Winter 2019/2020 - General Discussion

M.T. Cranium wrote: »

This may also be one of those winters where extreme cold moves south from Siberia into China, Korea and Japan.

It was actually pretty "mild" here in northern China (Dalian) last winter, when compared to the previous two. The coldest day I can remember last winter was actually in December. Other than that it was pretty consistently between 0 and -7 with almost no snow.

I hope really hope we don't get extreme cold. The problem where I am is not so much the actual temperature, but the wind chill. Makes me want to cry just thinking about.

John.Icy wrote: »

I'll go against the grain and go for a cold winter with plentiful snow. Mild start, increasingly cold towards the end of December followed by one proper cold spell in early/mid January. Couple of one-day snows in February and early March.

I'll join you going against the grain.

More so because we're going into an enso neutral period but also because there's more cold water in the eastern Pacific that could push us into a La Nina.
And we had a La Nina in 2010 when we had our cold winter and we had wavy jetstreams then as are now being forecasted on the long range on the gfs. And it was a solar minimum time too as now.
There's northerlies and easteries being forecasted on the same forecast too.
So I'll throw my hat in the ring but go for an early winter.

Infrequently stormy. I'm not even sure what to expect with that.

The GFS 18z, 0z and 06z last night/this morning give a good example of the kind of setup I was thinking of for this winter when I said that the jet may become meridional at times.

Molly007 wrote: »

Why would the amount of berries indicate cold to come ???

It's just one of those weather folklore with no scientific evidence. I seen a fair bit of them last year too.

Gonzo wrote: »

Yep, we rarely get more than 1 or 2 decent winters every 10 years. The 1980s were a bit of an exception. Most winters are Atlantic driven with a few brief north-westerlies delivering wet snow showers to the west and north. 2010 and 2018 of course brought plenty of snow, so right now we are not due another decent winter for some time. However there is no guarantee what any winter brings, we could get lucky this year.

I think we're due another one soon, grand solar minimum etc. Hopefully this year!

What I find interesting with the current model runs that despite it being blocked and cold, the stratosphere remains cold and looks set to get even colder which should mean an increase in the mean zonal winds and an intensified jet stream. Strat and trop disconnecting unless we see a dramatic change in the outlook which is often the case in this country!

I said I would look at winters following exceptional mild ones in Ireland and this is what the reanalysis shows of these winters combined (with the exceptions of 2016-17 and 2017-18 following on from 2015-16 and 2016-17 respectively as NOAA/NCEP 20th Century Reanalysis only goes up to 2015) for Europe, both from a 500mb height perspective and a MSLP perspective.

There is not a lot we can pull from the 500mb height anomaly besides weak below average heights around the North Atlantic and a strong anticyclone sitting to the north of Russia. There is also below average heights over the med into North Africa. A strange chart.



A lot more information can be interpreted from the MSLP anomaly however with a strong Icelandic Low driving in the westerly winds across the North Atlantic but the two elements described in the 500mb height anomaly still are evident here, the high over Russia and the low in the Mediterranean. There is a lack of Euro High ridging from the Azores. This is a very wet and zonal chart but not the average mild and westerly driven one you see. The way I see it is that instead of the lows going west to east across northern Europe, they would attempt to dive southeastward at times. There'd be the possibility of the high to retrogress into Scandinavia I would have thought but such moments would be temporary with the active Atlantic.



This looks very similar to that of the pattern that Winter 1938-39 had :cool: . Two differences though include the Western Europe cyclone in the reanalysis above of the winters following exceptional mild ones being more over Iceland compared to over Ireland in 1938-39 and the extension of the high in 1938-39 from Russia was closer to the Arctic and was larger also (although this probably down to the severe cold spell in mid-December 1938 so this likely skewing it somewhat).



Anyway, this little analysis was just for a bit of craic but a bit coincidental how it shared similarities with 1938-39, a winter I mentioned only recently.

There continues to be the signal of an intensified stratospheric polar vortex during the first half of November, whilst being quite strong already, but the troposphere remains disconnected with a lot of blocking showing in the northern latitudes. This blocking has been a recurring theme all the way back to second half of April when the weather went unsettled following the warm Easter.

If the troposphere and stratosphere reconnect, we should see the NAO go strongly positive which is usually associated with stormy, mild to very mild and wet but currently no signal of that all. Instead, the first week of November is looking a bit on the cool and wet side and NAO on the relative weak negative side.



North Atlantic SSTs are mainly on the warm side generally with very little cooler than average regions besides an area between 40-60N. Not much sign on the tripole front at this point in time.

To conclude the October snow advancement index (SAI) for this season, this October had an above average SAI. The chart below by the World Climate Service shows the correlation between the Arctic Oscillation (AO) and Eurasian snow cover advancement through October. N.B. SAI is inverse on this graph so negative numbers represent above average years whilst positive numbers represent below average years. Meanwhile, positive numbers represent a positive AO so low pressure over the Arctic and negative numbers represent a negative AO so high pressure over the Arctic.

Whilst this was a good predictor back in the early years of this decade for the winter, now the correlation is completely gone with every season since 2014 having an above average SAI but also +AO vast majority of the time. The theory by Cohen and Jones (2011) stated that above average SAI through October is an indication for +AO in the following winter. This has just not happened in the past 5 years for whatever reason.

In the farming community winter has set in early this year. Most cows and cattle have been housed within the last couple of weeks. Fortunately we have bumper fodder crops. Last year fodder was scarcer due to drought conditions and a late spring. Cattle weren’t housed until late November and there was plenty of grass by late February this year. This coming winter could be much longer than last winter.