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Big Freeze in early/mid February?
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The latest GFS has the colder NE/E influence taking effect in Ireland earlier than previous runs. Looking great so far.
It most definitely is looking very good Wolfe. 850mb Temperatures holding at -10 out to T+144..
Fantastic 12Z UKMO also with deep cold beginning to be advected towards us at T+96..
An excellent chart at T+120:
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the position of that high pressure system to the east of iceland is a real contributory factor to this thing coming off and being a potent lasting cold spell. Should these runs come off they would deliver plenty of snow potential for many.
In terms of longevity, it really is quite uncertain at the moment & factors such as this will be very uncertain beyond T+144. However, the orientation of the High, with a centre over Iceland is very positive at T+120. Another important point from that chart is the residual linking between further largescale Heights, (both surface and geuine), to the East.
SA
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Whilst the ECMWF 12Z Evolution may not offer the same degree of snowfall potential as 12Z GFS/UKMO Operational, an overall blend of the major three is likely to be nearer to the final verification trend. In addition, UKMO is performing exceptionally well at the moment, level with & ahead of ECMWF on several occasions.
ECWMF is very rapid with the evolution and advects the cold pool westwards from Scandinavia in rapid time. Into Monday (T+96) we have Easterly winds across the country & 850mb temperatures range from -5 in the far Southwest to -7 in the East. There could well be light snow showers into Eastern areas from such an evolution. It is very rapid though & somewhat suspect regarding the speed of the evolution, in light of the other Guidance available to us tonight.
There would be ample opportunity for snow showers, generally light in nature, in the East & Southeast between T+90 & T+125. In addition, there would also be a likelihood of further snow showers towards T+168.
There is no point in looking at snowfall potential in an in-depth manner until we are within T+48 Hours of the event, as it is exceptionally difficult to forecast.
Perhaps even more noteworthy is that the entire 12Z ECWMF Evolution is generally cold to extremely cold on occasions. A very long cold spell is indicated with winds eminating from the East & Northeast throughout. With pressure rising towards T+144 & T+168, there would be some very cold upper air trapped at the surface leading to conditions similar to those experienced in early January.
This is a very fluid evolution at the moment but in terms of ratings for overall wintry developments & sustained cold, I would give the following ratings:
ECMWF 12Z Op - 7/10
UKMO 12Z Op - 10/10
GFS 12Z Op - 09/10
The main point is that we now have agreement at T+96 from all three sources of major model guidance of a cold spell developing.
SA 0 -
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Eh ECM 12z does not go down well at all.
Very disappointing but thats why i say don't be thinking its set in stone just yet for ireland.
At first glance it looks ok-ish, but I am not convinced either that it is all that great. The 144hrs chart looks suspicious to me:
Classic sinker set up, yet at 168 the high builds north again.
as for temps, there is nothing out of of the ordinary showing up for Ireland from this run. Frosty nights with temps around -2c to -5c but daytime figures at or just below average. All I see so far is a continuation of the same non-descript weather for the foreseeable.0 -
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Deep Easterly wrote: »At first glance it looks ok-ish, but I am not convinced either that it is all that great. The 144hrs chart looks suspicious to me:
Classic sinker set up, yet at 168 the high builds north again.
as for temps, there is nothing out of of the ordinary showing up for Ireland from this run. Frosty nights with temps around -2c to -5c but daytime figures at or just below average. All I see so far is a continuation of the same non-descript weather for the foreseeable.
I agree that at T+144 it doesn't look that great, but at T+144 to T+168, the evolution is strikingly similar to that of what occured in the first week of January with regard to the formation of the HP over Scandinavia, combined with a southward sinking block in the Mid Atlantic. There is enough energy in the southern arm of the jet combined with renewed WAA up into Greenland to provide for a subsequent pressure build at T+168 onwards. The position of the pool of 552 DAM Air at T+144 is indicative of the evolution.
All academic of course because we are seeing such changes out to T+120 on each evolution that commentary almost still becomes invalid within 12 Hours about general features, even largescale ones.
I would think DE, that temperatures are quite a bit below average on this run overall. Minima of lower than -5C would indeed occur on that evolution tonight, if it were to verify exactly as shown - but as ever that won't happen.
Of course I could be completely wrong but overall, mean temperatures would end up below average through to Day 10 if ECMWF were to verify in my opinion.
I think it's a massive step forward in light of what was shown in recent days, but it also depends on preference for weather etc.
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Yep good analysis Snowaddict.
Joe b points this out.
Very interesting series of Charts Redsunset.
Historically, they have been inaccurate but this winter have been almost 'on the money' so to speak.
I remember that they indicated significant blocking patterns as early as September & October and so far that has verified to quite an extent.
