Thursday/Friday Snow Potential

Iancar29 · 16-12-2011 10:17pm

Its looking very marginal , sleet and snow at high levels , dont think ill see any like this morning again.

Su Campu · 16-12-2011 10:18pm

Slashermcguirk wrote: »

Brass monkeys in north Dublin. Car is frozen solid outside. Surely will fall as snow if it arrives here, far too cold for rain anyway. Further it travels over the cold landmass it surely increases chances of snow??

A frost at the surface this early may only mean that there is still only a shallow cold layer, maybe 10 metres thick. Above this layer, the air is actually warmer. The longer the frost lingers, the more cooling takes place and the deeper this cold layer gets. So by morning time this morning, after a whole night of cooling, the cold layer was deep enough to offset any melting that would have naturally taken place with upper temperatures the way they were.

So if the showers come soon then the shallow cold layer at the surface will not yet be thick enough to prevent melting, so they will most likely fall as rain.

Vudgie · 16-12-2011 10:24pm

Su Campu wrote: »

Slashermcguirk wrote: »

Brass monkeys in north Dublin. Car is frozen solid outside. Surely will fall as snow if it arrives here, far too cold for rain anyway. Further it travels over the cold landmass it surely increases chances of snow??

A frost at the surface this early may only mean that there is still only a shallow cold layer, maybe 10 metres thick. Above this layer, the air is actually warmer. The longer the frost lingers, the more cooling takes place and the deeper this cold layer gets. So by morning time this morning, after a whole night of cooling, the cold layer was deep enough to offset any melting that would have naturally taken place with upper temperatures the way they were.

So if the showers come soon then the shallow cold layer at the surface will not yet be thick enough to prevent melting, so they will most likely fall as rain.

Fascinating analysis keep up the good work.

Properly freezing in Dublin tonight it will be interesting to see how this plays out.

JanuarySnowstor · 16-12-2011 10:25pm

Su Campu wrote: »

The difference is the airmass in place tonight. The 850 hPa theta-w is around +4 °C tonight, around 2 degrees higher than last night. Also, at 1350 m, the 850 hPa level is around 150 m higher than it was yesterday (1200 m), which means that although it's the same temperature, that temperature is now that bit higher up, meaning a thicker layer for snow to reach the ground. The higher theta-w means that there is less effective evaporational and sublimational cooling of the air as the snowflakes melt, meaning they will melt higher up.

There was also a hard frost already set in at this stage last night, but the increased cloudiness and humidity has offset that cooling this evening.

Last night

This evening

That's a very informative post thank you

mountainy man · 16-12-2011 10:30pm

Rain and wet hail here ,don't think its cold enough even at this height for snow.

Su Campu · 16-12-2011 10:31pm

PurpleSt4in wrote: »

From my limited experience on the Weather forum, you seem to be relatively well-informed! I was just curious as to whether you and the other knowledgeable posters (Wolfe-something & Irish & MT) were able to forecast the heavy snowfalls we got last year?

As in a few hours before the event were you saying 'Dublin (or X or Y) will get substantial dumping of snow overnight'

Or is this tough to predict and unlikely to just creep up on us? (I'm remaining ever hopeful of a White Christmas)

Last year the airmass was a different beast, in that it was an easterly/northeasterly, with much less sea track to cause it to modify. Airmass snow parameters were so much more indicative of snow that it wasn't too difficult to predict it.

This time, the cold airmass has travelled from northeasern Canada/Greenland, over a long ocean track. The strong winds earlier in the week meant it had less time to become modified by the warm waters, and reached us in a colder state. Over the past 24 hours, however, the flow has slowed down, and we are now seeing the effects of warmer and more humid low levels.

This should change again over the next 24 hours though as the flow strengthens again from a more northerly component, allowing colder air to reach us, so I would imagine we will see the snowline come down again through tomorrow, although with pressure rising, the chances of heavy showers will be reduced as the weekend goes on.

