Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

Winter 2018/2019 - General Discussion

134689144

Comments

  • Registered Users Posts: 2,477 ✭✭✭Kamili


    someone has written an article on this and all

    http://www.msn.com/en-ie/news/newsireland/dublin-weather-forecast-snow-and-storms-forecast-by-met-eireann-as-winter-approaches/ar-BBNBZoU?li=AAmb2oK&ocid=ientp
    Deirdre Lowe, a Met Eireann forecaster said: “There’s likely going to be snow at some point in the Northwest, but we don’t know when.”

    Thats like predicting a bear taking a wee in the woods. Its likely to happen, we don't know for how long and when...

    But then they contradict the whole thing with
    “We can also expect below-average precipitation in the period up to December, predicted by the UK’s official forecasters as falling into the driest of our five categories, with 20 per cent likelihood - and slightly less likely to be wetter than average.


  • Registered Users Posts: 18,078 ✭✭✭✭JCX BXC


    Well yeah, there's likely going to be snow in the Northwest, there's snow every year without fail in that region. That's like forecasting sun for the Mediterranean.


  • Moderators, Business & Finance Moderators, Recreation & Hobbies Moderators Posts: 24,647 Mod ✭✭✭✭Loughc


    JCX BXC wrote: »
    That's like forecasting sun for the Mediterranean.

    Cue next headline... Met Eireann expert "JCX BXC" predicts Summer Heatwave to last 90 days for Summer 2019.


  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    Artane2002 wrote: »
    Sryan, here's another question (sorry if I have been tiring you with all my questions recently, especially the topic I'm about to bring up): I know the Atlantic SSTs aren't great and can result in unsettled weather but does it necessarily mean that the jet stream will be directed towards us and the UK? Or could it maybe take a path towards France instead depending on other factors?

    The jet stream could direct low pressure systems to France yes if other things are setup to support such a scenario. Unless something as significant as a sudden stratospheric warming or polar vortex split occurs, Greenland blocking is nearly out of the question with how the sea surface temperatures are and have been. The theory of why we've seen such persistent low pressure over Greenland and Iceland this Summer is the cold sea surface temperatures around that region unlike pretty much every year back to 2007 when it has been quite warm around there supporting blocking to occur at some stage which would give us unsettled Summers. I showed the resemblance between 1946 and 2018 in the Atlantic (also Norwegian Sea) in a post. High pressure in that Winter tended to be around Scandinavia and Russia than Greenland though it did retrogress at times to there. We all know how 1947 fared of course in terms of the weather here..... if you don't, well this image is all you need...

    73bL1Hl.jpg

    1946-47 was such an interesting Winter in many ways, not just the weather that actually took place but also the teleconnections. As somebody corrected me once (when I mistaked it as just after solar minimum), it was near solar maximum which for such a blocked Winter as 1946-47 begs some questions. Could there have been a major stratospheric warming (records for the stratosphere only go back to the early 1950s)? What could have caused such persistent blocking throughout the season (after all, the January to March 1947 easterly spell was one of the longest easterlies known to occur in Ireland and the UK)? I have a theory that the Atlantic sea surface temperatures helped to make Winter 1946-47 as snowy as it was. They caused unsettled weather to push across the Atlantic but on a southerly tracking jet stream. With the persistent easterlies keep bringing cold air via monster northern blocking, these low pressure systems interacted and gave a ton of snowfall over both countries (with lake-effect snow added on of course); resulting in the snowiest Winter since at least 1878-79 but probably even 1813-14.

    So yes very possible that the jet stream doesn't directly go for us if my theory would verify.

    Another year with a strikingly similar Atlantic sea surface temperature profile (also Norwegian Sea interestingly) to 2018 was 1990. 1990-91 was another cold Winter (not exceptionally so) as I'm sure a lot of you know with a Beast from the East type event near early February. Cannot show the sea surface temperature map right now as the NOAA SST anomaly site is down at the moment but here's a reanalysis of September 1990's SSTs:

    ylLWEmh.png


  • Registered Users Posts: 1,976 ✭✭✭Artane2002


    Thanks a lot Sryan! Here are the SSTs as of 24 September. I think it's supposed to be updated later today. I think the cold blob has warmed slightly and the warmth off the east coast of the USA has shrunk a little. Small improvements but every little helps.

    kXHszKs.gif?1


  • Advertisement
  • Registered Users Posts: 3,426 ✭✭✭ZX7R


    Kamili wrote: »
    someone has written an article on this and all

    http://www.msn.com/en-ie/news/newsireland/dublin-weather-forecast-snow-and-storms-forecast-by-met-eireann-as-winter-approaches/ar-BBNBZoU?li=AAmb2oK&ocid=ientp



    Thats like predicting a bear taking a wee in the woods. Its likely to happen, we don't know for how long and when...

