Significant Snow Risk Friday 7th/Saturday 8th January discussion

darkman2 · 04-01-2011 8:33am #1

I did ellude briefly yesterday that there was a small risk of significant snow during Friday and Saturday. It's still a relatively small but increasing risk that there will be a significant snowfall in many areas or at the very least snow for a time. Please keep this thread for discussion on this as it could be a disruptive snowfall. Most models are playing up the risk of disruption this morning but this could change.

Basically the country will find itself sandwiched between two different air masses - mild to the South, cold to the North - it's been many years since we had a frontal snow event in Ireland and so if one does occur it could be disruptive. More later...:)

Have to watch this one closely

Vudgie · 04-01-2011 9:08am

I see that MET Eireann are now suggesting that most of the country could see snow on Friday from the south with up to 10cms in places and possible drifts due to winds.

One to watch alright, though with the potential fluctuations in temps and the potential for rain around it is probably unlikely that we will see the dramatic freezing of snow.

Snowman10 · 04-01-2011 9:52am

We dont want snow. Too much hassle the last time and i've only got my water back from frozen pipes.

irish1967 · 04-01-2011 9:55am

Lol. Think a change of name might be called for there Snowman.

04-01-2011 9:57am

I doubt coastal areas of the East including Dublin will see snow from this if the wind is directly off the irish sea.
The cold pool is simply not cold enough for to modify that kind of mixing.
10 miles inland in leinster and above 500ft asl,it's a different story entirely

It could well be a full snow event for much of inland ulster and all of Connaught and North munster.
I'd rule out snow from any of the get go in coastal waterford and cork also and maybe further north of there exposed to an onshore wind if it's Easterly.

One to watch alright.At this stage it's a significant chance which may reduce or increase depending on developments.

darkman2 · 04-01-2011 10:02am

That is a possibility in coastal areas. But atm on the GFS and UKMO the minimum requirements are satisfied for sea snow on Friday that is sub zero dew points and 850hpa temperatures starting out at sub -8C in the Irish sea (for a time on the GFS, more so on the UKMO). Inland it's less marginal as usual but we don't know yet what the wind direction will actually be and the whole lot could still miss us enitrely. Unlikely but possible.

Rebelbrowser · 04-01-2011 10:07am

Deleted User wrote: »

I doubt coastal areas of the East including Dublin will see snow from this if the wind is directly off the irish sea.
The cold pool is simply not cold enough for to modify that kind of mixing.
10 miles inland in leinster and above 500ft asl,it's a different story entirely

It could well be a full snow event for much of inland ulster and all of Connaught and North munster.
I'd rule out snow from any of the get go in coastal waterford and cork also and maybe further north of there exposed to an onshore wind if it's Easterly.

One to watch alright.At this stage it's a significant chance which may reduce or increase depending on developments.

Just wondering would this be potentially like the 10 Jan fall last year which came from the South? That was pegged as marginal all that week but eventually came good for some. In fact, unusually, it gave good falls to South Munster (where it was always called as a sleet event by ME) but fell as rain on East coast.

04-01-2011 10:09am

Agreed.
I don't like a surface feed off the irish sea though when theres no surface cold advection to feed upon.
So I'm sticking with rain on coasts below 150 metres up to 10 miles inland,like the sunday event at the end of the january 10 spell.

Thats if the system comes up,yes of course.

DOCARCH · 04-01-2011 10:09am

Deleted User wrote: »

I doubt coastal areas of the East including Dublin will see snow from this if the wind is directly off the irish sea.

Such a shame the M2 bouy is down. Will feel like being only partially sighted!

04-01-2011 10:11am

Rebelbrowser wrote: »

Just wondering would this be potentially like the 10 Jan fall last year which came from the South? That was pegged as marginal all that week but eventually came good for some. In fact, unusually, it gave good falls to South Munster (where it was always called as a sleet event by ME) but fell as rain on East coast.

Similar but different.
This system has to meet the cold air to turn to snow and it's unlikely to be meeting it as early as cork unlike that sunday jan 2010 event..
The colder air is going to be further north.
It certainly won't meet it in cork city.

04-01-2011 10:15am

DOCARCH wrote: »

Such a shame the M2 bouy is down. Will feel like being only partially sighted!

Doc,theres a crucial,very crucial difference here.
There are no snow fields over the UK south of the north of England or there won''t be .
In january 2010 there were and the surface feed was coming over that freezing area before being modified over the irish sea.Even with that freezing surface air then,the mixing caused sleet and rain on the coast.This is more marginal that that.
This time if the wind is East snow is going to have a hard time making it to the ground at sea level near to the coast.

darkman2 · 04-01-2011 10:20am

Deleted User wrote: »

Similar but different.
This system has to meet the cold air to turn to snow and it's unlikely to be meeting it as early as cork unlike that sunday jan 2010 event..
The colder air is going to be further north.
It certainly won't meet it in cork city.

