Winter 2018/2019 - General Discussion

Birdnuts wrote: »

RU shure?? I usually don't see them until the middle of October


PS: Mistle Thrushes tend to flock at this time year and have a similar call

User name checks out. I think we can trust this guys expertise.

Jezz if those charts were realised , you'd be talking about something akin to the winter of 1962-63. It would be hard to see any atlantic influence for a long time. By the way that post about February 1969 was very interesting. It seems as if the effects of the canadian warming were felt two months later. I wonder what the snow depth at Claremorris was from the snow showers.

Before I get onto the hurricane post today, wanted to share this chart from the CFS 12z of yesterday for December 2018. That's about as perfect as you can get for cold and snow. It will change but very nice to see and look at. Would certainly wet snow and cold lovers' appetites to the max.

By the way, hope you have been enjoying these frequent updates on Winter.

sryanbruen wrote: »

An active Atlantic hurricane season is one of the things we look at for Winter as it dumps a lot of warm water in the North Atlantic Ocean which can then be advected into the North Pole and promote northern blocking. 2010 was an active hurricane season. 1995 was an active hurricane season. 1887 was an active hurricane season. These are three examples of years that had active hurricane seasons and were followed by cold winters. However, it's not impossible to receive a cold Winter with an inactive hurricane season, 2009 was such an example and was followed of course by 2009-10. 2009-10 was an a moderate El Nino Modoki and as a result had increased vertical wind shear which led to the inactive hurricane season but as it was El Nino Modoki, we had a cold Winter. El Nino Modoki is very good for cold Winters in the UK and Ireland! The El Nino which is forecast by the models and agencies this year is a modoki and I expect it to be a modoki but there is uncertainty on if it will reach El Nino threshold which is 0.5c or more above average. 1990-91 was an El Nino Modoki but did not reach the threshold though it was a cold Winter with a notable cold and snowy spell in early February 1991. Anyway, I'm going off on a bit of a tangent, thought you'd might like that extra info with this post.

The SST profile in the Atlantic we want to see is one like this from 14 December 2009, bands of warm-cold-warm. What is the least favourable for a negative NAO in our current SST profile is the cold anomalies to the south of Greenland, we would want to see them disappear by Winter time and not to mention, the warm anomalies off the coast of America. They are two problems with the current state of the North Atlantic which are not favourable for negative NAO especially with a more powerful Polar Vortex as Winter gives. Things can change like they have since May as the Atlantic is more favourable now than it was in May but it's getting kind of late especially as it takes quite a bit of time for the temperatures in the North Atlantic to change unlike say the Irish Sea or the North Sea. Nevertheless, in spite of 1976 being similar to 2018 in terms of the Atlantic SST profile, 1976-77 was a cold Winter with a cold December and January but mild February.

As described in the quote above, an active hurricane season is one of the things we look at for the Winter season solely for the fact that:

1. It dumps a lot of warm water in the Atlantic Ocean. The warm air is advected into the Arctic to promote northern blocking. During Winter time pre-cold spells, you'll hear "warm air advection" mentioned a lot of the time which is what happened before the beast from the east in February 2018 as high pressure built to the east against the Atlantic. The battle of two brought winds into the south which whilst cold on the surface had warm 850hPa temperatures being advected up to the pole where the southerly winds were pointed at. This gave away to cold air being shunted out the other side of the anticyclonic block over Scandinavia and via easterly winds (helped by SSW) came to us.

2. The warm tropics form one band of the North Atlantic tripole which is explained in the quoted post.

This table I have made categorises different Atlantic hurricane seasons from 1914 to 2017 based on the number of storms that occurred. Some maybe swapped to other categories but I think I categorised the seasons well for analogues. I have highlighted in yellow the hurricane seasons that preceded really cold Winters or Winters that contained a notable snowy/cold spell at some stage.

As you can see, there's actually quite a mix to be seen here. 16 inactive seasons preceded such Winters, 5 average seasons preceded such Winters, 13 active seasons preceded such Winters whilst 6 very active seasons preceded such Winters. The latter is notable because there's only 9 examples of very active seasons in this sample space and 2/3 of them seasons were followed by such Winters. Another very active season that comes to mind is 1887 which was followed by a cold Winter.



1978, though ended up average overall (very active during the Autumn of 1978), was very quiet in terms of Atlantic tropical cyclones pre-September with little activity going on. Let's compare the Atlantic SST profiles of May 1978 and May 2018.





They have some similarities like the main development region (MDR) for Atlantic hurricanes by Cape Verde near Africa was cold in both years. The Gulf of Mexico is warm in both years. However, in 1978, the eastern seaboard in the US had much colder waters and same with the Norwegian Sea. 1978's Atlantic SST profile is rather close to a tripole unlike May 2018.

The models are picking up on at least 3 tropical cyclones to develop in the next 14 days in the Atlantic Ocean. Why is this happening suddenly after a quiet start to the season? Well we're coming up to when the season usually peaks in terms of developments and also, the main development region has significantly warmed up since May as shown by the graph below given by Levi Cowan. This doesn't look like anything big given the anomaly is close to average but it is a major difference to the potential for tropical developments in the Atlantic Ocean.

As you know, the sea surface temperatures in the Atlantic Ocean are one of the biggest issues this year so far for the coming Winter but maybe tropical developments coming up will make a little difference in that.

