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Turning progressively colder through the week, Very cold with snow showers later

  • 24-01-2010 10:49am
    #1
    Banned (with Prison Access) Posts: 8,633 ✭✭✭darkman2


    Morning! It looks like things will be turning colder from the North with each day through this week with frost becoming severe later in the week. To start with the Jet Stream profile is getting much more condusive to a Northerly plunge that could end up being a longer duration then is currently modelled by the GFS.

    Rtavn11414.png


    Everything North, South.

    The result is actually quite a potent, allbeit, brief incursion of very cold weather

    Rtavn1142.png





    Rtavn1261.png


    GFS goes on to sink the Northerly by the end of the weekend but still very cold for Sunday and milder Westerlies follow on.



    ECM has a similar outlook.

    Recm1441.gif


    UKMO is the coldest of them all with something probrably a bit more sustained.

    Rukm1441.gif

    That is next weekend though so plenty of time for things to change. In the mean time turning colder this week with a strenghtening Northerly wind. Frosts becoming severe again at night.


    Rtavn4817.png


    Tuesday night typical of the temperatures to expect during the week at night.


    Fog should not be as much of an issue generally next week. It should be mostly dry though to Thursday at least. Then those snow showers at the weekend with the North, West and East all at risk.

    It's a developing situation for the end of the week. Frost, Ice, and Snow returning. The only question is for how long?

    More later...


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Comments

  • Closed Accounts Posts: 5,550 ✭✭✭Min


    Something to prepare for.

    I noticed on the Met Eireann charts on the farming forecast for the week it is starting like the previous cold period - the high pressure will move to the west of us, low to the east or north east - a northerly flow and the high possibly heading towards Greenland with a ? mark there, have to wait and see.

    Definitely does look a return to the cold...can't say I'm looking forward to it. Still have a tiny bit of snow leftover from a drift here...its waiting for more....


  • Banned (with Prison Access) Posts: 8,633 ✭✭✭darkman2


    Min wrote: »
    Something to prepare for.

    I noticed on the Met Eireann charts on the farming forecast for the week it is starting like the previous cold period - the high pressure will move to the west of us, low to the east or north east - a northerly flow and the high possibly heading towards Greenland with a ? mark there, have to wait and see.

    Definitely does look a return to the cold...can't say I'm looking forward to it. Still have a tiny bit of snow leftover from a drift here...its waiting for more....


    The North Atlantic Oscillation is positive so that is mitigating against a proper retrogression of high pressure into Greenland.

    The Polar Vortex, the excitable atmospheric conditions depicted by the deep blue and purples on the charts above, for a long cold period like we had earlier this season would have to go into Scandinavia and stay there and preferably move south then.

    There is little sign yet of a big pressure rise over Greenland but we have seen this forcast change in the past much closer to the time. For the moment it looks like the much colder weather will be temporary 48hr thing. However that can change. And given recent events there is not much reason to believe it won't change. My own feeling is that the cold will last longer then currently forcast and will get deeper during the coming weekend. At least lasting into the early days of next week. That's just my own interpretation. It could pan out exactly as forcast but that's unlikely.


    Keep an eye on the NAO forcast. It is still positive or neutral but is forcast to go more negative in the next few days which could have interesting consequences in the next few forcast model runs.

    nao.sprd2.gif


    The Artic Oscillation menwhile continues it's slide into deeper negativity

    ao.obs.gif


    These signs look ominously familiar. The risk of a prolonged colder period is increasing. But we are not there just yet.


  • Registered Users Posts: 763 ✭✭✭H2UMrsRobinson


    Mmmnnnn...interesting!;)


  • Closed Accounts Posts: 1,186 ✭✭✭Kippure


    SUNDAY NOON LONDON TIME
    Winter spreads back west


    If one looks at the London-Berlin example I was using as a contributor to the global temp challenge of Jan 1-10, we find the idea of a return to normalcy posted here a couple of weeks ago was right. The first 15 days of the month ran 7.5 below normal, by far the most widespread cold in populated areas of northern Europe for this harsh part of winter since the 80s. The last 8 days have seen Berlin stay in the cold, and this is what I had said, the further east you went the more the cold would hold... they have been -6.5 SEVERE COLD is taking hold over Germany. However London is 1.6 above normal since Jan 16.

    The cold is getting ready to expand west again!