I would not go along with that

UW72-7.GIF?04-06

For a frontal event it's sub -4c that is the crucial marker esspecially for inland snow. Sub -4 and a frontal system over your head is highly likely to be snow and there are other reasons why that is the case whereas in a showery setup it's not as likely and the most major one I suppose is evaporative cooling. That can change rain to snow in supprising places where it would not have been expected and it's happened loads of times in the past in Ireland. Frontal snow events do happen in Ireland and they have happened in my area right on the coast - if we look at it in a broader sense, yes this setup could be marginal but do we have a better shot this time then maybe other years? Id imagine so given what we have already had this year. It is extraordinary considering the last 3 winters have been so cold that there has not been a decent prolonged snow event yet. Remember SST's are below average now aswell and that has to be taken into account. We are due a significant snowfall. Maybe Friday and Saturday who knows....

thomasj · 04-01-2011 10:32am

darkman2 wrote: »

better shot this time then maybe other years? Id imagine so given what we have already had this year. ....

04-01-2011 10:33am

darkman2 wrote: »

I would not go along with that

For a frontal event it's sub -4c that is the crucial marker esspecially for inland snow. Sub -4 and a frontal system over your head is highly likely to be snow and there are other reasons why that is the case whereas in a showery setup it's not as likely and the most major one I suppose is evaporative cooling. That can change rain to snow in supprising places where it would not have been expected and it's happened loads of times in the past in Ireland. Frontal snow events do happen in Ireland and they have happened in my area right on the coast - if we look at it in a broader sense, yes this setup could be marginal but do we have a better shot this time then maybe other years? Id imagine so given what we have already had this year. It is extraordinary considering the last 3 winters have been so cold that there has not been a decent prolonged snow event yet. Remember SST's are below average now aswell and that has to be taken into account. We are due a significant snowfall. Maybe Friday and Saturday who knows....

So the rain in Dublin on that sunday event in january 2010 was falling at -4c 850's or higher was it?
Show me a historical chart for that day that tells me that and I'll except your point.

From experience,I've never seen it to snow on the East coast with a weather front coming up from the south in Easterly winds when 2 of the following things are not in place already and those are,an established surface cold pool over Ireland and a freezing surface air feed in that easterly flow from Britain.

jay-me · 04-01-2011 10:33am

Accuweather doesn't have the same predictions

Does anyone know if it is likely the airport will be affected again?

senordingdong · 04-01-2011 10:35am

Vudgie wrote: »

I see that MET Eireann are now suggesting that most of the country could see snow on Friday from the south with up to 10cms in places and possible drifts due to winds.

One to watch alright, though with the potential fluctuations in temps and the potential for rain around it is probably unlikely that we will see the dramatic freezing of snow.

I think they have a subscription to Darkman2s threads.

darkman2 · 04-01-2011 10:40am

Deleted User wrote: »

So the rain in Dublin on that sunday event in january 2010 was falling at -4c 850's or higher was it?
Show me a historical chart for that day that tells me that and I'll except your point.

From experience,I've never seen it to snow on the East coast with a weather front coming up from the south in Easterly winds when 2 of the following things are not in place already and those are,an established surface cold pool over Ireland and a freezing surface air feed in that easterly flow from Britain.

BB, my dear fellow, you do have a short memory.

I remember that "event" and I was very clear at the time that it would only snow on the coast for a short time...I was very specific about it because I was having an argument with Su Campu. I was right. I saw the snow - the guy who works in Dublin port and posts here saw the snow. That was directly off the sea and upper temperatures were more marginal then what is currently forcast (subject to change!) but it did not last long as the transition was too fast because of the orientation of the LP at the time.

Im fairly sure this was it here but not 100% on the 13th of January

You may well be right. But I would not rule anything in or out yet as it's still a few days off.

WolfeIRE · 04-01-2011 10:44am

Latest GFS rolling out now. Those banking on a countrywide snow event should not get to excited just yet. Only the highest ground in the southern half of the country will see any snow while any snow would be confined to higher ground again further north. That is according to the GFS and ECM. UKMO is much more favourable for snowfall.

Darkman may be correct but some shifting south of cold air needs to occur first. This may happen in the next run or two.

ps...the use of the word 'significant' in the post thread is a little premature. If it turns out that snow doesn't fall then boards.ie weather forum will look silly. Of course, if it does happen then Darkman becomes King and I but a mere jester:)

04-01-2011 10:47am

darkman2 wrote: »

You may well be right. But I would not rule anything in or out yet as it's still a few days off.

