Ireland regional discussion 21/12/12 and beyond

[The watcher]

Good post by Stormforce and backed up by BFTV.

Those are the 3 main things I look at when determining snow risk. 850hpa at or below -5, dewpoints at or below 0c and 500 heights at 528 or below.

Anything greater than these 3 (2c higher 850, 1c higher DP and 530dam) is marginal snowfall but can still happen.

I know John Holmes has a guide in the learning section which includes other factors (freezing level, 2m temps) so if you need any more info pop on over. The 3 mentioned though are generally enough.

[mountain shadow]

The first thing you need to look for when looking for snow is precipitation and that is the big missing thing aside from the front moving down on Monday which will see a short lived band of rain/sleet/snow at higher levels.

[Su Campu]

The first thing you need to look for when looking for snow is precipitation and that is the big missing thing aside from the front moving down on Monday which will see a short lived band of rain/sleet/snow at higher levels.

Good post by Stormforce and backed up by BFTV.

Those are the 3 main things I look at when determining snow risk. 850hpa at or below -5, dewpoints at or below 0c and 500 heights at 528 or below.

Anything greater than these 3 (2c higher 850, 1c higher DP and 530dam) is marginal snowfall but can still happen.

I know John Holmes has a guide in the learning section which includes other factors (freezing level, 2m temps) so if you need any more info pop on over. The 3 mentioned though are generally enough.

I've never known it to snow in Ireland with 528 dm thicknesses unless there's already a cold pool in place. 522 is really the benchmark for a setup such as we are looking at in the next few days.

[mountain shadow]

The 18z GFS ensembles certainly show that it is cold enough for snow over the weekend and into early next week but there is just not enough precipitation.

[The watcher]

I've never known it to snow in Ireland with 528 dm thicknesses unless there's already a cold pool in place. 522 is really the benchmark for a setup such as we are looking at in the next few days.

Well 2nd December 2010 as an example:

Nearly a similar synoptic as what we are looking at the next few days but with things a tad further West and the Atlantic knocking on the door. You are right about the cold being embedded, but this would have an effect on lying snow rather than falling.

[Su Campu]

That chart shows 500 hPa geopotential, not thickness. Actual thickness over Ireland at that time was 516-520 dm, as shown by this analysis (colour-shading is thickness, black line is 500 hPa geopotential).

http://www2.wetter3.de/Archiv/GFS_05Grad/2010120200_1.gif

[sundog]

Well it does look like the gfs and ecm have come to an agreement as regards later next week- milder air from the Atlantic rolling in. That could change but i think a proper sustained cold spell seems unlikely now. All weve got to show from this saga well what looks likely atm is a cold snap with little snow for us which i find rather disheartening tbh.

Edited January 12, 2013 by sundog

[mountain shadow]

Not quite Sundog.

ECM ops run as poor as you can get, however pretty much everything else prolongs the cold.

Another 12 hour wait for consensus.

[The watcher]

That chart shows 500 hPa geopotential, not thickness. Actual thickness over Ireland at that time was 516-520 dm, as shown by this analysis (colour-shading is thickness, black line is 500 hPa geopotential).

http://www2.wetter3....010120200_1.gif

Just checked again and you are right "1000-500mb thickness (DAM) less than 522dm, lower if you are on the coast, but as high as 540dm it is possible in a heavy shower, but unlikely."

Seems I got mixed up with the 2.

[Su Campu]

I like the look of the GFS for Leinster on Tuesday. Stiff easterly with T850 -8 to -9 °C, T925 -3, theta-e around 9 and 850-1000 PT of 1285 m. Any streamers should be shallow enough (10,000 ft tops), but enough to generate some flurries of snow and graupel.

Edited January 12, 2013 by Su Campu

[Beaufort12]

Upgrades for Ireland in the latest charts according to boards.ie

What are your thoughts guys? Thanks

Edited January 12, 2013 by Beaufort12

[sundog]

Yes upgrades for Ireland on the latest gfs charts,the cold lasts longer and out in fi a greater chance of snow as the Atlantic tries to move in againest the cold block. I suppose Its all going to be down to how strong the cold block will be.

[stormforce 10]

http://www.wetterzen...cs/Rukm1441.gif

ukmo great for prolonging the cold, although more frost,ice and fog rather than snow.

better than mild mush.

the ukmo could retrograde the hp to bring another cold blast which is in line with gp's thoughts.

this is gfs t144. this has potential.

http://www.wetterzen...s/Rtavn1441.png

this is ecm t144

http://www.wetterzen...cs/Recm1441.gif

ecm t144 is disappointing and we all know where this is going= mild south westerlies.

again I think t96is fi. but cold lasting until thurday at the earliest if gfs and ukmo are on the ball. lets hope a better ecm this evening.

Edited January 12, 2013 by stormforce 10

[Su Campu]

A bit of a downgrade in the GFS for the east coast Tuesday/Wednesday. Cold shifted a little to the east. ECM trying its best for us before going with that milder flow later on.

[stormforce 10]

interesting ecm tonight. one word =potential.

[The watcher]

Su Campu, can you see if I have an account on boards.ie? Would be under "The watcher". Was going to join the other day but wasn't sure if I had an account already or not. I was wondering what your username meant and searched it on google, it came up as a mod name on boards.ie. Handy.

[Su Campu]

Su Campu, can you see if I have an account on boards.ie? Would be under "The watcher". Was going to join the other day but wasn't sure if I had an account already or not. I was wondering what your username meant and searched it on google, it came up as a mod name on boards.ie. Handy.

Sorry, I'm no longer on boards.

[stormforce 10]

cold night tonight. current outside temp -1.5c.

[ronan]

Bitter cold out tonight!! What really annoys me is that this band of RAIN that's coming in later should be snow! It's so frustrating!

[Su Campu]

GFS 18Z is a stinker, even for the east coast on Tuesday/Wed. Just too far west for the cold again. Some Cu and Sc is the best it offers as a strong cap takes hold.

[FreezingFog]

I'll be bothered if the next ECM goes down the GFS pub run, but not until then. Only GFS i bother with now are the 0z and 12z.

[Ice Cube]

Looks better for the East Coast this morning and the met sound more confident http://www.met.ie/

[ForeverPomeroysnow]

Houston - we have snow - wet snow, but snow none the less!!

[ronan]

Nice one Pom!!! Looking like we could get snow on Thursday/Friday if the precip charts are anything to go by. Likely to change but!

There's a snow depth chart posted in the model thread a shows some Impressive depths for us this time next week! Could definitely be a big snow event coming up!

Edited January 13, 2013 by ronan

[mountain shadow]

Told you Pom always got snow.!!

Just rain at the moment in Carryduff.