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

nacho libre · 08-02-2021 2:12pm

Well, i hope our old friend Weathercheck is right with the "may" and that the transition would be in parts of the west and south, rather than all of the west and south.

I certainly don't relish it being 3 or 4 degrees with cold rain on Thursday night. I'd sooner it all fizzled out in that case.

Gaoth Laidir · 08-02-2021 2:35pm

Cloudtops are still low over the UK, showing at around 2900 m at Albermarle 12Z sounding. Still that very strong 700 hPa inversion. Steering flow there roughly ESE. Snow depth at that station is 3 cm, but fairly respectable 20 cm in SE England from that frontal event and 28 cm at Aboyne, Scotland.

Rebelbrowser · 08-02-2021 2:56pm

Big difference in DPs from North East to South West

D9Male · 08-02-2021 3:05pm

I am intrigued with Thursday -> Friday event. If the front is struggling to make its way up from the south west, I suspect that will compound the rain shadow effect on Dublin city from the Dublin mountains. Or do I have that wrong?

snowgal · 08-02-2021 3:07pm

yes thats my understanding too, hence the East actually might not fair well at all.....but it seems to be knife edge situation..

Steopo · 08-02-2021 3:08pm

nacho libre wrote: »

As Auntysnow mentioned previously they have access to data we don't see. The Chief forecaster seemed confident something would happen on Thursday, but obviously would not commit to anything until she had to. I imagine Met Eireann also share data with the UKMO. Bear it mind it was mogreps (UKMO'S own model) ,afterall, that indicated that this cold period would be extended, and that the other models would start to back that scenario. It now looks like that will happen.

Be interested to know if they do. Know they’ve collaborated with UK on storm names & weather observations (wow.met.ie) but have never indicated they use UKMO model for forecasting. Public info indicates they use HIRLAM for short term & ECM for forecasts up to 10days with obviously professional versions of those & advanced visualisation (met.ie/science/forecasting-centre www.iblsoft.com ). ECM has consistently indicated a snow event on Thurs since MetE mentioned the risk so would have thought that’s where they’ve picked it up?

nacho libre · 08-02-2021 4:08pm

Steopo wrote: »

Be interested to know if they do. Know they’ve collaborated with UK on storm names & weather observations (wow.met.ie) but have never indicated they use UKMO model for forecasting. Public info indicates they use HIRLAM for short term & ECM for forecasts up to 10days with obviously professional versions of those & advanced visualisation (met.ie/science/forecasting-centre www.iblsoft.com ). ECM has consistently indicated a snow event on Thurs since MetE mentioned the risk so would have thought that’s where they’ve picked it up?

I could imagine a scenario whereby the UKMO would share model info' with them for potentially impactful events for Ireland the UK, but they don't rely on the UKMO for guidance, as you say they use the ECM and Hirlam for that.

Oneiric 3 · 08-02-2021 4:49pm

ECM 6z struggles to bring the 'snow line' below (Edit: actually above) 200m away from very SW during Thursday.

Any potential snowfall from this front looks light to moderate at best and on this run at least, it struggles to make it into Ulster.

munsterlegend · 08-02-2021 4:53pm

Oneiric 3 wrote: »

ECM 6z struggles to bring the 'snow line' below 200m away from very SW during Thursday.

Any potential snowfall from this front looks light to moderate at best and on this run at least, it struggles to make it into Ulster.

It’s always looks promising until the models get a firmer grip of the higher uppers coming in with an Atlantic front. I am expecting a sleety mess in most of Cork except very high ground as that what happens 9/10.

Oneiric 3 · 08-02-2021 4:57pm

munsterlegend wrote: »

It’s always looks promising until the models get a firmer grip of the higher uppers coming in with an Atlantic front. I am expecting a sleety mess in most of Cork except very high ground as that what happens 9/10.

I agree. This is all just speculation for now and no doubt models will chop and change big time up till (and during) Thursday. Would instinctively expect a ****ty sleety transition here at best as well. Nacho and those further north of here tend to do better in these set ups by and large.

nacho libre · 08-02-2021 5:03pm

Oneiric 3 wrote: »

I agree. This is all just speculation for now and no doubt models will chop and change big time up till (and during) Thursday. Would instinctively expect a ****ty sleety transition here at best as well. Nacho and those further north of here tend to do better in these set ups by and large.

Well yes, its subject to change, but if it were to pan out as the current Met Eireann guidance suggests, i would sooner it decays before reaching here. I love snow, but a quick transition to several hours of cold rain, no thanks. Nacho in refusing snow shocker:eek:

Calibos · 08-02-2021 5:08pm

Does that chart mean its game over for decent snow on Thursday even further north and east for the Wexford to Galway line?

TheMilkyPirate · 08-02-2021 5:11pm

GFS better than ICON keeping the front intact over much of the country. Turning to rain in the south west.

Second front on Saturday and has it snowing until Valentines day in the inland south east. Large pinch of salt needed with that at this stage.