That's a series amount of anomalous cold for all of Europe, programmed for the month of February. Extreme anomalous warmth indicated for Greenland & towards the High Arctic over Canada.
Perhaps a trend towards a more West Based -NAO signature towards Day 18 - 20 onwards, with the significant core of blocking shifting even further Northwestwards?
Certainly, if we are to get another decent cold spell this month it will have been one of the coldest winters for quite some time.
SA 0 -
Snowaddict wrote: »I agree that at T+144 it doesn't look that great, but at T+144 to T+168, the evolution is strikingly similar to that of what occured in the first week of January with regard to the formation of the HP over Scandinavia, combined with a southward sinking block in the Mid Atlantic. There is enough energy in the southern arm of the jet combined with renewed WAA up into Greenland to provide for a subsequent pressure build at T+168 onwards. The position of the pool of 552 DAM Air at T+144 is indicative of the evolution.
All academic of course because we are seeing such changes out to T+120 on each evolution that commentary almost still becomes invalid within 12 Hours about general features, even largescale ones.
I would think DE, that temperatures are quite a bit below average on this run overall. Minima of lower than -5C would indeed occur on that evolution tonight, if it were to verify exactly as shown - but as ever that won't happen.
Of course I could be completely wrong but overall, mean temperatures would end up below average through to Day 10 if ECMWF were to verify in my opinion.
I think it's a massive step forward in light of what was shown in recent days, but it also depends on preference for weather etc.
SA
Yes SA, you are right, I am just being hasty and am annoyed that in all that throughout this winter, we have yet to have a real deep continental airflow over Ireland. Most of the cold airmass we did have came from the northeast. This might sound pedantic but we all have our own preferences as you say and that is mine.
As you say, temps will be below average but by how much will not be known until the set up becomes an absolute.
Consider the latest ECMWF temps for Dublin:
http://www.yr.no/place/Ireland/Dublin/Dublin/detailed_long.html
Not impressive, but more encouraging for the midlands:
http://www.yr.no/place/Ireland/Offaly/Birr/detailed_long.html
and west:
http://www.yr.no/place/Ireland/Mayo/Strade/detailed_long.html
but nothing spectacular showing up yet. Of course, as Redsunset says, plenty of scope for upgrades on later runs. Just a matter of firming up the very delicate prognosis.0 -
Deep Easterly wrote: »Yes SA, you are right, I am just being hasty and am annoyed that in all that throughout this winter, we have yet to have a real deep continental airflow over Ireland. Most of the cold airmass we did have came from the northeast. This might sound pedantic but we all have our own preferences as you say and that is mine.
As you say, temps will be below average but by how much will not be known until the set up becomes an absolute...
Very much agree in that regard. My own preference also would be for a direct Polar Continental flow, with exceptionally deep cold air, but those events, in which we get 850mb temperatures of -15 advected across the country are so rare that they are usually only once in a 20 Year event.
As you say, nothing exceptionally significant showing up as of yet as the generated temperatures that you have posted show.
I can also understand your view with regard to the lack of any ''real weather'' so to speak.
Let's just hope we can get a blend of ECMWF/GFS/UKMO & I think that would be an excellent outcome.
As you say, it's a very difficult and rapidly changing evolution that has yet to be firmed up on.
I would think that we can have approximately 75% confidence in renewed cold at this point - the question is just how cold & will there be sustained potential for snowfall?
SA 0 -
Snowaddict wrote: »Very much agree in that regard. My own preference also would be for a direct Polar Continental flow, with exceptionally deep cold air, but those events, in which we get 850mb temperatures of -15 advected across the country are so rare that they are usually only once in a 20 Year event.
I would think that we can have approximately 75% confidence in renewed cold at this point - the question is just how cold & will there be sustained potential for snowfall?
SA
As usual, you are the voice of reason SA!. I think we are well overdue one of those once in a 20 year Polar Continental events. Frosty weather will be welcomed however, but I am becoming a little bored with all that. I want a real easterly, or a violent Atlantic storm; those would finish off this most unusual winter nicely! 
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Deep Easterly wrote: »As usual, you are the voice of reason SA!. I think we are well overdue one of those once in a 20 year Polar Continental events. Frosty weather will be welcomed however, but I am becoming a little bored with all that. I want a real easterly, or a violent Atlantic storm; those would finish off this most unusual winter nicely!
Your own analysis is excellent on here DE, as is that of the many other posters. Combined, everyone is able to thrash out decent discussion & come to a general consensus on what NWP Guidance is showing & we are able to ascertain as to whether what is being shown is realistic.
How about a Polar Continental & Deep Easterly flow, followed by an approaching Atlantic depression from the Southwest bumping into a deep cold pool already in place as a more West Based -NAO becomes established
We can but dream!
SA 0 -
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