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

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

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.

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!

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

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.

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.

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.

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:

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 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’

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.

Ugh

pad199207 wrote: »

Ugh

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

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

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]