Focussed Model Discussion

[karlos1983]

6 minutes ago, Sperrin said:

Would @bluearmy or anyone else have time to give a quick explanation of a wedge? Am I right in thinking its an increase in application of a high pressure cell that causes the jet to come in on a NW/SE axis causing a PM flow as opposed to full on Greenland block?

A wedge of heights to the N or NE of the UK that can direct low pressure system on a more SE trajectory in a sliding fashion over the UK! Is my understanding. 

[johnholmes]

1 hour ago, karlos1983 said:

A wedge of heights to the N or NE of the UK that can direct low pressure system on a more SE trajectory in a sliding fashion over the UK! Is my understanding. 

https://www.google.com/search?q=in+meteorology+what+is+a+wedge%3F&rls=com.microsoft:en-GB:IE-Address&ie=UTF-8&oe=UTF-8&sourceid=ie7&gws_rd=ssl

various links but all say ridge of high pressure

[karlos1983]

11 minutes ago, johnholmes said:

https://www.google.com/search?q=in+meteorology+what+is+a+wedge%3F&rls=com.microsoft:en-GB:IE-Address&ie=UTF-8&oe=UTF-8&sourceid=ie7&gws_rd=ssl

various links but all say ridge of high pressure

Yes exactly John. But I think when we use the term it’s usually to our N or NE forcing sliding lows over the uk and bringing snow chances. Obviously wedges of heights could appear anywhere on the globe, but this is usually when many would refer to said wedges on this forum... I think

[phil nw.]

1 hour ago, Sperrin said:

Would @bluearmy or anyone else have time to give a quick explanation of a wedge? Am I right in thinking its an increase in application of a high pressure cell that causes the jet to come in on a NW/SE axis causing a PM flow as opposed to full on Greenland block?

 

 

 

1 hour ago, karlos1983 said:

A wedge of heights to the N or NE of the UK that can direct low pressure system on a more SE trajectory in a sliding fashion over the UK! Is my understanding. 

 

 

 

23 minutes ago, johnholmes said:

https://www.google.com/search?q=in+meteorology+what+is+a+wedge%3F&rls=com.microsoft:en-GB:IE-Address&ie=UTF-8&oe=UTF-8&sourceid=ie7&gws_rd=ssl

various links but all say ridge of high pressure

 

 

 

9 minutes ago, karlos1983 said:

Yes exactly John. But I think when we use the term it’s usually to our N or NE forcing sliding lows over the uk and bringing snow chances. Obviously wedges of heights could appear anywhere on the globe, but this is usually when many would refer to said wedges on this forum... I think

 

Something along these lines from Jan. 2013 ,a pattern not dis-similar to our current one but with that one notable difference to our ne.

As karlos said we see the jet forced se like now but with that "wedge" of heights like an island within a vast area of low heights across the pole.This is the difference to now  because Atlantic fronts bringing the rain turns to snow as it reaches the uk because the flow is backing and bringing continental air from the se with lower dew points.

We live in hope that if the Canadian vortex backs off a bit then we get something like this in our current pattern.

[feb1991blizzard]

30 minutes ago, johnholmes said:

https://www.google.com/search?q=in+meteorology+what+is+a+wedge%3F&rls=com.microsoft:en-GB:IE-Address&ie=UTF-8&oe=UTF-8&sourceid=ie7&gws_rd=ssl

various links but all say ridge of high pressure

To me a wedge is a door wedge shaped ridge pointing towards the polar regions as we see it on the actual weather map, any high pressure is a ridge, if you think of it in 3D, looking from a height, as the heights will be higher relative to the air surrounding it, best way to think of it is like oceanic waves, except within the Atmosphere - thats my take anyway.

[Nick F]

Despite my more cautious approach from now on after being burnt one to many times last week after the failed easterly, will try to inject some Monday Motivation this afternoon.

