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Turning progressively colder through the week, Very cold with snow showers later
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24-01-2010 10:49AM#1Morning! 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.
Everything North, South.
The result is actually quite a potent, allbeit, brief incursion of very cold weather
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.
UKMO is the coldest of them all with something probrably a bit more sustained.
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.
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...5
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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.
The Artic Oscillation menwhile continues it's slide into deeper negativity
These signs look ominously familiar. The risk of a prolonged colder period is increasing. But we are not there just yet.0 -
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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.
SA
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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.
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2manyconditions wrote: »Wintery showers next week end, will these be heavy or is this just a prediction very much subject to change?
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 change0 -
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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 Black Briar
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.0 -
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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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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.
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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.
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.
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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.
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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.
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.0
https://www.youtube.com/watch?v=7b5rcamAVm8
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