JanuarySnowstor · 16-12-2011 10:36pm

Of course the warmer air has lead to more ppn.
Easterlys can be notorious for being dry away from onshore coasts
Cork has pbly seen as much snow already this year as last, though it's been the slushy type that melts quickly.

JanuarySnowstor · 16-12-2011 10:39pm

Su Campu wrote: »

This should change again over the next 24 hours though as the flow strengthens again from a more northerly component, allowing colder air to reach us, so I would imagine we will see the snowline come down again through tomorrow, although with pressure rising, the chances of heavy showers will be reduced as the weekend goes on.

As you say colder air moves down again tomorrow.
Hard to identify the wind getting stronger though so it appears to me the air gets colder for no apparant reason obvious to the eye.
Indeed the wind veers more west of north.
Just one of the peculiarities of weather

Elmer Blooker · 16-12-2011 10:55pm

Mullingar: 3c and rain now so those of us in the Capital shouldn't be getting too excited, I'm -0.2c at the moment and its now clouding over. Snow from a north westerly is extremely rare in eastern areas anyway.

DOCARCH · 16-12-2011 11:00pm

Elmer Blooker wrote: »

Snow from a north westerly is extremely rare in eastern areas anyway.

.....except for this morning!

BLIZZARD7 · 16-12-2011 11:03pm

Elmer Blooker wrote: »

Mullingar: 3c and rain now so those of us in the Capital shouldn't be getting too excited, I'm -0.2c at the moment and its now clouding over. Snow from a north westerly is extremely rare in eastern areas anyway.

How ? Im at 2.2C here, DP is 0C, frost melting rapidly! I think we are getting rain or sleet

Dan :cool:

Deep Easterly · 16-12-2011 11:05pm

JanuarySnowstor wrote: »

As you say colder air moves down again tomorrow.
Hard to identify the wind getting stronger though so it appears to me the air gets colder for no apparant reason obvious to the eye.
Indeed the wind veers more west of north.
Just one of the peculiarities of weather

Are you talking about wind chill?

Min · 16-12-2011 11:52pm

The temperature rose this evening, the warmest part of the day here at 220m asl in north Kilkenny was at 20:34 this evening when the temperature rose to 3.9C.
Now it is 3.0C with a dewpoint of 1.0C.

Snow is unlikely, unless the temperature is dragged down by heavy precipitation.

bassy · 16-12-2011 11:55pm

min what part of north kk you in ?.

Min wrote: »

The temperature rose this evening, the warmest part of the day here at 220m asl in north Kilkenny was at 20:34 this evening when the temperature rose to 3.9C.
Now it is 3.0C with a dewpoint of 1.0C.

Snow is unlikely, unless the temperature is dragged down by heavy precipitation.

Min · 17-12-2011 12:32am

bassy wrote: »

min what part of north kk you in ?.

Muckalee area.

http://www.kilkennymet.com

4Sheets · 17-12-2011 12:43am

I knew it would snow its snowmageddon at the mo!!
I didnt get where I am today by not knowing if it was gonna snow.:pac:

https://www.youtube.com/watch?v=drlPbIWAz-E

CASEMENT W 12 RECENT SHOWER 3

kenmc · 17-12-2011 1:27am

tallaght m50 cam shows snow. Ballinteer shows nothing

weathermaiden · 17-12-2011 1:32am

Nothing in Bray either, only rain, surprise surprise! Holding out hope for MT's January prediction....

Mountainsandh · 17-12-2011 1:37am

Nothing in Co Waterford 190masl, no precip, and not even any frost so far, although now winds have somewhat calmed down frost might just settle. There was a hint of a snow shower this morning that didn't lead to much, despite the ground frost.

I'm soooo happy for you guys who got some snow, really I am. :mad:

4Sheets · 17-12-2011 1:45am

Really? I remember last year during snowmageddon places like Kiltipper got way more snow than places a few km away ,,

http://www.dublincity.ie/dublintraffic/

Inconclusive?

