Stratosphere Temperature Watch

[chionomaniac]

c,

As a warming this is really quite incredible, as it has almost reached the highest stratospheric temperatures for any time of the year since 1979. This has to be a quite extraordinary event.

As to the effects, well looking at the ECWMF NH charts it seems to be influencing projected NH heights now with a 1045 mb high over the pole. Is this it - or is this just the start and as the effects become more "modellable" the true influence will become clearer?

Given this is such a large event and that it is still in development, my view is that there is much more to come in terms of a negative AO and all that entails.

We shall see.

MM

Yes this is an extraordinary event MM. One with great tropospheric potential. Let's hope that this is realised.

Classic propagation node showing up. Negative zonal wind anomalies are now established at all levels and mean negative zonal winds have made it to around 50 hPa with some slowing of the rate of downwelling. Still looks like an impact with the upper troposphere somewhere between 10-20 February although we should note that blocking is already becoming established c/o those -ve anomalies.

It's good to see such great propagation potential, GP. Too many MMW events do not show this.

The models are showing a trend presently out to T+168 where the Siberian half of the split vortex stretches out in a finger into the mid Atlantic. When I look at the lower stratospheric modelling for the same time low behold this is following the trend of the split vortex. The net result tends to be that we are seeing the coldest air want to diagonally cross north of Scotland into the mid Atlantic. Can we use the lower stratospheric models as a guide in these scenarios?

Is this just a result of the stratospheric vortex split or more reflective of the propagative MMW properties?

Hopefully the former as it is slightly at odds with the GWO profiles.

I would not be surprised if this has something to do with the intense heatwave in Australia, with the effects also being felt in the southern hemisphere as well.

I may be wrong of course.

OT I know but my brother in Adelaide said they got up to 33.9ºC today. I thought nice summer's day, until he told me that was a night time minimum!

c

Edited January 29, 2009 by chionomaniac

[leroys41]

when the mmw is on the models say 10th february onwards are we talking another february like 1947

[Guest Mike W]

I did ask this before somehwere but couldn't see a reply to it, so apologies for asking again, but what is a MMW?

[Rob]

I did ask this before somehwere but couldn't see a reply to it, so apologies for asking again, but what is a MMW?

yeh me too loL!

[Guest North Sea Snow Convection]

MMW stands for Major MidWinter Warming

CH & GP

Nice to see that propagation. Despite the gnashing and wailing of teeth in the model thread the fun has barely begun...

Edited January 29, 2009 by North Sea Snow Convection

[picog]

With the warming apparently being so strong and the winds changing direction so convincingly, and things propopagating nicely down to the troposphere, there absolutely has to be effects on the weather in the NH.

I guess the big question is what will they be, will they affect the UK, and will they be cold effects? I have every faith and I will not be downhearted by the MO thread comments!

[chionomaniac]

With the warming apparently being so strong and the winds changing direction so convincingly, and things propopagating nicely down to the troposphere, there absolutely has to be effects on the weather in the NH.

I guess the big question is what will they be, will they affect the UK, and will they be cold effects? I have every faith and I will not be downhearted by the MO thread comments!

Yes, stick in here and avoid the pendulum swings of the GFS and subsequent MO moods.

We probably still have a couple of weeks to wait still before the second antinode of negative winds establishing themselves at the middle stratosphere, propagate down to the troposphere. And before that we are more than likely, rather than experiencing the full force of the MMW, we are now seeing the changes being brought about by switching off the polar vortex. The MMW will increase high latitude blocking at the NP, whilst the polar vortex switch off is leading to a more confused model output we are seeing presently.

Looking at the latest mean zonal wind forecast we now see when the mean zonal winds are likely to revert back to westerly. This is forecast to be around 7th Feb. I make that around 2 weeks negative wind anomalies!

c

[Guest North Sea Snow Convection]

I think that the avid GFS model watchers should bear all this in mind with regard to the likely stratospheric impacts ahead. I have stopped looking at the GFS atm, plus I rarely take it seriously these days beyond four/five days at the best of times.