Longing · 08-02-2021 5:19pm

GFS Saturday and Sunday looks fun.

Donegal Ken · 08-02-2021 5:26pm

Calibos wrote: »

Does that chart mean its game over for decent snow on Thursday even further north and east for the Wexford to Galway line?

No it doesn't mean game over. There still is good potential for some areas to see snow on Thursday into Friday. Long time between now and Thursday.

arctictree · 08-02-2021 5:26pm

Christ almighty the latest GFS has pretty much constant snow for Leinster from Thursday to Sunday. The Atlantic just not getting through with each push.

squarecircles · 08-02-2021 5:33pm

if that transpired that would almost be a red alert for Leinster.
72 hours of continuous snowfall.

Gonzo · 08-02-2021 5:34pm

latest charts are looking very snowy for Leinster over the weekend. If these chart verify some places could be in trouble. Very unlikely to verify but teh GFS 12z is predicting between 18 and 80cm of snow in Leinster by Monday. (30 to 80cm more for the wicklow mountains)

But a huge pinch of salt to bear in mind as the fronts may break up on their way to Leinster depending on how well the cold block remains. On the other hand the Atlantic and it's warmer uppers could make this all very marginal. However right now it looks some parts of Leinster could be in for serious dumpings of snow over the weekend.

TonyMaloney · 08-02-2021 5:37pm

The Icon sees it as a pretty marginal event for most

Cloudio9 · 08-02-2021 6:03pm

squarecircles wrote: »

if that transpired that would almost be a red alert for Leinster.
72 hours of continuous snowfall.

No six nations match on Sunday then.

Gaoth Laidir · 08-02-2021 6:03pm

Still no sign of any increase in convection upstream for later. 700-600 hPa has cooled by about 5 degrees over NE England in the last 24 hours but the very low dewpoints are reducing surface instability to offset this. Windspeed is a little too strong to allow enough residence time to bring up dewpoints a little and destabilise the surface parcels a little more. We need the wind to abate a little, but there seems to be only a narrow window for this overnight. For now, cloudtops remain at or below 3000 m.

Donegal Ken · 08-02-2021 6:07pm

Status Yellow - Snow/Ice warning for Dublin, Kildare, Louth, Wicklow, Meath and Monaghan
Met Éireann Weather Warning

Snow accumulations of 2 to 5 cm in places.

Valid: 18:00 Monday 08/02/2021 to 18:00 Tuesday 09/02/2021

Issued: 16:00 Monday 08/02/2021

[Deleted User] · 08-02-2021 6:20pm

I am getting mixed signals from this thread.

Rebelbrowser · 08-02-2021 6:33pm

Deleted User wrote: »

I am getting mixed signals from this thread.

That'll be the mixed signals!

Gonzo · 08-02-2021 6:34pm

Deleted User wrote: »

I am getting mixed signals from this thread.

In summery: light to moderate snow showers from now till tomorrow evening/night along eastern coastal counties. Much of this will be hit and miss depending on streamers and shadows. Small accumulations of 1 to 5 cm possible between now and Wednesday, a few lucky places could get a little bit more than this maybe up to 8 or 9cm. Some places in the highlighted counties may get nothing at all if they avoid all the streamers.

Forget about Thursday onwards for now, so much can go right or wrong with Thursday to Sunday at this point.

Calibos · 08-02-2021 7:15pm

Eagerly awaiting what the ECM has to say for itself.

Gonzo · 08-02-2021 7:20pm

GFS 12z has completed.

Most GFS members are trending towards a continuation of the cold spell and a fairly significant increase in the snow potential for this weekend and early next week before a warm up takes place. The mild weekend blip is non existent at this point.

ens_image.php?geoid=64969&var=201&run=12&date=2021-02-08&model=gfs&member=ENS&bw=1

ens_image.php?geoid=64969&var=201&run=12&date=2021-02-08&model=gfs&member=ENS&bw=1

giveitholly · 08-02-2021 7:25pm

Gonzo wrote: »

GFS 12z has completed.

Most GFS members are trending towards a continuation of the cold spell and a fairly significant increase in the snow potential for this weekend and early next week before a warm up takes place. The mild weekend blip is non existent at this point.

Would that be for all of Ireland or is it still going to get mild in the south of the country?

TheMilkyPirate · 08-02-2021 7:30pm

ECM 12z for 8pm Thursday

[Deleted User] · 08-02-2021 7:40pm

Calibos wrote: »

Eagerly awaiting what the ECM has to say for itself.

Cursory glance, but not Good news,might struggle to hold onto hill snow in the east Friday morning
The 2nd front obviously will then be all rain
A win for the Atlantic
Look at where the air originates feeding in on Friday
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UK fax has the occlusion over the east at noon Friday but with the airflow from the south

1394525914_Fax10Feb2021.png.d0dc1fd3656bbbbc6e2e1185788a95b0.png

1394525914_Fax10Feb2021.png.d0dc1fd3656bbbbc6e2e1185788a95b0.png

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

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