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Stratosphere temperature watch - 2016/17


Paul

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Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
20 minutes ago, karyo said:

Do you think there is a problem with the data which makes the split questionable?

The problem is due to it being Christmas! :rofl:

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Posted
  • Location: st albans
  • Location: st albans
21 minutes ago, karyo said:

Do you think there is a problem with the data which makes the split questionable?

No - because the run has very much over amplified, the wave data will be overstated 

the split generates the wave activity up from the trop - thats why it's best to wait for a less outlandish run, even though the strat modelling is usually less prone to wild swings.

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Posted
  • Location: Brighton (currently)
  • Location: Brighton (currently)
Just now, bluearmy said:

No - because the run has very much over amplified, the wave data will be overstated 

the split generates the wave activity up from the trop - thats why it's best to wait for a less outlandish run, even though the strat modelling is usually less prone to wild swings.

Thank you bluearmy.

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Posted
  • Location: st albans
  • Location: st albans

A more conventional NH profile in yesterday's op and still plenty of wave activity high up. Methinks the vortex may now lose some of that intensity it's built up over the past couple weeks. 

Others will have a view as to whether we are likely to see it go pop, given its strengthended so quickly ahead of renewed wave breaking. 

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Posted
  • Location: Alston, Cumbria
  • Weather Preferences: Proper Seasons,lots of frost and snow October to April, hot summers!
  • Location: Alston, Cumbria
On 12/23/2016 at 14:52, northwestsnow said:

Ian, for someone who got the Autumn really pretty badly wrong your last sentence needs a caveat or three ...sorry.

@northwestsnow. Firstly I did not see this post earlier and I hope you are enjoying the festive period: Even without the lack of snow where you are.

I used my understanding of meteorology to make the prediction for Autumn at the end of July, relevant to this thread I made predictions based on the QBO (very high altitude winds in the Equatorial Stratosphere) and the fact that warmth on the fringes of the Arctic (and reduced sea-ice extent) would lead to Westerlies in higher latitudes going into autumn. For Britain as a whole October was not that far wrong because I predicted a cool dry spell with easterlies associated with high-pressure over northern Europe- just the easterlies went on longer than expected. Rainfall was close to what I would have expected for much of Britain but the North West and Scotland were much drier because of the prevalence of easterlies much more than I anticipated for October back at the end of July. November I expected to be mild and wet based on strengthening south-westerlies due to the warmth of the far NE Atlantic encouraging deeper depressions, as it turned out there was much more high-pressure around and a few sub-arctic spells brought much colder weather for much of the country. Interesting that December (so far) has been dominated by the pattern I expected to set in by November. September was warmer than I expected but the fact remains there was a good deal of dry warm weather (as I predicted).

Indeed, some of the Autumn of 2016 was not as I predicted originally (such is to be expected in making long-term forecasts), though when it became clear that November would be more blocked (in late October) I did provide one update to my earlier forecast in late October.

My understanding of  meteorology, the fact that there are very strong Westerlies in the Stratosphere on the fringes of the Arctic, the fact that the QBO is exceptionally westerly convinces me that my outlook for winter 2016/17 should NOT be changed. On the whole it will be a little milder than normal in January/February but there will be a couple of much colder spells of weather during the winter with some hard frosts (one of these much colder spells will unfold in the New Year); by the way I put this in my original winter forecast. I am not about to add any caveats!

All the best for 2017.

Ian Pennell 

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

I just knew the MJO would trigger something of interest, be it via a tropical cyclone or otherwise, despite what the H-W plots were showing... interference from Rossby waves a possible reason as Nick F mentioned in his excellent MOD post yesterday (I was glancing at the forum even on the big day - what has become of me!).

I'm hesitant to claim 'victory' just yet though - the bit of data absence shouldn't have too huge an impact on charts at 5-6 days range but you never know with the chaotic atmosphere we live within.

Who knows though, the MJO might actually make itself known in phases 7/8/1 after all, rather than just about 1 as the latest GEFS show (while JMAN is more enthusiastic today). Then again, ECMF and UKME are now showing a return to the IO instead, although they've been well wide of the mark in recent times (all models have been out of line in fact, but the European ones by the largest amount, UKME most of all).

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
33 minutes ago, iapennell said:

My understanding of  meteorology, the fact that there are very strong Westerlies in the Stratosphere on the fringes of the Arctic, the fact that the QBO is exceptionally westerly convinces me that my outlook for winter 2016/17 should NOT be changed. On the whole it will be a little milder than normal in January/February but there will be a couple of much colder spells of weather during the winter with some hard frosts (one of these much colder spells will unfold in the New Year); by the way I put this in my original winter forecast. I am not about to add any caveats!

All the best for 2017.

Ian Pennell 

One major complication that has to be considered is the scope for the troposphere and lower stratosphere to remain highly perturbed by wave activity which, from what I understand of research papers and historical evidence, can leave even the most violently rotating mid-to-upper vortex kind of like a drive shaft that's trying to connect to a gear which keeps wobbling about - it's very tricky for the upper-mid and lower vortex to get into sync. 

