Cold Spell - Feb 7th to 13th 2021 - Chat

King of Spades

Nqp15hhu wrote: »

-11c 850hPa and still 1c in Lerwick! It would seem you need far lower for an ice day (not with fog)!

Not sure if you’ve been there (I was once) but Lerwick town is virtually surrounded on all sides by the Atlantic. That will heavily influence temperatures there. 1 degree at lunchtime will still feel bitter there though.

Bogwoppit

King of Spades wrote: »

Not sure if you’ve been there (I was once) but Lerwick town is virtually surrounded on all sides by the Atlantic. That will heavily influence temperatures there. 1 degree at lunchtime will still feel bitter there though.

10 degrees feels bitter in Lerwick!

John.Icy

Nqp15hhu wrote: »

-11c 850hPa and still 1c in Lerwick! It would seem you need far lower for an ice day (not with fog)!

Far more to an ice day than 850s - especially soon after the arrival of the cold.

We had several ice days in the first 10 days of December in 2010 in rather modest 850s. Slack winds, many days of snow cover, Barrow valley cold pooling etc.

Nqp15hhu

Pretty sure -11c 850hPa’s in the US would bring far colder temps.

Anyway, my point is that there always seems to be a shallow surface layer that is above freezing here. Locally we even managed to record a 1c high with -14c 850hPa a few years ago!

Kermit.de.frog

Attention needs to turn soon to intensity of the snow showers. Seeing good trends. Need to see more over the next day or so. :cool:

TTLF

Kermit.de.frog wrote: »

Attention needs to turn soon to intensity of the snow showers. Seeing good trends. Need to see more over the next day or so. :cool:

can u link that? I wanna see it slowed down hahaah

JanuarySnowstor

Met Eireann seem to be saying East/Northeast winds next week. Surely the winds are clearly southeast bringing snow to south coast. Anyone know why they think Northeast winds??

Kermit.de.frog

TTLF wrote: »

can u link that? I wanna see it slowed down hahaah

http://www.meteociel.com/modeles/icon-eu.php?ech=3&mode=42&map=510

@JS

That's from ICON model. Just one but shows more northeasterly but more unstable so enhanced shower activity.

Nqp15hhu

JanuarySnowstor wrote: »

Met Eireann seem to be saying East/Northeast winds next week. Surely the winds are clearly southeast bringing snow to south coast. Anyone know why they think Northeast winds??

No. Winds are ENE, almost NE through the week.

Donegal Ken

Zogabomb wrote: »

Just heard on Newstalk that Met Eireann are briefing Local Authorities about a potential snow event next week. Are they expecting the cold to put up more of a fight I wonder?

As I said yesterday don't expect any massive updates from Met Eireann until the weekend. A weather advisory will most likely be issued today followed by warnings later Saturday or Sunday morning. There most likely will be a meeting of Emergency Coordination Group later this weekend or Monday if they are confident of a big snowfall event next week. The streamers coming in of the Irish sea especially later Monday until Wednesday could give some good accumulations of snow with models not picking these up fully. Later in the week a more widespread snowfall event is also possible something that they will be watching very closely. Met Eireann have much more data resources available to them than any one on here and will be in close contact with the Met office in the UK also.

Le Bruise

Kermit.de.frog wrote: »

Attention needs to turn soon to intensity of the snow showers. Seeing good trends. Need to see more over the next day or so. :cool:

Wicklow town just about making it out of the Anglesey shadow there!:)

esposito

Donegal Ken wrote: »

As I said yesterday don't expect any massive updates from Met Eireann until the weekend. A weather advisory will most likely be issued today followed by warnings later Saturday or Sunday morning. There most likely will be a meeting of Emergency Coordination Group later this weekend or Monday if they are confident of a big snowfall event next week. The streamers coming in of the Irish sea especially later Monday until Wednesday could give some good accumulations of snow with models not picking these up fully. Later in the week a more widespread snowfall event is also possible something that they will be watching very closely. Met Eireann have much more data resources available to them than any one on here and will be in close contact with the Met office in the UK also.

