular synoptic pattern in the north/central Atlantic that would help trigger such large scale atmopheric phenomenon?

Nqp15hhu

Oneiric 3 wrote: »

That photo is perfectly possible. Where I live, NE Galway, you can regularly see the hills of north and west Mayo and all the more so if they are snowcapped. Climb above 50m, which is considered Himalayan around these parts, and it is perfectly possible to see the hills of Tipperary and north Kerry when the air is dry and cloud base is high.

I recall looking up a superzoom 'Canon' lens years ago, and its zoom capacity was breathtaking. Saw one image where a photographer on the south coast of England took zoomed shots of actual buildings on the north coast of France using this particular lens (which I can't recall the name of right now)

I wouldn’t doubt that. I could see individual windmills in Kintyre from Torr Head.

mcburns07

Has this become the Official Tell Us What You Can See thread? :pac:

Kunta Kinte

mcburns07 wrote: »

Has this become the Official Tell Us What You Can See thread? :pac:

Tyrone212

mcburns07 wrote: »

Has this become the Official Tell Us What You Can See thread? :pac:

I spy on roids

Chris_5339762

Well, Leeds was absolutely buried today. Major problems on all routes with hours of delays everywhere.

https://www.leeds-live.co.uk/news/leeds-news/live-leeds-snow-ice-traffic-19621999

sryanbruen

Oneiric 3 wrote: »

Is there any historic strat data available Syran to allow us to to maybe run a few correlation tests with SSW events and potentially colder weather down the line? I see much talk on Twitter about this but I always find explanations about SSW vague at best, which just increases my apathy towards it.

Is there a way of predicting when a SSW might occur? From what little I know, they nearly always seem to triggered around the far west of the greater Med area? Is there a reason for that and is there any particular synoptic pattern in the north/central Atlantic that would help trigger such large scale atmopheric phenomenon?

The following link shows geopotential height anomaly cross sections at 60-90N for every winter back to 1979-80 which was the first year of the ERA5 record. This is a basic way of trying to see if downwelling does occur although not perfect and does not necessarily show a favourable cold pattern for us either which you need to look at the actual synoptics for of course.

https://fh004579.webs.act.reading.ac.uk/pcap_xc/

I have done one here as an illustrated example with the major SSW in February 2018 being very visible at the top of the stratosphere which would downwell quickly towards the surface.



Other sites with stratospheric related data include that might be of interest:

https://csl.noaa.gov/groups/csl8/sswcompendium/
https://ozonewatch.gsfc.nasa.gov/meteorology/wind_2018_MERRA2_NH.html
https://www.geo.fu-berlin.de/en/met/ag/strat/produkte/northpole/index.html
https://acd-ext.gsfc.nasa.gov/Data_services/met/ann_data.html

A paper that I always find myself coming back to for anticipating SSW events in advance outside of modelling is Cohen's "Tropospheric Precursors and Stratospheric Warmings".

Yes, these warming events are caused by tropospheric patterns sending atmospheric waves to stratosphere via upwelling. This results in the stratospheric polar vortex getting disturbed and being weakened - this has been known for a long time but what has been studied more recently is for these stratospheric phenomena to then downwell back to the troposphere and result in blocked patterns that mean for a more meridional jet stream.

What are these tropospheric patterns that cause upwelling to the stratosphere? It's blocking over the Urals and low pressure over the Aleutians. The figure below shows mean sea level pressure anomalies averaged between 45-0 days prior to/after displacement and split major SSW events respectively in the study. Both Ural blocking or ridging and low pressure over towards the Aleutians is evident pre-displacements and pre-splits with blocking in the Arctic following both types of events. The European low is further west and deeper with displacement events as compared to split events so not quite as conducive to cold weather conditions for Ireland.

Zonal wavenumbers (number of troughs and ridges in a full circle around the globe) are another way of looking at these events but in spite of theories, an interesting new study which GL posted in the stratosphere thread discussed that a wave-2 split is no more likely to propagate downward or downwell than a wave-1 split or a wave-1 displacement which I find riveting to ponder at.



I have updated the table in the paper named to include the recent major SSW events since 2010. 5 January 2021 is an estimated central date. The central date is when the zonal mean zonal wind at 10 hPa 60N reverses from westerly to easterly.



I've said it very simply I can but if you would like more details, I'd recommend to indulge in more papers like that one.

I wouldn't even be reading papers like it if it weren't for recommendations given to me over the years from fellow enthusiasts on here or on other mediums.

Chris_5339762

Niall145 wrote: »

Hi all,

I am the photographer behind the capture of Snowdon taken from Howth Summit (an avid lurker on this forum too i must admit). It was taken Tuesday afternoon from the Ben of Howth (171m). Was a mostly cloudy day here but with exceptionally clear conditions in the Irish sea (Isle of Man and the Mournes also visible). That combined with the snow still lying on Snowdon definitely helped in getting this shot! It's on my instagram too at ncarroll22 (Niall O'Carroll on FB).

Its a cracker of a photo, I got one years ago of the Welsh Mountains from Bray Head. Its only on a very, very clear day that you can see it.



