Cold Spell - Feb 7th to 13th 2021 - Technical Discussion

Slashermcguirk · 09-02-2021 8:53am

I don’t get the fuss. Thursday into Friday was always the main event. The weekend only came into play yesterday so I don’t think many people really saw the weekend as a likely outcome. If big snow falls from Wednesday night until Friday morning I would take that any day before milder air on Friday. Weekend was rarely discussed on here and to be honest that’s nearly 5 days away and I wouldn’t fully trust the models that far out regardless of whether they were good or bad

KingdomRushed wrote: »

There is a near total flip if not total flip to milder in the GFS ensembles. I can't see any snow risk post Friday myself now. The scatter is gone. I presume no more scandi highs developing in the set.

Gfs operational is all rain too from Friday night onwards. Thereafter lots of potent rain systems move through leading to likely flooding concerns especially for Munster.

I have to say after the promise of a 2-4 day whiteout it is disappointing. At least we will still see some frontal snow Thursday, but don't snooze on it, it won't be around long

pad199207 · 09-02-2021 8:58am

“Patchy falls of snow” on Friday according to the 7:55 forecast

Certainly didn’t have any of the pizzazz on Claire Byrne last night

M.T. Cranium · 09-02-2021 9:00am

This is about the third reversal of model trends (the switch to milder output beyond the weekend) and I don't trust it entirely, would not be that surprised if we get yet another reversal back to the colder theme. It's an odd looking pattern over North America and models may have gotten one of those false energy signals from an impulse crossing the Rockies.

The breakdown snow looks more and more likely to be disruptive on Thursday into early Friday. This has proven to be quite a powerful blocking regime and so I am not that confident about relatively weak Atlantic lows just pushing it aside. There is heavy snow on the ground all over central Germany and parts of Holland and Belgium, as well as southeast England. That's likely to have a feedback effect that may not be fully diagnosed yet.

Slashermcguirk · 09-02-2021 9:00am

What did they say about Thursday? It was always due to ease off on Friday. My understanding from met Éireann was it would start Wednesday night and through Thursday finishing up on Friday morning

pad199207 wrote: »

“Patchy falls of snow” on Friday according to the 7:55 forecast

Zogabomb · 09-02-2021 9:02am

pad199207 wrote: »

“Patchy falls of snow” on Friday according to the 7:55 forecast

If we get 12 hours of moderate snow before that, I'll gladly bank that now!

Supercell · 09-02-2021 9:03am

T+96 fax doesn't look great for a lot of the Republic, including coastal SE areas in particular.
528 dam too far north, strong SE wind flow, we'd want to be having ice days or close to it in advance of that and that's not happening so far. I'd say upland areas in Wicklow will get plastered (for a while) as well as some well inland areas though. Northern Ireland may hang on to the cold though and it could be epic up there.

By Saturday its going to be thawing/raining pretty much everywhere except the mountains.

pad199207 · 09-02-2021 9:03am

Slashermcguirk wrote: »

What did they say about Thursday? It was always due to ease off on Friday. My understanding from met Éireann was it would start Wednesday night and through Thursday finishing up on Friday morning

As you were for Thursday with hazardous conditions

D9Male · 09-02-2021 9:04am

All three major models is bad enough, but the ensemble support is the nail in the coffin.

Gaoth Laidir · 09-02-2021 9:07am

Supercell wrote: »

T+96 fax doesn't look great for a lot of the Republic, including coastal SE areas in particular.
528 dam too far north, strong SE wind flow, we'd want to be having ice days or close to it in advance of that and that's not happening so far. I'd say upland areas in Wicklow will get plastered (for a while) as well as some well inland areas though. Northern Ireland may hang on to the cold though and it could be epic up there.

By Saturday its going to be thawing/raining pretty much everywhere except the mountains.

500-1000 thickness is irrelevant in this case as the warmer, moist uppers add thickness to the column but the lowest layers can still be cold enough. 850-1000 hPa thickness is much better, and if it's below 1290 m then snow is fairly certain. But even then, that's not 100% reliable if the cold layer is well below 850 hPa.

