Winter 20/21 - General Discussion

NK76 wrote: »

Hi All ...I've noticed the leaves browning and even falling already...seem to be lots of berries early this year...is this a sign of a cold winter ?

No, the state of the flora is a result of preceding weather conditions and the plants are not predicting the future. Should it be a colder than normal winter, it's a coincidence.

NK76 wrote: »

Are there any winter predictions yet

❄☃️❄

https://youtu.be/8cxNNzdp8eU

This summer certainly has been one of the windiest I can remember. Regarding this winter, let's hope next weeks Scandi high eventually retrogresses to Greenland and stays with us till next February. If only the Atlantic could be shut out for that long!

sryanbruen wrote: »

Well whatever the winter brings, it can only be better than the sheit we endured for the past 2 years surely. 2017-18, when you remove the BFTE event, was an average winter and I'd certainly take that if I was offered it.

I 'd take an average winter overall if we had an event like Storm Emma this winter. The only downside to that beast from the east was the timing, even with day time temperatures close to or below freezing the snow still melted.

nacho libre wrote: »

I 'd take an average winter overall if we had an event like Storm Emma this winter. The only downside to that beast from the east was the timing, even with day time temperatures close to or below freezing the snow still melted.

Easily satisfied so

Harry Palmr wrote: »

I thought we'd just had Winter 20/21

100%
my prediction is that winter will just be a slightly colder version of what we've had all "summer"

Well if there is a lag between low sunspot activity and its effects on our weather, then hopefully this Winter will end up being a good one.

Took on the marketing of a fire protection client last week. Turns out he stocked up on rock salt after the beast as he reckoned last winter would be bad..... I hope to jaysus we get a cold start to winter

SeaBreezes wrote: »

Leaves were burnt here too (south west) with the cold wind last 2 weeks april first 2 weeks may.

All the same (windward) side they didnt recover all summer.

Its a thing. Cant remember the name (scairbhin?)

Can someone help me out?

Yep. Destroyed the begonias, so it did.

I'm hopeful this winter could be a good one for cold lovers. For the last number of yrs I have thought that the early 2020s might deliver some good cold spells due to the solar minimum, as we start to come out on the other side of the solar minimum.

SeaBreezes wrote: »

Leaves were burnt here too (south west) with the cold wind last 2 weeks april first 2 weeks may.

All the same (windward) side they didnt recover all summer.

Its a thing. Cant remember the name (scairbhin?)

Can someone help me out?

I'm right on the coast, lawn and flowers grew like mad, greenest I've seen them

Looking at the weather the past few months, I noticed the wind coming from the north or northwest a lot. Seems like our weather is totally upside down, and I really think our seasons no longer match the weather we get.
My prediction for this winter is that the Atlantic will dominate and we’ll have mild mucky weather. A few blasts of frost, but little to no snow.
This is also not based on science just what I think.

Teleconnections this far out don't mean much, but one thing people should be aware of is that in terms of Sea Surface Temperature analogs (that is, previous years in which the global SST anomaly resembled this year's so far), 2010 and 2017 have consistently shown up as the two strongest analogs. And as we all know, both of these years were followed by absolutely spectacular winter snowfalls.

Unfortunately, 2013 has also consistently appeared as an analog, and we all remember what a disappointing Winter that was. Even so, there's clearly at least some potential there.

Not saying this to get anyone's hopes up, just an observation! I've been keeping an eye on the SST analogs all year for the purposes of predicting the hurricane season and this has been a consistent feature since very early in the year.

One thing to note is that horrible cold pool in the North Atlantic to our West, which did feature throughout summer 2017 but was noticeably absent from summer 2010. I have no idea if this has any basis in reality, but logic would denote that this makes any epic event this winter more likely to be backloaded a la 2017-18 as opposed to frontloaded a la 2010.

One final observation is that the large warm pool in the North Central Pacific bears a strong resemblance to that of 2013, and it does concern me that this may provide the jet stream with a crap-ton of energy. But still too early to say.

Thoughts?

The current SSTA compared with the analog years:

Current (last 30 days):



August 2017 (closest analog):



August 2010 (2nd closest analog):



August 2013 (3rd closest analog):

hatrickpatrick wrote: »

Teleconnections this far out don't mean much, but one thing people should be aware of is that in terms of Sea Surface Temperature analogs (that is, previous years in which the global SST anomaly resembled this year's so far), 2010 and 2017 have consistently shown up as the two strongest analogs. And as we all know, both of these years were followed by absolutely spectacular winter snowfalls.

Unfortunately, 2013 has also consistently appeared as an analog, and we all remember what a disappointing Winter that was. Even so, there's clearly at least some potential there.

Not saying this to get anyone's hopes up, just an observation! I've been keeping an eye on the SST analogs all year for the purposes of predicting the hurricane season and this has been a consistent feature since very early in the year.

One thing to note is that horrible cold pool in the North Atlantic to our West, which did feature throughout summer 2017 but was noticeably absent from summer 2010. I have no idea if this has any basis in reality, but logic would denote that this makes any epic event this winter more likely to be backloaded a la 2017-18 as opposed to frontloaded a la 2010.

One final observation is that the large warm pool in the North Central Pacific bears a strong resemblance to that of 2013, and it does concern me that this may provide the jet stream with a crap-ton of energy. But still too early to say.

Thoughts?

Like last year, my updates will be fewer and further between with no plans to issue a seasonal forecast as compared to pre-2019 years just due to loss of interest or life getting in the way. You're probably better off because I tend to waffle a lot

However, every now and then, I will post an update on teleconnections or analogs that I feel could guide us through this annual rollercoaster.