I'm now living down in Cobh, and from one of the high points of Cobh last week I could see the Galtees (55km), the Knockmealdowns (45km), the edge of the Comeraghs (55km) and Mullaghinish down near Macroom (about 55km). Its rare that it is that clear, but its awesome when you do see it.


AFAIK you can't QUITE see Carrauntohill (100km) but I'll keep an eye out next time.

Nqp15hhu

The cold weather is back and it’s 2c. Doesn’t feel as cold as the previous weather..

Cluedo Monopoly

There is talk of a cold snap with potential snow next week. Is that still on the cards?

Oneiric 3

sryanbruen wrote: »

The following link shows geopotential height anomaly cross sections at 60-90N for every winter back to 1979-80 which was the first year of the ERA5 record. This is a basic way of trying to see if downwelling does occur although not perfect and does not necessarily show a favourable cold pattern for us either which you need to look at the actual synoptics for of course.

https://fh004579.webs.act.reading.ac.uk/pcap_xc/

.

Absolutely epic Syran. Thanks! It is explanations like this, and from someone that is genuinely invested and interested in the topic that helps myself and others gain a better understanding of things like this the most.

Birdnuts

Chris_5339762 wrote: »

Well, Leeds was absolutely buried today. Major problems on all routes with hours of delays everywhere.

https://www.leeds-live.co.uk/news/leeds-news/live-leeds-snow-ice-traffic-19621999

Would u believe the lad giving that forecast is my Nephew!!:eek:

Dazler97

Birdnuts wrote: »

Would u believe the lad giving that forecast is my Nephew!!:eek:

Feck off, that's a small world we live in, aiden is my favourite forcaster next to Philip Avery

spoonerhead

Dense freezing fog in D12 starting to clear now. Left a covering of frost along with it, we’ve had a decent winter so far for frosty mornings

ZX7R

Where I'm living now in Poland.
It's been snowing lightly to at times moderate since 3PM yesterday.
Roughly just over 10cms of snow -6 at the moment but to drop further during the day to-15 or below.
Temperatures are forecasted to drop below -20 over the weekend.

circadian

spoonerhead wrote: »

Dense freezing fog in D12 starting to clear now. Left a covering of frost along with it, we’ve had a decent winter so far for frosty mornings

A light frosting here in D9, wasn't expecting it. Car is completely frozen over too, was a little surprised when I popped my head out to grab the milk!

Artane2002

surprisingly very frosty in Dublin 5, didn't expect it.

Nqp15hhu

No more double figures in my forecast for the next week.

https://blog.metoffice.gov.uk/2021/01/14/why-the-beast-from-the-east-is-unlikely-to-roar/

Read it and weep

atmosphere early in January has led to reports a so called ‘Beast from the East’ is heading our way and speculation of extreme cold weather to come.

A sudden stratospheric warming (SSW) sees a rise in temperature and change in wind direction in the atmosphere high above the Arctic. This happens at an altitude of about 30 km so has a delayed influence on weather at the earth’s surface. We usually start to see knock-on effects on the jet stream a couple of weeks later, which can in turn affect the day to day weather across Europe and the UK.

Met Office Chief Meteorologist, Paul Davies, said; “The unsettled, wintry weather forecast for next week is consistent with the expected effects of an SSW and there is a chance there could be more snow in parts of the UK and Europe.

“However, the winds will be generally from a northerly direction not from the east, as cold air from Scandinavia is drawn across the UK. So perhaps not a Beast from the East but normal wintry weather from the north.”

The cold northerly air is likely to be once again held to the east side of the UK as milder air pushes in from the west. Where these two air masses meet weather fronts will bring rain, which could be heavy at times and turn to snow, especially over higher ground. This suggests the potential for big differences in the weather across the UK next week, with temperatures most likely to be rather cold for the north and near-or slightly above-average across the south. There is always uncertainty when conflicting air masses meet, however, so some cold spells can’t be ruled out here also.

nacho libre

It's not a surprise to me or a disappointment to read that because i have accepted that the ship has sailed on us getting a sustained cold spell. You have to hand it to the UK Met Office in house model as it had envisaged things panning out like this even before the SSW had begun. All that said we could get colder interludes, starting later this week with some snow about, before a milder push again.

In other words,a normal winter
#scamstrat

Captain Snow

Potential Ninja Snow for some on Saturday. Higher Ground.




Brief mild spell Tuesday.



From Wednesday onwards winter returns.
Wintery Showers etc





Something better developing after that...




So far its been the best model watching in years.

In 3 days the models will have changed again....lol

Gonzo

Captain Snow wrote: »

Potential Ninja Snow for some on Saturday. Higher Ground.


So far its been the best model watching in years.

In 3 days the models will have changed again....lol

It's been the best since 2018 without a doubt in terms of interest but has failed to deliver anything noteworthy to Ireland up to now. Hopefully the models will be changed in 3/4 days to something much more interesting, unstable and longer term in terms of cold and snow. Next week's cold spell has all the similarities of the last week of December in that it will be mostly dry once we get the push of mild and wet weather out of the way early next week. Showers will be mainly of cold rain and some hill snow mainly for Northern Ireland. After a few days we get the push of mild air from the south-west again so we do need some major upgrades in the models over the next week.