Winter 2018/2019 - General Discussion

Mount Vesuvius · 06-12-2018 9:51pm

M.T 's latest thoughts.

https://www.netweather.tv/forum/topic/72635-the-seasonal-forecast-thread/?do=findComment&comment=3933701

Oneiric 3 · 06-12-2018 10:09pm

Can't believe it's been 3 years since this event. A wet period that was on par with the infamous November 2009 event.

Met Éireann chart for December 5th 2015:

Up to 80mm fell in some parts of the west and northwest on the 5th alone and which was coupled with persistent high winds.

This chart, from Met Éireann, shows the 7 day rainfall totals up to December 6th 2015 and shows just how wet it was at this point of the year 3 years ago.

Data and images from Met Éireann.

igCorcaigh · 06-12-2018 10:52pm

Damn warm and sticky out there.
12C and 100pc humidity.

nacho libre · 06-12-2018 10:58pm

Well, given events like storm Emma are quite rare events, it's very unlikely we will see snowfall comparable to that event, so that's a safe prediction you make. I do think though we will get a notable cold spell sometime in January or Februray. In a modoki el nino, December is nearly always dominated by the Atlantic, blocking episodes are more favoured later on in the winter. Couple this with low solar activity and all the other factors at play our odds increase of a notable cold spell, but of course we could be unlucky and end up with a west based - NAO, which would likely means we end up with blocking in the wrong place to deliver a good cold spell

M.T. Cranium · 06-12-2018 11:26pm

I just closed the winter forecast contest to further entries. This is a summary of what 22 of your fellow boards weather forum members have predicted for the winter of 2018-19 ... almost all of the participants are long-time monthly contest forecasters and have made winter forecasts several years previously, so as far as some experience goes, this is about as good as you're going to find outside the locked doors of the weather agencies. (or maybe better, who knows?)

The participants foresee a slightly colder winter than normal, with all of the negative departures likely to fall in January and February after a slightly milder than average December. The average for Jan-Feb is expected to be about 0.7 deg below normal, with some going as low as 3.5 degrees below. A minority of the forecasters believe the full winter season will stay mild, as most think December will be, generally 0.5 above normal.

The consensus calls for a near normal range of temperatures from -9 to 15 degrees, and on the maximum there is only a small spread of opinion. As it has already reached 14.2 in early December, few think it will get much warmer but when they do, they mention February as the more likely month (some mentioned January). On the coldest temperature, there is a wide spread of opinion. Some believe we will not see colder readings than we already had in November (minimum -5.2 is the highest value in the contest). About one-third think it could get down below -12 C. These are the same forecasters calling for heavier snowfall (at Casement, the contest validation site). Here, the range is quite large too, from 2 cms to 41 cms. The consensus value is 12.0 cms for Casement. Recent analogues would suggest that means 25-40 cms in snowier parts of Leinster ... the contest question avoids any insight into snow potential from northerlies in Ulster and Connacht. Personally I think that looks to be no different from long-term averages. The snowfall season for the contest includes March and early April so this would not all necessarily have to fall in the winter months. As far as strong winds are concerned, the spread of forecasts is fairly tight and the consensus is a maximum gust of 76 knots, while the range is from 65 to 84 knots. Nobody entered an extreme value in the 90-100 kt range but I was being conservative, the scoring in any case is by rank order of forecasts so it wouldn't impact much on your score if you were ten knots low, as long as everybody else was too.

Most of the forecasters believe December will be a little wetter than normal, while January and February are likely to be on the dry side of normal (which correlates well with their colder than average calls). The ranges are not extreme, with few individual forecasts outside the range of 80 to 120 per cent of normal for any month. The range for the season is from 89% to 124% of normal precipitation, and the consensus is very close to normal.

(it should be mentioned that consensus varies considerably from the milder and colder forecasts in the group, this is by no means a shared consensus)

M.T. Cranium · 06-12-2018 11:40pm

On the subject of weather forum forecasts for the winter, I could mention too that in the U.S., weather contest expectations for the winter seem to be generally calling for a 2010 style winter there, it comes up as one of the more likely analogues so many snowfall predictions are above normal for parts of the northeast trending more to average in the Midwest (especially given that November produced above average snow there and the forecasts are for the rest of the winter).

Basically, I think we are seeing two camps of forecast opinion, one being a highly blocked winter like 2009-10, the other being a long onslaught of zonality with weak blocking tendencies towards the end like 2006-07.

hatrickpatrick · 06-12-2018 11:48pm

Just playing devil's advocate (and snow hopeful!) here, but does anyone else notice how the GFS always seems to blow any type of blocking away as soon as you switch over to the 192+ low res part of the run? Is this something to bear in mind or is it wishful thinking? I've noticed on a few runs both now and also during the heatwave in the summer, that you'd have high pressure reasonably stable up to 192, then you'd click over to the low res section and the whole forecast would go to hell.

