Model output discussion - proper cold spell inbound?

[ALL ABOARD]

3 charts from the GEFS all at +384 showing a very similar pattern. 

2010 I raise you. 

JFF.

Perb 16 wed be part of the new Artic.

 

 

Edited February 10, 2018 by ALL ABOARD

[karlos1983]

Seems like we are paddling up hill a bit in fl at the moment. With the GEFS, not had a chance to look at individual runs, but nothing note worthy in terms of cold in there yet.

ECM ens look like we have two options on the table, cold and mild.

what does that tell us? Not much other than more runs needed. Groundhog Day 

 

Edited February 10, 2018 by karlos1983

[bluearmy]

The eps clusters are fairly revealing - if you ignore the euro high options then you are left with the op evolution which builds an upper ridge north through nw Europe and the control cluster which has an Atlantic feel into the extended at which point a scandi ridge extends west (presumably from the Russian ridge pushing west or the polar ridge dropping south). All likely a response to the ssw 

however, the poor AO numbers from the suite still troubles me 

[E17boy]

Hi goodmorning great people hope you all Have had a good start to the weekend. This is the very first time I am posting on this thread and firstly I just want to thank all the posters who display some great information and make it so much easier for the less knowledgable ones it's so nice to see the time and effort spent on these.

i myself have only seen one decent snowfall this winter about a cm that was in my location Walthamstow N/E London back on the 10th December. Since then there has been the few odd times when there have been flurries but nothing of note. I can tell you every piece of heart is crying for this SSW to deliver something decent and I am sure there is s lot more others on here who will say the same thing. 

We know something is going to happen in the coming weeks but I think as human nature dictates we want this so much that any good output we see on a model gives us hope even if it is in the extended timeframe it still gives that bit of hope that maybe....

i have been really hard on myself now and said I am not going to get overexcited in any little decent model output that shows up this then widens the dissapointnent when the expected does not happen. This is what our weather is all about we can't control it. 

I really hope this coming SSW gives us something to remember but caution is always the best until the reliable timeframe. I know a lot of us are clinging to this as our last hope of seeing this winter out with a bang but it may ior might not happen. This event does tot guarantee our little island with the pleasure of winter. 

I hope I have not gone on too much let's just sit back and watch what unfolds but with caution, next week is going to be the most nail biting critical period fingers crossed  that we get what we have all be waiting for. 

Lets hope winter will leave us with a smile ?

Wish you all a great Saturday 

keep up the great posts 

kind regards ????

[Daniel*]

The GFS ensembles are much better here at T+240 the mean is also promising with blocking to our north.

 

[Catacol]

1 hour ago, johnholmes said:

The post above by ba is perhaps the most constructive one I have seen since the anticipated reaction to the 'warming' and how it 'might' affect the UK.

I have to confess to being at odds with a lot of the euphoria on here and not really convinced by my ex colleagues at Exeter over this deep cold possibility from a point east of the UK. Staying colder than normal into the next 2 weeks I quite agree with but to me, most of what I can see from this forum and data we can all pick up from various weather centres suggests that the cold is going to come from a westerly not easterly point, more like NW and at times perhaps N. That is in the 14 day time scale from now. What happens beyond is not my sphere.

The 500 mb anomaly charts are not as solid as needed for a definite take but all 3 I use have consistently shown height rises across much of the northern part of our hemisphere but with not much, to me, to suggest that any upper or indeed surface ridging is going to come from other than the Iceland/Greenland area, again I stress in the next 14 days.

The upper heights from northern Russia all the way across into the far NW of N America mean that the surface lows may well end up being further south than currently. Behind one of these I suspect a burst of polar air is likely. Beyond that then I am uncertain how it may play out. If the expected effect on the Troposphere occurs in our area at such a time then the snowy wonderland so hoped for on here might well happen-I don't know.

Bit coldish, even cold at times is the weather for 2 weeks or so.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

I think one thing is certain - we are going to learn a lot over the next few weeks. The extent to which a split and SSW can impact on patterns in the trop is gong to get some excellent data to add to that which we already have.. and we must all admit that we don’t have a wealth of such data to go on in terms of major strat event combined with the lagged impacts of a very strong mjo progression.

In essence there is some educated guessing going on.

I have hardly disguised my sense that the vortex imprint will imprint favourably and that sharp reduction in westerlies at 55/60N will combine with twin shard location, subsequent warming over the US and a pattern set to retrogress (perhaps) will bring cold. But words of experience and wisdom are equally valid, and even in my most optimistic mindset moments as we look at next weeks events I am aware that alternative scenarios are on the table and are evident in some model runs. 

In the end.. all we can do is wait and see.

[Frosty.]

The GEFS 6z also shows plenty of support for a late Feb freeze!

[Ice Day]

In amongst the current NWP chaos, I think the GEFS at 192 are quite revealing.  Not one shows an organised PV, with blocking cropping up all over the show. It looks like the favoured option is the original ECM one of heights climbing somewhere between Greenland and Iceland. It's what happens thereafter that will keep us on the edge of our seats.  

Back in time for the 12z's for no doubt a GFS downgrade, ECM upgrade and UKMO being the 'middle ground'.

[alexisj9]

2 hours ago, ICE COLD said:

What is confusing me is why the PV is still strong over Canada when you have this happening there ? 

Exactly what I thought yesterday, I'm expecting that to break up much more than is being modelled, which is why analysing anything past three to four days via a waste of time in my view.

[bluearmy]

27 minutes ago, alexisj9 said:

Exactly what I thought yesterday, I'm expecting that to break up much more than is being modelled, which is why analysing anything past three to four days via a waste of time in my view.