    So folks in the battle of Britain and France that at least has allowed winter to let up a bit here ( mind you the "thaw" is to around normal and part of the winter forecast... that cold centered over the east and maritime air masses would do battle) is going to come to a crashing end later this week. And while when its all said and done the CORE OF COLD WILL BE WHERE IT WAS IN 02-03 its simply that this winter is even colder than that one for the areas targeted.

    Now you want to see a real thaw... and by the way winter is returning to the states also, look at the Us contributors to this: Chicago and NYC the first 15 days of the month...-3.9. Since then: PLUS 8.4 So they got a major break but winter is about to close in on them also.

    So make sure the winter woolies are ready anew... its coming later this week

    ciao for now

    joe b


  • Registered Users Posts: 490 ✭✭Snowaddict


    darkman2 wrote: »
    The North Atlantic Oscillation is positive so that is mitigating against a proper retrogression of high pressure into Greenland.

    The Polar Vortex, the excitable atmospheric conditions depicted by the deep blue and purples on the charts above, for a long cold period like we had earlier this season would have to go into Scandinavia and stay there and preferably move south then.

    There is little sign yet of a big pressure rise over Greenland but we have seen this forcast change in the past much closer to the time. For the moment it looks like the much colder weather will be temporary 48hr thing. However that can change. And given recent events there is not much reason to believe it won't change. My own feeling is that the cold will last longer then currently forcast and will get deeper during the coming weekend. At least lasting into the early days of next week. That's just my own interpretation. It could pan out exactly as forcast but that's unlikely.


    Keep an eye on the NAO forcast. It is still positive or neutral but is forcast to go more negative in the next few days which could have interesting consequences in the next few forcast model runs.

    Interesting update Darkman 2.

    A couple of points also if I may. Firstly, the NAO is actually currently in a weakly negative phase, as indicated by the charts you have posted above. This was confirmed by NOAA in their Extended Forecast Discussion yesterday. However, it is only weakly negative it has to be said, at least at the moment.

    I would tend to agree with your own feeling on the longevity of any cold incursion. Or at least, maybe it is a case that a slight interlude may be reached only for blocking to return again. Each NWP Operational evolution is subsequently building stronger pressure over Greenland for the timeframe on the previous run - a clear example of this being the overnight UKMO Evolution.

    Apart from the NAO & AO Signal, by far the most interesting at the moment is that of the 30mb Temperature Profile. Latest observations indicate that immediate downwelling, or penetration to the troposhere, of the warming event, is taking place. The general signature of such warming at the tropospheric level is for largescale blocking to develop.

    Overnight multi-model guidance is certainly in favour of a rather potent variable Northerly flow during the second half of the coming week. Again, there is much emphasis upon a semi-retrogressive block with at least some real height rises over Greenland, associated with this HP Block centred in the High Northwest Atlantic. Forcing, generated by the segment of the Polar Vortex dropping into Scandinavia will aid in the Westward progression of this block.. Longer term signals are very mixed, with no clear pattern emerging. It is quite possible that we will remain in a Polar Maritime airflow, after a Polar flow later in the coming week. There is even no general trend beyond Day 7 at the moment, however most Guidance overnight models a gradual collapse of this Block, by the end of the week.

    If the overnight 00Z Guidance from ECMWF & UKMO were to verify, then we would be looking at rather widespread and relatively severe frosts during the second half of the coming week, with the threat of sleet & snow showers mainly across Northern districts and in coastal areas, but also into Eastern areas if the general evolution were to occur as modelled on the overnight UKMO 00Z Evolution. A certain amount of cold troughing is likely across the continent in the latter part of the week, with deep cold air in place.

    A cold incursion does look increasingly likely during the second half of the week, but is by no means a certainty at this time.

    The 30mb Temperature is now quite some way above average, still rising almost vertically, at about an angle of 87 Degrees overall. If we are to see another 5 - 7 degress of warming, we could be very optimisitc for at least some influences at the tropospheric level later into February.

    pole30_nh.gif

    SA :)


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  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    Yes, all very interesting indeed. It looks like the Arctic outbreak currently down the Davis Strait and Labrador Sea will deepen the west atlantic trof, forming a cut-off low southweswards of the Azores, allowing the retrogression of the European high to mid Atlantic, a setup very similar to the early January situation. But it looks with the polar vortex never showing proper splitting, there could be enough energy coming from northern Canada next weekend to shove the High southwards, as the global pattern takes on a more progressive 7-wave pattern.