Confirmation bias or an actual thing?

Mount Vesuvius · 07-12-2018 12:42am

Some hyperventilating going on from people about the latest EC46 charts.
They do indeed look very good for strong blocking at such a long range. Weeks 3,4,5 and 6. Perhaps they have picked up the Stratospheric Warming signal. However even an SSW can go wrong but encouraging signal end of December into January. Anyway here's hoping it's on to something.

Graces7 · 07-12-2018 7:39am

Wild out here but yesterday was so mild. I still have flowers blooming. Chilly now but not biting cold ...Out here it is the wind that rules.

West mayo offshore island

Artane2002 · 07-12-2018 9:01am

nacho libre wrote: »

Well, given events like storm Emma are quite rare events, it's very unlikely we will see snowfall comparable to that event, so that's a safe prediction you make. I do think though we will get a notable cold spell sometime in January or Februray. In a modoki el nino, December is nearly always dominated by the Atlantic, blocking episodes are more favoured later on in the winter. Couple this with low solar activity and all the other factors at play our odds increase of a notable cold spell, but of course we could be unlucky and end up with a west based - NAO, which would likely means we end up with blocking in the wrong place to deliver a good cold spell

I agree with this post. The signal on the EC46 for so far out is unusually strong.

After looking at more models, the heights over Scandi look like they will be blown away but the GFS is being stupid with that super deep low.

Graces7 · 07-12-2018 9:13am

Sudden vicious hailstorm !

west mayo offshore island

Heavy hard, wind driven showers.... the ocean to the north is a maelstrom.

Clonmel1000 · 07-12-2018 9:29am

Nice bright calm morning here this morning a little on the cool side but not bad at all.

Rock Lesnar · 07-12-2018 10:29am

Clonmel1000 wrote: »

Nice bright calm morning here this morning a little on the cool side but not bad at all.

Same up here, great to see the sun and blue sky again

circadian · 07-12-2018 11:12am

A little flurry of sleet here in Dublin city centre. Bitter breeze about the place too.

JCX BXC · 07-12-2018 11:34am

Ferocious shower of graupel in West Clare, great to see some exciting weather. Temperature 4.6c and dropping.

KingdomRushed · 07-12-2018 12:06pm

Looking like it’s going to be storm watch next week given the latest GFS output. Severe weather likely. A very violent depression showing for next Thursday.

irishrover99 · 07-12-2018 12:35pm

KingdomRushed wrote: »

Looking like it’s going to be storm watch next week given the latest GFS output. Severe weather likely. A very violent depression showing for next Thursday.

From what i've notice over the last few months following these threads is that anything over 24hrs seem to be FI when it comes to any storm so i'd expect or wouldn't be suprised to see that downgraded.

Today, its bloody freezing now in Dublin, i'd expect some of that rain we are having to fall as snow in the Wicklow mountains.

Reckless Abandonment · 07-12-2018 12:42pm

irishrover99 wrote: »

From what i've notice over the last few months following these threads is that anything over 24hrs seem to be FI when it comes to any storm so i'd expect or wouldn't be suprised to see that downgraded.

Today, its bloody freezing now in Dublin, i'd expect some of that rain we are having to fall as snow in the Wicklow mountains.

I'm with you. They nearly always spin N/W from where they are plotted a week out.. 7 days out I'll be more interested in a storm heading for France.

nacho libre · 07-12-2018 1:18pm

John Hammond, a former UK Met Office forecaster, wrote the following on his blog:

"There are signs of more severe cold as we head into the New Year

You’ll have inferred, then, that I am not yet going to commit: Green or White Christmas? It’s simply too far off!

However, there are several reasons within the set-up of the atmosphere this winter that suggest the cold air will be back sooner rather than later. El Nino is one; the cycle of spots on the sun is another even more distant influencer.

Additionally, in the last few weeks I’ve spoken of signs that the usually strong stratospheric westerly winds that circle the Arctic (know as the Polar Vortex) may weaken markedly as December ends. This signal is becoming more ominous. It’s important because it introduces the possibility of a ‘Sudden Stratospheric Warming’ in which the Polar Vortex goes fully into reverse. Ultimately, it was this which led to the severely cold spell that struck the UK late last winter.

From start to finish, this process takes several days, if not weeks, before such a reversal works its way down to ground level. But on balance, there is an increasing chance that cold air will return from the north or the east as we go later through the Christmas period, and more particularly into the New Year.

Exciting times ahead – for the child and the weather enthusiast in all of us!"

Also, Ian Ferguson, a current Uk Met office employee, has said their main model(glosea5 ?) suggests a SSW will occur at the end of the month

leahyl · 07-12-2018 1:40pm

nacho libre wrote: »

John Hammond, a former UK Met Office forecaster, wrote the following on his blog:

"There are signs of more severe cold as we head into the New Year

You’ll have inferred, then, that I am not yet going to commit: Green or White Christmas? It’s simply too far off!