Exceptionally low Arctic sea ice appears to have had a very interesting affect on both the AO and poleward heat flux so far; there's a lot more potential energy to be used in cyclogenesis, so the AO has been able to reach very high positive values at times as deep storms move close to or over the pole, but at the same time, this process transports highly anomalous heat and moisture to the high Arctic, where interaction with surface cold pools and in some cases mountain ranges can result in upward propagation of some energy (vertical wave activity flux; WAFz) - hence the lower stratosphere can be perturbed alongside the troposphere, despite a strong mid-upper vortex state.

Ironically perhaps, the positive AO state earlier in the month, in response to the Canadian Warming (or close to it) event late Nov, shut off the poleward heat flux for a while and allowed the mid-upper vortex to gather strength. Had the warming had a heavy impact higher in the stratosphere, this negative side-effect may have been avoided. Bigger events in years past have still allowed a fairly robust vortex to exist, but displaced toward Asia for a long period of time.

Interestingly there are signs of the vortex at 10 hPa moving toward Eurasia in the 8-16 day period. I wonder of CWs can in some way encourage this sort of behaviour recurrently through a season... but now I'm getting very speculative all of a sudden!

Here's to 2017 bringing us all much cheer - and progress! :drunk-emoji:

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Posted
  • Location: Alston, Cumbria
  • Weather Preferences: Proper Seasons,lots of frost and snow October to April, hot summers!
  • Location: Alston, Cumbria
1 hour ago, Singularity said:

One major complication that has to be considered is the scope for the troposphere and lower stratosphere to remain highly perturbed by wave activity which, from what I understand of research papers and historical evidence, can leave even the most violently rotating mid-to-upper vortex kind of like a drive shaft that's trying to connect to a gear which keeps wobbling about - it's very tricky for the upper-mid and lower vortex to get into sync. 

Exceptionally low Arctic sea ice appears to have had a very interesting affect on both the AO and poleward heat flux so far; there's a lot more potential energy to be used in cyclogenesis, so the AO has been able to reach very high positive values at times as deep storms move close to or over the pole, but at the same time, this process transports highly anomalous heat and moisture to the high Arctic, where interaction with surface cold pools and in some cases mountain ranges can result in upward propagation of some energy (vertical wave activity flux; WAFz) - hence the lower stratosphere can be perturbed alongside the troposphere, despite a strong mid-upper vortex state.

Ironically perhaps, the positive AO state earlier in the month, in response to the Canadian Warming (or close to it) event late Nov, shut off the poleward heat flux for a while and allowed the mid-upper vortex to gather strength. Had the warming had a heavy impact higher in the stratosphere, this negative side-effect may have been avoided. Bigger events in years past have still allowed a fairly robust vortex to exist, but displaced toward Asia for a long period of time.

Interestingly there are signs of the vortex at 10 hPa moving toward Eurasia in the 8-16 day period. I wonder of CWs can in some way encourage this sort of behaviour recurrently through a season... but now I'm getting very speculative all of a sudden!

Here's to 2017 bringing us all much cheer - and progress! :drunk-emoji:

@Singularity; Interesting to note, in the light of this shift of the Circumpolar Vortex towards northern Siberia that some of the model runs for 10 days to a fortnight out suggest deep depressions penetrating over Scandinavia and northern Russia; with high-pressure over Greenland (again suggested in the surface pressure predictions) this is suggesting that northerlies from well within the Arctic Circle will be sweeping south across the United Kingdom during this period.

This Canadian Warming event high in the atmosphere in late November was possibly caused, in part, by underlying surface conditions- much of North America was unusually warm in November and Hudson Bay has only just frozen over completely. We are much less likely to get anomalous warmth penetrating into the upper atmosphere over Canada now as it has now become very cold there with Arctic air well in place at the surface (-30C in Winnipeg the other day). In any case, upper troposphere/stratospheric warmings over mid-latitudes tend not to result in much in the way of really cold weather over Britain in winter; even if these occur west well of Britain and increase the likelihood of prevailing winds from the north-west (as we will probably have over the next week or two) because if thickness heights are still very low aloft further north and east that still increases depression intensities in high latitudes: Cold spells from the north or NW are liable to follow depressions moving east further to the north and with the advance of the next system winds shift back to west/south-west- bringing warm wet conditions from the North Atlantic over Britain before another shot of cold north-westerlies.

We shall see; it is encouraging that the "Cold Blob" has re-appeared in the North Atlantic south of Iceland (sea-surface anomalies of -2C locally there) so any west or NW winds arising from the earlier Canadian Warming stand a better chance of maintaining near-freezing air at low levels until reaching Britain. However, sea-surface temperature anomalies around and north of Iceland are still some 2 to 4C above the seasonal norm which means a stronger warming effect on any Maritime Arctic air-masses travelling directly south-east from eastern Greenland.

All the same, upper troposphere and Stratospheric warmings need to occur within the Arctic Circle in winter in order that the high-latitude blocks capable of bringing prolonged and severe cold (from the north-east) to Britain can occur. Unfortunately, looking at the stratospheric wind and temperature profiles over high latitudes at present, it is going to require something truly spectacular (and unexpected) to deliver this over the next couple of months!