    168_1_nh.gif


  • Registered Users Posts: 2,904 ✭✭✭cian1500ww


    Will we be getting as cold temperatures as we had ??


  • Closed Accounts Posts: 454 ✭✭irishdub14


    It has gotten noticeably colder today and yesterday, maybe this is Part II of the 'Big Freeze', hopefully!!!


  • Registered Users Posts: 16,533 ✭✭✭✭nacho libre


    cian1500ww wrote: »
    Will we be getting as cold temperatures as we had ??

    no. - 5 or -6 at most, by night, i'd say. the cold won't last too long either - three-four days at most.


  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    The Eagle said the northerly would be dry, apart from a few wintry showers for the north and west. He mentioned frost as being the main event by the end of the week.

    The exact details of the week ahead are likely to change back and forth a bit, but certainly January looks like ending the coldest month relative to averages for a helluva long time!


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  • Closed Accounts Posts: 88,978 ✭✭✭✭mike65


    I don't see too much to get depressed/excited about. Not enough to close the schools anyway! :pac:


  • Moderators, Science, Health & Environment Moderators Posts: 7,144 Mod ✭✭✭✭pistolpetes11


    A bit of cold weather and the masses will come flocking back to the weather forum :D

    I am only managed to get signed in again myself this evening after the outage !


  • Registered Users Posts: 16,533 ✭✭✭✭nacho libre


    so no chance of an active trough or polar low crossing down over us then:(

    just to see a bit of snow falling at this stage would be enough to get me excited:D


  • Registered Users Posts: 1,776 ✭✭✭Joe Public


    A small snow flurry on the east can cause an avalanche on the forum.


  • Closed Accounts Posts: 218 ✭✭2manyconditions


    Wintery showers next week end, will these be heavy or is this just a prediction very much subject to change?:confused:


  • Moderators, Science, Health & Environment Moderators Posts: 7,144 Mod ✭✭✭✭pistolpetes11


    Wintery showers next week end, will these be heavy or is this just a prediction very much subject to change?:confused:

    Just a predication at the moment , a bit to far out to tell and seems that we are dealing with the good old Irish weather,its very much subject to change


  • Closed Accounts Posts: 5,150 ✭✭✭Deep Easterly


    I am not convinced at this stage that anything this weekend is worth even talking about. Looks to be a bit cooler once again with the greatest risk of anything wintry in the north (as usual) but I am guessing that south Connacht will once again miss out due to the lack of any notable troughing in the weekend northerly on the latest models.

    However, it is very early yet and who knows, maybe the next few runs will up the depth of showery troughs for the coming weekend. There is room for this to happen certainly, but whether it does or not remains to be seen at this stage.


  • Banned (with Prison Access) Posts: 8,633 ✭✭✭darkman2


    Joe Public wrote: »
    A small snow flurry on the east can cause an avalanche on the forum.

    Indeed. They can also call 1850 sneachta if they get really concerned;) See if you can guess which caller is Harlow Gifted Liquor :p






    On the outlook as stated above it is still a bit far out for certainties. It's going to get colder but the minor details will have to wait another couple of days.


  • Closed Accounts Posts: 2,693 ✭✭✭Redsunset


    I agree with DE,we seem to be a tad too far west.
    Sure it will be colder but nothing to be getting too excited about im afraid.
    Hope im wrong and the models spring a surprise but not seeing it yet.


  • Registered Users Posts: 16,533 ✭✭✭✭nacho libre


    If it's windy, as predicted, then in a north westerly airflow the showers will push well inland from the coast and not die out. ok they may not make it to the south east and east, but it still counts if it snows outside of Dublin;)

    Also, the longer the cold airflow lasts, without being weakened by the high pressure close by, or modified by the sea temps, the greater the chance of an unexpected feature popping up. With this in mind let's hope the GFS is right about the cold returning for the early days of February, but it's the ECM that usually gets it right when the models differ :(:(


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  • Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 17,595 Mod ✭✭✭✭DOCARCH


    ........but it still counts if it snows outside of Dublin;)

    :eek:


  • Banned (with Prison Access) Posts: 8,633 ✭✭✭darkman2


    It may well turn a little milder by Monday. In the meantime severe frosts and Ice are coming back. Also on Thursday Night into Friday a frontal feature will cross the country from the Northwest. There is a risk of this turning to snow during late Thursday night and Friday morning.

