weatherguy

Really? Even if this comes to fruition at +240h (it won't), it's nowhere near awful for long term prospects. The atlantic is still pretty much shut down and the PV is draining east. In order to see the relative potential of the above...look no further than a chart I've grabbed from the archives. Blergh.

Yup, the ICON giving us the lovely "surprised bear" NH pattern at 120h... Good to see the high being cut off slowly in the east.

+150h GFS12z. Keep an eye on that developing low south of newfoundland - that's the trigger for retrogression if all goes smoothly.

It certainly is interesting. Before the potential fun and games begins around the 24th (caveat as always being that this can and will change, but alas), we have uppers around -4c/-5c by +138h. Usual wisdom dictates that -5c/-6c is usually sufficient for snowfall, but with low dew points as seen with easterlies then anything below 0c should be snow. With the high SSTs coming from the time of year, then this helps us on the conduction side of things, but also this certainly modifies the situation regarding the required uppers. The result of my rambling? Inconclusive. Lamp-watching will be required for this early period...Perhaps limited to night-time.

The classic period of March-April 2013?

Well well well...No hopefully needed there - the 12z GFS goes on to be a thing of immaculate beauty! Brings back memories of "that ECM" a few years back with an incredible long-fetch north easterly!

By 186 we see some lovely WAA heading up to greenland...hopefully this leads to some retrogression of the HP and that siberian PV lobe drops in behind.

+162 Ooft. Beautiful for the time of year.

Steady she goes....

The earliest potential difference would be at +72h: If the energy from that LP system doesn't split to send some heading SE (as happens by +96 in the second image), the burgeoning high would sink somewhat. The longwave pattern means the end result would be similar, just likely with a HP centred further south and thus the cold pool not reaching our shores. There are several moments throughout the evolution where slight differences such as these can create starkly different end results in terms of our locale. Don't let this detract from what is wonderful model output for this time of the year though - heck, it's enough to bring me out of my summer slumber of model watching abstinence!

The sky has gone very dark and another blizzard is beginning it seems...Could well have 20cm of snow here, with more in the drifts.

Absolute blizzards here with drifting snow! Must have around 5-6" on the ground right now. Edit - I suppose my altitude is helping a fair bit

Well things certainly picked up around 8pm, got around 4-5cm here now; here's hoping for plenty more topups!

Had a fair few showers through the day here but nothing of note, light dusting in some spots where it hasn't melted

Both are correct. The lows are having a tougher time breaking through the block, yes, but their orientation actually means that milder air penetrates faster from the south-west.

Watch the jet....Come on, hold south...

Indeed, convection-based snow will not be affected between now and thursday. The potential disappointed is instead focused around what path exactly those LP systems take going into friday, as right now it looks unlikely we'll be getting a huge snow event there. Time for things to change however; slight differences could change things drastically

+120 comparison (GFS left, ECM right): Very similar, aside from more robust blocking over greenland. Also from the NH view we can see there's less disturbance to the east which should provide more resistance to LP penetration, and that siberian PV lobe looks set to flood south. Fingers crossed, hopefully I'm not talking utter tripe! Time will tell... EDIT: 120 has vindicated my views! huzzah! The LP is pushed back west, and the HP to our east is eroded, paving the way for a reload. Nice. What we really want to see is that LP start to disrupt and sink south in the next frames...

Stark differences already between GFS (left) and ECM (right) at +96. Blocking appears both more robust and pushing west stronger. ECM is also notable for delay of the 2nd LP system running behind the 1st, which should prevent the block eroding as seen in the GFS run..

ECM +48, whole UK into the freezer...

it's because by the time the LP tracks far enough north it actually loses most of its strength. All it does is pave the way for the second GFS LP system to obliterate the cold pool. Thankfully, other models aren't supporting this evolution. http://www.xcweather.co.uk/forecast - someone introduced me to this link in another thread I believe, it uses the GFS-data for snow-data so offers a good overview of what to expect for your area. Hopefully we see the forecast improve as we get closer to the time.

Monday's showers starting to come into range on the hi-res modelling

What a wonderful profile picture you have

Anyone able to shed some light on how I may fare over in Sheffield please? I'm pretty poor when it comes to predicting how far snow showers may penetrate inland, and this is the first full blown easterly I'll have experienced in this neck of the woods!

It's incredibly amusing watching the GFS flail around like a drunk just dying to get some progressiveness into the run... What's more though is that not even the LP-track of nightmares can warm up the 850s enough to prevent probable blizzard conditions. Still, in the bin for me.