Firstly, yes good analogs there for North Atlantic SSTs. What I will say is that this is the most important factor to consider for winter. SST anomalies in both Nov 2018 and Nov 2019 were favourable of positive NAO, that's what we got. The latter year had a North Atlantic tripole (NAT) through the summer of 2019 and an extreme level of blocking corresponded with this around Greenland but this signal was well and truly gone by November. Nov 2017 was favourable of positive NAO too but that "cold blob" you speak of could have been associated with the rather unusual amount of cold zonality the season had. It wasn't a typical unsettled winter and the north had it very snowy overall in particular akin to the winter of 1983-84 which was known for its cold northwesterlies. These SSTs are not the be all and end all (what is with weather?) as shown by 2017's situation and in the exceptional mild winter of 1997-98, we did get a NAT with a negative NAO but we often got a "Sceuro High" (Scandinavian-Euro high) scenario with winds often from a southerly quarter. Let's see where the SSTs are by November.

Secondly, we have a La Nina in development in the Pacific. Historically, La Ninas favour the earlier part of the winter to be colder with a higher chance of positive NAO later on. The reverse is true with El Ninos. If we get a strong event however of either, it sort of scuppers the chances of high latitude blocking developing - again speaking historically rather than scientifically. There was an interesting paper published late last year (see link below) of the impacts of ENSO on the MJO and the results for the North Atlantic Oscillation which of course is the index that reflects the pressure pattern in the North Atlantic. Researchers found that +NAO is strongly teleconnected during El Nino years with the opposite for La Nina years and SSW events more likely during La Nina years too which makes sense.

The long range modelling suggests a weak to moderate La Nina is likely whilst a minority forecast a strong event. This is a matter of nowcasting and watch how the situation develops in the Pacific. If I were a betting man, I would say moderate at most with highest chance being a weak event much like 2017-18.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL084683

Thirdly, this is a new thing I'm discussing because research confirmed this impacted the Northern Hemispheric winter pattern of 2019-20, however I never heard anyone mentioning before then so not sure what to make of it myself! I have linked another paper below discussing how the Indian Ocean Dipole (IOD) was a driver in the positive NAO phase of 2019-20.

Key points made include: The El Nino-Southern Oscillation (ENSO) was in neutral state for much of the winter so believed to have had little impact. With the winter being well forecasted to incredible extents, there must have been a driver of some sorts that would strongly correlate with a very positive NAO. Using the observed SSTs in the Indian Ocean in November 2019, what happened was a Rossby wave originated in the Indian Ocean and propagated through the Pacific into the Atlantic. This wave train reduced the magnitude of the Aleutian cyclone which typically acts as a buffer to the development of the stratospheric polar vortex (SPV) but due to the reduction, this allowed the SPV to take off to anomalously strong levels.

This year, the IOD is on the weak to negative side so likely to not have the same impacts as last year.

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005

sryanbruen wrote: »

Like last year, my updates will be fewer and further between with no plans to issue a seasonal forecast as compared to pre-2019 years just due to loss of interest or life getting in the way. You're probably better off because I tend to waffle a lot

I think I speak for everyone here when I say

However, every now and then, I will post an update on teleconnections or analogs that I feel could guide us through this annual rollercoaster.

I think I speak for everyone here when I say:



With that out of the way, fantastic and ridiculously informative post as always Sryan. If you think you waffle too much, just remember that you're frollicking amongst us weather nerds on this forum and as such no amount of waffle from an expert such as yourself can in any way be described as too much

I've never actually considered the IOD as a factor in Irish Winter or indeed Irish Weather generally, simply because teleconnections generally propagate from West to East with events diminishing in impact the further West one goes from the starting point. On the other hand, having literally only just begun to learn about upper atmospheric waves and VP anomalies this summer, it makes a lot of sense that the Indian Ocean could start a chain reaction as you describe, in much the same way as it's known to influence ENSO. The lack of a positive IOD has been widely commented on with regard to hurricane season in the Atlantic, as has the likelihood of a weak to moderate La Nina, so from the sound of things we could well be in with a chance of seeing something interesting this year - at the very least, it sounds like model watching will be far more interesting this Winter than it was last year, with only one or two interesting scenarios showing up even in FI if I remember correctly.

It's interesting that you've mentioned a weak to moderate ENSO event giving us a better chance at wintry conditions than either extreme end of the scale - reminds me of the paradox in certain hormone or neurotransmitter medicines and dietary supplements in which the effects can completely reverse if one increases the dosage too much. It's amazing how often this occurs in nature, wherein too much of a usually X promoting factor can actually inhibit far more than too little of it.

Remind me at what time of year one can begin to monitor the SPV for signs of how strong or weak it may end up establishing itself?

And given your intention to step back from forecasting, feel like nominating a successor to create our Strat Watch thread? I'm still nowhere near knowledgeable enough to do it myself, the opening post would be horrifically lacking in details

Tabnabs wrote: »

Huge crop of blackberries here on the east coast this year, have been ripe and ripening for over a month now. Two apple trees laden with fruit also. A bumper year for us.

Will we have snow this winter? god no. It will be rain, 14 degrees at Christmas and the odd blast of a storm. It's Ireland...

Same in kerry. Berry's are ripening. Already got 3kg on Monday.

So, just to recap here:

hatrickpatrick wrote: »

Not saying this to get anyone's hopes up, just an observation!

SeaBreezes wrote: »

My Hopes are definately up after HatrickPatrick and Syran updates!!