Winter 2018/2019 - General Discussion

It is fine margins and GFS OP was a an outlier in the longer term but ECMWF is sticking to its guns.

This is why you don’t get excited about +240 charts but the building blocks are there. My hunch is it will take a few bites of the cherry for the real cold to arrive and being honest I’d much rather it in a few more weeks, too early is not as much fun imo.

Slieve Gullion wrote: »

On the ball. There was extremely heavy rainfall for a solid few days in the run up to that big freeze.

Looks like there could be a repeat of that as a LP looks like it will anchor itself just off the SE coast for a good few days as milder air to our West battles the frigid stuff to our East.

kittyn wrote: »

Does anyone remember the week before the first cold shot in November 2010 it was unseasonably warm too or is my mind playing tricks on me??

Was it not November 27th 2009?

sryanbruen wrote: »

Will try and give a detailed response when possible, don’t have any strong thoughts on such happening, in fact quite the opposite. Sorry to sound like a Scrooge.

As for Christmas itself, that’s very random. Even in mild and or wet December’s, a white Christmas can occur. The whitest Christmas in the last 50 years in terms of snow falling in places was 2004 which was in an otherwise mild December and a forgettable Winter too. 1993 was another example in a mild and very wet December.

My thoughts have not changed despite the model runs of the past week with some very abnormal charts. 0z runs this morning continue to downgrade with southerly winds becoming present in FI now as low pressure heads west and high pressure exerts influence into Europe and the Med.

Cork Boy 53 wrote: »

Not to mention the "Are orange/red warnings warranted" threads if we do get some severe wintry weather.:rolleyes:

And the meltdowns by posters pre-snow onset. Grumpy old pensioners one was funny as he was never seen again,as was sryanbruens late night capitulation only to rise from the ashes stronger and better.
Bring on the sneachta.

Kermit.de.frog wrote: »

The trend is really positive for those who want a sharp start to winter.

Don't be hung up on charts run to run. It's the overall trend that matters.

;)

SleetAndSnow wrote: »

That gfs 18z tho. Hurricane force blizzards anybody? (300hrs into FI so definitely not gonna happen. Just a typical pub run being drunk )

I do love those drunken chart runs of the 18z, ya know the real mad ones that show Ireland getting like literally buried in snow with huge snow drifts and gale force winds and wishing/dreaming that they would happen......

It happened in March 2018 ;-)

That map strains the imagination beyond its normal limits, that's for certain. It's an evolution that I don't think I could find anywhere in the historical maps, something fairly similar to a Midwest U.S. late November blizzard set-up. Just for the sake of "what if" though, I'm not so certain about heavy heavy snowfall with that, despite the low thicknesses, more like localized heavy snow streamers bringing severe blizzards to much of Ulster and Connacht, trending more to sporadic snow of various intensities further south. Winds would certainly be extreme however. Something like NW 100 to 140 km/hr would be likely. It would certainly be a life-threatening situation for anyone attempting to travel on roads in the northwest, or caught out in it. Temperatures would be something like -2 C with wind chills of -20 C.

And I also don't think it could verify. Storms on that track almost always have a more gradual onset of colder air, that looks very North American as if there's no Atlantic there at all.

Will see what the 00z run coughs up there and update if there's anything out of the ordinary.

As to what 2009 and 2010 brought before cold weather arrived, my recollection is 2009 was fairly mild all through November and gradually turned more easterly after mid-December. There was a heavy rainfall event in mid-November 2009. As to November 2010, there was about a week to ten days of mild Atlantic southwest flow, a windstorm around the 12th then progressively colder with the flow really sinking fast followed by the northeast fetch snow events. That lasted into first week of December, there was a brief milder interval, then it got more extreme in the second bout of cold and snow, all ending rapidly on the 26th with just minor teasers after that in early January (2011).

nacho libre wrote: »

Why exactly are you leaning to a backloaded winter, with the declining QBO easterly phase surely that favours a milder end to winter? What factors do you see overriding this?