    But then they contradict the whole thing with

    Surprised met earann would even suggeste there be snow anywhere


  • Registered Users Posts: 1,976 ✭✭✭Artane2002


    Breaking news: SEVERE Arctic plunge forecast as night temperatures PLUMMET down to 0C! ;)

    (Most of you should know that I'm just making fun of the media)


  • Moderators, Business & Finance Moderators, Recreation & Hobbies Moderators Posts: 24,647 Mod ✭✭✭✭Loughc


    2yttqty.jpg

    A 4 month cold snap lol. The country would shut. I hate click bait bull.


  • Registered Users Posts: 14,240 ✭✭✭✭leahyl


    Joanna Donnelly on the LLS tonight talking about climate change....perhaps she'll mention something about snow prospects for this winter ;):pac:


  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    A bit late but analogue #4 for Winter 2018-19.... and it's on cold Marches because somebody suggested to me to do this one.

    The 500mb height anomaly reanalysis from NOAA with these Winters shows a blocking area of high pressure over Greenland and Iceland. There is a trough of below average heights over the majority of Europe and some of that is getting up to the UK and Ireland. These below average heights provide the moisture for snow and it's most certainly a snowy and cold reanalysis, perhaps even exceptionally cold. The mean wind direction would be a northerly to northeasterly and is very December 2010-esque. I was very surprised with this reanalysis because when I originally thought of cold Marches, I could have sworn the results would be very mixed. For instance, March 1962 was followed by Winter 1962-63, the coldest Winter of the 20th century but March 2013 was followed by Winter 2013-14, the wettest Winter on record.

    df4d06_9b6fa863afcd4eb8ace13b30a31c0d37~mv2.png

    This is the December 2010 500mb height anomaly reanalysis as a comparison.

    df4d06_89f52a61e61b47a5b4f90682633c3f34~mv2.png

    Looking at the individual Winters, there is mixed results after all especially for December which has a mean bang on the 1981-2010 average with these Winters combined. There are some freezing cold Winters like 1962-63 and 1916-17 in there (also to some degree, 1955-56 and 1985-86). Seeing this, it is strange how the 500mb height anomaly reanalysis turns out like it does. I'd also like to add that these are cold Marches based on the UK mean temperature, there would be rather different years for the Central England Temperature or Ireland if I were to do them. For instance, March 2010 would be one that is not in there which was of course followed by December 2010 which has a very similar reanalysis to the analogue. I guess you could also say that some of these years had high solar activity like 1947-48 so they're not good matches to 2018-19 which will be the solar minimum Winter going into solar cycle 25.


  • Advertisement
  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    Reports of record breaking high pressure near or over Alaska.... a persistent block in the eastern Pacific/Alaska area can often (but not always) be a precursor to a Vortex splitting event according to the paper titled "Blocking precursors to stratospheric sudden warming events".

    https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009GL038776

    https://twitter.com/ZLabe/status/1042832866957127680

    zdCsNvJ.jpg


  • Registered Users Posts: 4,668 ✭✭✭SleetAndSnow


    What does that mean for us Sryan? I remember it splitting last year and seeing comments that it will affect us in a few months, which it did.


  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    Before I answer the above question, 1990..... now where did we see that year appear before in regards to September? :D

    https://twitter.com/danholley_/status/1045923056630345728

    https://twitter.com/JohnDuncombe4/status/1045948584494084096


  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    What does that mean for us Sryan? I remember it splitting last year and seeing comments that it will affect us in a few months, which it did.

    The sudden stratospheric warming in February 2018 was an example of Polar Vortex splitting. A Polar Vortex split is a type of major warming within the stratosphere where the Polar Vortex splits into two or more vortices. This completely disrupts the zonal flow and the stratosphere significantly warms over the North Pole.