Been studying the GOES and GFS NAM plots through all the layers of the atmosphere over the past month, picking a few dates, 10th, 15th and 21st projections below, worth noting GOES has been pretty off the idea of easterlies in the stratosphere impacting the troposphere looking at 10th and 15th, whereas GFS has been on and off between 25th-31st, however, most recent plot (today's) both GOES and GFS in agreement of easterlies propagating down through the trop very end month / start February. Probably being flushed down by resurgence downwards of westerlies at top of the stratosphere.

10th

GOES GFS

15th

GOESGFS

Today's

GOESGFS

 

So, don't give up on the easterlies following the SSW downwelling and impacting the troposphere circulations at high latitudes yet, i.e. increased high latitude blocking. However, we wait to see how the models handle this long-awaited potential over the coming days

Edited January 21, 2019 by Nick F

[knocker]

I'm sorry but this to me this is the subtropical anticyclone ridging north within the fluid movement of the warm/cold, air with the trough being driven south east by the jet, I leave the wedges to McCains

Edited January 21, 2019 by knocker

[Sperrin]

Hi guys, thanks for your help. Much clearer now.

[Singularity]

30 minutes ago, knocker said:

I'm sorry but this to me this is the subtropical anticyclone ridging north within the fluid movement of the warm/cold, air with the trough being driven south east by the jet, I leave the wedges to McCains

True that 'wedges' often come and go much as they do on people's dinner plates, what people are considering (whether they realise it or not) is one that has some stratospheric support which enables it to stick around for a few days. That being what took place in Jan 2013.

If we're going to see such a thing then it'll likely turn up at less than a week's notice, as the relatively localised strat-trop connection is a tough one for numerical modelling to resolve.

 

@Nick F, that's a nice spot regarding the downwelling - the models have mostly been hesitant with it bar the odd run finding a much quicker route. There was for some time much expectation of a landing point around 22nd but this was based on the 'average' downwelling time for diffuse events; about 15 days from the initial split. EPS spent a while indicating that this may prove accurate but sadly this hasn't been the case and we're now looking toward the most lagged outcomes in observed history; some 25 days from initial split. Hard to believe it could lag much beyond that, but today's model trends give cause to wonder if we're in uncharted territory.

Also I should clarify; I'm referring to some significant downwelling on a regional scale to begin with; the most widespread impacts can have much greater lag; up to 60 days like we saw in 2013.

Edited January 21, 2019 by Singularity

[chionomaniac]

Unfortunately re strat the Canadian vortex has restrengthened at 50hPa day 10 on Berlin. Not what we wanted to see

[bluearmy]

36 minutes ago, knocker said:

I'm sorry but this to me this is the subtropical anticyclone ridging north within the fluid movement of the warm/cold, air with the trough being driven south east by the jet, I leave the wedges to McCains

It is - that’s why we don’t get a wedge and the trough topples into nw Europe 

[Singularity]

3 minutes ago, chionomaniac said:

Unfortunately re strat the Canadian vortex has restrengthened at 50hPa day 10 on Berlin. Not what we wanted to see

Hmm - that seems implausibly fast to be via the upper stratosphere though, could be a fluctuation from below?

Regardless, it's a good job the MJO projections have improved today with respect to taking it into phases that should help take down the Azores High and allow more of a 'runners into the base of a cold trough' type pattern to develop for the UK. That's the one way that the Canadian vortex staying stronger could be used in our favour, provided we see enough counter-zonal forcing near-NW or N of the UK... both the stratosphere and tropical forcing are capable of supplying this so you never know, we could do quite well for widespread snowfall, albeit tending to favour high ground more often than many would like.

[chionomaniac]

Just now, Singularity said:

Hmm - that seems implausibly fast to be via the upper stratosphere though, could be a fluctuation from below?

Regardless, it's a good job the MJO projections have improved today with respect to taking it into phases that should help take down the Azores High and allow more of a 'runners into the base of a cold trough' type pattern to develop for the UK. That's the one way that the Canadian vortex staying stronger could be used in our favour, provided we see enough counter-zonal forcing near-NW or N of the UK... both the stratosphere and tropical forcing are capable of supplying this so you never know, we could do quite well for widespread snowfall, albeit tending to favour high ground more often than many would like.