If El Nino does occur, vertical wind shear will increase and the Atlantic hurricane season will continue to be quiet. However, I am getting more and more skeptical about the chances of El Nino occurring this year with the models being biased to warmth. There is still little sign from the ocean right now for El Nino to occur and if one does occur, it's likely to be weak which is the kind of ENSO event apart from neutral that has little impact on the atmosphere unlike say a very strong El Nino that last occurred in 2015-16.

This year, bake your own bread!

Did somebody order a Beast from the East?

Mobhi1 wrote: »

That's a bit far out. There can't be any reliability in that, can there? I didn't think charts would be even produced that far out.

None whatsoever, you'd be as well off ask farm animals.

JCX BXC wrote: »

None whatsoever, you'd be as well off ask farm animals.

When would we expect to have some credible predictions for this?

Elmer Blooker wrote: »

Yeast from the east?

That sounds like a nasty infection!

sryanbruen wrote: »

Don't have an answer for you unfortunately (I wish I knew myself) but this might interest you: http://www.nws.noaa.gov/om/csd/pds/PCU3/CFS/purpose.htm

Thanks! I'll have a full read of this later on but from skimming the intro it looks like the model is designed to chart the slow-moving climate 'oscillations' such as ENSO, NAO, AMO and so on - and that the surface pressure charts produces as a result are essentially a quirky by-product of doing those calculations. Makes sense since those climate cycles change and develop incredibly slowly, so if we have El Nino conditions today for instance, we're almost certainly still going to have them tomorrow, albeit marginally cooler or warmer. In that context, it's possible that it's useful for spotting general trends, even if it's totally useless for day-to-day surface weather.

SleetAndSnow wrote: »

Reading that the charts are changing their mind about a settled September. Just a question for the knowledgeable ones, a settled september, would that be good or bad for a cold winter? I'd say its already been answered a lot, sorry if it has, just couldn't find it

Answering this here as it's the appropriate thread for it SleetAndSnow. If you go by history, the best chances for a cold Winter is an unsettled September but there have been settled Septembers followed by cold Winters. You don't have to go back far to find an example of such - 2009.

For the sake of this, I'm gonna use the England & Wales Precipitation (EWP) and Central England Temperature (CET) datasets because they have data going back to the period I want to look back to. Let's look at the EWP for the Septembers that preceded notably cold Winters or Winters that stand out to people (back to 1870) and the CETs for those Winters. Remember that the 1981-2010 EWP average for September is 77.2mm whilst the 1981-2010 CET average for Winter (December to February) is 4.5c.

In our sample space here, I have chosen 49 different years and out of 49, 27 of those years contained a wet September (for the EWP anyway, there would be some wetter and drier Septembers elsewhere like in Ireland or Scotland for example where 1985 was wet compared to the EWP series) which is just over half of the number of the years in the sample space so there's not really much correlation with an unsettled or settled September for the EWP and a cold Winter though it is interesting, three of the most severe since 1940, 1946-47, 1962-63 and 1981-82 were preceded by wet Septembers.

I looked at unsettled Septembers for last year's Winter and I found there is an increased chance of a colder Winter for 2017/18 because of this. We had a colder Winter indeed so that turned out rather well.



Data comes from the UK Met Office.

hatrickpatrick wrote: »

Out of interest, what's the actual point of the CFS if it's totally inaccurate? I mean, doing 50/50 FI runs out to 10 or 15 days is one thing, but surely they wouldn't dedicate valuable supercomputer processing time to running such a long and I'm assuming CPU-intensive model unless there was at least some tangible benefit to doing so?

Five days (and often a lot less!) seems to be the limit for accurate forecasting, a couple of days ago an Indian summer was odds on now it looks like many will be putting on their heating for the first time this week! How often do we hear forecasters say "uncertain? - all the time.
Around thirty years ago accurate forecasting was about three days so we haven't come very far despite the huge technology advances.

Typical.

My 2007 car bought new is very low mileage (nearly 30,000km as of today). Up till this time last year it was still on the original tyres but they had to be replaced due to rubber cracking as opposed to tread wear. I had always planned to replace the Summer tyres it came with, with a set of those new Michelin Cross Climates which have 99% of the respective performance of both Winter and Summer Tyres and yet wear as slowly as Summers. ie. The pinnacle of All Season due to the new rubber compounds. So the time finally came to change them in August 2017 after 10 years on the originals but I choked at the last minute and bought another set of Summers cause......when were we ever going to have another pair of Winters like 2009-2010 LOL

Well only a few months later as it happens! Another thing happened that would mean Winter Tyres would be useful even without snow. My brother started borrowing the car very very regularly, started travelling the country in it and started dropping and collecting his Fiancee to and from work high up in the Wicklow Mountains several times a week. Those Winter/All Season tyres would have definitely been worth it after all as it turns out.

He's saving for a wedding and I am financially embarrassed at the moment so can't afford a set of Winters at around €150 a corner so I just hope he remembers to take it very easy driving up there this Winter unlike how he forgot to take off the Snow Socks I bought for the car in March when he was back on the dry tarmac of the N11. ie. Shredded them on their first use. I feckin warned him to take em off before back on tarmac. Lucky for him the ones I bought were cheap.

Anyway, Yeah, Reasonable chance of Snow this coming Winter?? Typical!! LOL.

https://twitter.com/judah47/status/1037333996064124928

Loughc wrote: »

What does that mean? :pac:

With the Polar Vortex weak and very disrupted, it makes blocking easier to occur around the Arctic (also higher chances of SSW events). There would be the possibility of seeing similar charts to this if it were to verify by later November or December to February.

Imagine if that chart had happened in Jan