That chart is T168

the effects from it will take a few days at least to work down to the trop 

so the trop output at days 4 to 8 should be fine in respect of the predicted Canadian warming 

Edited February 10, 2018 by bluearmy

[ICE COLD]

8 minutes ago, bluearmy said:

That chart is T168

the effects from it will take a few days at least to work down to the trop 

so the trop output at days 4 to 8 should be fine in respect of the predicted Canadian warming 

So with all this going on with in the next 3 weeks we still have a very good chance of a HLB to favour us in the uk ? The first push of heights may not get there or give us what we want but there should be plenty of more opportunities over the next few weeks ? Few bites of the cherry and all that ? 

[Frosty.]

As well as all the support for a late Feb freeze from the GEFS 00z / 6z..There is no downgrade from Exeter regarding the longer range signal covering towards the end of Feb and approx first half of march...so, despite some operational model wobbles, the longer term trend is still the coldies friend!

Edited February 10, 2018 by Frosty.

[chrisbell-nottheweatherman]

3 hours ago, TEITS said:

Going to disagree with John H here.

Plenty of support that our weather will eventually be coming from the E over the next 14 days even despite this mornings ECM.

For starters we have the GEM & GFS Operationals and looking at the UKMO +168 that is heading the same way. More significantly is the GEFS mean at +300 plus has consistently suggested a flow from the E.

Evidence of blocking to our N & E continues to be suggested by the models and a flow from the E/NE looks favourite. However the depth of cold is impossible to predict at the moment,.

I'm not arguing with you, TEITS, but my inexperienced interpretation of that output suggests a weak northerly.  What are you getting from that that I'm not?

[Froze were the Days]

The above ensemble mean (above) shows heights to the north east and a slack area of lower heights to the west/south west so probably a degree of an easterly in that if I'm reading that right. (correct me if I'm wrong).

[bluearmy]

10 minutes ago, chrisbell-nottheweatherman said:

I'm not arguing with you, TEITS, but my inexperienced interpretation of that output suggests a weak northerly.  What are you getting from that that I'm not?

 Unlikely to get a handle on the likely wind direction at day 15 on a mean chart like that 

The gefs slp clusters are going to be more informative (these are the 00z run)

 

Edited February 10, 2018 by bluearmy

[Frosty.]

34 minutes ago, Frosty. said:

As well as all the support for a late Feb freeze from the GEFS 00z / 6z..There is no downgrade from Exeter regarding the longer range signal covering towards the end of Feb and approx first half of march...so, despite some operational model wobbles, the longer term trend is still the coldies friend!

Reading between the lines, approx. the last third of Feb and first third of March could deliver a proper nationwide cold spell with plenty of frosty weather and if we get an Easterly as is still being suggested, I'm sure there would be snow showers feeding in off the north sea!❄❄❄❄❄❄

[Interitus]

3 hours ago, ICE COLD said:

What is confusing me is why the PV is still strong over Canada when you have this happening there ? 

The question/answer is the wrong way round - the warming is happening there because the tropospheric vortex is still strong over Canada.

[Jonathan Rhodri Roberts]

Well I can't remember the last time we saw such big temperature swings each 24 hours!

Thu max 10C mild/sunny spells, Fri max 4C snow a.m, today max 10C rain/fog and tomorrow max expected 5C with further snow showers unbelievable weather! 

Edited February 10, 2018 by Jonathan Rhodri Roberts

[Man With Beard]

ECM ensembles - mean Scandi high at D15 (not quite as strong as GEFS)

[Ali1977]

As mentioned in this tweet, effects from the SSW just aren’t being modelled correctly yet.  So, maybe a few days to push before knowing where we go, how quick we see a response and which part of the world gets hit by a freeze etc....V interesting period ahead. 

[Mark Parsons]

4 hours ago, Frosty. said:

And here is my evidence, pretty comprehensive i think most will agree!!❄❄❄❄❄❄❄❄❄

Two weeks away!!

[SMU]

Afternoon-

The last 3 GFS updates for the warming ( oldest first )

 

Shows the convergence on -40M/S - This is record breaking - Wayyy stronger than any date in history back to 1979 on Interim ERA data ( -32 Ish being the record )

With such a broken vortex - one would assume that theres no return from there for Feb or for March.....

[E17boy]

11 minutes ago, Steve Murr said:

Afternoon-

The last 3 GFS updates for the warming ( oldest first )

 

Shows the convergence on -40M/S - This is record breaking - Wayyy stronger than any date in history back to 1979 on Interim ERA data ( -32 Ish being the record )

With such a broken vortex - one would assume that theres no return from there for Feb or for March.....

Very interesting Steve, let's hope it does our island some favour. 

Still sitting here wishing away who knows what kind of horizon will be knocking on our door sooner or later. 

Its definately going to be an exciting week of model watching. 

Keep up the good work 

regards ?

[chapmanslade]

42 minutes ago, Ali1977 said:

As mentioned in this tweet, effects from the SSW just aren’t being modelled correctly yet.  So, maybe a few days to push before knowing where we go, how quick we see a response and which part of the world gets hit by a freeze etc....V interesting period ahead. 

Indeed so.

I've just returned from a Met Office open day tour at Exeter and the topic came up there. The forecaster I spoke to was suggesting a 70% chance of cold / Easterly at the beginning of next week which he said was a very high percentage certainty at that range, whilst emphasising there is still the other 30%. He was also showing the 'London Model' 333m output but cautioned that in terms of improving model resolution the limit was quantity of input data rather than computing power. Still the current 4 day accuracy is the same as the 1 day accuracy from the early 80's.

 

[Frosty.]

3 minutes ago, chapmanslade said:

The forecaster I spoke to was suggesting a 70% chance of cold / Easterly at the beginning of next week

 

Just to clarify, surely you mean the week after next...i.e..w/c 19th Feb when it's supposed to become more settled and colder.