Severe Frost countrywide + Occasional Snow Showers in the East from Thursday 9th Feb

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Gonzo wrote: »

I get the feeling this will be very much knife edge stuff. Looks very marginal with warmer zones never too far away. Also looks like most of us will experience the Isle of Man shadow at some point with north-easterly's then turning south-easterly as the coldest section passes to our west.

We've experienced these sort of weak easterly's before where it's simply not cold enough with rain showers down the east coast that only turn to snow about 35 miles inland.

This could be our one and only shot at snow this winter, and in many parts of Leinster, the first shot at snow in 7 years. Hopefully it will be colder than I think with at least a 24 hour period of white gold.

Thought you had snow a few weeks ago? :pac:

IOM needs to ship itself 150km south!

Iancar29

Rebelbrowser wrote: »

Sorry if stupid question, but if winds are due east on Friday, could there be enough of a fetch for streamers to hit us on the south coast? I ask as:-

1. Ireland's south coast is actually east facing in that it is angled that way;
2. The fetch is much longer from, say, Cork to mid Wales than further up our east coast: and
3. Looking at Euro 04 for early Friday (see below), even then its -7 air travelling over the Irish sea which at Buoy 5 off Wexford is currently reading Sea temps of 10c. Big enough differential for lake effect snow isn't it?

Any basis for think such streamers are possible? Sorry if daft question...

No thats a great question.

I would say that its just a case that more factors for streamers to occur down that way just don't come together as often.

For example wind shear and relative humidity come into play too. You need directional shear to be low for the cells to have easier route to the higher layers of the atmosphere, thus cooling down quicker and increasing in intensity.

Relative humidity levels would need to be high too.

I think the GFS had some showers progged for the south, but i have a feeling they won't be strong enough to bring down the freezing level enough for snow. Now casting it'll come down to Id say as mentioned already, its very knife edge synoptics.

Gonzo

Jordan Quiet Comma wrote: »

Thought you had snow a few weeks ago? :pac:

IOM needs to ship itself 150km south!

it did snow but wasn't proper snow you could build a snowman with.

if it was up to me I would leave the IOM where it is and ship Ireland into the North Sea just off the dutch coastline. Our weather in the summer and winter would be considerably more seasonal.

Rebelbrowser

12z gfs rolling out now and the downgrade continues I'm afraid. -8 uppers are becoming -6s and -6s are becoming -4's. Not sure it even will be knife edge stuff....

Iancar29

Rebelbrowser wrote: »

12z gfs rolling out now and the downgrade continues I'm afraid. -8 uppers are becoming -6s and -6s are becoming -4's. Not sure it even will be knife edge stuff....

Can't see much of a downgrade myself. Still on par to whats been stated here.

Rougies

Rebelbrowser wrote: »

12z gfs rolling out now and the downgrade continues I'm afraid. -8 uppers are becoming -6s and -6s are becoming -4's. Not sure it even will be knife edge stuff....

Yeah worrying signs for the increased precip for saturday evening into sunday morning. It was already very marginal so we can't afford downgrades of any kind. In saying that it's only Wednesday so let's wait and see.

Gonzo

Rebelbrowser wrote: »

12z gfs rolling out now and the downgrade continues I'm afraid. -8 uppers are becoming -6s and -6s are becoming -4's. Not sure it even will be knife edge stuff....

defo a downgrade, probably just snow on mountaintops at this stage.

Met Eireann are forecasting rain and hail showers which is probably what we'll end up with.

also there is no snow cover in the UK and a very weak fetch of cold compared to a true easterly.

Doctor Shivering

Relax the cacks folks
Just look at the dew points at the source of the air we're advecting by Saturday
Image attached

Even if there's a 2c rise in 850's,which isn't certain the shower creating lapse rate is more than adequate

John.Icy

Rebelbrowser wrote: »

12z gfs rolling out now and the downgrade continues I'm afraid. -8 uppers are becoming -6s and -6s are becoming -4's. Not sure it even will be knife edge stuff....

Gonzo wrote: »

defo a downgrade, probably just snow on mountaintops at this stage.

Met Eireann are forecasting rain and hail showers which is probably what we'll end up with.

also there is no snow cover in the UK and a very weak fetch of cold compared to a true easterly.

The 850's on the 12z GFS are pretty much the same as the 6z. It was only ever a brief window of -8's before they rose slightly again. Relax - for now. Slight changes in how the pool of -8 or below moves across us will vary for another few runs.

EDIT: Also important in this case to take into account where changes in predicted 850's occur. Doesn't matter if half the country is under warmer air so long as Eastern parts retain a colder airmass as that's where the bulk of any precipitation will be.

