Yarmy

The best Dec snow event in decades IMBY. Heavy, lake-effect, powder snow on the night of the 17th left several inches and a power cut at about 4am. Far better than Dec 10 which was bitterly cold, but largely dry here.

UKMO T168 looks a lot more like the ECM than the GFS 0z or 6z with the ridge building to the west of the UK:

I know it can seem like that, but it really isn't true. See here, page 18 in particular: https://www.ecmwf.int/sites/default/files/elibrary/2016/16924-evaluation-ecmwf-forecasts-including-2016-resolution-upgrade.pdf The graphs represent the days at which mid-trop forecast accuracy drops below 80%. For the NH, it's an improvement from approx 3.7 days in 1981 to approx 6.6 days in 2016. The SH improvement is even more striking: 2.2 days to nearly 7 days.

Not by the SILSO count (which is the one used in the table above). Boulder might have done though. But for a very short-lived spot on the 13th Nov, the current count would be 43 days which would have been the longest streak in over 100 years.

Certainly yes. There’s a much more extensive observer network now, so more likely that those short-lived spots get, er...spotted. That’s why I’m always banging on about using the SSN as a better measure, because that is adjusted to account for those differences.

Worth keeping an eye on this table now: Spotless Days | SILSO SIDC.OMA.BE Regular solar observers have noticed that since mid-2016, the Sun has occasionally been devoid of sunspots. These spotless disks will gradually become a familiar feature as the solar cycle is heading for... Currently the second longest streak in over 70 years.

Genius, but the only thing missing was a zoomed in picture of some random part of the Northern hemipshere.

We haven’t equalled 2008. The 2008 number is the SIDC count so you need to use the current SIDC count if you want to compare. The number you are quoting is the Boulder count.

I think that's literally the first cold long range forecast I've seen made by a professional organisation, and not some bloke in his shed throwing sticks in the air. It's private company though rather than the Italian MetO.

It's not that difficult to chase a waterfall, although perhaps ill-advised.

UKMO T168 Hard to tell on these charts, but close to the ECM, it would appear.

Anomalies though, aren't they. Not that great when looking at the actual 500hPa mean:

From the 15th-20th November (subtract 384 hours from each date on the x-axis). It's interesting that the FV3 has a stronger positive bias than the GEFS has a negative bias at that range. Perhaps @Interitus could do the same chart for T240 lead times?

BBC switched from the MetOff to Meteogroup some time ago. I don't know what models they use, but it's unlikely to be MOGREPS.

The MetO outlook referenced above is presumably informed by MOGREPS output. Perhaps there's a signal for more disruption there, but there's little point speculating on a model to which us plebs have no access.

It's not all about the Atlantic. I'm keeping an eye on the sharpened Alaskan ridge in this afternoon's runs.

Asserting as fact that which is to be proved. Who said it has? Evidence for this? If we only consider orbital dynamics, then the Earth should be in a cooling period.

To my eye, there appears to be huge uncertainty even early on in how the depressions being ejected across the Atlantic will disrupt, elongate, slide (whatever you want to call it). E.g. GFS 06z T90 vs UKMO 00z T96: The UKMO has the depression south of Greenland more organised and consequently it barrels across before filling out mid-ocean . The same feature on the GFS is already under pressure (literally!) and stretched. The consequences a couple of days later are stark; GFS T138 vs UKMO T144: A long way to go before even that period is resolved without worrying about home counties blizzards later on.

At least next year the GEFS will be using the FV3 model, so we might not get led up the garden path so often.

I don't know about the GEM ens, but anyone still giving any credence to the GEFS is deluding themselves. The only reason they get such prominence is that the data is freely available.

Ha, yes, it's not a bad pattern match. I'd say the trop polar vortex was more distressed then, but still.

I wasn't on here then, but the Strat thread showed mounting optimism from November onwards.

According to the paper I read above, about 66% of all major SSWs (i.e. reversal at 60N 10hPa) propagate down to the Trop in a way that generates a -NAO response. However, the timing can be anything from a few days to a few weeks.

Yes, at 6pm too, 2-3 hours after peak temp. Something is screwed up. Any Weatherbell subscribers got more info or charts?

FAO BBC Weather. Fog is not a “risk”. I like fog.