    fax84s.gif


  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    I think this week we can expect nothing more than a cold raw wind this week, with at most shallow Atlantic convection affecting the north and northwest. We're just in the wrong place for anything decent, too far west - again! Being on the easterly flank of the upper ridge, convection will be very limited. The only real exception I see is with this little shortwave trough Friday morning. It could give enhanced precipitation for a while, but what it falls as is not clear at the moment - snow on high ground, maybe at lower levels too along the east. But at this stage there's no point speculating on the finer details.
    90_27.gif

    It does look like come Saturday though, energy from northern Canada quickly shoves the high southwards, bringing a more zonal pattern to the north Atlantic, and possibly a chance of a brief snowy trough transiting southeastwards Sunday night/Monday.

    162_27.gif


  • Registered Users Posts: 18,069 ✭✭✭✭fryup


    bitterly cold out there at the moment, different to that two weeks ago


  • Banned (with Prison Access) Posts: 8,633 ✭✭✭darkman2


    The 12z ECM now has 2 different potential snow events - the first on Thursday night, the second on Saturday night. In between and after harsh frosts and Ice and scattered snow showers. Snow showers again on Sunday mainly, but not exclusively, in the North and West. Very cold by day. At most low single figures.


    Su Campu, you may be correct in your analysis, but with respect I don't think you will be. Though I will gladly acknowledge if you are right and also acknowledge if I am wrong.


    Recm721.gif

    Recm961.gif

    Recm1201.gif

    Recm1441.gif


  • Registered Users Posts: 699 ✭✭✭glossy


    :D hope your right Darkman2


  • Closed Accounts Posts: 2,693 ✭✭✭Redsunset


    Yes i too am liking the latest ECM.
    Earlier i was thinking the same as Su Campu as you can see in my previous post but if this ECM were to not downgrade i would then be hopeful of wintry precip a plenty in showers.


  • Closed Accounts Posts: 5,150 ✭✭✭Deep Easterly


    Tonight's ECM keeps the cool, slack northerly going for an extra day or so, but apart from coastal showers, which may not necessary be 100% snow, I am thinking another quite, cool spell with some night time frosts at best, which will be most severe in the south due to the direction of the wind. I cannot be excited about this upcoming spell yet, but plenty of scope for upgrades in later runs.

    Has been a terrible winter for snow in my patch, I have seen more in one day in milder winters than for the entire period in this this cold one. A good storm or 5 would compensate nicely but nothing but mild, HP based south westerlies showing up on the long term ECM tonight. :mad:


  • Moderators, Science, Health & Environment Moderators Posts: 16,668 Mod ✭✭✭✭Gonzo


    Tonight's ECM keeps the cool, slack northerly going for an extra day or so, but apart from coastal showers, which may not necessary be 100% snow, I am thinking another quite, cool spell with some night time frosts at best, which will be most severe in the south due to the direction of the wind. I cannot be excited about this upcoming spell yet, but plenty of scope for upgrades in later runs.

    Has been a terrible winter for snow in my patch, I have seen more in one day in milder winters than for the entire period in this this cold one. A good storm or 5 would compensate nicely but nothing but mild, HP based south westerlies showing up on the long term ECM tonight. :mad:

    agreed same here this winter so far hasnt been great for snow in my patch either, 4 falls of snow to make up 2 inchs of snow from the 'big freeze'. Saw way more snow last February and the January in the winter before that.


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  • Closed Accounts Posts: 4,279 ✭✭✭Su Campu


    darkman2 wrote: »
    The 12z ECM now has 2 different potential snow events - the first on Thursday night, the second on Saturday night. In between and after harsh frosts and Ice and scattered snow showers. Snow showers again on Sunday mainly, but not exclusively, in the North and West. Very cold by day. At most low single figures.


    Su Campu, you may be correct in your analysis, but with respect I don't think you will be. Though I will gladly acknowledge if you are right and also acknowledge if I am wrong.


    Recm721.gif

    Recm961.gif

    Recm1201.gif

    Recm1441.gif

    Of course I could well be wrong, it's just my opinion, but I must admit I can't see what you mean by a snow chance Thursday night from the charts you posted above? I agree a much better chance Saturday, but Thursday night just doesn't look remotely snowy to me from those charts, or indeed from any other models. As I said, maybe the shortwave Friday morning may produce mixed precipitation at best, but the coldest air will still be to come behind it.


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