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

vizualpics

Central Mayo - light flurries since 1pm, but looking at the Met E radar the precipitation is evaporating as it hits the cold air, its more than likely running up and over it and mixing. Not heavy enough to stick. Shame really, Might improve over the next few hours.

D9Male

Fingers crossed for Friday night into Saturday now.

Looking at the latest models (12z UKMO and GFS), there does seem to be a slight increase in temperatures compared to the 6z, which I think will mean it turns back to sleet and snow that little bit quicker for everyone.

We should all see snow, but those of us on the east coast may want to set the alarm clock early if we want to play in it before it washes away.

Oneiric 3

TTLF wrote: »

This gives a real idea on how extensive the colder air is against that front. Going off the reports from Auntysnow and UpTheHillFrom saying it didn't even get to reach Wexford or Wicklow (as of right now)

As an average, and frankly poor forecaster, I could see this probably going two ways for tomorrow night's low.

1. With the cold pool of air possibly more inland than models predicted, the new front could stall over Leinster giving higher accumulations, especially over the Wicklow and Leinster Mts.

2. The front finally "breaks through" the colder air and stalls a little like today's low before breaching into the Irish sea.

Probably only accumulations of 4-5cm lowland but highland maybe 10cm? It reminds me of a December 2017 where the Wicklow Mts got pasted... except this time no onshore drift ruins it for the E coast.

We'll see how it goes anyway, even today's low has brought many surprises good and bad across the country. On the bright side, the ICON anyway hasn't downgraded the precipitation for tomorrow as it sweeps the country, the midlands (Offaly etc) might get a decent amount if it worked out for them, but that's just me guessing. :P

The only changes I'm seeing to the ICON is the timing, was supposed to reach Dublin by 11pm tomorrow, now it looks like 3am or 4am Saturday... Do I stay up? or do I wake up early...

Your guess is as good as any one else's.
I hope you get your snow.

Gaoth Laidir

I'm now not expecting to see any snow at all this evening. May get a few flakes overnight but the latest runs are not filling me with much hope. I'd be very surprised to see more than a few sugar crystals on the car in the morning. The arse is falling out of this particular event, so let's see what Saturday brings.

barney 20v

AuntySnow wrote: »

Bone dry in Arklow
Precip never got past Wexford

Never got to wexford dispite coming straight in off the Sea...

I've literally traveled from the sea to the Blackstairs Mt's and not one bit of snow.
Zero precipitation.

5 to 20 cm on highground in South leinster was the forecast haha

Gaoth Laidir

Fair play to the wesht. Athenry, Belmullet, Gurteen.

PsMETAR ANRY 111600Z AUTO 11013G24KT 7000NDV -PL OVC009/// M00/M01 1016 MSL=
PsMETAR BELM 111600Z AUTO 13016G31KT 3900NDV -SN OVC022/// 02/M02 1014 MSL=
PsMETAR GURT 111600Z AUTO 10014KT 9999NDV -SN OVC016/// 01/00 1017 MSL=

And Mace Head was hard at the snow earlier too. Now turned to sleet. I'm sure if Knock and Claremorris were reporting they too would be reporting good snow right now.

Sleet in Athlone

METAR EIAC 111630Z AUTO 12013KT 9999 -SHRASN FEW023/// BKN028/// OVC035/// 01/M02 Q1018=

Nqp15hhu

TTLF wrote: »

This gives a real idea on how extensive the colder air is against that front. Going off the reports from Auntysnow and UpTheHillFrom saying it didn't even get to reach Wexford or Wicklow (as of right now)

As an average, and frankly poor forecaster, I could see this probably going two ways for tomorrow night's low.

1. With the cold pool of air possibly more inland than models predicted, the new front could stall over Leinster giving higher accumulations, especially over the Wicklow and Leinster Mts.

2. The front finally "breaks through" the colder air and stalls a little like today's low before breaching into the Irish sea.

Probably only accumulations of 4-5cm lowland but highland maybe 10cm? It reminds me of a December 2017 where the Wicklow Mts got pasted... except this time no onshore drift ruins it for the E coast.

We'll see how it goes anyway, even today's low has brought many surprises good and bad across the country. On the bright side, the ICON anyway hasn't downgraded the precipitation for tomorrow as it sweeps the country, the midlands (Offaly etc) might get a decent amount if it worked out for them, but that's just me guessing. :P

The only changes I'm seeing to the ICON is the timing, was supposed to reach Dublin by 11pm tomorrow, now it looks like 3am or 4am Saturday... Do I stay up? or do I wake up early...

D9Male wrote: »

Fingers crossed for Friday night into Saturday now.

Looking at the latest models (12z UKMO and GFS), there does seem to be a slight increase in temperatures compared to the 6z, which I think will mean it turns back to sleet and snow that little bit quicker for everyone.