    Late Autumn is a time when the Polar Vortex reorganises itself (as a result of the atmosphere cooling dramatically in the Northern Hemisphere and cause a great contrast between the tropics and the pole) well and truly reaching a peak of strength by the end of the year into the New Year. However, what is happening here or is expected to happen is that the Polar Vortex is weakening as soon as it attempts to wake up from hibernation. This will lead to an increased chance of northern blocking somewhere around the Arctic Circle, whether on the European side of the pole or not is open for questions.

    The record breaking high pressure over Alaska is probably helping Canada to have an unusually snowy September but if that were to couple with the Siberian High and form one massive block of high pressure over the Arctic then there's no way of getting out of cold.

    There's a lot of hype from enthusiasts of getting excited over the fact this October is looking really strange because of what models have been showing (such as the Scandinavian High and easterly winds) and this weakened Polar Vortex. Well.... you don't need to go back far to find a very easterly October, 2016 was the last instance. I think we need to be very careful here and just wait and see how it all goes through this latter part of the Autumn.


  • Registered Users Posts: 4,668 ✭✭✭SleetAndSnow


    Brilliant thanks! Oh I love this waiting game but hate it at the same time


  • Registered Users Posts: 269 ✭✭Mount Vesuvius


    Just to follow on from Syranbruen and on teleconnections,
    The QBO (Quasi-biennial Oscillation) is looking very fine indeed, easterly, And the image below shows a great view through the years. Remember it's helps with a weaker Polar Vortex but not guaranteed .
    Late 2010 had us entering westerly phase of QBO but ya see there is enough easterly mix still in the frame to keep the PV at bay.
    6034073

    The stratosphere temperatures watch doesn't really kick off till start of November but here's current trend.
    6034073

    The PDO ( Pacific Decadel Ossicillation) is going negative too once again

    6034073


  • Registered Users Posts: 269 ✭✭Mount Vesuvius


    The PV winds at the top of the Stratospheric circulation 1hpa to 3hpa, (Orange top right) is showing 20plus Metres per second as we enter the approaching winter.
    Anyway early days yet.

    462710.gif


  • Registered Users Posts: 83 ✭✭morticia2


    sryanbruen wrote: »
    The sudden stratospheric warming in February 2018 was an example of Polar Vortex splitting. A Polar Vortex split is a type of major warming within the stratosphere where the Polar Vortex splits into two or more vortices. This completely disrupts the zonal flow and the stratosphere significantly warms over the North Pole.

    Late Autumn is a time when the Polar Vortex reorganises itself (as a result of the atmosphere cooling dramatically in the Northern Hemisphere and cause a great contrast between the tropics and the pole) well and truly reaching a peak of strength by the end of the year into the New Year. However, what is happening here or is expected to happen is that the Polar Vortex is weakening as soon as it attempts to wake up from hibernation. This will lead to an increased chance of northern blocking somewhere around the Arctic Circle, whether on the European side of the pole or not is open for questions.

    The record breaking high pressure over Alaska is probably helping Canada to have an unusually snowy September but if that were to couple with the Siberian High and form one massive block of high pressure over the Arctic then there's no way of getting out of cold.

    There's a lot of hype from enthusiasts of getting excited over the fact this October is looking really strange because of what models have been showing (such as the Scandinavian High and easterly winds) and this weakened Polar Vortex. Well.... you don't need to go back far to find a very easterly October, 2016 was the last instance. I think we need to be very careful here and just wait and see how it all goes through this latter part of the Autumn.


    Canada is certainly getting a few dumps; friends in Edmonton reporting snow before end September and Calgary getting snow in the last few days. Not unprecedented, but early for sure. Even for Alberta.

    Meanwhile, frost here by the seaside last weekend. Inland, not that unusual, but I don't recall any frost where I am here on the East Coast in Sept in the last few years. Warmed up again now, but......:cool:


  • Registered Users Posts: 32,634 ✭✭✭✭Graces7


    morticia2 wrote: »
    Canada is certainly getting a few dumps; friends in Edmonton reporting snow before end September and Calgary getting snow in the last few days. Not unprecedented, but early for sure. Even for Alberta.

    Meanwhile, frost here by the seaside last weekend. Inland, not that unusual, but I don't recall any frost where I am here on the East Coast in Sept in the last few years. Warmed up again now, but......:cool:

    some parts of Canada had snowfall in summer,.