But, as you say, we live in hope- I am one who cannot stand persistent wet mild weather in winter and the prospect of at least some cold weather next week gladdens the heart! And talking of Canada, that is where I hope to go (with my brother) for a holiday next month and I will be guaranteed to get a snowy frosty fix there!

All the best for 2017- here's hoping for something a little more exciting as we approach the years of Solar Minima! 

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

Thanks for your input @iapennell. I've looked into stratospheric warming events and cold spells lasting at least a week in this country and found a link as expected - but it was far from absolute, with evidence of lengthy cold spells from mid-latitude blocks. Ideally a study needs to use 500 mb height patterns for analysis of tropospheric response but I had neither the resources or the time.

I do think with a disrupted lower stratosphere blocks can prove surprisingly resilient sometimes - when the AO actually stays neutral or weakly positive and so WAFz can continue even during the HLB period. A special circumstance, if you will.

 

Anyway - something I'd overlooked in my festive slumber; the warming at 10 hPa for days 8-10 has gained a fair bit of oomph in recent days on GFS:

12_195_arctic10.png?cb=485 12_237_arctic10.png?cb=485

Which explains the winding down of the zonal means being depicted going forward. Every little helps :ball-santa-emoji:

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

Something is brewing in the Strat - as per Singularity's post a few days ago. Wave 1 attack looks fairly strong now

ecmwfzm_ha1_f240.gif

... and flux forecasts are also fairly impressive

ecmwfzm_vt1_f240.gif

Will need monitoring - should the vortex become stressed and displaced over to Canada at the same time as we have tropospheric ridges holding tight to the North Pacific and mid Atlantic then to my amateur eye any arctic outbreak along the fringes of these ridges may be enhanced. Interesting to see how this develops.

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Posted
  • Location: st albans
  • Location: st albans

As catcol posts, seems this wave 1 increase will force the strat displacement towards N Canada. this makes the idea that anything more than transient Greenland heights are viable in the short term quite a stretch. it would make the sciceland ridge more of a likely route and this is now being payed out in the extended nwp

 

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
49 minutes ago, bluearmy said:

As catcol posts, seems this wave 1 increase will force the strat displacement towards N Canada. this makes the idea that anything more than transient Greenland heights are viable in the short term quite a stretch. it would make the sciceland ridge more of a likely route and this is now being payed out in the extended nwp

 

Yes - may indicate a stronger tendency for an Iceland/scandy ridge over time. Of interest too was an article I was reading yesterday theorising that flux transport to the pole encourages a southward movement of the jet. I wonder if we can hope for a scandy type ridge in the latter half of January with a jet bound for Iberia... 

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

Just for fun, this caught my eye on the day 10 EC at 10 hPa, wave number 2 attack and PV split?

ecmwf_z10a_nh_41.png

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
1 hour ago, Nick F said:

Just for fun, this caught my eye on the day 10 EC at 10 hPa, wave number 2 attack and PV split?

ecmwf_z10a_nh_41.png

Yep - I noticed that. Berlin graphic also shows substantial trop squeeze and near split as early as 8th Jan. Things are going to get really interesting if we get a vortex split on top of established high lat blocking and a sustained -PNA. Fingers crossed we can also keep some momentum in the MJO to help support the block more long term.

 

ecmwf150f240.gif

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Posted
  • Location: Portrush. (NI) UK
  • Location: Portrush. (NI) UK

IMG_3102.PNG

The elusive Canadian stratospheric warming event. If it evolves as GFS predicts then cold Feb inbound ala 1980's style.

 

*Warning* It is the GFS 6z.

Edited by KyleHenry
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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
1 hour ago, bluearmy said:

The 00z run looks less inclined to split.

Still seeing the signal myself.

ecmwf150f240.gif

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Posted
  • Location: Brighton (currently)
  • Location: Brighton (currently)
9 minutes ago, KyleHenry said:

IMG_3102.PNG

The elusive Canadian stratospheric warming event. If it evolves as GFS predicts then cold Feb inbound ala 1980's style.

 

*Warning* It is the GFS 6z.

Quite a few recent runs have shown a similar warming (not as intense though) in the North Atlantic.

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Posted
  • Location: frome somerset 105m ABSL,
  • Weather Preferences: cold snow, thunderstorms
  • Location: frome somerset 105m ABSL,

Would this lead to the above chart

IMG_2220.JPG

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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

So the GFS is showing a vortex split.

gfsnh-10-384.png

npst30.png

If this were to occur, what tropospheric profile could we expect from it?

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
1 hour ago, Weather-history said:

 

Not dissimilar to what we were seeing for mid-Dec in the output of late-Nov... except that the anomaly is much larger and stronger this time around.

ALL_emean_phase_full.gif

ECM also sees the MJO heading back toward the Pacific in the 10-16 day range, with the arrival moved forward by two days since yesterday's 12z and increased in mean amplitude.

GEFS shows little inclination to follow suit, while the other models have gone AWOL, perhaps out of weary submission after the recent poor performance ;)

Okay, I'll be fair - that was more an issue of how the H-W diagram depicts the MJO. Indeed it may be an ongoing issue based on M. Ventrice's MJO products.

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