Mark Bayley

Wait till you see the parallel Steve!

Steve will probably like this run! Better heights to the N/NE and increased cold potential We can only dream >

GFS 18z is as perfect example of what this set up can throw up. A snow event on Tuesday for anywhere the midlands north (probably the north Midlands/Yorkshire/NW favoured based on ensembles and both GFS). Of course, it may disapear, but shows with cold air in place surprises may happen! Admitidly with distance north and west. GFS P furthest north

Sadly to be gone tomorrow (most likely) but shows what such a set up can potentially throw up Mind you, some precipitation on the NAVGEM, although doesn't make much of that small low

Agree with most on here. I certainly think more could made of the technical thread, as often that is rather quiet. As it stands, the ramp threads, the general model discussion and technical are good.

Have we ever had 930mb low cross the northern UK? Of course that ensemble is far too extreme, although a potentially nasty storm seems likely. Will be interesting to see if the models trend the low further north, with the bulk of strong winds across Northern England and Southern Scotland.

Had a few hail showers in the past 30mins, although not expecting much else. Focus now on a potential nasty wind event next week!

Some monster ensembles!

Interesting last frames of the GFSp. If only those lows tracked a little further south.. There seems to be trend, towards the last third of the month, for a relaxation of the PV to our north, allowing the possibility of height rises and a route to cold. The GFS (and to a lesser extent, GFSbc) are still keen on the MJO progressing through to phase 7/8, whereas the ECM and UKMO (ensemble) have tropical convection dying a death as it crosses the western Pacific, entering the 'circle of death'. There has been greater movement towards the GFS solution of the carrying the MJO through to phase 7 (ECM previously restricted to phase 5), with the JMA and UKMO (deterministic) progressing into phase 7, although of lower amplitude. As alluded to by other posters, progression of topical convection (to MJO phase 7) teleconnects to increased ridging in the mid-Atlantic, as illustrated by recent GFS runs, and the latest ECM. So far this may seem to be transient. However, with a possible decrease in the strength of the PV to our north the possibility of something a colder increases towards the last 1/3 of January and into February http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

I wouldn't have much faith in trend shown by the GFS (of mid-Atlantic ridging) until there is greater certainty on the MJO. The GFS was on its own (excluding 1 or 2 lesser models) in progressing through to phase 7; whereas the ECM has it dying a death in phase 6. Unfortunately the GFS charts are down. If the MJO struggles to make much progression, as the case has been through this winter, then something akin to the end December seems more likely. Sadly i see little support for any sustained cold, short or long term

From what i remember the BC output was less enthusiastic about progression to phase 7 (made it through to 6 before seeming to die) Edit: * yesterdays MJO forecast

GFS continues to a hint at the PV relenting somewhat as we progress past mid-month. A light at the end of the tunnel? A possibility of the MJO reaching phase 7 supports a mid-Atlantic ridge as indicated by the OP and P. The GFSp ends very nicely..

Unfortunately my forecast has so far been wrong (December and January). The polar vortex has remained relatively strong and will no doubt remain fixed across Greenland for the foreseeable future. This is despite stratospheric warmings and continued atmospheric wave activity. December was expected to the mildest month, however i favoured a greater number of cold spells and for the AO to be neutral/negative, as opposed to mostly positive. A significant stratospheric warming event was forecast for the end of December/early January. This has not and will not verify till at least the last 1/3 of January, in which case the impacts may only be felt for the very end of the month and February. Seemingly a number of favourable factors have been overridden. IMO sea ice conditions in the Barents/Laptev/Kara seas has acted to reinforce low geopotential heights (i.e. an intense polar low) that has inhibited the formation of a strong Siberian high as suggested by the Cohen snow cover theory . As hinted in my initial forecast, sea ice anomalies in these regions was near normal and higher than previous years. I suggested that the sea ice anomalies potential to force -AO may be less strong than previous winters. Rather than a reduced influence, sea ice conditions may have acted to sustain the +AO and +NAO pattern so for experienced this winter. Of course, i am no scientist, so could be entirely wrong! Further to this, other climatic variables that may have come to our aid, such as the MJO, have failed to gain amplitude to the phases that we desire. Am writing off winter? Certainly not! I think we can be confident that the first half of winter (Dec 1 -Jan 15) will not deliver the sustained cold and snow that many of us crave. The PV is resistant across Greenland, with the Azores high to our south remaining notably close (as shown by most deterministic long-range models). The best we can hope for, imo, is for the azores high to weaken and for troughing to sink south and eastwards, giving us shots at colder zonality. This has been hinted in the long term. There are hints from the GFS of progression of the MJO towards phase 7, offering a possible pattern change post mid-month (MJO 7 teleconnects to a mid-Atlantic ridge). However, many models such as the ECM remained locked in phase 5, suggesting low heights across the UK, but may offer support to colder zonality. Unfortunately, the ECM returns the MJO to 'circle of death'. Further stratospheric warmings and wave breaking will no doubt pressure the PV, although im uncertain as to when the knockout blow will occur. When it does, we may be game (depending on what gets sent where!). The last 1/3 of January/February now offer the best hope of sustained cold/snow. February still has every potential for delivering a significant -AO month

The strongest warming yet on the NAVGEM, although not sure on its accuracy (old NOGAPS model?). A contrast to the GFS 12z. Interesting update from Cohen lending more support to the ECM. Unfortunately i've been busy this winter so mainly followed the posts as opposed to the data however it looks as though its about to get interesting! @WS: Yeah, it seems sea ice conditions in this region may have acted to counter the SAI feedback. There's a few recent papers suggesting that positive sea ice anomalies in this region correlates with a stronger PV.

In terms of sustained cold and snowfall, the 12z GFS is of course horrific with the PV dominating over Greenland. However, some transient snowfalls, especially with distance north, would occur, depending on track of those deep Atlantic lows (and amount of cold air flooding in behind them). Mostly average sums it up. Unfortunately i see no evidence of losing the low heights to our north till at least mid-month despite apparent warmings in the strat. Other factors, such as the MJO, remain unfavourable > Some may start writing winter off, however, the last third of January onwards is still all to play for, should the strat play ball.

I'll plump with 3.5c. A milder first half, cold second.

Had a small thaw although temperatures dropped back down 0c early morning. Currently sunny and 0.2c

Seems the snow is bringing a few trees down!. This just round the corner from me

Final one from me. What i thought would be a few cm's has turned out to be a very good snow event, with now 10-11cm of snow (with mini powercut thrown in, although most likely unconnected). Although only 10cm, it has damaged a few of the shrubs, although these are delicate. Snow still coming down and should be for another hour so, with perhaps another cm or two. Heres some pictures. Hope everyone got at least some snow

Now we are having powercuts! I've just had to go out and rescue half my shrubs as they are nearly to the floor. The snow is wet and heavy

10cm now with the snow getting heavier. Temp risen slightly to 0.2c

The main ones should be. Side-roads may be a bit dicey but by late morning i should you'll be okay

Haha its a make shift ruler. Every year this happens to me, i always lose it when the snow comes! Hopefully you get some snow showers later!

Think you'll be able to make it over? I'll admit i was quite wrong about this event, i thought it seemed to marginal for those away from the peaks. GFS 18z clears precipitation post mid-night, although at this stage its just a case of radar watching

Odd the radar shows its getting lighter yet its the heaviest its been in a long while! Seems its about stall over South Yorkshire before moving south, i may see my 10cm! @craigers if you're online. Snowboarding is on tomorrow, if you can make it there