virtualsphere

34.1C Suffolk on Sat 16th

16.5C and 58mm please

Most of this article on the 1989 Halifax storm is behind a paywall but there's an interesting free map on the rainfall distribution around the area. Just a moment... RMETS.ONLINELIBRARY.WILEY.COM

14.8C and 108mm please.

14.2C and 47mm. Feeling like a hot one this year & the gap between 1833 and the rest has to be filled at some point!

8.3C and 65mm please

Probably a statistical quirk, but interesting how many of those fell within a year or so of a notable cold winter spell: 2013, 1995, 1980 ('79), 1962/4 ('63), 1916/18 (1917)

6.2C and 59mm please

3.7C and 49mm please.

4.4C and 87mm please

Although the models seem to have trended away from some of the colder options (for now), still a lot of uncertainty for the Christmas weekend and next week. The setup with Atlantic lows approaching reminds me a bit of Feb 2007 here in Wales - anyone remember the unexpected heavy snowfall that was forecast to turn back to rain but didn't? These can be marginal and there's a risk of cold rain, but if everything falls in to place they can be one of the best synoptics for significant snowfall in our part of the world, and if we can hang on to that block for a bit longer, if the first attempt fails then we may get several attempts. Most of the current modelling seems just the wrong side of marginal at the moment (might be better for those in the north), but if you look at the 850hpa temps for the 2007 event they weren't that impressive so I think a few minor tweaks and if the low is slightly further south than modelled at present we could end up with a seasonal snow event.

Thanks for all the replies, interesting stuff. Looking at those forecast videos, SW Wales looks to be one of the few areas with rain rather than snow which is probably why I don't remember much! One memory I do have of that period is driving back to Wales from the south coast of England just before Christmas 2000 and hitting some pretty dense fog on the M4. @LetItSnow! yes I believe autumn 2000 was the wettest on record for the UK as a whole, possibly the wettest season as well at that point but I think it was overtaken by winter 2013-14. Source: https://www.metoffice.gov.uk/research/climate/maps-and-data/uk-temperature-rainfall-and-sunshine-time-series I think 2000/01 was a La Nina / eQBO combination like we have this winter. There's been a few good posts on here recently about this combination being a potential driver for a front-loaded winter with the polar vortex recovering later in the season. Certainly looks like a strong vortex in place by mid-Feb 2001:

I was surprised to see some northern blocking over Christmas / Boxing Day 2000 while looking through some archive charts. I don't remember any notable weather from this spell here - did anyone get a white Christmas from this? We did get snow a year later on Boxing Day in 2001. 2000: 2001:

I'm not sure about 1976 but there was a notable tornado outbreak in the UK in November 1981: 1981 United Kingdom tornado outbreak - Wikipedia EN.WIKIPEDIA.ORG For me, the January 1990 storm is probably most memorable, our school roof blew off and we were sent home. Our chimney cap also blew down on New Years Day 2014 so that would be another memorable one: the storms in late December 2013 and early 2014 probably the severest run of multiple depressions I can remember. Also quite a lot of damage reported locally from Storm Arwen last month, unusual for a north-westerly rather than south-westerly gale. Strong SW'lies are fairly common here near the SW Wales coast, while strong winds from other directions are relatively unusual which probably had an impact.

5.1C and 89mm please

There's some interesting data on long term model verification from the WMO Lead Centre for Deterministic Forecast Verification, and you can create your own plots: https://apps.ecmwf.int/wmolcdnv/ These are all based on northern hemisphere 500hPa. At 144 hours out, there seem to be significant improvement in the lead up to 2010, then what looks like better verification between around 2015 and 2018 but perhaps a slight drop back with more variation since. Out to 168 and note the scale is different, similar kind of pattern with biggest improvements to 2010/11, ECM especially performing well in the years leading up to 2020 but then a bit more variation in the last couple of years. 192: and 240: So while there's certainly been improvements in verification (and admittedly this only looks at one particular forecast type), nothing perhaps as significant in the last decade as the years between say 2005 and 2010. With the slight drop back in the last couple of years at the mid range, we're maybe still on a par with the period around 2012 if I've interpreted these correctly. Interesting to compare with shorter range forecasting: e.g. ECM at 72 hours seems to show improvements in the last few years so perhaps this is where they are concentrating their efforts.

ECM MJO ensembles give a little more amplification in phase 7 in the extended range. A lot of spaghetti in there and many members also staying close to the COD. Still, some promise here for potentially a colder spell as winter begins perhaps.

