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I'm still a learner in here, but we seem to be at an interesting stage in autumnal developments atm with trop vortex struggling whilst up above the strat vortex is looking organised. So presumably a disconnect at the moment and the big question - how will things develop from here? Will the strat filter down or the trop disrupt up??

ECM charts:

500hPa 19th Nov 5a04c40b1247b_ECMNH500hPa19Nov.thumb.png.253f39434483e61a47940dd0b00cb3e1.png10hPa 18th Nov 5a04c41609223_ecmwf10f24010hPageotemp18Nov.thumb.gif.eba14cdfd097e23a5d8b16198064eeb1.gif

 

 

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2 minutes ago, Blessed Weather said:

I'm still a learner in here, but we seem to be at an interesting stage in autumnal developments atm with trop vortex struggling whilst up above the strat vortex is looking organised. So presumably a disconnect at the moment and the big question - how will things develop from here? Will the strat filter down or the trop disrupt up??

ECM charts:

500hPa 19th Nov 5a04c40b1247b_ECMNH500hPa19Nov.thumb.png.253f39434483e61a47940dd0b00cb3e1.png10hPa 18th Nov 5a04c41609223_ecmwf10f24010hPageotemp18Nov.thumb.gif.eba14cdfd097e23a5d8b16198064eeb1.gif

 

 

The strat will filter down and couple. A period of westerly dominated weather is inevitable - even 1962, after an early Canadian Warming, had to wait until late December to show that the trop vortex was smashed.

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....but with an E-QBO this winter and the anomalous warmth in the Arctic, will the vortex be on 'steriods' this winter when/if it does couple with the troposphere, and will it be more vulnerable than in times of W-QBO to attacks from above and/or below? Questions, questions...!!

Davd

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It's the battle between a tropospheric-stratospheric linked vortex and anomalous ridges - usually kicked up by tropical forcing - pushing toward the high latitudes that tends to be how strong vertical wave flux takes place to produce large stratospheric warming events, which is essentially why a full winter of persistently blocked and cold weather is (AFAIK) unheard of in this country.

The best winters see early internal wave breaking events leading to a HLB period with the blocks aligned nicely for the UK (the bit we're really struggling to resolve this year), then the vortex winding up but only briefly thanks to some tropical activity for example having also got going and driven poleward ridges that come up against the vortex, trigger vertical wave flux, and so on.

It's true as Catacol posted that - after an often chilly and at times cold Nov - Dec 1962 was very mediocre in terms of the UK's weather until shortly before Xmas, and the major cold didn't set in until Boxing Day, but looking back at the stratospheric analysis, it appears that was actually internally driven, with the Nov weather related to the Canadian warming event. Amazing really that it persisted so long afterwards... and I really wonder how?

Edited by Singularity
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As Dennis posted there was a decent warming north of canada in late Oct..wonder if this is impacting on the pv..

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3 hours ago, northwestsnow said:

As Dennis posted there was a decent warming north of canada in late Oct..wonder if this is impacting on the pv..

probably coincided with the big uptick in flux activity we saw in early october

Edited by jonboy
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On 11/9/2017 at 21:34, Catacol said:

The strat will filter down and couple. A period of westerly dominated weather is inevitable - even 1962, after an early Canadian Warming, had to wait until late December to show that the trop vortex was smashed.

So after the strat couples with the trop and we have a westerly dominated period (as seems likely), then what? What are the possible routes back to cold?

Thank you, I have only a basic understanding of these matters

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10 hours ago, Bruegelian said:

So after the strat couples with the trop and we have a westerly dominated period (as seems likely), then what? What are the possible routes back to cold?

Thank you, I have only a basic understanding of these matters

In my interpretation (because others may disagree) we need to see two things in particular: Nina start to trend back towards neutral from a low point that isn't too low.... and date line convection in the pacific maintain a decent profile in order to provide a good boost to AAM from the next phase of the MJO. The October phase was a big one - the next one is unlikely to be so big but needs to be big enough to support mid lat ridges moving further to the north.

From a Strat angle also, a decent MJO forcing will aid in any disruption we might get to the vortex. The vortex will build through December but as we hit January there may be an opportunity to put it under pressure. To aid MJO forcing it would be good to get some spikes in frictional and mountain torques - top of my list there would be to see the a waning of the Aleutian high and more of a trough in the north pacific. There are some on American WX who think this may occur thanks to a PDO trending closer to neutral than for a fair while.

In essence its all up for grabs. A strong Nina, weak MJO, sustained Aleutian ridge - and I think any sustained cold spell is dead in the water for Jan/Feb. But these are not certain.

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23 hours ago, northwestsnow said:

As Dennis posted there was a decent warming north of canada in late Oct..wonder if this is impacting on the pv..

What the anomaly animation shows is at the same time as warming over the Alaska/Canada area is a cooling over the north Atlantic/European region - this is just a redistribution of temperatures as the vortex moved. There was only a little warming as can be seen in the graph of 60-90°N 10mb temperature; compare this year to the significant warming of Autumn 2016 -

6090T.thumb.png.44f950a5e098350ff9e2cca0222ab0eb.png

https://acd-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra2/temp/t60_90n_10_2017_merra2.pdf

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4 hours ago, Catacol said:

In my interpretation (because others may disagree) we need to see two things in particular: Nina start to trend back towards neutral from a low point that isn't too low.... and date line convection in the pacific maintain a decent profile in order to provide a good boost to AAM from the next phase of the MJO. The October phase was a big one - the next one is unlikely to be so big but needs to be big enough to support mid lat ridges moving further to the north.