We should all see snow, but those of us on the east coast may want to set the alarm clock early if we want to play in it before it washes away.

This is confusing.

Nqp15hhu

vizualpics wrote: »

Central Mayo - light flurries since 1pm, but looking at the Met E radar the precipitation is evaporating as it hits the cold air, its more than likely running up and over it and mixing. Not heavy enough to stick. Shame really, Might improve over the next few hours.

That’s what I am worrying will happen on Saturday! The air is very dry here.

greenpilot

Gaoth Laidir wrote: »

Fair play to the wesht. Athenry, Belmullet, Gurteen.

PsMETAR ANRY 111600Z AUTO 11013G24KT 7000NDV -PL OVC009/// M00/M01 1016 MSL=
PsMETAR BELM 111600Z AUTO 13016G31KT 3900NDV -SN OVC022/// 02/M02 1014 MSL=
PsMETAR GURT 111600Z AUTO 10014KT 9999NDV -SN OVC016/// 01/00 1017 MSL=

And Mace Head was hard at the snow earlier too. Now turned to sleet. I'm sure if Knock and Claremorris were reporting they too would be reporting good snow right now.

Sleet in Athlone

METAR EIAC 111630Z AUTO 12013KT 9999 -SHRASN FEW023/// BKN028/// OVC035/// 01/M02 Q1018=

Nope. Sitting here near Knock. Raining. No snow I'm afraid.

Gaoth Laidir

Only a very slight chance of snow before midnight at Casement. More sure thereafter.

TAF EIME 111700Z 1118/1203 11015KT 9999 SCT015 BKN028
TEMPO 1118/1203 12016G28KT
PROB30 TEMPO 1118/1120 4000 -SN BKN010
PROB30 TEMPO 1122/1124 4000 -SN BKN010
TEMPO 1200/1203 4000 -SN BKN008=

Similarly Dublin Airport, but an hour later.

TAF EIDW 111700Z 1118/1218 13017G27KT 9999 SCT018 BKN030
TEMPO 1118/1210 13020G32KT
PROB30 TEMPO 1122/1201 5000 -SN BKN010
TEMPO 1201/1207 4000 -SN BKN008
PROB30 TEMPO 1201/1206 2000 BKN004
BECMG 1210/1212 14020G32KT
PROB30 TEMPO 1212/1217 13022G37KT=

Gaoth Laidir

greenpilot wrote: »

Nope. Sitting here near Knock. Raining. No snow I'm afraid.

Really? Are you up near the airport? Currently air and dewpoint -0/-4.

PsMETAR KNOC 111700Z AUTO 13019G38KT //// // ////// M00/M04 1017 MSL=

greenpilot

Gaoth Laidir wrote: »

Really? Are you up near the airport? Currently air and dewpoint -0/-4.

PsMETAR KNOC 111700Z AUTO 13019G38KT //// // ////// M00/M04 1017 MSL=

I'm about 1km from the airport, on the Kilkelly side. Precipitation varying now between misty rain and an odd, tiny snow flake.. I'll drive up to EIKN in a sec

Lip Out

This chart posted earlier today shows a reinvigoration of precipitation later tonight for the south east. Is it just a howler or still in prospect?

https://twitter.com/MetEireann/status/1359761421752533000?s=20

Lip Out

Lip Out wrote: »

This chart posted earlier today shows a reinvigoration of precipitation later tonight for the south east. Is it just a howler or still in prospect?

https://twitter.com/MetEireann/status/1359761421752533000?s=20

I'd say it will be completely wrong for the southeast as it was last night
Attached radar image has no precipitation at all I'm under it and can confirm that

lucernarian

I'd consider reports of rain/sleet 1km near Knock to be a fairly bad sign tbh for low level and coastal locations anywhere as this event continues.

Gonzo

latest GFS 12z is a downgrade for snow in the greater Dublin region, the snow shadow now even bigger than on previous runs. At this stage i'm expecting not much more than flakes in the air based on current model.





Once the mild air moves in we do get all the rain of course.

Icon very similar





Arpege has the front making it across on Saturday but it turns to rain over Dublin and the commuter belt.

esposito

Gonzo wrote: »

latest GFS 12z is a downgrade for snow in the greater Dublin region, the snow shadow now even bigger than on previous runs. At this stage i'm expecting not much more than flakes in the air based on current model.





Once the mild air moves in we do get all the rain of course.

Icon very similar





Arpege has the front making it across on Saturday but it turns to rain over Dublin and the commuter belt.

What a joke this is. So hard to get decent snow in the east. I want one more cold blast before mid March with decent snow showers piling in.

Gonzo

esposito wrote: »

What a joke this is. So hard to get decent snow in the east. I want one more cold blast before mid March

This is rough stuff indeed, we got dealt the worst summer in all of Europe during 2020 and now it looks like this final chance of snow has a high probability of being a bust too.