Yes, more than likely

[bluearmy]

9 minutes ago, chionomaniac said:

Unfortunately re strat the Canadian vortex has restrengthened at 50hPa day 10 on Berlin. Not what we wanted to see

Next run at same timescale ed

Splits at day 10

[inghams85]

2 minutes ago, chionomaniac said:

Yes, more than likely

Spotted this myself. If it's not too progressive I'm ready to call time on significant SSW impacts for this side of the hemisphere 

[knocker]

The gfs steady as a rock Anyway I'm still mulling over Chio's use of the majestic plural pronoun

Edited January 21, 2019 by knocker

[chionomaniac]

9 minutes ago, bluearmy said:

Next run at same timescale ed

Splits at day 10

You would think that that type of pattern would be highly beneficial for us! We just need the Cancian segment to nudge a bit more west.....

Edited January 21, 2019 by chionomaniac

[bluearmy]

Quite a few of the 00z ops were playing with an upper scrussian ridge as we go into week 2 .... updated ukmo also now on that page ..... seems a logical consequence of the strong  jet on a nw/we axis and surely plays into the possible slider scenario ...  - the wedge chart from 2013 posted above .... we could develop an upper ridge in that area from a scrussian opening .....

[bluearmy]

If someone can post a gif of the gem NH profile from day 7 to 10 I think you will find it very revealing ......classic downwelling wave imo as the purples lighten to blue across a swathe of the NH .... may not be right btw !

[IDO]

[chionomaniac]

22 minutes ago, bluearmy said:

Quite a few of the 00z ops were playing with an upper scrussian ridge as we go into week 2 .... updated ukmo also now on that page ..... seems a logical consequence of the strong  jet on a nw/we axis and surely plays into the possible slider scenario ...  - the wedge chart from 2013 posted above .... we could develop an upper ridge in that area from a scrussian opening .....

Was about to post something similar, Nick. I guess looking at the NW/SE jet axis alongside the 50hPa profile then the logical area for any block to appear is from Russia to Scandinavia. Whether it will be too far NE remains to be seen.

[winterof79]

30 minutes ago, bluearmy said:

Quite a few of the 00z ops were playing with an upper scrussian ridge as we go into week 2 .... updated ukmo also now on that page ..... seems a logical consequence of the strong  jet on a nw/we axis and surely plays into the possible slider scenario ...  - the wedge chart from 2013 posted above .... we could develop an upper ridge in that area from a scrussian opening .....

I did post earlier that could be the trend.No point re posting GEFS as they will update soon.

UKMO

GEM

Edited January 21, 2019 by winterof79

[bluearmy]

2 minutes ago, winterof79 said:

I did post earlier that could be the trend 

UKMO

GEM

 

2 minutes ago, chionomaniac said:

Was about to post something similar, Nick. I guess looking at the NW/SE jet axis alongside the 50hPa profile then the logical area for any block to appear is from Russia to Scandinavia. Whether it will be too far NE remains to be seen.

If gem is onto something then it probably wouldn’t matter !  Either way it shouldn’t be quiet in here going forward ......

[chionomaniac]

6 minutes ago, chionomaniac said:

Was about to post something similar, Nick. I guess looking at the NW/SE jet axis alongside the 50hPa profile then the logical area for any block to appear is from Russia to Scandinavia. Whether it will be too far NE remains to be seen.

 

2 minutes ago, bluearmy said:

 

If gem is onto something then it probably wouldn’t matter !  Either way it shouldn’t be quiet in here going forward ......

Lol just like this Nick - too far NE!

 

[winterof79]

11 minutes ago, bluearmy said:

 

If gem is onto something then it probably wouldn’t matter !  Either way it shouldn’t be quiet in here going forward ......

FI but you get what I mean. We have been wedged.

 

Posted in wrong order so numbered sequence

 

 

 

3

1

2

Edited January 21, 2019 by winterof79