JanuarySnowstor

Probably time to close this thread. The potential has evaporated over the last 36 hrs and it doesn't warrant a warning now imo.
Chance of hill snow Saturday but nothing noticeable.
Adios Winter 16/17......We thought last Winter was rubbish but your euroslug high has bored us all to tears!

Easterly Beasterly

JanuarySnowstor wrote: »

Probably time to close this thread. The potential has evaporated over the last 36 hrs and it doesn't warrant a warning now imo.
Chance of hill snow Saturday but nothing noticeable.
Adios Winter 16/17......We thought last Winter was rubbish but your euroslug high has bored us all to tears!

Where's the warning? It's a thread about occasional snow showers and severe frost.. That's still forecast!!

JanuarySnowstor

Easterly Beasterly wrote: »

Where's the warning? It's a thread about occasional snow showers and severe frost.. That's still forecast!!

The vast majority of the country looks cold and dry. With a strong Easterly wind frost will be kept to a minimum

Doctor Shivering

Easterly Beasterly wrote: »

Where's the warning? It's a thread about occasional snow showers and severe frost.. That's still forecast!!

Aye plenty of opportunities for Dubs and North wicklow's on higher ground to go sledging
It might include the M11 beside the sugarloaf even
I can't see the 850's on the phone here but minus 8's with the lapse rate of 18c,there's big potential for showers and with zero dew points on the coast,white stuff inland would be inevitable
It's a very short window ending probably Sunday night but at least it's a weekend when people in the greater Dublin region could go out to enjoy it
A few pints at lamb Doyle's would do it

Doctor Shivering

JanuarySnowstor wrote: »

The vast majority of the country looks cold and dry. With a strong Easterly wind frost will be kept to a minimum

Aye but up to half the population are in the potential zone
Not Cork of course

SEPT 23 1989

Marginal frost

This is what we are reduced to?

Gonzo

SEPT 23 1989 wrote: »

Marginal frost

This is what we are reduced to?

there should be 2 or 3 nights of decent frost, maybe wintry showers by night but with daytime temps around 5 or 6C the chance of lying snow during the day in low ground areas is very slim. Even in the UK there isn't much snow forecasted.

John.Icy

These aren't half bad synoptics...I'm sure someone will see some decent snow falling at some point from Friday-Sunday. Little changes here and there I'm sure still to come. It's easy to forget a few days ago this was modeled by some to be a pretty dry affair with a gentle SE breeze - I'll take what's on offer at the moment considering the winter thus far.

kingshankly

Wow there can't be many straws left to clutch folks
A thread of its own about a bit of frost first week in February
Illustrates how deprived folks have been of some snow

mirrorwall14

Can we not have a thread in the weather forum where people aren't saying it should be closed or complaining that it's open or judging those who are following it? It's a weather forum ffs. Any weather. Extreme or not. The thread title is appropriate and if you've no interest just scroll on past the thread like every other forum on boards

lucernarian

mirrorwall14 wrote: »

Can we not have a thread in the weather forum where people aren't saying it should be closed or complaining that it's open or judging those who are following it? It's a weather forum ffs. Any weather. Extreme or not. The thread title is appropriate and if you've no interest just scroll on past the thread like every other forum on boards

I'm not getting worked up about it, or at least trying

But really, opinions of all sides should be welcome. While it's a bit tedious to see people make the same point again and again, that's inevitable when you're on a discussion forum. Even if that's an opinion on the thread title or its prediction.

I don't think it will be as dramatic as the thread title. it gets the level of interest mainly because a whole bunch of Dubs and folk from the Pale, myself included, should see the more interesting weather.

I'll be following updates from the home country, at the bellwether height of 152 metres

Still suspect daytime temps won't allow for sticking snow but Friday night looks very interesting.

jack o shea

I hear it could hit 0 degrees, the winter of 63 ain't a patch on this,

Rebelbrowser

Yeah it would be much better if we only opened threads when snow was virtually certain within 24 hours. Of course that means we wouldnt have opened any threads in winter since 2013 but thats clearly the better course of action rather than all this "speculation" and general enthusiasm about the small possibility of interesting weather. The opening of threads when snow isn't certain and imminent is an evil which has the potential to cause near irreparable harm and we must ruthlessly stamp out this kind of activity.

See you all again in 2019 or whenever next the necessary de minimus criteria are met for the opening of such a thread.

jack o shea

More like 2039 before we get another once in a generation snowfall worth talking about.

Rougies

lucernarian wrote: »

I'm not getting worked up about it, or at least trying

But really, opinions of all sides should be welcome. While it's a bit tedious to see people make the same point again and again, that's inevitable when you're on a discussion forum. Even if that's an opinion on the thread title or its prediction.