SSWs are relatively frequent (60% of years between 1958 and 2019 according to this paper), but getting one in the heart of winter is rarer, and getting one which results in a cold outcome for the UK isn't guaranteed either - in some instances the UK seems to have had more cold weather from the precursor pattern leading to the SSW than after the event itself. EQBO seems to increase the chance of a SSW (90% according to the paper I posted). Looking at this, there were SSW events in Feb '79, Feb '80, Mar '81, Dec '81, Feb '84, Jan '85, Jan '87, Dec '87, Mar '88 and Feb '89: there was then no further SSW until 1998. Thinking of how some of the memorable UK cold spells of this period fit in, 1979 was cold from January suggesting the precursor pattern may have had an impact; the Dec '81 SSW was at the beginning of the month so may have led to that cold December and early Jan '82; the SSW on 1 Jan '85 may have aided the cold Jan and Feb that year. The Jan '87 SSW was on 23rd, which was slightly after the famous deep cold spell. 1987/88 and 1988/89 were both mild winters. There was no SSW in 1990/91 or 1995/6 which both saw cold weather. '

Re. ENSO, here's some analysis I did last year comparing the historical Nino 3.4 / 1+2 region data for the October to December period with the following winter CET which could be worth sharing again. This would seem to suggest it's El Nino we definitely don't want for a colder winter, and while neutral is fine, a slightly stronger La Nina signal may not be a deal breaker, especially in the 1+2 region. Strong La Nina can certainly lead to very warm winters, but doesn't rule out cold - the strongest El Nino does seem to result almost exclusively in warm winters. According to this, most forecasts currently going for between -0.5 and -1.0 for OND which is pretty much where we want to see it, if we want a chance at a colder winter from an ENSO perspective. (source: IRI – International Research Institute for Climate and Society | October 2021 Quick Look IRI.COLUMBIA.EDU

8.0C and 132mm please

Looking at Octobers preceding some colder and warmer winters, using some recent examples both seem to feature blocking over the UK and low heights north of Scandinavia - one key difference seems to be the area around western Canada, south Alaska, north Pacific region, with significant blocking in years preceding warmer UK winters and a trough here in years preceding cold UK winters: If the current modelling pans out, plenty of low pressure forecast in this region during the coming month:

I believe there was an early Canadian warming in 1962/63 but there are doubtless other examples with a less extreme outcome for the UK...

Simplifying things a bit, 1998 is close to a series of ascending solar cycle colder winters for the UK that includes 1956, late 70s*, 1987, Dec 2010: *1979 is nearer solar max due to the fast ascending phase: Jan '77 and Feb '78 may fit in this particular cycle. Often we see a cluster of at least two colder winter spells together, the first close to minimum (e.g. 1977, 1985-6, 2009-10) and the second shortly after (1979, 1987, 2010). In that particular cycle we had 1995-96 and 1996-97, ending with the warm Feb '97, so not far off. Worth mentioning that significant colder weather still can still show up close to solar max (e.g. 1947, 1979 and 2013). On this basis I think we could see a colder winter or two coming up in the next few years depending on the other factors in play.

According to this "Average wind speed and deviations from the long term mean (ET 7.2)": The July 2021 average wind speed was 5.7 knots, 2.4 knots lower than the same month in 2020 and 2.2 knots lower than the 10-year average covering the period 2002 to 2011. July 2021 was the least windiest July in the series. The average wind speed for the three months March 2021 to May 2021 was 7.8 knots, 0.7 knots lower than the same period a year earlier, and the lowest recorded for this 3 month period since 2012. The average wind speed for the three months April 2021 to June 2021 was 7.2 knots, 0.6 knots lower than the same period a year earlier, and the lowest recorded for this 3 month period since 2010. The average wind speed for the three months May 2021 to July 2021 was 6.8 knots, 1.2 knots lower than the same period a year earlier, and the lowest recorded for this 3 month period in the series. But... The 2020 average wind speed was 9.1 knots, 0.8 knots higher than in 2019 and 0.2 knots higher than the 10-year average. Ten named storms affected the UK during 2020 which resulted in 2020 being the windest year in the series since 2015. The data only goes back to 2002, and 2010 was less windy that anything since to date. Feb 2020 looks like the windiest month since Jan 2010 with Dec 2015 and Feb 2014 coming next. Energy Trends: UK weather - GOV.UK WWW.GOV.UK Quarterly and monthly data on weather patterns, including temperature, heating degree days, wind speeds, sun hours and rainfall.

10.8C and 74mm please