Stu_London

Pendulum swinging back to an old school easterly where models (GFS worst offender) will suggest atlantic breakdowns only to back track in the 0-96 hr range. Whether or not it's quite right for a snowy cold spell remains to be seen but it does look like we will have plenty of cold at the surface and as others have stated, get the cold entrenched and its likely that snow events will pop up, sometimes at very short notice.

A hint of spring in the low res part of the 12z GFS. Personally after the potential incoming cold spell, it's springlike weather I will be looking for - so I can get out and play a bit of golf.

A few cracks appearing this morning. Will remain sceptical myself until the METO get on board. Media forecasts are suggesting a dryer, colder period which would suggest that they are seeing things considerably watered down compared to the publicly available models. I wouldn't rule a cold spell, perhaps even a significant one, but some expectation management might not be a bad thing at this range.

The OP is on the cold side which is consistent with the last few runs and fits in with the SM theory that with easterlies, the operational leads the way and the ensembles catch up later. What does encourage me is that there is a really tight cluster up to about day 5. If they were less clustered, it would in my opinion signal that the model is struggling to pick the correct pattern and would lower confidence.

18z follows the normal uk winter mantra in that anything that can go wrong will go wrong. I think given the lack of solid ensemble support it was inevitable that GFS would throw something like this particularly given the short term variables on offer. I would still say 70% chance still of some sort of cold shot, with some snow Perhaps 25% of something noteworthy (Noteworthy being a Feb 2009, Jan 2010 type event) Less than 5% of something epic (Epic being Feb 1991, Jan 1987)

12z has us partying like it's 1991!

Another GFS run where the Operational is very much on the cold side of the ensembles. Not unheard of the operational to lead the way in these scenarios. I seem to recall in the run up to December 2010 we had a series of outputs where the operational was cold and the ensembles caught up later. Perhaps it's resolution or quality of data.

Or maybe plain old "thermal" - this being around the turn of the month

I think there will be a lot of sleetiness until the dps get to zero.

Huge Wintryness upgrade on the NW radar in the last 10 minutes. Areas now affected Cotswolds, Chilterns, West Mids, Dartmoor, Exmoor, Mendips, most of Wales

Seen it happen 3 or 4 times in my life, last time over the Chilterns in March 2013. Actually a wonderful phenomena as the greys get whiter and whiter until everything is all white.

Some wintry precipitation now over Exmoor, Dartmoor and the Cotswolds. Still think Kent will be ok later. I'm nicely placed in Orpington with some elevation.

Welcome back. Nice to see someone else from the beginning. Just need to get Mr Crazy Snowfan posting now. On Topic, Models firming up on the most significant cold weather event since March 2013. As for snow, I think there's a lot of marginality in the short term and it may be rather dry in the more medium term, so there might be disappointment for some. As ever the evolution in the modelling has been fascinating though.

Hi don't get time to post much these days, but the operational run would be like a 1987 event but for 10 or more days instead of 4 and would probably trump any single event in the 20th or 21st century. Thankfully it is deep in FI and an outlier because if it did come to pass it would be nothing short of catastrophic for us. Some low lying snow for a couple of days cheers most people up, but I wouldn't be wishing for 06z operational outcome for a single moment.

I'd be surprised if the rolling total goes above 11C in the next few days, let alone 12C. Yes the GFS is showing some mild nights and days but it never quite seems to come off.

Yep I rather suspect the high water mark was set on the 1st. That's not to say that the next week won't be above average because it does very much look that way.

GFS 06z operational suggests something like 10.6C before adjustments with a few ups and downs along the way. A lot of that is in FI however, so there is plenty of margin for error. In the nearer term, a dip below 11C in the next week looks likely.

Certainly looks like today might be the peak for the month. Unless the mid-term outlook changes CET should head south for quite a while. If the last week is cool/cold, I fancy sub 10C

Based on current output I would expect something around 11C-11.5C at the mid month point which I am guessing around or just above the various relevant rolling averages. The door would be open to cold (sub 10C) month, although mild days pushing the value up are as plausible as cold ones bringing the average down in the second half of October. The FI output from the 6z today demonstrates this quite nicely.

Looks like 3 days of solid rises to come, followed by a cool down

In 2015, it looks entirely possible that one or more of the first few days in October will record a daily value higher than every day recorded in September. Not sure how remarkable this is - but I would imagine it's a pretty rare occurrence.

The rolling annual CET is likely to dip below 10C for the first time in a while during the next fortnight also!

13.2C to the 17th The timings of various areas of rain forecast in the next week will be a factor. If they arrive in the evening to the CET area they will likely keep temps from falling - daytime rain bands will suppress maxima. Either way I don't see it moving more than 0.1C to 0.2C from where it is currently during this timeframe.

I'm not in the competition but if I was, I would be very happy with something between 12.5C and 13.0C as things stand currently

A couple of little interesting nuances for this month. Looks quite likely that the CET in running will not breach 14C on any given day in the month. Quite a rare occurrence in recent times (1992 the last September this happened) Similarly to 1992, the CET looks like operating in a particularly narrow range (in 1992 the CET in running was always between 12.2C and 13.4C) Based on the provisional data for 2015, the range is currently 12.8C to 13.7C - this might of course get blown off course with revisions (particularly if the comments earlier in the thread hold any water) but quite interesting none the less.