After heavily researching the QBO in the past year since I did my 2017-18 forecast, I think too much weight is put on the QBO. I posted a chart previously in this thread (quoted below) showing the correlation between QBO and Winter CET, there was not much correlation though the severest Winters tended to be on the easterly QBO side (like 1962-63) but this could be more of a coincidence than anything. Winter 1978-79 was a westerly QBO Winter (albeit weak) coming out of a peak of the westerly QBO in Summer 1978 whilst Winter 1979-80 (the easterly QBO Winter then) was mild and wet.

GavsWeatherVids did a good analogue analysis on the QBO in his latest Winter update going back to the 1950s. As you can see from this video, Winter 1977-78 was a transitional easterly to westerly QBO Winter and it was probably the most similar Winter you can find to 2017-18 in terms of our conditions (funny how it was exactly 40 years before). February 1978 had a severe blizzard for the south of Ireland and a notable cold spell. February produced the coldest conditions of the Winter despite being westerly QBO. That's just one example. Other examples include 1985-86 (which was one of the coldest Februaries ever recorded with an enormous amount of northern blocking and persistent easterly winds) and 2008-09 (which had the very snowy spell in early February and was preceded by a major SSW in January).



Looking at the reconstructed QBO cross-section, other Winters that transitioned from easterly to westerly QBO (before 1950) include 1945-46, 1939-40 (mmmm), 1933-34 (nice and frosty), 1931-32, 1925-26, 1913-14, 1911-12, 1909-10, 1907-08. Very interesting to see 1939-40 here, one of the most severe Winters of the 20th century and the first Winter of World War 2. Ironic how the first three Winters of World War 2 were all severe Winters, as well as 1916-17 (the Winter of Ireland's worst snowfalls) of World War 1.

Overriding signals of the westerly QBO can include stratospheric warming events (and we are the most favourable phase of the QBO cycle for a SSW event to occur according to Eric Webb - see stratosphere watch 2018/19 thread that I've been regularly updating as much as I can) and the Atlantic SST profile. Mind you, the Atlantic SST profile is still not particularly favourable for a negative NAO - not impossible for one to occur though.

Just because this Winter is going to be westerly QBO doesn't mean it can't be an epic one. It all depends on how everything lines up. 2008-09 was westerly QBO as was 2010-11 as was 1978-79 as was 1977-78 as was 1946-47.... you could go on and on.

I don't think it will be a straightforward backloaded Winter as one might assume from my post that you quoted nacho libre. As M.T. describes, expect a lot of volatility this Winter. Analogues so far have been very strong on an intriguing January and March with mixed results for December and February. I will not say anything further as I'll give too much away on my Winter 2018-19 forecast in 9 days now.

sryanbruen wrote: »

My graph I generated below shows the QBO for every Winter back to 1949-50 up to 2017-18 (y-axis) along with the Central England Temperature for each of the Winters (x-axis). We can see colder Winters (the Winter average is 4.5c) tend to occur relatively more during easterly QBO years than westerly QBO years especially if it's very/extremely cold levels such as 1962-63 or 2009-10. Not impossible to get a severe Winter in westerly QBO, one in particular there stands out like a sore thumb; 1978-79 which contained the last subzero January for the CET and the last New Year blizzard we have had. 1978-79 was very weak westerly QBO though so explains that.

circadian wrote: »

I've been trying to figure it out for years. I bet it's something really obvious too.

Your head must be empty if you haven't figured it out

Took me a while also to get it though

Ohhh I just got it

The final frames of the ECMWF shows Scandanavia cooling down considerably (-12c uppers) which is some good news. A low pressure system is expected to developed in the atlantic this day week and the exact westward path of that system will probably create a lot of variation in the model output until it is resolved.

I only got it just before the Beast from the East this year and I've been on boards longer than some of you have been alive (lookin' at you Sryanbruen ;-)

Was telling a family member about MT Craniums' prognosis on the Beast from the East and they stopped me and said, "Empty Cranium???". I laughed and said, "Nooo!! LOL. Its M.T. Craniu........Oh dear God!!"