That said, all the models are going to keep struggling with the impact on the PV, and the radical atmospheric changes that are getting underway, and can only keep increasing, and in turn increase further the model volatility. So things are not going to improve in that respect, that is for sure.

In the interests of personal sanities for some members, if I had my way I would cut the timeframes of all the models atm - as further outlooks on there are like having flurries on the Grand National!

It has been seen how much more accurate and consistent the stratospheric forecasts have been over the tropospheric one's so far in this epic.

Edited January 30, 2009 by North Sea Snow Convection

[chionomaniac]

I think that the avid GFS model watchers should bear all this in mind with regard to the likely stratospheric impacts ahead. I have stopped looking at the GFS atm, plus I rarely take it seriously these days beyond four/five days at the best of times.

That said, all the models are going to keep struggling with the impact on the PV, and the radical atmospheric changes that are getting underway, and can only keep increasing, and in turn increase further the model volatility. So things are not going to improve in that respect, that is for sure.

In the interests of personal sanities for some members, if I had my way I would cut the timeframes of all the models atm - as further outlooks on there are like having flurries on the Grand National!

It has been seen how much more accurate and consistent the stratospheric forecasts have been over the tropospheric one's so far in this epic.

You have snow on the brain!

[chionomaniac]

Looking at the longer range tropopause forecasts I see potential for a Greenland/Iceland high to form from the 8th Feb.

Both the ECM and NCEP seem to suggest this possibility looking at the 100 hPa charts. I thought I would mention it because in these situations it is worth seeing if we can use all the information available to us.

If you look around Greenland on both charts it is possible to make out an area conducive to upper pressure rises below.

The 400K vorticity charts also seem to suggest this is an area with reduced magnitude.

It's worth a go because at worst I'll be wrong which is no worse than some fancy computer!

I wonder what GP reanalysis GWO composites show is likely for the same period as he has most success compared to anyone at this distance out.

c

[Glacier Point]

I wonder what GP reanalysis GWO composites show is likely for the same period as he has most success compared to anyone at this distance out.

c

The GWO will not reflect an upper level event propagating event. With a phase 1-3 orbit now very likely for the forseeable future, the inference from composites is of a -PNA type pattern with ridge building over the central Atlantic and troughing into Scandinavia.

If we are basing the assumption of the MMW superc-charging the atmospheric state, that would suggest to me a tendency to shift the mean ridge in the Atlantic to Greenland and enhance the trough over Scandinavia dropping a large wedge of the PV into central western Russia.

Might be worth later composing some reanalysis for phase 1-3 GWO for 3-5 weeks after warming events to see if there is any trend...

[chionomaniac]

The GWO will not reflect an upper level event propagating event. With a phase 1-3 orbit now very likely for the forseeable future, the inference from composites is of a -PNA type pattern with ridge building over the central Atlantic and troughing into Scandinavia.

If we are basing the assumption of the MMW superc-charging the atmospheric state, that would suggest to me a tendency to shift the mean ridge in the Atlantic to Greenland and enhance the trough over Scandinavia dropping a large wedge of the PV into central western Russia.

.

Thanks for that GP. So fingers crossed the GH forms and PV in western Russia comes to fruition. Something to watch out for.

Edited January 30, 2009 by chionomaniac

[Guest North Sea Snow Convection]

With that set-up being the sort of development we have expected/anticipated, the question now is when might it happen? (I am happy to make the assumption that something along these lines does actually happen here)

The popular estimate has been from just prior to mid month. We have seen very good propagation signals so far, so that is hopefully achievable - if we backdate from the start of the event and go forward.

[tundra]

A lot of my calls regarding the upcoming weather pattern are from stratospheric pressure patterns from 7 to 9 days ago looking at the 50hpa patterns and reflecting this down to the surface.

This is why despite what the models show i am confident of a strong high pressure cell between Greenland and Iceland moving more towards Scandinavia as we pass mid month.

This could be a load of old tosh but i would be more surprised if this doesn't happen.