We just have to hope the models have got this wrong, but based on today I wouldn't be surprised if this is correct. Hope i'm wrong but these models are far from inspiring.

Gonzo

Gonzo wrote: »

This is rough stuff indeed, we got dealt the worst summer in all of Europe during 2020 and now it looks like this final chance of snow has a high probability of being a bust too.

We just have to hope the models have got this wrong, but based on today I wouldn't be surprised if this is correct. Hope i'm wrong but these models are far from inspiring.

I'm seeing Spanish friends in a Swiss ski resort in my insta feed having driven there from Madrid...its not helping!
If its any consolation those same models has tonnes of snow this evening in wickliw and wexford
12 hours of it
They were wrong
OK only supposed to start at 80m but not a hope of it
There should be a model tribunal

compsys

The irony that during an easterly it's the north, south and west that ends up with all the snow.

Billcarson

AuntySnow wrote: »

I'm seeing Spanish friends in a Swiss ski resort in my insta feed having driven there from Madrid...its not helping!
If its any consolation those same models has tonnes of snow this evening in wickliw and wexford
12 hours of it
They were wrong
OK only supposed to start at 80m but not a hope of it
There should be a model tribunal

And a cold spell tribunal. Wtf went so wrong this week?
Heights over Scandinavia not strong enough. ?
In future I will only really get sucked in when the heights are yellow on the charts not green .

Artane2002

Billcarson wrote: »

And a cold spell tribunal. Wtf went so wrong this week?
Heights over Scandinavia not strong enough. ?
In future I will only really get sucked in when the heights are yellow on the charts not green .

the two main issues were that heights over us weren't low enough and thicknesses were too high.

greenpilot

lucernarian wrote: »

I'd consider reports of rain/sleet 1km near Knock to be a fairly bad sign tbh for low level and coastal locations anywhere as this event continues.

I took this just 40 mins ago. Passing the end of the runway. No snow at knock, despite reports.

Billcarson

Artane2002 wrote: »

the two main issues were that heights over us weren't low enough and thicknesses were too high.

I did think the fax charts from the uk met office looked strange given the wind from the east and the 528 dam line only partially over the country a number of days ago.

Brz555

Ramping up in galway city again

Squidvicious

Billcarson wrote: »

I did think the fax charts from the uk met office looked strange given the wind from the east and the 528 dam line only partially over the country a number of days ago.

That's always been my rule of thumb for snow. If you're not on the right side of the 528 dam line, you won't generally get snow. I know that there are other factors and you may not get it even if you are on the right side, but it's a very good guide. That said, today, the biggest problem for most of us was a lack of rainfall intensity. Some areas did get snow, it's just that the front fragmented over most of the country. If the front had only been more active, we'd have been fine.

Daz_

AuntySnow wrote: »

I'm seeing Spanish friends in a Swiss ski resort in my insta feed having driven there from Madrid...its not helping!
If its any consolation those same models has tonnes of snow this evening in wickliw and wexford
12 hours of it
They were wrong
OK only supposed to start at 80m but not a hope of it
There should be a model tribunal

Seems like a great idea travelling from spain to Switzerland in a pandemic for some skiing
Also why compare with Swiss Alps in the desire for snow ?!
The heavy snow build up / hype for this week has been fairly ridiculous

Nqp15hhu

Gonzo wrote: »

This is rough stuff indeed, we got dealt the worst summer in all of Europe during 2020 and now it looks like this final chance of snow has a high probability of being a bust too.

We just have to hope the models have got this wrong, but based on today I wouldn't be surprised if this is correct. Hope i'm wrong but these models are far from inspiring.

This won’t be the last snow, it always snows in March. Just stop looking to the east for snow, it’s not reliable. Look North.

Nqp15hhu

Billcarson wrote: »

And a cold spell tribunal. Wtf went so wrong this week?
Heights over Scandinavia not strong enough. ?
In future I will only really get sucked in when the heights are yellow on the charts not green .

- Convective cap limited the intensity of snow showers (warming with height above the 800mb level).
- Strong winds kept temperatures up at night limiting ice days and melting any light accumulations.
- Stratus clouds (sheet cloud) kept temps up at times.

So with the next cold spell look for lower heights, a more stable sounding (temp dropping with height to all levels) and limited wind.

Stop looking to warm fronts to deliver snow. It doesn’t usually work for us.

space2ground1

I think despite my interest in meteorology, this will be my last time setting up followed threads for a weather event.
Through no fault of anyone here, yet another rollercoaster slows to a stop and falls over sideways. The models seem to have predicted 45 of the last 3 snow events.. rendering them less than useful.

I have learned a lot from the regular posters though so thank you! You deserve better from the models. I've always said there should be en element of mathematical probability built into them.