Weather advisory issued a few mins ago by Met Eireann covering Sunday to Wednesday inclusive.

Davaeo09

All the talk about shadows and distance needed for proper "lake effect" snow, has had me drawing lines on google maps like I actually know what I am doing

I always used to get frustrated watching streamers go North of me, then the next day to the South.
How variable can the wind direction actually be over the space of 12-24 hours???
Many questions, much confusion.

Donegal Ken

JanuarySnowstor wrote: »

Met Eireann seem to be saying East/Northeast winds next week. Surely the winds are clearly southeast bringing snow to south coast. Anyone know why they think Northeast winds??

Winds are northeast/east much of the week but turning southeasterly later Wednesday as that Atlantic front comes in.

Snowbiee21

Weather Advisory for Ireland

Sunday, Monday, Tuesday and Wednesday will be very cold with temperatures in low single figures by day and with sharp or severe frosts and icy patches at night.

Showers of sleet or snow at times in eastern counties from Sunday evening onwards.

Hazardous conditions on roads and paths.

Valid: 06:03 Sunday 07/02/2021 to 18:00 Wednesday 10/02/2021

Issued: 13:00 Friday 05/02/2021

redsteveireland

Nqp15hhu wrote: »

No. Winds are ENE, almost NE through the week.

Tuesday looks like the only day I would have a chance of a beefy shower train reaching me from the Irish Sea, the first chance of snow here looks like Thursday but then it's looking like a snow /rain transition day.

SouthWesterly

Can we have some dry warm weather in kerry while the east coast gets blasted with snow?.. Pretty please:D

Chalkitdown147

So who misses out on a E/ENE wind ie IOM Shadow?? I'm Ongar D15, which I think will just miss the shadow if it goes ENE

highdef

Nqp15hhu wrote: »

No. Winds are ENE, almost NE through the week.

I'm completely open to correction on this but I thought the clouds/showers move in the direction of the steering winds which are at (and often above) the 850mb level and that the low level/ground level wind charts that you posted can not be relied on for the trajectories of clouds.

Having said that, the direction of the winds for the early days of next week at 850mb does look pretty similar to 10m level that you posted but just highlighting that relying on 10m for this purpose is probably not such a good idea.

On the upside, with the wind trajectory being generally similar near ground level and at the 850mb (and even up to the 700mb level), I would imagine that this will only help the showers to develop readily owing to the lack of shear.

Calibos

Nqp15hhu wrote: »

No. Winds are ENE, almost NE through the week.

These wind charts and Kermits link to the ICON Precip animation that I could advance frame by frame put my mind somewhat at ease compared to last night when I got the impression the forecast had changed to pure easterly or South easterly even Monday and Tuesday which put my location in Bray into the Angelsey and Wales Shadow for the duration. So late last night after the days models I was downbeat because not alone did it look like the Slider Low Frontal event for Wednesday was off the cards and instead likely to end the whole event Wednesday but It looked like I was going to miss out on anything more than a dusting on Mon and Tuesday too turning it all into a poor or non event for Bray.

Sounds like from todays charts and rumblings from Met Eireann its all still to play for, even the Slider Low isn't totally off the cards as of today.

I'll be thrilled with 4 or 5 inches that sticks around till Wednesday night but over the moon if we get a frontal Dumping from that low too and then that stays on the ground till that swathe of positive uppers rolls in on Saturday.

Squidvicious

redsteveireland wrote: »

Tuesday looks like the only day I would have a chance of a beefy shower train reaching me from the Irish Sea, the first chance of snow here looks like Thursday but then it's looking like a snow /rain transition day.

Not sure where you are but Tuesday does seem to be the favoured day for shower activity. However, that could change - airflows of this kind are not easy to predict. Wind direction will be important too. I'm in the South East so I'm hoping that the winds will swing around a little more North-Easterly and a small change in the wind direction may make a big difference to some areas.

