APerez

Evening all, not much to add to the thoughts in here today. Given the solid agreement in the reliable timeframe, there aren't any wholesale changes compared to yesterday. In the short-term, our attention of course turns to the snow potential. A few different perspectives on offer here with inland areas at elevation predictably looking best placed for modest amounts of accumulating snow. Far from a done deal, mind! Here's a few different takes on early tomorrow morning... ARPEGE: WRF-NMM: EURO4: HIRLAM: You can see the WRF and EURO4 favouring northern parts of Yorkshire with much of any accumulating snow falling over the Pennines and NY Moors, while ARPEGE and HIRLAM take a southerly track with South Yorks and the N Mids more in the firing line. In all cases the precipitation begins to fizzle and break up as it heads further south and west during the latter part of the morning. Looking at Wednesday's potential for the south, it looks fairly likely that the famed 'M4 corridor' will be best positioned, though some question marks over rain/snow distribution as well as track will likely remain until the event itself. Given how these things usually progress, the further north you are in the precip band, the better... ECMWF IFS HRES: is the pick of the bunch and presumably the reason behind the BBC's bullish optimism! Note the more southerly track of the WRF-NMM for the same timeframe... Nail-biting stuff if you're of snow-starved persuasion further south! The latest FAX charts don't exactly calm the nerves, either! ... t+60: t+72: It's gonna be a close one - fingers crossed on the ECM track Still, as other members have mentioned, the FAX charts will be an invaluable resource this week and beyond as they pick up small disturbances at short notice. A bit of luck and we can all see a flake or three at some point during this lengthy cold spell. I say lengthy cold spell because the extended ECM 32-dayer looks set on below average conditions for the next fortnight at least... Full link here: ECMWF | Charts APPS.ECMWF.INT Enjoy your evening guys and gals Alex

Great to see the mood in here so jovial this evening, and for good reason of course Looking at the shorter term we have a snow risk for the western half of England as well as Wales going into Monday morning as an occluded front swings south... Further interest later in the day as the low circulates eastwards. On the northern side of the circulation we have interest coming in off the North Sea as precipitation moves inland. Potential for a spell of snow to affect the Wash and the E Midlands. One expects further changes and a 'nowcast' situation as these disturbances continue to challenge the hi-res models... Further disturbances will likely appear within the 24-36hr timeframe as we head through next week. You can see just how busy the t+36hr FAX chart is this evening... I'm sure most of us are wary enough not to trust precipitation models at mid to long range, as well as being healthily sceptical of short-range output, especially when marginal wintry situations present themselves. If anything that makes the coming days that more fraught with excitement as I'm sure some surprises will await ( for balance: as well as crushing disappointments ). Heading towards the end of next week, we have lovely consistency at t+120 with a slack flow from the north-northwest and strong WAA in the mid-Atlantic which later forms high pressure to the north or north-east... ECM: GFS: GEM: You can see looking at the t+192 chart from the ECM the effect of that warm air advection with a lovely profile to the north... Without wanting to go chart crazy, I will note that the GFS and GEM play on a similar theme and it seems all roads lead to a deepening of cold. Perhaps not as deep as one might hope for such a favourable time of year, but we have to accept that for what it is an appreciate the stunning synoptics we have at the moment. Should we see such prolonged cold then the uppers become less important as our landmass becomes ever colder anyway Still, as I mentioned before, the pattern leads to deeper cold anyway as we see an easterly solution become the favourite by day 10... ECM: GFS: At this point we have lower pressure to the south which enables us to import colder air from the east, as seen on the ECM 850s below. The GFS is less settled at the same stage, bringing low pressure closer to our shores and the risk of a rain to snow event for many. ECM 850s at Day 10: It is worth noting that even when the GFS trends less cold for a time at Day 10 it never actually becomes 'mild'. Instead we see the low pressure trundle eastwards allowing a renewed surge of cold air to plunge down from the north with signs thereafter of further amplification in the Atlantic... and this is at t+384 I'll finish with a very enticing ensemble set from the GEFS 12z. We're in the infancy of this cold spell and many of us will no doubt have to be patient when it comes to snow. With such prolonged cold on the horizon though the chances surely increase with every frigid day that passes. It's been a long while since we've been able to witness such wonderful charts and these snow row figures for Sheffield below are the most impressive I've seen so far this winter (sorry, Sheffielders I've picked you because you can often do well in cold spells) (albeit the GFS snow rows are temperamental and prone to change) and should hopefully boost those who are in need of one at this early stage given the risk of snow is not yet a widespread one Alex

Hello folks, it seemed the perfect time to create an account on here and get posting to help further my weather education. I'm hoping Mr Gaze can do the same thing for me over on T.W.O. Anyway, a really positive GFS 12z unfolding and hopefully one that returns the model to form after an iffy spell, especially for the operational. When the full ensembles come out later I expect this will be tucked in nicely with most of the suite rather than poking its head above the 0C threshold like some curious meerkat. Looking at the latter part of the run - post 240hr, it looks like we have low pressure drifting up from the south, ushering in less cold upper air but at the same time bringing precipitation that would be ripe for a battleground snow event with such entrenched and prolonged cold air (and ground) in place... What entices me is the prospect of ice days in such a cold and slack setup. Having read through this thread pretty religiously over the past week or two the risks of freezing fog and hard frosts have been noted. Going into the New Year, conditions seem ripe for ice days given we would have had cold air in place for some time, with ever more slack conditions establishing... Finally, what is most encouraging to me is that, though I'm posting charts in fantasy land, it's not like the short-term is mild and horrible. We're into this cold spell right now and, if anything, conditions going into 2021 look colder and colder still Alex