Ireland regional discussion 21/12/12 and beyond

[Baltic Regions]

Its official!

We have snow in Ballyclare! Not a mission of it lying as it looks a little wet for that but raises hopes for the potential later this week!

[gingercat]

All forecasts point to n.i not even getting a sniff of the snow!

[ronan]

All forecasts point to n.i not even getting a sniff of the snow!

I have confidence that we will later in the week! Let's see what the 06z gives us!

[gingercat]

2.5c in Newtownabbey and sleet/rain mixture

[BIG LAD]

light drizzle here and temp up to 0.3c. what do we have to do to get a bit of snow in this country?

[mountain shadow]

First few flakes of snow have arrived, very sleety mix.

Poor output this morning it has to be said for the island.

Edited January 13, 2013 by mountain shadow

[Baltic Regions]

Just the lightest of flutters now!

My mate down in Downpatrick says the sun is shining!

Opposite picture here!

[sundog]

Bit of a flurry here now temp 1.5c

[gingercat]

We're having periods of snow quickly followed by rain. Temp is hovering between 2 and 2.5c.

[mountain shadow]

All snow now but not settling.

[skywatcher]

All snow now but not settling.

Unfair! We're three miles down the road from you (Four Winds) and not a flake - not even a raindrop!

[SNOWPLOUGH]

Snowing in athlone/Kildare/Meath/West Dublin in past hour or so according to boards.

Dan

[Su Campu]

Weather and dewpoints at 12 pm. Dewpoints mostly above zero.

Edited January 13, 2013 by The watcher

[SNOWPLOUGH]

Weather and dewpoints at 12 pm. Dewpoints mostly above zero.

Might be just me but cant see those pics su.

Dan

[The watcher]

The fact that some have already seen snow in what was expected to be rain is a promising sign for things to come. Not sure what the precipitation was here in Bangor, will have a look at radars now and see.

Broken links SU.

Edited January 13, 2013 by The watcher

[Su Campu]

Sorry, I forgot that the Ogimet live images only last for a short while. Here are the links

http://www.ogimet.com/cgi-bin/gsynop?lang=en&esc=2&nav=Yes&lat=55N&lon=005W&proy=orto&base=bluem&ano=2013&mes=01&day=13hora=12&vsg=Sg

http://www.ogimet.com/cgi-bin/gsynop?lang=en&esc=2&nav=Yes&lat=55N&lon=005W&proy=orto&base=bluem&ano=2013&mes=01&day=13hora=12&vtd=Td

[BIG LAD]

temps up to 2.7c now and have barely had enough precip to wet the ground. band must have really fizzled out as it moved SE wards

[ronan]

Nice to see that some of you seen some snow today. This week should stay cold with Wednesday night probably seeing the coldest temps. Big question mark on Friday and i just hope that the cold pushes further west so when that Atlantic front pushes in then we get snow! I'll be really annoyed if we get let down again! Knowing our luck we will get sod all and the mainland gets it all but the potential is certainly there for plenty of snow on Friday if we can get the right setup!

[Su Campu]

1400Z Temps/dewpoints for Ireland

Belmullet 8/4

Ballyhaise 3/2

Belfast Aldergrove Airport 2/2

Belfast City Airport 2/2

Casement Aerodrome 3/3

Claremorris 7/5

Connaught Airport 6/4

Cork Airport 6/4

Derry Eglington Airport 6/5

Donegal Airport 8/4

Dublin Airport 2/2

Finner 7/5

Gurteen 5/4

Johnstown Castle 5/2

Kerry Airport 7/6

Mace Head 7/6

Malin Head 7/4

Mullingar 3/3

Oak Park 2/1

Roches Point 6/4

Shannon Airport 8/7

Sherkin Island 9/7

Sligo Airport 7/6

Valentia 9/7

Waterford Airport 5/3

[ForeverPomeroysnow]

Well the Sperrins have a covering on them - quite happy considering we where forecast rain!!

[snowmore]

No snow here this morning :-( foggy now and 5^o

[Su Campu]

Today was a good example of why just looking at 850 temperatures may sometimes be misleading. There was some brief front-edge snow in the east this morning even though T850 was around -3 °C. This quickly turned to rain, which is what we would expect with such uppers. But the most important layer for snow is just below the 850 hPa level, and in some setups that will not be shown by purely looking at the 850 level when there is a cold surface layer in place.

The GFS forecast soundings for Dublin Airport this morning (09 and 12Z) show warm air advection at around 850 hPa above the much cooler surface layer from last night. The normal lapse rate was not present here, with only very slow cooling with height, so the normal extrapolation of 850 temps down to the surface would lead to a large warm error. The cool and relatively dry surface layer ahead of the front allowed evaporative cooling to take place along the front edge of the rainband, leading to some brief snow before the rain then followed in behind.

The sounding text for both times gave the following thicknesses.

09Z

500-1000: 530.3 dm

850-1000: 1299 m

12Z

500-1000: 530.6 dm

850-1000: 1301 m

These values would be typical "wrong side of marginal" values and would always mean rain, which is what has happened by and large. It's just that those brief first few minutes of snow that seemed to come as a surprise to some low-lying areas are an illustration of how many different variables there are to consider when it comes to snow vs rain and why looking at just the 850 hPa layer is not wise. Forecast soundings, 950 or 925 hPa temperature and RH, winds and surface dewpoints need to be considered too.

Edited January 13, 2013 by Su Campu

[sundog]

I wonder is there a good chance of back- edge snow on the next front?

[Su Campu]

I wonder is there a good chance of back- edge snow on the next front?

I wouldn't think so. The airmass coming in behind will have been modified during its long sea track.

Tuesday night into Wednesday looks like a good battleground on the 12Z GFS. This is the accumulated snow up to 12Z Wednesday with 0 °C isolevel, and theta-e.

Edited January 13, 2013 by Su Campu

[ronan]

Gone someone explain the METO 120hrs that everyone in the model thread is creaming their pants about! Will this benefit us?