You are pretty much raising Dublin snow lovers hopes by discounting the lack of a freezing surface cold pool overland and a freezing surface advection from the UK.
Both of which were present on that sunday event and yet produced rain [yes with a short period of wet snow thanks to those two items being present]

The lack of those two things make coastal snow a big ask from a warm system moving up from the south with only cold uppers[and not very cold only -8c] to help.

darkman2 · 04-01-2011 11:10am

6z GFS going for something lighter in terms of snow. The cold air gets somewhat further South and no issue with the minimum criteria for snow either inland or on most of the Irish Sea on Friday afternoon.

Sorry for using this chart - I know it is for France but it is the highest resolution we have for the GFS

81-574.GIF?04-0

All these charts will change back and forth for the next couple of days.

Smokey Bear · 04-01-2011 11:36am

Here is a 1km GFS for Dublin if its any help also available a 27km North atlantic option

http://www.belgingur.is/vedurkort/

(On Region tab click Dublin 1km to see GFS forecast or North Atlantic 27km GFS forecast)

Smokey Bear

darkman2 · 04-01-2011 11:47am

Smokey Bear wrote: »

Here is a 1km GFS for Dublin if its any help also available a 27km North atlantic option

http://www.belgingur.is/vedurkort/

(On Region tab click Dublin 1km to see GFS forecast or North Atlantic 27km GFS forecast)

Smokey Bear

Thanks, never used that before. Having that high a resolution is fantastic. Only qualm is there is only temperature at ground level.

derekon · 04-01-2011 1:02pm

Is it just me or has Met Eireann totally lost the run of themselves - has Evelyn been allowed to type up the attached forecast published on the ME website this morning at 05.14am ? !! Very brave to publish the forecast below given how far out we are...........

A sharp frost will develop over much of the country on Thursday night. A band of rain will develop in the southwest early in the night and gradually spread northwards to all areas overnight and through Friday morning. At the moment it looks like it will fall as sleet and snow over much of the country and there could be up to 10 cm of snow in many areas with possible drifting due to fresh, gusty easterly winds

My own experience of any system coming from the south is that it will fall as rain so I would take the above with a very large pinch of salt

Big Daddy Cool · 04-01-2011 1:14pm

derekon wrote: »

Is it just me or has Met Eireann totally lost the run of themselves - has Evelyn been allowed to type up the attached forecast published on the ME website this morning at 05.14am ? !! Very brave to publish the forecast below given how far out we are...........

A sharp frost will develop over much of the country on Thursday night. A band of rain will develop in the southwest early in the night and gradually spread northwards to all areas overnight and through Friday morning. At the moment it looks like it will fall as sleet and snow over much of the country and there could be up to 10 cm of snow in many areas with possible drifting due to fresh, gusty easterly winds

i think she has allowed herself to be influenced by some of the posts about potential snow on here

flanzer · 04-01-2011 1:38pm

Big Daddy Cool wrote: »

i think she has allowed herself to be influenced by some of the posts about potential snow on here

I welcome Met's new stance. At least they're warning the public of the potential and not nowcasting like they did on the last 2 events.

If the public realise it's potential snow, it's no harm. Better to be prepared than not.

As long as the public don't call for them to be burnt at the stake if nothing materialises though, which will probably happen :pac:

nacho libre · 04-01-2011 1:46pm

derekon wrote: »

Is it just me or has Met Eireann totally lost the run of themselves - has Evelyn been allowed to type up the attached forecast published on the ME website this morning at 05.14am ? !! Very brave to publish the forecast below given how far out we are...........

A sharp frost will develop over much of the country on Thursday night. A band of rain will develop in the southwest early in the night and gradually spread northwards to all areas overnight and through Friday morning. At the moment it looks like it will fall as sleet and snow over much of the country and there could be up to 10 cm of snow in many areas with possible drifting due to fresh, gusty easterly winds

My own experience of any system coming from the south is that it will fall as rain so I would take the above with a very large pinch of salt

yes the perils of basing the forecast on one overnight run which will likely change by the next run. so i'd be very surprised if tomorrows update isn't completely different

cherryghost · 04-01-2011 1:49pm

Netweathers experimental forecasts a couple of cm or so

Big Daddy Cool · 04-01-2011 1:50pm

flanzer wrote: »

I welcome Met's new stance. At least they're warning the public of the potential and not nowcasting like they did on the last 2 events.

If the public realise it's potential snow, it's no harm. Better to be prepared than not.

