Model output discussion - proper cold spell inbound?

[jethro]

3 minutes ago, pureasthedriven said:

Worst case scenario would be a slow burner trop response a la Jan 2013 and we end up with a cold and bland start to spring without snowy possibilities nor without that much craved for early warmth that (I at least) tend to look for around mid-March. 

I'd be a little less impressed if that were the outcome although if memory serves me right, those further north had an amazingly snowy time from that. What I definitely don't want is early warmth followed by cold and frosty, would like the apple blossom to at least stand a chance of turning into juicy apples.

[Polar Maritime]

The Net-Wx MR take on snowfall risk into Tuesday. Not to be taken literally at this range..

[Duane S.]

I think what needs to be put into perspective as well, is the sheer size and depth of the vortex. 

Even with this colossal warming / reversal event, the vortex is likely going to take time to weaken sufficiently, as the (virtually stationary) centre pulls in. It will appear at times that it’s not weakening at all but it will be, constantly, until past the point of no return and then it’s shred time and what happens next!?

[pureasthedriven]

2 minutes ago, jethro said:

I'd be a little less impressed if that were the outcome although if memory serves me right, those further north had an amazingly snowy time from that. What I definitely don't want is early warmth followed by cold and frosty, would like the apple blossom to at least stand a chance of turning into juicy apples.

Sorry, I meant that given the trop response was around forty-odd days (someone may correct me) in Jan 2013, we ended up with that incredible March. Here and now, we’re circa one month later and I really don’t want a cold, anticyclonic but otherwise unremarkable early April! Still, horses for courses and speculative at best at this stage. 

[Duane S.]

11 hours ago, nick sussex said:

It’s best to remember that Chinese proverb!

A bad chef can make a rubbish dinner with 5 star ingredients !

Regardless of how good the strat reversal is what counts for coldies in here is the weather on the ground .

The SSW does increase chances but we still need some luck with where any blocking sets up and also where any Euro low heights are located.

But on the other hand...

Any chef (the models) could also make a rubbish dinner (forecast outcome) with poor ingredients (inaccurate data). A good chef may, or may not, be able to make a better dinner, depending on how poor those ingredients were.

[pureasthedriven]

12 minutes ago, Mr Frost said:

Morning all

Some people seriously need to relax - just let it play out and enjoy the rollercoaster without getting sucked in with charts so far out. 

Summer Sun just posted in the Model Tweets Thread - with all the talk of the SSW here it is below. 

If you are craving snow/cold weather stay positive - at least it won’t be mild...

Have a good Sunday! 

 

Here’s hoping, though on current model showing France will be far from very cold by the time we eventually source the aforementioned SE’ly from there. 

[stotm]

Hi, would it not be the case all these forecast systems are programmed to follow just a set of rules given them by experts on weather systems and physics? So like beep blue the chess program was told the rules of chess and when it played enough games could bet the worlds best players, but the rules are all known and the starting positions are known.

So these weather forecast  are not sure on start positions of pieces and don’t know the all the rules. So how can any of these outputs after day five (not good at the best of times)have a chance of being correct cold or mild  if we do not have enough data on how to respond to major warming and or split that we have only had about 20 total examples of?

How did the outputs deal last time in the run up to ssw? I am only guessing but I bet it was not good but then so are the models.

[Duane S.]

GEFS still sniffing at the notion of an initial ridge...

Edited February 11, 2018 by s4lancia

[Jason M]

I think what were seeing today is the start of a QFR (Quick Forum Response). 

FWIW the GEFS look broadly similar to what we have been seeing in recent days (ignoring the earlier run). Plenty of better options with the majority going easterly. I suspect we will get an easterly, but the real question is around what type of easterly and that's the bit I'm far from convinced over.

[Frosty.]

4 minutes ago, Jason M said:

plenty of better options with the majority going easterly. I suspect we will get an easterly, but the real question is around what type of easterly and that's the bit I'm far from convinced over.

Right now I would settle for any type of easterly after seeing the Ecm 00z!

 

Ps..where's steve murr?

Edited February 11, 2018 by Frosty.

[BLAST FROM THE PAST]

I think the modelling and synoptic pattern over next 2 weeks will be quite messy.  As mentioned a while back A Scandi block likely but potentially in wrong place and a la Fergie we could get SSE flow thus could be a Sceuro.  Watch for deep LP system towards end of the month that may be the propellant/trigger for the real hurrah.  Got this feeling the picture will be quite messy and ‘where do I go from here’ for most of this month.

I Think there’ll be an initial attempt for the Easterly set up come 1+ week but ultimately fail.  Cold March anyone?

Right shedloads to do...laters

BFTP

Edited February 11, 2018 by BLAST FROM THE PAST

[bluearmy]

Lots of eps clusters (six by day 8 )

whilst the initial v amplified ridge looks less likely by the run, I wouldn’t discount anything becoming the direction of travel post day 7. FWIW, the ec op is in the smallest cluster days 5/7. 

Edited February 11, 2018 by bluearmy

[Chris101]

Quick question- Am i right in thinking that in an ssw the first response of downwelling is that the vortex will try a big push to organise itself before a full split occurs?

[Man With Beard]

To summarise succinctly - the signal for a Scandi High between 20th Feb and 25th Feb has been almost lost (though not totally):

There is a 25% cluster still going for something similar

But the ensemble mean pressure chart for mean D12 is going backwards on both ECM and GEFS:
  

This still sees a SE flow at the surface, so still "chilly and dry" in the words of IF, but less likely to contain deep cold uppers and snowy troughs from the east.

Lots of energy still spilling over the top of the Sceuro High. Worth bearing in mind, too, the outside chance of milder air getting up from the East Med - that sun is starting to warm up too so could even end up spring-like!

 

[Chesil View]

Any one thinking that current runs have anything past the end of this week pinned down is in my mind whistling in the reverse zonal wind. ☺

[johnholmes]

Some on here are comparing run to run at way out time scales. This will never give you a consistent pattern. Beyond 144h perhaps 168h compare like with like.

My memory of 3 days ago and the much hyped up GFS chart showing a build of surface heights NE of the UK is not showing to any degree on the 168-192h charts. If this had been going to happen then it should be there.

The probability of any marked height rises has, to me, using the 500 mb anomaly charts out to day 14, never been anywhere other than west of not east of the UK. The Iceland/Greenland/Spitzbergen areas for the centr of Gravity of any upper ridge. So the surface feature was not really looking like being other than the meridian or west of it, around 60+ north.

There did seem a good degree of consistency in this prediction. However, not unlike the 00z ECMWF this morning the EC version on the EC-GFS output this morning drops this idea. Is it correct? Well of course 1 run of any model is never to be taken too seriously but it is a change and with NOAA continuing with the pattern, now for several days, see below, then it does lend doubt to just what is going to happen within 14 days from now. Possibly a touch less cold than previously expected from the 500 mb outputs. With no solid consistency from the 3 then I back off making any prediction until there is a more definite pattern from all 3. It is not often though that the NOAA outputs are far off. It does happen hence my caution at any definite prediction for the next 2 weeks. Strong winds/gales spells of rain (hill snow from Wales north) do seem the most likely. Interspersed with weather much as today.

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

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

Remember the usual caveat with these charts, they are mean charts, so any single day the upper pattern may differ to some degree from the pattern shown. But it would be unlikely to last more that 24-36 hours.

 

[That ECM]

17 minutes ago, Man With Beard said:

To summarise succinctly - the signal for a Scandi High between 20th Feb and 25th Feb has been almost lost (though not totally):

There is a 25% cluster still going for something similar

But the ensemble mean pressure chart for mean D12 is going backwards on both ECM and GEFS:
  

This still sees a SE flow at the surface, so still "chilly and dry" in the words of IF, but less likely to contain deep cold uppers and snowy troughs from the east.

Lots of energy still spilling over the top of the Sceuro High. Worth bearing in mind, too, the outside chance of milder air getting up from the East Med - that sun is starting to warm up too so could even end up spring-like!

 

This mean was being talked about as amazing, stunning, incredible but today it's now not relevant? Not being funny, genuine question. We had great charts much was to be resolved, we now have "rubbish" charts but imo still much to be resolved. Just seen JH post above and he says it better than I do. I do disagree with JH to a certain extent in that I can see the heights drifting ne from over us and bring a easterly feed. 

Edited February 11, 2018 by That ECM

[Man With Beard]

12 minutes ago, That ECM said:

This mean was being talked about as amazing, stunning, incredible but today it's now not relevant? Not being funny, genuine question. We had great charts much was to be resolved, we now have "rubbish" charts but imo still much to be resolved. Just seen JH post above and he says it better than I do. I do disagree with JH to a certain extent in that I can see the heights drifting ne from over us and bring a easterly feed. 

That's a fair point. It's just been my experience that extremely positive or negative anomalies on mean charts tend to be quite close to the truth, even if they are in the D10-D15 range. I've traced 1030mb mean highs over Europe for years on GEFS and they usually result in high pressure near to the spot (and that's why I don't completely agree with JH's point, with all due respect!). They don't normally disappear so quickly. And actually it hasn't disappeared yet! So maybe my first post today was a little OTT - maybe I was expecting too much because of the SSW hype - but here it is, the 1030mb high over Scandi, tiny, but still there!!

 

Edited February 11, 2018 by Man With Beard

[Frosty.]

Some good news anyone?

The GEFS 6z still shows quite a few wintry / very wintry possibilities during the late February period!

[Daniel*]

Anyway plenty of interest in GEFS T+240 I don’t understand in a time of particular uncertainty more are reckoning it’s a done deal ECM knows all, thanks for the humour.  

[Scandinavian High.]

Short term some parts of uk are seeing snow today and Monday Tuesday / north and west . The ssw is just getting going I don't think we'll see any think in models yet  there a lag time give it a week or too we just need to be bit more patient ..

[cobby]

Simon Lee‏ @SimonLeeWx

 

 

 

 

Per 06Z GFS analysis, 10 hPa #PolarVortex has split, but not yet such that zonal mean zonal wind at 60°N has gone easterly...meaning it's not yet hit the major #SSW threshold. Eagerly awaiting 12Z.

 

[nick sussex]

Trying to find a crumb of positivity so far today.

I’ve sent out the search party!

The ECM is still poor in terms of cold however the rounded PV blob which we saw last night modeled at day ten has thankfully not continued.

In terms of the SSW given the size of the reversal and the state of the AO at the onset of that it would be very surprising to not see an impact on the NH pattern.

The problem is how long this takes to show , we don’t have the luxury of weeks to play with.

 

[Frosty.]

15 minutes ago, abbie123 said:

Short term some parts of uk are seeing snow today and Monday Tuesday / north and west . The ssw is just getting going I don't think we'll see any think in models yet  there a lag time give it a week or too we just need to be bit more patient ..

Yeah I'm sure the models will improve again soon and as I said the GEFS 6z shows some cracking output. Incidentally, there is no downgrade to the longer term cold signal, indeed it should become colder and more settled after the unsettled week ahead and there is still the easterly mentioned with very cold temps and snowfall continuing well into early March!

[Gael_Force]

1 hour ago, Chris101 said:

Quick question- Am i right in thinking that in an ssw the first response of downwelling is that the vortex will try a big push to organise itself before a full split occurs?

I think, in this instance, it's the split that is actually fortifying the Canadian segment. The separation is not ideal as it leaves the dominant chunk in a position to drive westerlies. I've looked through the animations of previous warmings but there are none I can see where the split is similar to this ... the good ones had the split up through Greenland ...and felled the vortex with first punch!