Supercell · 09-02-2021 9:08am

Slashermcguirk wrote: »

What did they say about Thursday? It was always due to ease off on Friday. My understanding from met Éireann was it would start Wednesday night and through Thursday finishing up on Friday morning

That may be based on older charts, fax charts say some wintry showers on Thursday, patchy rain on Friday and a wet day on Saturday, becoming windy later for most. I'd love to be wrong but that's what the charts are saying to me.

Zogabomb · 09-02-2021 9:08am

D9Male wrote: »

All three major models is bad enough, but the ensemble support is the nail in the coffin.

I guess it depends on your expectations though. Yes we would all love a prolonged cold and snowy spell but to be honest, if we got 24 hours and a few cm of snow, I'd be more than happy with that.

Sometimes we overlook what is going to happen short term for what might happen long term.

average_runner · 09-02-2021 9:11am

Us Irish are great at being negative, we thrive in it. To be honest the models aren't worth the paper they are printed on till about 36 hrs out

Supercell · 09-02-2021 9:13am

Gaoth Laidir wrote: »

500-1000 thickness is irrelevant in this case as the warmer, moist uppers add thickness to the column but the lowest layers can still be cold enough. 850-1000 hPa thickness is much better, and if it's below 1290 m then snow is fairly certain. But even then, that's not 100% reliable if the cold layer is well below 850 hPa.

That may be so GL, and I definitely value your input, but long experience here is that these charts spell sleety rain at best in my back garden! (coastal Wicklow/Dublin), would love for that to be wrong though.

bazlers · 09-02-2021 9:29am

Supercell wrote: »

That may be so GL, and I definitely value your input, but long experience here is that these charts spell sleety rain at best in my back garden! (coastal Wicklow/Dublin), would love for that to be wrong though.

Where you see the greatest potential fordisruptive snow?
From what i see the south and south east is showing heaviest precipitation but might not be all snow. Percipitation getting patchy as you head north but would more than likely be snow especially further east you go.
Is that about right?

bazlers · 09-02-2021 9:32am

pad199207 wrote: »

“Patchy falls of snow” on Friday according to the 7:55 forecast

Certainly didn’t have any of the pizzazz on Claire Byrne last night

Come on Pad there is a mini 1947 brewing here. You know it and i know it :pac:

Supercell · 09-02-2021 9:38am

bazlers wrote: »

Where you see the greatest potential fordisruptive snow?
From what i see the south and south east is showing heaviest precipitation but might not be all snow. Percipitation getting patchy as you head north but would more than likely be snow especially further east you go.
Is that about right?

Thats about it yes, with inland and higher areas most likely to see snow, charts can change though, we are still a few days out, we live in hope!

bazlers · 09-02-2021 9:39am

KingdomRushed wrote: »

There is a near total flip if not total flip to milder in the GFS ensembles. I can't see any snow risk post Friday myself now. The scatter is gone. I presume no more scandi highs developing in the set.

Gfs operational is all rain too from Friday night onwards. Thereafter lots of potent rain systems move through leading to likely flooding concerns especially for Munster.

I have to say after the promise of a 2-4 day whiteout it is disappointing. At least we will still see some frontal snow Thursday, but don't snooze on it, it won't be around long

There is a bazler science to this. Your disappointment is a direct correlation to the amount of time you have expended to this thread and dedication to the various times of model outputs. If you have given the full month to this thread ( well thats how long it feels at this junction:pac:) you wil feel like your heart has been ripped from your chest and thrown under a herd of stampeding African elephants:pac:

TheMilkyPirate · 09-02-2021 9:41am

Met Eireann updated their forecast again 5 minutes ago and it's as you were for Thursday/Friday

Issued at: 09 February 2021 08:32

Thursday: Sleet and snow will slowly extend northwards from the southwest across much of Munster, Connacht and Leinster, with snow accumulations leading to hazardous conditions. Highest temperatures of 1 to 3 degrees. Feeling colder in fresh and gusty southeast winds, strongest in western and southwestern counties.

