Snowaddict

Both GFS and GME are suggesting a snow event at T+132 - T+140 timeframe on both of today's 12Z outputs... With low pressure undercutting and approaching from the south, with renewed easterly winds and very cold air in place. This is definitely something to watch because this is the third GFS run to show this. SA Steve, GME 12Z also has this evolution.. As I posted below, GFS is quite consistent on it.. What's your opinion?

The latest UKMO update at the moment is fantastic in my opinion.. An easterly feed of sorts is suggested into next week.. If we can get something similar to the 06Z GEFS Mean @ T+144, then I will be thrilled. SA

Pressure will be lower on Thursday in Ireland AZ92, Winds will be stronger to an extent.. From experience they penetrate on average up to 75 miles inland, which is very good in terms of Ireland. You could be right but I'm very conifdent of seeing considerable inland penetration later on Thursday into Friday in Ireland, winds will be stronger and mroe direct here for a time. EDIT: Any takers for NOGAPS @ T+144? http://www.meteociel...&mode=0&carte=0 Also, exceptional GEFS Ensembles - Stunning really. SA

GFS Control @ T+126 also shows that feature approaching from the southwest, running into very, very cold air.. Something to be definitely watched as we go ahead nearer to the timeframe: http://www.meteociel...ode=0&runpara=0 EDIT: Out to T+144 & it has outbreaks of snow quite widely across the UK in a strengthening easterly wind! SA

Hi Azores92 Plenty of snowfall potential for eastern Ireland from this Thursday through to Friday. The overnight ECMWF run clearly models this from Thursday into Friday, with more organised snow at times. A strong easterly/northeasterly always delivers for Eastern Ireland. Take February for example - copious snow showers off the Irish sea. With cold to very cold 850mb temperatures, instability and strong northeasterly winds, these snow showers will affect many parts of the east and southeast in Ireland. The other difference is that this is a Northeasterly and in essence the fetch is not so long. If it was a due easterly then yes it would be much more difficult, but still the Irish Sea is a great generator for snow showers for Ireland - in fact it is one of the only ways in which eastern Ireland can get meaningful snowfall. This is also modelled quite well on the 06Z GFS Operational run. SA

I agree with TETIS regarding how on earth people are disappointed?? I haven't seen one decent snowfall yet this winter apart from some transient snow earlier last week & yet I am thrilled with the last cold spell and projected upcoming synoptics. Some people continuously thrash out: ''Downgrade, downgrade - I won't get snow'' or ''I can believe this run'' etc etc.. Stop, sit back and look at the synoptics. Lets take GFS 06Z @ T+150 shall we: 850mb temperatures of -8 to -11 across the UK & Ireland, several chances for snow showers beforehand into both Eastern Ireland, Eastern UK & Scotland. In addition, a feature to be watched towards T+120/T+132 that could potentially bring snowfall to southwestern parts. Some will never be happy. How long have we waited for these synoptics? Get some perspective on things, the outlook is fantastic, with relatively deep cold on offer. SA

GFS Operational is quite persistent about that small but definite area of low pressure approaching from the southwest towards Day 5 / Day 6... ECMWF has this further south but with 850mb temperatures of -8 to -11 in place, with an easterly feed, this could well give some snowfall to southwestern areas as well as Ireland.. GFS has been quite persistent on this so something to be watched.. SA

I must say I like the look of the 18Z NAE at T+18 Also, an absolutely stunning 18Z GFS Operational out to T+168 from what I can see. Also, relatively deep cold from the east moving westward over open water... Localised heavy falls possible in convective situations. SA

I think that is the link that TETIS posted earlier? If I'm reading it right then shorter term wise excellent, but ECMWF Op & Control both mild outliers towards the end, but with close correlation between both.. SA

Mild outlier there Steve, but followed by the Control. Stunning ensemble mean there for De Bilt.. Could well be some ice skating on the cards... SA

I'm getting blood pressure looking at the 12Z GFS evolution to T+168! It's fantastic, don't care - time for a ramp!! That's severe cold into the UK & Ireland.. Further out - just look at that propensity to undercut at T+168.. Another further 100 mile shift southwards on the 18Z with the same evolution as the 12Z otherwise and I'll bank the GFS! SA

I agree that it's a possibility Matty, although I would like to see another 100 mile shift southwards on GFS to be more confident. 12 NAE has widespread snow over Ireland at times over the next 48 hours. It would seem that significant accumulations are possible on high ground. I agree though, the potential is there for a snow event.