BTW My post above is an attempt at humour ,,was only rain here and now theres a bit of moon out

zzzzzzzzzzzzzzzzzz

nacho libre · 17-12-2011 1:51am

4Sheets wrote: »

I knew it would snow its snowmageddon at the mo!!
I didnt get where I am today by not knowing if it was gonna snow.:pac:

https://www.youtube.com/watch?v=drlPbIWAz-E

Good old CJ

John Barron was a legend!

All rain this evening. Not too bothered as yesterday morning's snow was a pleasant surprise.

bassy · 17-12-2011 2:07am

i heard there was snow in rhode co.offaly tonite,can anyone confirm?.

aurora 527 · 17-12-2011 11:13am

Mountainsandh wrote: »

Nothing in Co Waterford 190masl, no precip, and not even any frost so far, although now winds have somewhat calmed down frost might just settle. There was a hint of a snow shower this morning that didn't lead to much, despite the ground frost.

I'm soooo happy for you guys who got some snow, really I am. :mad:

Looks like we will just have to wait till January, and hope for snowmageddon
then for us south easties!!

pcasso · 17-12-2011 2:45pm

As you can see from my post count, I am relatively new to Boards and have only very recently stumbled upon this part of the site.

I was shocked and surprised to find so many sad, presumably adult posters, nearly wetting themselves and squealing like excited six year olds, at the mere chance of seeing a flake of snow fall. Incredible.
I thought I was the only one like that;)

It is a great sub forum and had become compulsive reading this last week or so for me.
Many thanks to all the posters who contribute with their forecasts and explanations of charts etc. for a weather ignoramus like me.
Cheers guys.

and here is hoping that there is a repeat of February 82 come January

derekon · 17-12-2011 2:47pm

pcasso wrote: »

As you can see from my post count, I am relatively new to Boards and have only very recently stumbled upon this part of the site.

I was shocked and surprised to find so many sad, presumably adult posters, nearly wetting themselves and squealing like excited six year olds, at the mere chance of seeing a flake of snow fall. Incredible.
I thought I was the only one like that;)

It is a great sub forum and had become compulsive reading this last week or so for me.
Many thanks to all the posters who contribute with their forecasts and explanations of charts etc. for a weather ignoramus like me.
Cheers guys.

and here is hoping that there is a repeat of February 82 come January

Welcome to the weather forum Pcasso - however I think you might have meant January 82?

D

pcasso · 17-12-2011 3:01pm

derekon wrote: »

Welcome to the weather forum Pcasso - however I think you might have meant January 82?

D

Don't think so.
It would have snowed in January that year all right, around new years day if I remember correctly but the major snow event occurred in February or at least that is the way I remember it.

I am getting old though.

I shall check it out

DOCARCH · 17-12-2011 3:07pm

pcasso wrote: »

Don't think so.
It would have snowed in January that year all right, around new years day if I remember correctly but the major snow event occurred in February or at least that is the way I remember it.

I am getting old though.
I shall check it out

Definitely January and in the first week. AFAIK, after that week of snow, the rest of that winter was pretty mild.

pcasso · 17-12-2011 3:11pm

Yep, my mistake. For some reason I have always believed that it was in February that the snow came. January 8th was the big day.
I remember it well;)

Bloody newbies, eh:cool:

4Sheets · 17-12-2011 3:48pm

pcasso wrote: »

As you can see from my post count, I am relatively new to Boards and have only very recently stumbled upon this part of the site.

I was shocked and surprised to find so many sad, presumably adult posters, nearly wetting themselves and squealing like excited six year olds, at the mere chance of seeing a flake of snow fall. Incredible.
I thought I was the only one like that;)

It is a great sub forum and had become compulsive reading this last week or so for me.
Many thanks to all the posters who contribute with their forecasts and explanations of charts etc. for a weather ignoramus like me.
Cheers guys.

and here is hoping that there is a repeat of February 82 come January

I for one find your choice of adjectives a little patronizing..if you are a sad 6 year old who squeals at snow thats cool but I doubt you will find too many others of your kind here.;)

gbee · 17-12-2011 4:06pm

4Sheets wrote: »

your kind here.

I think you forgot the smiley there!

Thursday/Friday Snow Potential

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