As long as the public don't call for them to be burnt at the stake if nothing materialises though, which will probably happen :pac:

yeah i would agree if the rain wasnt coming from the south west, i'm no expert on this matter but the chances of snow from it has to be very very slim, and i would guess this forecast will be changed before thursday night and they will be burned at the stake

WolfeIRE · 04-01-2011 1:54pm

http://www.thejournal.ie/nationwide-blanket-of-snow-predicted-for-friday-2011-01/
IT’S SNOW JOKE: Met Eireann is forecasting a new nationwide blanket of snow for this Friday.
Temperatures have dropped noticeably in the past few days with temperatures expected to drop as low as -1 degrees Celsius in some parts tonight. While rain and sleet showers will break out over Connacht, Ulster, west Munster and north Leinster tomorrow, Friday is the day to make sure you are wrapped up warm. According to Met Eireann, a sharp frost will develop over much of the country on Thursday night and rain will spread countrywide on Friday morning.
However, these showers are forecast “at the moment” to convert into sleet and snow all over the country and “there could be up to 10cm of snow in many areas” with “possible drifting” due to gusts from the east. Snow is expected to settle and roads will be icy but the good news is that Saturday will be less cold with temperatures reaching a high of 5 degrees Celsius.
Sunday will not be a day of rest for the wintry weather though – the national meteorological service predicts that there will be “further wintry showers” to round off the weekend.

inabina · 04-01-2011 2:09pm

derekon wrote: »

Is it just me or has Met Eireann totally lost the run of themselves - has Evelyn been allowed to type up the attached forecast published on the ME website this morning at 05.14am ? !! Very brave to publish the forecast below given how far out we are...........

A sharp frost will develop over much of the country on Thursday night. A band of rain will develop in the southwest early in the night and gradually spread northwards to all areas overnight and through Friday morning. At the moment it looks like it will fall as sleet and snow over much of the country and there could be up to 10 cm of snow in many areas with possible drifting due to fresh, gusty easterly winds

My own experience of any system coming from the south is that it will fall as rain so I would take the above with a very large pinch of salt

Believe it or not, this was Gerry Murphy. Well, I have strong reason to believe that the person who writes the 5am update on met.ie reads the 755 radio 1 forecast, and he did read that forecast this morning. He also used very very similar words, if not the same words.

04-01-2011 2:09pm

darkman2 wrote: »

Thanks, never used that before. Having that high a resolution is fantastic. Only qualm is there is only temperature at ground level.

What does the 1km refer to in that chart?
Surely not the temperature at circa 3000ft asl?

Villain · 04-01-2011 3:19pm

Deleted User wrote: »

What does the 1km refer to in that chart?
Surely not the temperature at circa 3000ft asl?

1km refers to the resolution scale

Pangea · 04-01-2011 3:33pm

First snow reported in 2011 fell in Donegal

The first snow of 2011 fell across parts of Co Donegal yesterday. Some parts of the county received a dusting of snow yesterday morning and in the early afternoon.

Temperatures were expected to fall to -5 in some places last night with warnings from Met Éireann that rain will fall as sleet and snow in many places.

Amateur weatherman and postman Michael Gallagher says we are set for another freezing spell.

Met Éireann is predicting temperatures of between 3 and 7 degrees today across the country.
http://oceanfm.ie/article/First-snow-reported-in-2011-fell-in-Donegal/

thetonynator · 04-01-2011 3:42pm

Pangea wrote: »

First snow reported in 2011 fell in Donegal

The first snow of 2011 fell across parts of Co Donegal yesterday. Some parts of the county received a dusting of snow yesterday morning and in the early afternoon.

Temperatures were expected to fall to -5 in some places last night with warnings from Met Éireann that rain will fall as sleet and snow in many places.

Amateur weatherman and postman Michael Gallagher says we are set for another freezing spell.

Met Éireann is predicting temperatures of between 3 and 7 degrees today across the country.
http://oceanfm.ie/article/First-snow-reported-in-2011-fell-in-Donegal/

There were showers in sever; places before yesterday weren't there?? i saw lots of reports of them anyway . . .

Pangea · 04-01-2011 3:47pm

thetonynator wrote: »

There were showers in sever; places before yesterday weren't there?? i saw lots of reports of them anyway . . .

Dont think so. There were reports of snow showers in other parts of Ireland yesturday aswell but not before yesturday , not in Donegal anyways.

typhooner · 04-01-2011 3:49pm

unusual for Meteireann to be so bullish on an event that is 3/4 days ahead, synoptics are close enough though you'd have to think 50/50 call at the moment for a countrywide snow event

04-01-2011 3:53pm

But what does that mean?