Thursday night: Remaining breezy overnight with sleet and snow continuing to fall over much of the east, midlands and north leading to further accumulations. However, precipitation will turn to rain in parts of the south and west. Lowest temperatures of -1 to +2 degrees with fresh southeasterly winds.

Friday: Some lingering falls of sleet and snow in the eastern half of the country, with outbreaks of rain elsewhere. More persistent rain will move into western counties during the evening. Southeast breezes will strengthen during the day, becoming strong and gusty in coastal counties. Highest temperatures generally of 1 to 4 degrees, however less cold in southwestern counties with highs of 5 to 8 degrees.

Friday night: A wet, windy night with rain turning to snow over the north, east and midlands, leading to some accumulations. Cold night for many, with lowest temperatures of -1 to +2 degrees however much of Munster and southern Connacht will be less cold with lows of 4 to 7 degrees. Fresh to strong and gusty southeast winds.

esposito · 09-02-2021 9:45am

TheMilkyPirate wrote: »

Met Eireann updated their forecast again 5 minutes ago and it's as you were for Thursday/Friday

Issued at: 09 February 2021 08:32

Thursday: Sleet and snow will slowly extend northwards from the southwest across much of Munster, Connacht and Leinster, with snow accumulations leading to hazardous conditions. Highest temperatures of 1 to 3 degrees. Feeling colder in fresh and gusty southeast winds, strongest in western and southwestern counties.

Thursday night: Remaining breezy overnight with sleet and snow continuing to fall over much of the east, midlands and north leading to further accumulations. However, precipitation will turn to rain in parts of the south and west. Lowest temperatures of -1 to +2 degrees with fresh southeasterly winds.

Friday: Some lingering falls of sleet and snow in the eastern half of the country, with outbreaks of rain elsewhere. More persistent rain will move into western counties during the evening. Southeast breezes will strengthen during the day, becoming strong and gusty in coastal counties. Highest temperatures generally of 1 to 4 degrees, however less cold in southwestern counties with highs of 5 to 8 degrees.

Friday night: A wet, windy night with rain turning to snow over the north, east and midlands, leading to some accumulations. Cold night for many, with lowest temperatures of -1 to +2 degrees however much of Munster and southern Connacht will be less cold with lows of 4 to 7 degrees. Fresh to strong and gusty southeast winds.

Wow was not expecting that forecast given the latest sh**ty model output. They are sticking their neck out there. As MT said the models can’t be fully trusted at the moment given all these flips.

The thing to take from that forecast update is ‘don’t underestimate the cold’

TheMilkyPirate · 09-02-2021 9:48am

ECM for 9pm Thursday. Hopefully MT is right about the cold block not being as easily pushed over as being shown this morning. Maybe even a push back to the colder solution on the 12Zs but for now I'll take a good snowfall on Thursday.

bazlers · 09-02-2021 9:51am

esposito wrote: »

Wow was not expecting that forecast given the latest sh**ty model output. They are sticking their neck out there. As MT said the models can’t be fully trusted at the moment given all these flips.

The thing to take from that forecast update is ‘don’t underestimate the cold’

Do remember it might be only spitting snow but for a longer period of time. I just cant see a constant moderate fall but some places might get lucky. Especially upland.

bazlers · 09-02-2021 9:51am

Supercell wrote: »

Thats about it yes, with inland and higher areas most likely to see snow, charts can change though, we are still a few days out, we live in hope!

Thanks Supercell. Always value your input.

pad199207 · 09-02-2021 9:56am

Ugh

DOCARCH · 09-02-2021 9:58am

pad199207 wrote: »

Ugh

Really not sure what she's smiling about.

Tickityboo · 09-02-2021 10:05am

pad199207 wrote: »

Ugh

She's not that bad!! (Nice blouse!!)