However, there are several reasons within the set-up of the atmosphere this winter that suggest the cold air will be back sooner rather than later. El Nino is one; the cycle of spots on the sun is another even more distant influencer.

Additionally, in the last few weeks I’ve spoken of signs that the usually strong stratospheric westerly winds that circle the Arctic (know as the Polar Vortex) may weaken markedly as December ends. This signal is becoming more ominous. It’s important because it introduces the possibility of a ‘Sudden Stratospheric Warming’ in which the Polar Vortex goes fully into reverse. Ultimately, it was this which led to the severely cold spell that struck the UK late last winter.

From start to finish, this process takes several days, if not weeks, before such a reversal works its way down to ground level. But on balance, there is an increasing chance that cold air will return from the north or the east as we go later through the Christmas period, and more particularly into the New Year.

Exciting times ahead – for the child and the weather enthusiast in all of us!"

Also, Ian Ferguson, a current Uk Met office employee, has said their main model(glosea5 ?) suggests a SSW will occur at the end of the month

Ah Nacho Libre, ever the positive voice for us cold lovers!

SleetAndSnow · 07-12-2018 6:00pm

bitterly cold in cork city with winds starting to pick up now and very heavy, squally showers out of nowhere. Goes from blue sky to darkness. Worst kind of weather. Come on the snow!

Graces7 · 07-12-2018 6:03pm

Ferocious winds out here now. Just nearly sucked out of the door letting a cat out.

Status Yellow - Wind warning for Donegal, Galway, Leitrim, Mayo, Sligo, Clare, Cork and Kerry
A further spell of strong winds will occur later today and tonight. Westerly winds with mean winds of 55 to 65 km/h and gusts of 100km/h are possible, especially in coastal areas. High seas will bring a risk of coastal flooding.

Issued: Friday 07 December 2018 13:35

Updated: Friday 07 December 2018 13:35

Valid from Friday 07 December 2018 16:00 to Saturday 08 December 2018 01:00

marine even higher.. west mayo offshore

highdef · 07-12-2018 6:37pm

SleetAndSnow wrote: »

bitterly cold in cork city with winds starting to pick up now and very heavy, squally showers out of nowhere. Goes from blue sky to darkness. Worst kind of weather. Come on the snow!

I think that was just daytime turning into night, given the time of around 17:00.

Graces7 · 07-12-2018 6:50pm

Dear Lord!

That was thunder and a massive gale gust. Worse than anything last night here. Startled,,Gutters and piping are rattling and shaking, and so am I.. .

long night ahead.

SleetAndSnow · 07-12-2018 6:57pm

highdef wrote: »

I think that was just daytime turning into night, given the time of around 17:00.

Haha but nah it was the clouds

because it went back to bright

Artane2002 · 07-12-2018 10:10pm

Both the ECM and CFS are agreeing on a Greenland high for mid January. Obviously six weeks out from now is very far out in weather terms but it is an unusually strong signal and the seasonal models have been hinting at this so I would say this is more likely to happen than usual. (If I was picky I'd like the Euro trough on the CFS to be further south like the ECM but I'm not gonna complain!)

https://twitter.com/MJVentrice/status/1071043172229439489

bazlers · 08-12-2018 9:54am

Mr. Empty heads spidy senses are twitching!
Will the polar express be testing the waters soon!?

derekon · 08-12-2018 10:27am

bazlers wrote: »

Mr. Empty heads spidy senses are twitching!
Will the polar express be testing the waters soon!?

Check out MT's update this morning, it would appear his seasonal forecast of a stormy run up to Xmas followed by an outbreak of arctic air late December / early January might now be coming into play.......

D

Graces7 · 08-12-2018 10:58am

derekon wrote: »

Check out MT's update this morning, it would appear his seasonal forecast of a stormy run up to Xmas followed by an outbreak of arctic air late December / early January might now be coming into play.......

D

Well OK! I can believe that. High winds here and sheeting icy deluges.. and guess who has to go out for turf.... will have a look at the ocean perforce... should be magnificently wild...

Snowbiee21 · 08-12-2018 11:25am

The hunt for cold -- I found it at T384. Diving low followed by true arctic outbreak, on Christmas Eve too. This could fade in and out for a few more days, something like that seems plausible once the increasingly cold zonal runs out of energy and the jet drops away further. Just about the same timing as 2009-10 in the last Modoki type El Nino.

(although that started up with some cold southeasterly stuff before a northerly developed)

The thing about this winter is, parts of the arctic are actually colder than normal, in particular, the Canadian arctic islands and north/west Greenland. So if that anomaly can either expand or shift east, we might get the rare synoptics that many crave.

Winter 2018/2019 - General Discussion

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