[Glacier Point]

Huge magnitude of the MMW now evident in terms of reversal of the zonal winds:

[chionomaniac]

Huge magnitude of the MMW now evident in terms of reversal of the zonal winds:

A pretty amazing chart GP. One can't tell from that chart what the longest duration reversal at 30 hPa has been for a winter month. But I can bet this beats it!

And how good is it to see such great propagation. -20m/s anomalies arriving at the tropopause now.

c

[leroys41]

what is the likely outcome of this huge mmw are we talking a record breaking cold spell mid february

Edited January 31, 2009 by leroys41

[chionomaniac]

what is the likely outcome of this huge mmw are we talking a record breaking cold spell mid february

Leroys41, a record breaking MMW does not mean record breaking cold conditions on the ground. As has been said before a propagating MMW event such as this gives us the best chance to see a more sustained colder period tropospherically. However conditions have to be right synoptically for this to occur and the models are suggesting that perhaps they are. Look at it like this, when baking you have no chance of making a good cake if you don't have all the right ingredients. Tropospherically, we have all the right ingredients to make that good cake, but they still have to be mixed and cooked correctly to produce the end result. I guess that is where we are now, hoping that the atmosphere mixes and cooks the cake (cold) correctly and deliver the perfect result (snow and prolonged cold) to the table!

Looking at the latest zonal mean winds they still aren't quite managing to return to westerly. Another day added on!

And another strong burst of negative mean zonal winds reaching the troposphere between 70-90ºN in the next few days.

And the warming even down to the 50 hPa level is a record for January

c

[leroys41]

thanks if everything falls in to place where is the block likely to be located are we talking a 2 week freeze like the 1980s or something else is a 1947 still possible this late in the year.

[bluearmy]

thanks if everything falls in to place where is the block likely to be located are we talking a 2 week freeze like the 1980s or something else is a 1947 still possible this late in the year.

impossible to say but 1947 was a very unusual winter spell and a two week freeze late feb would take some very particular sypnotics to occur. a below av period is more likely with some less cold interludes which will mean some colder spells.

[tundra]

I am not saying a 47 is coming but that bitterly cold spell did not start until the 25th of Jan. So although not as cold as back then this very cold spell is starting only one week later.

[Snowyowl9]

This cold spell which has already starting now is a similar time to the end of January 1986 a few day earlier then.

[chionomaniac]

Still the mean zonal winds are forecast to remain negative for another day. The recovery is painstakingly slow, which is great news for those who want to see high latitude blocking in the troposphere. Every extra day with these negative winds is an extra day of increased cold (risk) this winter.

The bulk of the stratosphere from almost 70 hPa to 3 hPa is still net opposite to normal with easterly winds at T+192. Unbelievable!

http://strat-www.met.fu-berlin.de/cgi-bin/...p;forecast=f192

c

[Guest North Sea Snow Convection]

Still the mean zonal winds are forecast to remain negative for another day. The recovery is painstakingly slow, which is great news for those who want to see high latitude blocking in the troposphere. Every extra day with these negative winds is an extra day of increased cold (risk) this winter.

The bulk of the stratosphere from almost 70 hPa to 3 hPa is still net opposite to normal with easterly winds at T+192. Unbelievable!

http://strat-www.met.fu-berlin.de/cgi-bin/...p;forecast=f192

c

Morning

This continues to be a 'work in progress' upgrade. As you say, another day to give winter a chance to play, and perhaps another day towards a FW.

If you take into account the likely feedback mechanisms in the atmosphere that will probably occur from this we could be looking at a very prolonged intermittent -AO period.

[chionomaniac]

Morning

This continues to be a 'work in progress' upgrade. As you say, another day to give winter a chance to play, and perhaps another day towards a FW.

If you take into account the likely feedback mechanisms in the atmosphere that will probably occur from this we could be looking at a very prolonged intermittent -AO period.

Morning.

Yes, yesterday I thought we would be looking at a positive zonal wind forecast today so to see a further delay was unexpected. I do think GP is right and that we could be looking at something far better later in Feb. Already we have Thursday in our sights after the next couple of days!

c