Chalkitdown147 · 09-02-2021 10:06am

pad199207 wrote: »

Ugh

I take it from MT (The Weather Oracle) that this will be a very marginal breakdown and it could easily sway either way, even that mild air only about breaches the east coast

bennyx_o · 09-02-2021 10:08am

pad199207 wrote: »

Ugh

Watched that also. She did say that's what they think will happen so it seems they're also not 100% sure yet either

Slashermcguirk · 09-02-2021 10:09am

I am not surprised, there is a real cold pool developing and the models have consistently struggled to shift the cold. Who is to say they might not back track again regarding Saturday onwards, still about 4 days away and I find it hard to trust the models 2-3 days away these days

quote="esposito;116215812"]Wow was not expecting that forecast given the latest sh**ty model output. They are sticking their neck out there. As MT said the models can’t be fully trusted at the moment given all these flips.

The thing to take from that forecast update is ‘don’t underestimate the cold’[/quote]

Slashermcguirk · 09-02-2021 10:11am

They havent a bean and the UK channels focus on the UK. BBC was showing rain for Friday in Ireland and are now giving snow for the east and north. They are constantly chopping and changing

quote="bennyx_o;116215961"]Watched that also. She did say that's what they think will happen so it seems they're also not 100% sure yet either[/quote]

TTLF · 09-02-2021 10:15am

In fairness, the BBC goes off the latest ECM run, so it's not really worth the time when the ECM moves and shifts a lot.

09-02-2021 10:22am

TTLF wrote: »

In fairness, the BBC goes off the latest ECM run, so it's not really worth the time when the ECM moves and shifts a lot.

They don't
They get their forecast material from meteogroup who also provide the analysis
Its often one run behind

TTLF · 09-02-2021 10:25am

AuntySnow wrote: »

They don't
They get their forecast material from meteogroup who also provide the analysis
Its often one run behind

ah, alright. My thinking about it was that "huge fail" where it was showing those mild south westerlies when it was an outlier ECM run, but that would make more sense.

Gaoth Laidir · 09-02-2021 10:27am

Supercell wrote: »

That may be so GL, and I definitely value your input, but long experience here is that these charts spell sleety rain at best in my back garden! (coastal Wicklow/Dublin), would love for that to be wrong though.

Ah, that's different, east coast, all bets are off in that strong southeasterly.

Danno · 09-02-2021 10:30am

TTLF wrote: »

In fairness, the BBC goes off the latest ECM run, so it's not really worth the time when the ECM moves and shifts a lot.

The BBC used to be supplied by the UKMO who use the ECM. However, around three years ago, the BBC struck up a contract with Meteogroup for their forecasts.

The UKMO are now just an online presence themselves, don't think they feed any UK TV station with forecasts?

Supercell · 09-02-2021 10:32am

Winds do turn briefly more NE overnight tonight, maybe some ninja snow for Dublin and Wicklow tomorrow morning. Some areas might get some streamer action and do well, lets see.

Bodjhrjekekr · 09-02-2021 10:39am

Looking good for snow Thursday in Cork County inland, or am I wrong?

Gaoth Laidir · 09-02-2021 10:45am

Massive downgrade in the ECM and GEM overnight, with the snow breaking up half way up the country. They have more focus on an pre-frontal snow band overnight Friday night into Saturday.

The GFS is still full gung-ho and the ICON is somewhere in between.

There were GFS indications yesterday that maybe that frontal dynamics would be breaking up the precip as it crosses the country, the 00Z has backtracked on that a little and shows the front still active at 9 pm on Thursday (negative Q-vector div. values below). The other models may be showing that breaking up, but this parameter is not available for them as it is for the GFS.

Still a lot of variability for now, so it's anybody's guess what will happen. The ICON is probably the most likely.

http://www1.wetter3.de/Archiv/GFS/2021021200_11.gif

munsterlegend · 09-02-2021 10:53am

Bodjhrjekekr wrote: »

Looking good for snow Thursday in Cork County inland, or am I wrong?

We’re definitely in with a shout. Tomorrow evening we should have a better idea either way.

D9Male · 09-02-2021 11:09am

Unfortunately, 6z so far (out to Saturday afternoon) gives broad support to the Atlantic breaking through after the snow event on Thursday.