Iancar29 · 04-01-2011 4:00pm

typhooner wrote: »

unusual for Meteireann to be so bullish on an event that is 3/4 days ahead, synoptics are close enough though you'd have to think 50/50 call at the moment for a countrywide snow event

We give out when they dont risk it for a biscuit... and we question them when they do?..... hahaha

LEt them.... ha

Villain · 04-01-2011 4:02pm

Deleted User wrote: »

But what does that mean?

It's accurate to 1km compared to say 27km. So it give different temps for each 1km compared to giving temps every 27km.

So it can give temp of say 5c 1km from coast and 4c 2km etc etc as where the 27km will give temp difference only each 27km

Pangea · 04-01-2011 4:11pm

Pangea wrote: »

rain will fall as sleet and snow in many places.

Rain in Disguise

Iancar29 · 04-01-2011 4:12pm

Pangea wrote: »

Rain in Disguise

BEASTERLY · 04-01-2011 4:22pm

Latest GFS shows a band of rain preceded shortly by mainly sleet and possibly some snow.

I hope im wrong but i would be extremely surprised if anybody saw any decent accumulating snow, never mind the 10cm are talking about, maybe ts just the GFS leading us astray , i wish:(

eigrod · 04-01-2011 4:24pm

typhooner wrote: »

unusual for Meteireann to be so bullish on an event that is 3/4 days ahead, synoptics are close enough though you'd have to think 50/50 call at the moment for a countrywide snow event

It'll be ME responding to the requirement for increased Public Sector effiencies under the Croke Park agreement

aboyro · 04-01-2011 4:24pm

todayfm news just mentioned the weather and used the words 10cm, snow and significant in the same sentence!!!!! interesting. i'm still thinkg rain for me though

04-01-2011 4:25pm

I can't actually open it on the phone.
I presume it gives this on a map.

How are they calculating this from the gfs data ie what formula.
Presumably its only possible to be reasonably accurate inside a 24 or 36hr timeframe and even at that gfs as any model has been out at times at that distance.
How accurate is it for today for instance.
It seems to be a new project so no validation stats other than over all gfs validation stats.

John.Icy · 04-01-2011 4:25pm

The thing on our side, is that when the milder uppers arrive at our shores, the precip has all but stopped, as all of the good stuff goes into England instead. Then by the time colder uppers return another band moves across the country, heavier than the first, and would bring snow again to places.

Though anyone looking for a signifigent event, its gone, All the heaviest of the precip feeds into England, where it falls only as rain, par Northern parts. As I thought, the closer we get to the event, the more changes. Last night on the 18z the low was delayed, today, it sends everything to Britan. The last two of these Lows moving up from the south in cold spell's, ended up in coming No-where near us, I really feel there's an outside chance of this.

Also, this is very marginal for parts, the futher north and inland you go the better of a chance. But really, if snow falls, it will be super wet, and it wont accumulate on anything but grass and cars.

Let's hope for an upgrade.

Iancar29 · 04-01-2011 4:26pm

BEASTERLY wrote: »

Latest GFS shows a band of rain preceded shortly by mainly sleet and possibly some snow.

I hope im wrong but i would be extremely surprised if anybody saw any decent accumulating snow, never mind the 10cm are talking about, maybe ts just the GFS leading us astray , i wish:(

No, i agree Beasterly, its not cold enough, thatll be mostly sleety rain at most, then just a short period of wet snow that wont stick. Hoping for a upgrade tough for temps to go a bit lower than expected!

maquiladora · 04-01-2011 4:40pm

Latest GME showing a wet & windy Sunday night/Monday morning at the end of it's run

gme-0-132.png?12

BEASTERLY · 04-01-2011 4:43pm

GFS is forecasting dewpoints to be above zero over much of the country by lunchtime friday, i dont know where met eireann are seeing the potential for prolonged snow ''across much of the country'', or anybody else for that matter.

The most northern reach of the front may well see the precip stay as snow but there it very likely to be light a short lived, anywhere where the precip is heavy or prolonged(where the mild air all ready has swaded in at that stage) will have mixed precip at best, most likely plain rain.(you might be lucky to see splodges of slightly sleety rain on your windscreen:D)

nacho libre · 04-01-2011 4:47pm

maquiladora · 04-01-2011 4:48pm

BEASTERLY wrote: »

GFS is forecasting dewpoints to be above zero over much of the country by lunchtime friday, i dont know where met eireann are seeing the potential for prolonged snow ''across much of the country'', or anybody else for that matter.

The 0Z ECM (at T24) shows colder uppers than the latest GFS for the same timeframe, I'd say thats why.

Significant Snow Risk Friday 7th/Saturday 8th January discussion

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