  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    Another day, another analogue. We previously looked at Winters following warm Junes as an analogue for Winter 2018-19 due to the fact that June 2018 was a very warm month. Now this time, we'll be looking at the Winters that followed on from very dry Junes because June 2018 was not only very warm, it was also very dry and anticyclonic.

    Here is the 500mb height anomaly reanalysis of the Winters that followed the top 20 driest Junes on record since 1910 (apart from 2018 obviously). There is blocking over Greenland and stretching back into Siberia (though weaker over there) with a trough over much of Europe. The trough is centred over Biscay and Iberia but it looks like a knife edge to me between very cold and snowy or very wet and windy. I'd think it looks like that because we have Winters like 2010-11 and 1988-89 which were very different to each other.

    df4d06_4257e74e339346889ce89fd73f189c4c~mv2.png

    The temperature anomalies reanalysis show average temperatures over us proving my point above BUT notice the warm pool over Greenland and the very deep cold pool to the northeast of Europe including over Scandinavia? The warm pool over Greenland shows the blocking which the 500mb height anomaly reanalysis has. If we were to tap into that cold pool over Scandinavia, it'd be a very cold Winter indeed.

    df4d06_14434bfdbce2415e9f338bc3e1a1a32b~mv2.png

    Here's the table of Winters following very dry Junes. It again only proves my point of the 500mb height anomaly reanalysis being a knife edge between mild, wet and windy or cold and snowy. You can see this clearly in the table below like 1988-89 vs 1962-63. Deviations are from 1981-2010 CET averages. The darker the blue, the colder the anomaly. The brighter the red, the warmer the anomaly.

    df4d06_fc8619d2253740e2b785d8abbc8fca96~mv2.png


  • Advertisement
  • Registered Users Posts: 1,976 ✭✭✭Artane2002


    Just a quick update on the Atlantic SSTs, the warmth off the east coast of the USA has cooled a tad but unfortunately the cold seas to the north of that have also cooled. In general I think the overall profile looks less alarming than it did back in August. The North Sea and Norwegian Sea are also cooling down with colder than average areas popping up.

    4qdYxcJ.gif?1


  • Registered Users Posts: 6,126 ✭✭✭screamer


    So even with all of the analysis in the thread and hats off to you for doing it, the answer is.... We just don't know.


  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    Very meridional jet stream on the GFS 06z this morning for mid-October here with Scandinavian blocking building up again. If this were to occur in Winter, at first it would be chilly and frosty but as the high would ascend northwards to Greenland and Scandinavia, we would pull in a bitter easterly flow of air.

    TxSQ8hB.png


  • Registered Users Posts: 12,778 ✭✭✭✭ninebeanrows


    Very few signals on the latest EC seasonal for this part of the world


  • Registered Users Posts: 1,008 ✭✭✭icesnowfrost


    Love this time of year. And so it begins ❄️


  • Registered Users Posts: 32,634 ✭✭✭✭Graces7


    screamer wrote: »
    So even with all of the analysis in the thread and hats off to you for doing it, the answer is.... We just don't know.

    The fun is in the seeking ;)


  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    Here's how October 1990 looked for SSTs (since it was the closest match to this year), notice how the north Pacific was colder then than it is now though this is a full monthly reanalysis average so could hide variation.

    Ntqw1Bl.gif

    By this point in 1946 (the other closeish match), much much warmer SSTs developed around Greenland though the cold eastern Atlantic and warm western Atlantic continued. Again notice how the north Pacific was colder then than now.

    F2veU08.png


  • Registered Users Posts: 12,778 ✭✭✭✭ninebeanrows


    sryanbruen wrote: »
    The ECM seasonal update doesn't become publicly available on their site or the Copernicus site until the middle of the month, don't know what you are looking at.

    It has been released and there is little signal on it.

    Still some slight high pressure anomalies across W Russia/ Scandinavia but nowhere near as stark as in the September issue.


  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    It has been released and there is little signal on it.

    Still some slight high pressure anomalies across W Russia/ Scandinavia but nowhere near as stark as in the September issue.

    It would be appreciated if you could post a link.

    EDIT: Oh I just realised who you are :o.


  • Advertisement
  • Moderators, Business & Finance Moderators, Recreation & Hobbies Moderators Posts: 24,647 Mod ✭✭✭✭Loughc


    Love this time of year. And so it begins ❄️

    Username checks out :pac:


Advertisement