I don't think it will be as dramatic as the thread title. it gets the level of interest mainly because a whole bunch of Dubs and folk from the Pale, myself included, should see the more interesting weather.

I'll be following updates from the home country, at the bellwether height of 152 metres

Still suspect daytime temps won't allow for sticking snow but Friday night looks very interesting.

The thread title isn't dramatic at all though, it's perfectly reasonable. The interpretation of the thread title by some posters is what's dramatic.

I think a "safer" thread title would help reduce the less cheerful posts, but I suppose there's no fun in that so I agree with your first point that all opinions are welcome

lucernarian

Rougies wrote: »

The thread title isn't dramatic at all though, it's perfectly reasonable. The interpretation of the thread title by some posters is what's dramatic.

I think a "safer" thread title would help reduce the less cheerful posts, but I suppose there's no fun in that so I agree with your first point that all opinions are welcome

You're welcome to your opinion on what's reasonable I still think it's dramatic relative to the current prediction.

Then again, some places will IMO see more wintry weather than suggested by posts this evening. It's a very Dublin-centric forum for better or worse.

squarecircles

Think I'll get a bottle of red for the weekend and read the snow reports...I hope I don't slip on an ice on the way to tesco.stay safe out there.

Doctor Shivering

The eagle was pretty bullish on the 755am radio one forecast this morning for widespread wintry showers in the East Saturday and Sunday

Please allow me decode that for you
There shall be snow:D

lawred2

relatively benign morning in Dublin

lawred2

Doctor Shivering wrote: »

The eagle was pretty bullish on the 755am radio one forecast this morning for widespread wintry showers in the East Saturday and Sunday

Please allow me decode that for you
There shall be snow:D

no mention of snow on Met Eireann

Rebelbrowser

Looking at the various models this morning, to my very untrained eye the following stands out:-

A lot of the ingredients needed for snow are there.

Upper air temps:- Even by early tomorrow there are seriously low upper air temps in the north east and by midnight tomorrow these are pretty widespread. See below from this mornings euro 04 short range model. These spread virtually everywhere over the following 24 hours. For snow we usually say you need -8 upper temps or lower. Where the weather is coming from the east (less mixing over warm sea) my understanding is you don't necessarily need it to be that low however.



Low Dew Points:- Again, as I understand it these need to be 1 or 2c max, but ideally negative. Ireland has very low dew points over the weekend - lower than Britain actually - so no problem there. See below from as soon as 3pm tomorrow:-



Thickness - This is where I get way out of my depth and I will let others talk of this. Crudely put this is to do with how much warm air snow must fall through to get to the ground without melting. The usual thing you look for is where the 528 dam line is (on RTE they sometimes call this the snow line). You want thickness to be less than 528. As far as I can see we are at 544 and above for most of the weekend but I note so is most of Russia! Not a factor when weather is incoming from the east perhaps?

Precipitation - Obviously cold without precipitation aint going to get you snow. However as most who come here from time to time will know there is the concept of lake effect snow where if there is a 13c differential between sea temps and fast moving air over it, and if that fast moving air comes from the right direction such that it has sufficient "fetch" (i.e. sufficient distance over the warm sea), then this can create its own showers called streamers. Think Dublin in Nov and Dec 2010 by way of example. This weekend the models are showing some precipitation around. Even if they didn't that wouldn't worry me. I remember on 18 December 2010 after lots of snow in the south and west the previous day all the Dublin posters were on here decrying that there was no snow forecast for them. And they were right, that was the forecast and the models showed no more precipitation around, just epic cold temps. Alas we all remember the streamers Dublin got in the following days. They tend to crop up unforecasted in other words. This weekend Irish sea temps are approx. 9c, upper air temps are approx. -8, and winds are strong from the east - so plenty reason to think that there will be streamers. Of course a streamer can fall as rain, sleet or snow....


So, will there be Snow?:- And this is the big concern for me from the models. Despite everything written above, there is not a huge amount of evidence of the models forecasting snow. The only three models I can access that show precipitation type are the gfs, hirlam and euro 04. Gfs (lower resolution so less accurate) shows precipitation alright in eastern and southern facing areas- buts its all rain. See typical chart below:-


The euro 04 which only goes out to midnight tomorrow shows much less precipitation but it does at least show some pink (i.e. snow)! As I said I'd worry less about the lack of precipitation forecasted so this is not all doom and gloom. See example below:-



Our star pupil this morning for coldies however is hirlam. It shows snow as white hatched areas and the darker the colour under the white hatching, the greater the amount of snow. Below chart accordingly should excite the M50 dwellers! From bitter experience I'm expecting nothing in my neck of the woods and I'm not overly hopeful for non-high ground in the east - but you never know....Happy hunting!