Stu_London

If severe winters were ranked on conditions indicated in the model output, rather than what actually happened - Jan 2013 would be number one ranked. There was one ECM suite that had the CET at about -6C - I think one member of this forum even changed his name off the back of it.

The Channel runner is the ultimate high risk system. Risk of it missing completely or coming in too far north leaving most of Kent and Sussex with rain My thinking is that the marginality is a bit riskier that the hi res models are suggesting - incoming after dark helps a bit with the air temps -not sure it's a lot of help with the dewpoints.

Nice eye candy on the 18z and good to see the parallel run move towards the op, a bit. Short ensembles are excellent too with no member over -4C from 2nd Jan for London. So a bit of improvement to finish the day, where earlier there have been a couple of wobbles in the medium to long term. I think FI is about 96-120, although there is a high probably it would stay on the cold side beyond that timeframe. The easterly now trending to be the right side of marginal, but that could flip back - would only take a shortwave feature to modify the flow. My worst fear is that this could end up like January 2013, which whilst not an awful month, delivering some snow for many, had many nirvana runs that just evaporated, or were very watered down come the end.

Biggest worry remains is that there is not enough mid latitude cold pools on our side of the globe. GFSP demonstrates how despite reasonable favourable patterns, the cold can run out of steam quickly.

GFS is still quite keen on the area of PPN wrapping back around - so all might not be lost Somewhere like Ashford might do quite well.

Horrible feeling it's all ending up in the channel - hopefully 12z runs will stop the southerly march

There is unusual output for sure. December 2010 had similarities for sure both in extraordinary patterns being predicted, which came off largely and the run up, with a stressed vortex. That was a 5 week spell and we are 2 days into this one so lots of twists and turns to come - we need to get some deeper cold entrenched here and in northern europe for it to progress to a classic.

Remember it quite well - lived in Central London at the time and saw lots of falling but precious little laying snow. I know some parts not far out of the centre did well as did a lot of the South East and Eastern England. Wasn't that the same year as that one of the most spectacular model busts of all time occurred. Seem to recall a very well signalled long lasting easterly (quite a bit more severe than what we actually got in the end) that was due a week or two before the cold set in completely imploding in the space of one or two GFS runs. Jan 2013 nearly made it onto the list, but from what I recall it promised far more than it delivered, not that I was concerned as spent most of the month in ICU. One more - the countrywide thundersnow event of 2003 (I think, maybe 2002), was one of the most remarkable events I have ever witnessed. Temps dropped about 5C from the start of the squall line to the end. Went from torrential rain to 2 inches of snow on a layer of about a cm of ice in Central London in the space of 20 minutes. Only an event in an otherwise non-descript winter, so doesn't make the noteworthy cut.

In all seriousness, whilst most on this forum are excited by a prolonged period of severe cold weather, we should remember that we are in a minority. On the back of CV19 and likely disruptions adapting to a post brexit world, this would in many ways be kicking the country whilst its down. All very well setting up mass vaccination hubs to vaccinate 2 million a week, if no-one can get to them. Remember the elderly and those with underlying health issues are supposed to be first up and they will find dealing with this a lot harder than the remainder of the population.

hope it doesn't all end in tears (or tiers) I try to stay grounded following countless disappointments over the last 20 years of watching the models and 17 and a half years on and off the forum, but I am now leaning towards a noteworthy cold spell being more likely than not and I am starting to entertain the possibility of something a bit more exceptional than noteworthy. To benchmark noteworthy and exceptional I give the following examples in the last decade or so Feb 2009 - noteworthy Jan 2010 - noteworthy Dec 2010 - exceptional Mar 2013 - exceptional Feb/Mar 2018 - noteworthy

Its still a massive ask - but certainly best chance since 2010.

Quite a bit more scatter which is interesting - I guess the nearer to the maritime influence, the more uncertainty.

I wasn't there but my understanding was that they weren't all that low most of the time - perhaps -5C to -10C most of the time. There was lots of surface cold due to longevity of snow cover and slack pressure patterns.

Sorry I wasn't clear. The cold spell being progged for Jan2021 has some similarities - mainly concerning the background signals around autumn. I did caveat with it not being as cold as December 2010 - agree - that was a brutal prolonged spell, the like of which I will be surprised to see again

There are a number of similarities to December 2010 - not as cold...yet The biggest similarity is that the Polar Vortex has been under extreme pressure since autumn. The biggest difference is that 2010 didnt have an SSW and the vortex got its proverbial together eventually which led to a relatively mild Jan and Feb 2011. We have the SSW looking likely this year, which gets a ticket in the raffle at least.

Have a bit of a battle with higher relative humidity before we reach the thermal minimum and higher dewpoints as a result - would be better in early February onwards but then the big orange thing in the sky increasingly become the enemy.

Wonder what the January 2021 CET would look like if the models and the background signals for the second half of the month come close to verifying. Got to be sub 2C, surely?

Parallel looks a bit ropey

LOL - still cold rain for me - you couldn't make it up!

wahay - tunbridge wells in the hunt for the sweet spot

The last third of Jan 1992 was sub zero - from memory I think it was largely due to freezing fog as I recall my entire clapped out ford fiesta freezing whilst driving south on the A1 The period 5th Jan 1985 to 20th Jan 1985 was pretty noteworthy at -1.5C, although the cold relented in the last week of the month.

Has the Western Hemisphere ever been so devoid of upper level cold in the deep midwinter ever before. Maybe the earth has dropped on its axis several degrees and no one noticed.

Lets see if the temporary breakdown from the south is still there at around 210 hours - plenty of ensembles have not been going with that scenario, so would be interesting to see an alternative evolution.

For mid-March you need really exceptional uppers to offset the solar influence. 1991 was very well timed - 2nd week of Feb - 2 weeks in the freezer.

much is made of the days being at there shortest at this time of year and therefore that being best for cold spells, however I would say that the relative humidity being generally higher at this time of year (and therefore dewpoints are higher) more than offsets the benefit of minimal solar heating. Case in point - last night - frost and sub zero temps followed two hours later by rain. I doubt that would happen in mid to late February as dewpoints would likely be at least 1 or 2 degrees lower in that set up. I think the actual sweet spot is probably last week of January and first week of February - if you can get the right set up then - BINGO.