12Z NAE to T+48 suggests that some snow is possible in Northern Ireland.. Meanwhile GFS @ T+66 suggesting a snow event for Ireland... All extremely marginal but GFS has clearly trended further south, albeit slightly, when you compare it to the 06Z run and especially the 12Z run.. SA

I've seen enough in the early stages to sugges that GFS is definitely backtrack, but only slowly.. It seems to me that GFS has been underestimating the strength of the Greenland Block..

Yes Matty, absolutely definitely.. That's 100 - 125 miles in two runs.. If you compare the precip charts on Meteociel, now suggesting possible snow event a good 70% in line with the latest NAE model guidance.. Regardless of the rest of the run.. Up To T+36.. GFS is trending south, colder air south etc.. SA

Excellent 12Z GME to T+66.. GFS to T+30.. If you compare with T+36 and follow the isobars.. Everything is slightly further south.. By about 50 miles from what I can see at T+30..

12Z NAE... To T+24: Looks quite good to me: Also, 12Z GME to T+42 looks very decent to me: http://www.meteociel.fr/modeles/gmee_cartes.php?&ech=42&mode=0 SA

In terms of conifdence, more cause for optimism.. The latest HIRLAM (which is a HI-Res Model used by the Irish Met) - very similar to that of NAE from UKMO also agrees with the NAE 06Z Hrs output.. NAE suggests snowfall for a large stretch of southern Ireland later tomorrow and this is reflected in the latest BBC Precip charts which show extensive snowfall across Wales, Southern Ireland and parts of the midlands.. In fact, the NAE 06 Hrs output is almost fantastic.. The HIRLAM Hi-Res Model also keeps the low to the south as with the NAE.. It also develops a small secondary low just off Cornwall towards T+48 as on the overnight ECMWF output.. Latest 5 Day stats are out and guess which model leads the pack - ECMWF.. http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz5.gif SA

A definite southward shift on the 06Z GFS evolution... I make it to be at least 50 - 75 miles in terms of Ireland.. If this were to continue on each consecutive run then by the 18Z this evening it would almost be in line with the other model guidance.. Positive trend in my opinion

No need for apologies BA, I can easily get it wrong also looking at any chart! At this rate we have looked at so many they all become a blur.. Also, the overnight NAE is much better than the previous 18Z one, with quite significant snows possible over southern Ireland, Wales and the Midlands towards later Tuesday and into Wednesday:

Morning BA, The above is a bit out of place from what I can see, the overnight ECMWF. The initial T+48 timeframe discussed above is virtually unchanged from yesterday, as seen from the two frames below: T+60 (Yesterday) T+48 (Today) For 12 Noon Wednesday the 00Z ECMWF has the low and colder air even further south than the 12Z yesterday, comparing the relevant timeframes from the 12Z/00Z.. SA

Overnight ECMWF @ T+48... Keeping the low to the south... T+48

18Z NAE is also very similar to ECMWF precip extent at that timeframe, just a little bit further north... Look at the low also, it is almost identical... the NAE has just shifted things a tad further noth is all and these variations will occur.. Calm, Calm :lol:

Steve, your confidence is very reassuring and I certainly agree about the 18Z ensembles.. However, I think it's vital that we see the 00Z GFS or at the latest the 06Z GFS evolution trend almost exactly towards this evening's UKMO and ECMWF evolutions.. We also need to see UKMO and in particular ECMWF, hold very firm. M

Hi TETIS, Some debacle this is this evening with GFS! Here is tonight's ECMWF Precip evolution, just change the url for the appropriate timeframe: http://en.vedur.is/p...227_1200_72.png SA :lol: