Model Output Discussions 06z 04/11/16

[Ravelin]

13 minutes ago, Mucka said:

Forgive me if some of this has already been addressed as only had time to read this mornings posts but I have to disagree with all this talk of a comprehensive victory for GFS over UKMO and ECM,

The reality is the models have reached a half way house solution as they so often to do.

I agree, my summation is that the GFS was slowly moving towards the Euro's solution (not just the UKMO/ECM either) before the Euros did a fairly sudden 'snap' towards the GFS. Not 100% sure where  the meeting point was, but probably more in favour of the GFS than the Euros tbh.

I'd give it another 24hrs at least though to see if they all hold firm on the current prognosis.

[knocker]

26 minutes ago, karlos1983 said:

I'm just wondering John whether it has anything to do with that Tropical feature in the Atlantic that heads straight for Greenland? Being modeled differently compared to a few days ago.

 

I don't have the answer to your query but assuming I'm picking up what you mean correctly the prediction on how this will evolve is quite interesting.

At T36 the feature that I assume you mean is here

From here it rapidly declines but at around T72 some energy shoots out of the upper low that is along the eastern seaboard and a new surface low forms incorporating the remnants of the original.

From this position cyclogenesis takes place as the depression tracks NE up the Denmark Strait driven by the strong jet running between the low pressure to the NW and the ridge to the SE

[Summer Sun]

NAO heading positive mid-month

[johnholmes]

52 minutes ago, karlos1983 said:

I'm just wondering John whether it has anything to do with that Tropical feature in the Atlantic that heads straight for Greenland? Being modeled differently compared to a few days ago.

 

Tropical features are often not dealt with at all well by any model no matter what range they are at. I must admit I had taken my eye off the ball so to speak with this one. If I get time this evening I will have a look and see if it does suggest that it might be the culprit. Thank you for highlighting this feature.

[Summer Sun]

ECM's update late last night for weeks 45 to 45

7th to 13th

Temperatures slightly below normal

Rain is below average in the west and closer to average in the east

14th to 27th has no strong signal for temperatures over the UK

Rain wise maybe slightly above average in parts of the west and Scotland WC 14th but again no strong signal for most

[Frosty.]

53 minutes ago, Summer Sun said:

NAO heading positive mid-month

Yes Gavin it looks like we are going to see a strengthening of the Icelandic low (s) and the Azores high in the run up to and including mid month leading to a broadly westerly flow but then hopefully the GloSea5 blocking will show itself in the model output later in the month and take us into a potentially colder December, I have to say, given how ridiculously warm and wet last December was and given the expected background signals, I would at the very least expect something resembling early winter.!

Edited November 4, 2016 by Frosty.

[knocker]

37 minutes ago, johnholmes said:

Tropical features are often not dealt with at all well by any model no matter what range they are at. I must admit I had taken my eye off the ball so to speak with this one. If I get time this evening I will have a look and see if it does suggest that it might be the culprit. Thank you for highlighting this feature.

As I posted above John I'm not sure it can be classed  as a genuine tropical feature as it virtually disappears never having been very significant but then is reinvigorated by the upper low off the eastern seaboard. And then cyclogenesis in the jet takes place. Anyway your expert opinion will be appreciated.

Edited November 4, 2016 by knocker

[Mucka]

GFS being GFS?

Might be worth taking a mental note of how GFS is forcing a flat jet by pushing virtually all the energy NE with little trough disruption through the mid term.

I expect this to be modeled quite differently in couple of days with lower heights through Central Europe and higher heights through Scandinavia as more energy is disrupted SE through 144/192, (I'm not suggesting a Scandi block though that is feasible, just) but right or wrong it will be interesting to see if GFS is repeating the same over progressive characteristics it often displays or it is correct to get a more organised lobe of PV form and push East. 

 

 

Edited November 4, 2016 by Mucka

[doghouse]

Whilst there is no one else on the garden path, thought I take the opportunity to acknowledge the wonderful post by Mr Holmes who acknowledges his interpretation of the models may have been slightly off the other day. Such a rare occurrence in this thread and one more people should follow.

[Summer Sun]

hmm a change back to something cooler / colder mid month?

12z                                                                06z

Edited November 4, 2016 by Summer Sun

[Ravelin]

3 minutes ago, Summer Sun said:

hmm a change back to something cooler / colder mid month?

Maybe, models still having a tendency to push any semblance of a vortex away from N.America/Greenland...

t204    t324

[Ali1977]

Nice 

[Mucka]

5 minutes ago, Summer Sun said:

hmm a change back to something cooler / colder mid month?

12z                                                                06z

The vagaries of FI from high pressure to deep trough in one run though the overall idea of dropping a trough into Europe in FI is something GFS fancies.

We will just have to wait for something more coherent to pop up.

[Frosty.]

The Gfs 12z eventually shows temperatures recovering well, especially across the south of the uk from next friday and the end of next week into the following week and also becoming more settled for a time as high pressure ridges in from the southwest with temps up to 14/15c but staying more changeable / unsettled further north with temps closer to average. Later in the run becomes progressively colder and more unsettled from the northwest with even some sleet and snow across high ground further north / west.

Edited November 4, 2016 by Frosty.

[Guest]

Still no sign of the PV setting up in its usual home at the end of the 12z GFS...lets face it we were never going to stay blocked all Autumn and winter... a little bit of zonal would be a welcome change... especially if it ends up being cold zonal.. still plenty of swings and roundabouts to come

 

[swfc]

12 minutes ago, Ali1977 said:

Nice 

its 14 days away ali altho it looks ok the 850s arnt great.also the blocking from earlier and fi easterly have gone!!!

[johnholmes]

46 minutes ago, knocker said:

As I posted above John I'm not sure it can be classed  as a genuine tropical feature as it virtually disappears never having been very significant but then is reinvigorated by the upper low off the eastern seaboard. And then cyclogenesis in the jet takes place. Anyway your expert opinion will be appreciated.

Yes I have spent a bit of time and initially it seemed to have a tropical airmass around it but that quickly disappeared as it was moved north and engaged with the cold air to its north west.

Looking at the Met O Fax chart from T+00 out to 240h (with their extended surface and upper air outputs), it seems to have caused the initial surface high around 50N to be shifted 10 degrees south. Looking at the 300mb chart and the development of the jet then I suppose that is where it would be expected to move. Not something the 500mb anomaly charts picked up but then they are 'mean' charts, 6-10 or 8-14 days. Thus, in the broad scale of things, hemisphere wise, this pretty deep low is not something they would likely show. It will be interesting to see how the NOAA outputs deal with the aftermath, as it becomes just another deep low by day 6 with the subsequent building of heights from out of the Azores. Very interesting to see in hindsight. I wonder what, if any, effect this may have on the longer term, say 2-4 weeks down the line. I wait for those with better understanding of these matters to perhaps suggest things. Tamara, unless I misread her last two outputs, did not suggest any marked or dramatic change in long term signals?

[Day 10]

No despair from me, the vortex is very different this year and doesn't seem to want to stick around the Greenland area for too long. I would rather there be downgrades in November than Dec, Jan & Feb. Quite a few factors are pointing to a cold/colder winter than the last few so lets see were we are by mid month. Remember it's only bonfire night as we stand at this point. We want the doozy charts and real weather on the ground when everyone has a chance of snow in Dec, Jan & Feb not just the hills in November! This winter will be better...

[Nouska]

11 minutes ago, johnholmes said:

Yes I have spent a bit of time and initially it seemed to have a tropical airmass around it but that quickly disappeared as it was moved north and engaged with the cold air to its north west.

Looking at the Met O Fax chart from T+00 out to 240h (with their extended surface and upper air outputs), it seems to have caused the initial surface high around 50N to be shifted 10 degrees south. Looking at the 300mb chart and the development of the jet then I suppose that is where it would be expected to move. Not something the 500mb anomaly charts picked up but then they are 'mean' charts, 6-10 or 8-14 days. Thus, in the broad scale of things, hemisphere wise, this pretty deep low is not something they would likely show. It will be interesting to see how the NOAA outputs deal with the aftermath, as it becomes just another deep low by day 6 with the subsequent building of heights from out of the Azores. Very interesting to see in hindsight. I wonder what, if any, effect this may have on the longer term, say 2-4 weeks down the line. I wait for those with better understanding of these matters to perhaps suggest things. Tamara, unless I misread her last two outputs, did not suggest any marked or dramatic change in long term signals?

The cyclone phase diagrams are a useful way of tracking how this type of feature is modelled. Warm core throughout - asymetric to symetric.

Although pretty weak in itself, it will still be a significant shot of warm air into the cold trough for strong cyclogenesis.

http://moe.met.fsu.edu/cyclonephase/

[knocker]

8 minutes ago, Nouska said:

The cyclone phase diagrams are a useful way of tracking how this type of feature is modelled. Warm core throughout - asymetric to symetric.

Although pretty weak in itself, it will still be a significant shot of warm air into the cold trough for strong cyclogenesis.

http://moe.met.fsu.edu/cyclonephase/

Very interesting so what role does the jet and the left exit play in this particular cyclonesis.

[Nouska]

35 minutes ago, knocker said:

Very interesting so what role does the jet and the left exit play in this particular cyclonesis.

I think that is more your or John's field when it comes to the geostrophic 'what entrance, what exit and the processes in between' physics. The diagram I posted was to show it is modelled to have tropical characteristics even though not immediately visible in the surface isobars.

Maybe the thetaE will show better what I mean.

Edited November 4, 2016 by Nouska

[knocker]

3 minutes ago, Nouska said:

I think that is more your or John's field when it comes to the geostrophic 'what entrance, what exit and the processes in between' physics. The diagram I posted was to show it is modelled to have tropical characteristics even though not immediately visible in the surface isobars.

Yes thanks for that but I'm still trying to get my head around the diagram.

[Ali1977]

2 minutes ago, knocker said:

Yes thanks for that but I'm still trying to get my head around the diagram.

What is it actually saying? 

[knocker]

4 minutes ago, Ali1977 said:

What is it actually saying? 

I refer you to Nouska's post above

[Scandinavian High.]

So it's looking like a brief mild interlude up to mid month then blocked pattern returning and looking to being on the cold side.