For Thursday into Friday morning, I think the snow will be marginal for those close to the south and east coast, and for those in Munster (apart from Tipperary and north Cork), I don't think there will be much lying snow as the south-easterly veering southerly winds will kick.

https://max.nwstatic.co.uk/gfsimages/gfs.20210209/06/102/h500slp.png

That is if the 6z verifies, of course.

sryanbruen · 09-02-2021 11:10am

AuntySnow wrote: »

They don't
They get their forecast material from meteogroup who also provide the analysis
Its often one run behind

They do BB for their extended. It was funny a week ago when they used that single ECM outlier showing a long fetched mild southwesterly airflow for 10 February. That worked out for them...

Gaoth Laidir · 09-02-2021 11:11am

Despite everything, actual 12 and 24-hour precipitation totals have been negligible in Ireland and the UK. Some parts of northern England have 10 cm of snow cover and yet registered near 0 mm of liquid equivalent in the past 24 hours!

Slashermcguirk · 09-02-2021 11:17am

Met Éireann update going for big accumulations for north and east up to Friday morning

D9Male wrote: »

Unfortunately, 6z so far (out to Saturday afternoon) gives broad support to the Atlantic breaking through after the snow event on Thursday.

For Thursday into Friday morning, I think the snow will be marginal for those close to the south and east coast, and for those in Munster (apart from Tipperary and north Cork), I don't think there will be much lying snow as the south-easterly veering southerly winds will kick.

https://max.nwstatic.co.uk/gfsimages/gfs.20210209/06/102/h500slp.png

That is if the 6z verifies, of course.

09-02-2021 11:21am

sryanbruen wrote: »

They do BB for their extended. It was funny a week ago when they used that single ECM outlier showing a long fetched mild southwesterly airflow for 10 February. That worked out for them...

Meteo must have had it in the script!
The meteo analysis does feed them the options and it's often a run behind by the looks of things
Thats not deliberate, it happens on RTE too,it's just timing and preparation with the deadlines of broadcast I think

Kermit.de.frog · 09-02-2021 11:25am

Some big enough changes locally on some models for the medium post Friday with the Atlantic getting through. Thursday and Friday themselves still look OK for decent amounts of snow in the Eastern half of the country in particular but also north Connaught and parts of Ulster.

I'll wait until this evening to verify this is now conclusive in terms of milder air gradually making it's way right across the country by Saturday. Certainly looks that way.

Light to moderate snow here atm. 0c.

Rebelbrowser · 09-02-2021 11:26am

Gaoth Laidir wrote: »

Despite everything, actual 12 and 24-hour precipitation totals have been negligible in Ireland and the UK. Some parts of northern England have 10 cm of snow cover and yet registered near 0 mm of liquid equivalent in the past 24 hours!

My brother in South East London (just about Kent) is annoying me with pretty impressive snow / falling snow photos this morning

D9Male · 09-02-2021 11:30am

Slashermcguirk wrote: »

Met reann update going for big accumulations for north and east up to Friday morning

They don't say big. Or even significant.

DellyBelly · 09-02-2021 11:33am

D9Male wrote: »

They don't say big. Or even significant.

So no need to stock up on the aul Bread then...ha ha ha

Slashermcguirk · 09-02-2021 11:35am

Accumulations leading to hazardous conditions pretty much suggests big to be fair

D9Male wrote: »

They don't say big. Or even significant.

nacho libre · 09-02-2021 11:39am

When they all form a consensus at this stage, it's unlikely they will flip back. The fact there is no scatter in the ensembles is a bad sign. I was kind of expecting these downgrades, it just sort of fits how this winter has gone so far. Still hopefully some places will get a decent snowfall before the milder air wins out.

D9Male · 09-02-2021 11:43am

Slashermcguirk wrote: »

Accumulations leading to hazardous conditions pretty much suggests big to be fair

I mean you clearly read what you want to read.

You don't need a big accumulation to lead to hazardous conditions.

They also say sleet, which is what I think will be seen on most of the coastal parts of the country.

Cold Spell - Feb 7th to 13th 2021 - Technical Discussion

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