IvySlayer

Chalkitdown147 wrote: »

So who misses out on a E/ENE wind ie IOM Shadow?? I'm Ongar D15, which I think will just miss the shadow if it goes ENE

I live in Lucan and if the shadow affects me there'll be serious fist shaking I can assure of that :mad:

Larbre34

Davaeo09 wrote: »

How variable can the wind direction actually be over the space of 12-24 hours???

In the right circumstances, a rapidly advancing front, squall line, low pressure centre etc, wind direction can change completely in the space of 30 minutes, not to mind 12 to 24 hours.

Bio Mech

Is there a list of banned words for this thread? If so I propose we add “Shadow”.

Also Anglesey, Mann and snow shield.

Gaoth Laidir

Just to note too that in a northeasterly, frictional convergence along the south Down coast (winds slower over land and hence more northerly) would enhance convection there, leading to higher precipitation totals in say Louth - Meath. You can see that in the last frames of Kermit's animation above.

That's one of the local effects that can tip the balance one way or the other.

Chalkitdown147

IvySlayer wrote: »

I live in Lucan and if the shadow affects me there'll be serious fist shaking I can assure of that :mad:

I think that it's ENE from true north so North Kildare/West Dublin should be in firing line regardless of the small wind changes......but I maybe open to correction by the wise weather folks in here

Nqp15hhu

highdef wrote: »

I'm completely open to correction on this but I thought the clouds/showers move in the direction of the steering winds which are at (and often above) the 850mb level and that the low level/ground level wind charts that you posted can not be relied on for the trajectories of clouds.

Having said that, the direction of the winds for the early days of next week at 850mb does look pretty similar to 10m level that you posted but just highlighting that relying on 10m for this purpose is probably not such a good idea.

On the upside, with the wind trajectory being generally similar near ground level and at the 850mb (and even up to the 700mb level), I would imagine that this will only help the showers to develop readily owing to the lack of shear.

Most research studies refer to the 850mb winds having the most influence.

Larbre34

Bio Mech wrote: »

Is there a list of banned words for this thread? If so I propose we add “Shadow”.

Also Anglesey, Mann and snow shield.

Why, these phenomena are a reality of sea convection in an easterly? Its quite likely there will be local effects from them.

Nqp15hhu

Calibos wrote: »

These wind charts and Kermits link to the ICON Precip animation that I could advance frame by frame put my mind somewhat at ease compared to last night when I got the impression the forecast had changed to pure easterly or South easterly even Monday and Tuesday which put my location in Bray into the Angelsey and Wales Shadow for the duration. So late last night after the days models I was downbeat because not alone did it look like the Slider Low Frontal event for Wednesday was off the cards and instead likely to end the whole event Wednesday but It looked like I was going to miss out on anything more than a dusting on Mon and Tuesday too turning it all into a poor or non event for Bray.

Sounds like from todays charts and rumblings from Met Eireann its all still to play for, even the Slider Low isn't totally off the cards as of today.

I'll be thrilled with 4 or 5 inches that sticks around till Wednesday night but over the moon if we get a frontal Dumping from that low too and then that stays on the ground till that swathe of positive uppers rolls in on Saturday.

That’s very good. I am sure you will have some sort of covering. It may not materialise on Sunday, perhaps Monday.

redsteveireland

Squidvicious wrote: »

Not sure where you are but Tuesday does seem to be the favoured day for shower activity. However, that could change - airflows of this kind are not easy to predict. Wind direction will be important too. I'm in the South East so I'm hoping that the winds will swing around a little more North-Easterly and a small change in the wind direction may make a big difference to some areas.

I am in East Galway and have benefited from Irish Sea streamers before.
I will hold off on the trip to Decathlon though.

https://www.decathlon.ie/ie_en/adult-tray-sledge-trilugik-green-en-s308184.html