Cavehill Snow

Getting this evolution nailed down is worse than getting a tooth pulled. You would like to think it will be sorted by Wed 12z or at worst Thur 0z. Hopefully thereafter we will only have to worry about longtivity and who gets the most snow. The current synoptic pattern does remind me of late 70's and early 80s. Maybe not having access to all the data we now have would be a blessing in scenario's like we have now, poring over every chart since the strat warming event.

I remember my mum hanging out washing during the great winters of late 70's / early 80's. Snow was on the ground but the sky was cloudless and temps below zero. Shirts & jumpers etc would have to be brought back into the house as they were stiff like cardboard having frozen over.

You need to re-draw your direction arrow on the 240hrs pressure chart a little further south than shown, then you would score a perfect 10 for artistic merit.

I have noticed this before also. Perhaps in complicated set ups with conflicting signals, the EC with its higher resolution and larger number of vertical layers may be seeing potential knife edge situations and resolving them at an earlier timeframe than before GFS spots the same scenario. Only a theory, i have no data proof.

UKMO 144 looks ok to my untrained eye, but would be a little fearful if the lows in N. Atlantic & S. North Sea were to phase in a manner which pushed the block too far north and put us on the mild side of polar front 1661732659_UKMOPEU12_144_1(1)-1.webp

Good info update. Btw, do you know what are the resolution levels for the op & ensembles? We know often the various Ops toy with a new evolutions, running with it sometimes, other times dropping it and exploring something new. We always look at how the EC Op differs from the other model Ops - would you have any past experience of at what timeframe the EC ensembles may be expected to fall into line when the EC Op latches on to a correct evolution? TIA

I think the models have been really struggling this season - whether this is because of atypical forcing creating unusual synoptic patterns being forecast i'm not sure. The models have been thrashing around for a few weeks now each day offering several "new" solutions, none of which as yet have been sufficiently picked up across the suites for more than a few runs and developed on a consistent basis. I feel the longer this uncertainty continues, the less likely a more winter nirvana solution will be the final outcome. However high level blocking has been projected often enough the last few weeks that it is highly probable that some wintry weather will occur, nothing too extreme or long lasting, with northern areas more favoured as you would expect.

We are only about half way through the journey to reach the potentially really deep cold next weekend. Not sure i've got the stamina to watch the runs 4 times each day until then.

As good as it looks to the north-east, we have 850's of +8C equi-distant to the south-west. Which will win out? No idea but we do have a great perpensity to clutch defeat from the jaws of victory.

Ridging from Pacific side up through the Aleutians - check Strong Arctic high - check 1065mb high covering almost all of Greenland in synch with Arctic high - check Cut off Scandi high - check Mega cold blast for Britain & Ireland surely - no. Lows to south west with positive tilt deepening rapidly probably created in response to the high stretching down US & Candian east coasts. Certainly great looking synoptics even if it don't deliver winter nirvana.

Typical - misses imby and goes into N Africa. Looks very impressive, but in reality you would expect some short waves to disrupt the flow somewhere along the track.

I cannot recall seeing such crazy synoptic patterns in a long time - probably more fantastic than any of the charts drawn up by snow mad members when they were little nippers as some were reminiscing the other night. Reasons not to happen:- Azores high in Iberia, too much Atlantic energy, MJO unreliable, our crud luck....... At least the charts brought a smile

Why is that low shown in the Norwegian Sea almost every run? Is it because of the temperature differential of cold Siberian air hitting the warm N. Atlantic ocean, or, is it a consequence of the pressure pattern with relatively high pressure circa Iceland / Greenland and the low pressure coming off the ESB and extending into the Atlantic?

Still learning - a quick question. Can we really expect the Arctic high to exert influence on the low pressure belt at our latitudes to help push them south if the Geop z500 colours for the Arctic high are light blue? Generally we look for yellow and orange colours to be indicated for a strong Greenland high to have confidence in its ability to exert a positive influence in our neck of the woods. The current GL which has been green and has been trending towards west based -NAO has had only very limited influence in our sphere. Do we need the Arctic high to intensify and / or move further south at our longitude to benefit us for colder conditions?

It would be good if it was to happen, unfortunately the trend has been over the last few days has been to lift the pattern further north and away from us. However you would think that if pressure could rise to our north in some way (perhaps the Artic high could allign better with the GL ridge) and shunt the whole patter south, then we would be in a great position to benefit as per your 1978 chart.

Thanks for the chart and clarification

Look at the unusual pattern of isobars between Iceland and NW Scotland - it looks like the isobars cross over one another on NW coast of Scotland. Usually the isobars blend in their path from one high or low pressure to the next. I think the highly unusual & conflicting signals are causing great difficulty for the algorithms.

After the cut & thrust of winter is over, it would be great if you were able to do an educational post regarding how to interpret the newly available ECMWF charts to which you refer in the attached post.

Not sure on that. But the col (area with no isobars) is unusually large. It is even more unusual when you see the tightness of the isobars throughout the remainder of the chart. Normally cols are larger in slack pressure gradient scenarios which this chart is not.

Some many conflicting signals all trying to impose themselves at the same time - so charts look unrealistic. Just look at that area without any isobars - stretches from N Spain to just south of Iceland and from the Isle of Man to about 500 miles of west coast of Ireland. Will never happen in reality

I know you concentrate on the NOAA anomolies charts, but do you know if the EC / GPS version pick up on this before the GPS model runs?

Just trying to learn, a few questions if I may:- Has the trop been uncoupled from the strat so far this year, or has the trop been leading the strat? If the stat is not leading the trop at time the time of SSW occurence, can the trop lead the response on this? TIA

I am mystified by this also - i acknowledge that many are looking for a cold / snowy outcome for our neck of the woods, but what i am perplexed by is that there will be much less high latitude blocking anywhere in the northern hemisphere @240 hrs compared to what we have seen over the last week.

Not so sure ref UKMO, it is very much a short range model out to 144hrs. Weather predictions up to 120hrs are very accurate nowadays (except for a few notable very complicated scenarios like the present), and the UKMO 144 hrs this season have been very hit & miss.

Hi, i'm a beginner, so please go gentle. I noticed that there has been a small trough in Moscow area on the charts for days which seems to me to prevent the 1055mb high pressure west of the Urals linking with the 1030mb ridge over Scandi. Could this be delaying a colder regime setting in for us?