From a Strat angle also, a decent MJO forcing will aid in any disruption we might get to the vortex. The vortex will build through December but as we hit January there may be an opportunity to put it under pressure. To aid MJO forcing it would be good to get some spikes in frictional and mountain torques - top of my list there would be to see the a waning of the Aleutian high and more of a trough in the north pacific. There are some on American WX who think this may occur thanks to a PDO trending closer to neutral than for a fair while.

In essence its all up for grabs. A strong Nina, weak MJO, sustained Aleutian ridge - and I think any sustained cold spell is dead in the water for Jan/Feb. But these are not certain.

Thank you, all very interesting.

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Yesterday's ec 12z promoted some activity high up and low down (nothing exceptional but more than we've seen recently). Today's 00z op shows the vortex at 30hpa doing something other than being very organised by day 10 with a potential split around 30/50 hpa. at timeframe day 10 I doubt too much should be taken from one run and given this ec op was the first in a while to head back down to AO -4, perhaps i should wait for the 12z before making this post ............

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On 11-11-2017 at 10:29, Catacol said:

In my interpretation (because others may disagree) we need to see two things in particular: Nina start to trend back towards neutral from a low point that isn't too low.... and date line convection in the pacific maintain a decent profile in order to provide a good boost to AAM from the next phase of the MJO. The October phase was a big one - the next one is unlikely to be so big but needs to be big enough to support mid lat ridges moving further to the north.

From a Strat angle also, a decent MJO forcing will aid in any disruption we might get to the vortex. The vortex will build through December but as we hit January there may be an opportunity to put it under pressure. To aid MJO forcing it would be good to get some spikes in frictional and mountain torques - top of my list there would be to see the a waning of the Aleutian high and more of a trough in the north pacific. There are some on American WX who think this may occur thanks to a PDO trending closer to neutral than for a fair while.

In essence its all up for grabs. A strong Nina, weak MJO, sustained Aleutian ridge - and I think any sustained cold spell is dead in the water for Jan/Feb. But these are not certain.

 

They expect a weak La Nina. According to research by Hood we should expect the large amplitudes and occurrence rates, and the weakest static stabilities in the tropical lower stratosphere, because we are in a state of QBOE and under solar minimum (SMIN)

http://onlinelibrary.wiley.com/doi/10.1002/2017GL072832/abstract

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36 minutes ago, sebastiaan1973 said:

 

They expect a weak La Nina. According to research by Hood we should expect the large amplitudes and occurrence rates, and the weakest static stabilities in the tropical lower stratosphere, because we are in a state of QBOE and under solar minimum (SMIN)

http://onlinelibrary.wiley.com/doi/10.1002/2017GL072832/abstract

Latest Metoffice update has the 3.4 region dropping to -1.5 or maybe lower... though some members are less cold. This isnt good. Takes Nina forcing into 1988/89 or 1998/99 territory. 

nino34_anom_20171101.png

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10 hours ago, Catacol said:

Latest Metoffice update has the 3.4 region dropping to -1.5 or maybe lower... though some members are less cold. This isnt good. Takes Nina forcing into 1988/89 or 1998/99 territory. 

nino34_anom_20171101.png

If anyone wants to know what the "3.4 region" is.....

https://www.ncdc.noaa.gov/teleconnections/enso/indicators/sst.php

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On 12/11/2017 at 08:10, lorenzo said:

 

 

gltotaam_sig.90day.thumb.gif.f7022c6ccdc322664d4ab0fd3ae2e644.gifgwo_90d.thumb.gif.829b743a79e5f2088d6b0ab3c8b74ac0.gif

 

 

Hey, where do you get these plots from? Thanks.

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11 hours ago, Catacol said:

Latest Metoffice update has the 3.4 region dropping to -1.5 or maybe lower... though some members are less cold. This isnt good. Takes Nina forcing into 1988/89 or 1998/99 territory. 

nino34_anom_20171101.png

I think 1.5 is the peak dip though - not the 3 monthly figure; take 88/89, the 3 month figure at the low was -1.8 for the 3 monthly period of Nov, Dec, Jan - which would be quite a lot stronger that the 3 month figure predicted in that MO graph.

http://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

I don't think La Nina will be major this coming winter - we've had a couple of noticeable positive burst in the SOI - but nothing that screams major Nina in-coming (yet at least):

https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/

Assuming that's true, then this La Nina, will not impact the stratosphere in the same way that the 89/89 98/99 events did. Those years also had a higher solar forcing than we've got now.

 

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22 minutes ago, beng said:

I think 1.5 is the peak dip though - not the 3 monthly figure; take 88/89, the 3 month figure at the low was -1.8 for the 3 monthly period of Nov, Dec, Jan - which would be quite a lot stronger that the 3 month figure predicted in that MO graph.

http://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

I don't think La Nina will be major this coming winter - we've had a couple of noticeable positive burst in the SOI - but nothing that screams major Nina in-coming (yet at least):

https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/

Assuming that's true, then this La Nina, will not impact the stratosphere in the same way that the 89/89 98/99 events did. Those years also had a higher solar forcing than we've got now.

 

Agree with all of that. MetO forecast trend is towards a deeper Nina though - in this case I hope the trend isn't the friend. SOI all over the place this year so far though since June again the trend is quite clear

2017.gif

Looking for that trend to halt soon.

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