Stratosphere Temperature Watch

[cooling climate]

We have not needed a MMW from top of stratosphere down so far this winter and

although one would not hurt I can see no reason why the cold will not come back without

one.

Breaking rosby waves induced by the mjo and convection around the date line pushing heights

up northeast pacific, Alaska and into the Arctic will I think continue to do the trick.

I do hope that we do see this manifest into a MMW though as the more information and data we

have of them the better.

[chionomaniac]

Good Morning all,

Here is the latest update. Firstly thanks for Brogdale for copying his post from TWO, I pretty much agree with your sentiments but especially that there is potential for surprise!

Yesterday I commented that there is uncertainty in the FI range of modeling a warming event and one can see from yesterdays mean zonal wind projections that the mean zonal winds were set to stall before reaching reversal stage at the 10 hPa level. This stuttering suggested that a MMW may not occur.

However, because the wave 1 amplitude was set to increase further I believed that this stuttering in the forecast is just temporary and this is borne out by the latest zonal wind forecast for the 10 hPa level.

Here we see the vortex very close to being displaced off the pole with the mean zonal winds down to 7.27m/s. With further warming seen at this level it shouldn't take much to achieve that full displacement and a subsequent MMW. The extent of the negative zonal winds forecast between 70-90ºN can be seen here at T+192.

Now what is interesting is that there appears to be a tropospheric based upwelling of negative mean zonal winds(-AO) which looks like joining the downwelling negative mean zonal winds form the upper layers of the stratosphere. Will this help produce another NH significant blocking event towards the end of the month? - it certainly looks on the cards.

To see where any northern blocking would occur it is worth looking at the lowest stratospheric charts (100 hPa level) to see where the vortex is strongest. The PV has followed the displacement from higher up the stratosphere and again we are seeing the bulk of the displacement over Eastern Siberia with that trailing arm towards Greenland.

We need to see what happens to that Greenland segment of vortex which I feel will be critical in determining whether we are likely to benefit from any northern blocking.

c

[bluearmy]

the 06z gfs fi shows a fast moving segment of p/v on its way to n greenland which collapses the developing ridge pretty quickly. i think, as with the development of the last two cold spells, the op runs wll struggle with the long term detail and produce some stellar and some not so great fi's.

[chionomaniac]

the 06z gfs fi shows a fast moving segment of p/v on its way to n greenland which collapses the developing ridge pretty quickly. i think, as with the development of the last two cold spells, the op runs wll struggle with the long term detail and produce some stellar and some not so great fi's.

Yes, I think that the models will find modeling heights around Greenland difficult over the coming week or so and there will be significant variance between runs and models until what is actually going to happen with that lower strat vortex segment is decided. If it stays where it is then it is unlikely to produce another significant cold spell. My feelings are at this point is that we are heading for a significant -AO but only neutral NAO as we will need that vortex segment to shift to achieve a -NAO.

[cooling climate]

Good analysis again Chionomaniac and this is what I referred to the other day when I said

a MMW if it occurs will probably only aid in tanking the AO again along with ridge building and

rosby wave dispersal into the Arctic from high pressure cells further south.

A repeat again of Atlantic ridge building north and linking with block to north is a good bet I

think, with a more east northeasterly flow there after.

[Guest North Sea Snow Convection]

I think that any potential downwelling from the upper stratosphere is not going to happen quickly enough to coincide with any upwelling. The upwelling phase doesn't have much left in reserve so there is a limited time for any 'phasing' here and people imo shouldn't take it for granted that this will result in a favourable blocking event for the UK in couple of weeks time.

I think that any propagation of the current warming might well take longer than is being envisaged.

It might come off - but I am less sure about this than others. The atmospheric state is becomg less and less conduisive for a stable blocking environment imo the longer time goes on and the Greenland area might not be so obliging as it has been so far this winter.

Not being negative, just how I see it.

Edited January 17, 2010 by North Sea Snow Convection

[weatherjunkie]

12z GEFS NAO outlook

It is predominately west based though, which I have no problem with in the U.S .

Keep the stratospheric updates coming. They are much appreciated.

[Weather-history]

Been quiet recently this thread but the warming is still in the forecast.

http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1

[chionomaniac]

Been quiet recently this thread but the warming is still in the forecast.

http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1

I am still monitoring this event Mr D!

In fact today is the first day that a prospective MMW is technically forecast.

The forecast has see-sawed somewhat because of repeated phases of warmings and the differing displacement shape of the vortex as it disintergrates.

Central date of the MMW probably on the 26th going by this.

c

Edited January 20, 2010 by chionomaniac

[cooling climate]

I posted this in the model thread, very impressive looking if it verifies.

http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=town&alert=1

[BrickFielder]

Stratospheric vortex looks to pushed right off the pole.

This looks to give us much more potential for high pressure at about 5 days outwards onwards.

Whether this materialises as a high pressure towards the UK is unknown, as residual energy in the troposphere and the effects of the MJO will have an impact. My feeling is that we will have the potential for a blocked pattern slowly moving eastwards over a period of about 2 weeks. I doubt whether models will handle this too well at this range as it will be against the historic norms which are pre loaded into the forecasts.

[BLAST FROM THE PAST]

Good analysis again Chionomaniac and this is what I referred to the other day when I said

a MMW if it occurs will probably only aid in tanking the AO again along with ridge building and

rosby wave dispersal into the Arctic from high pressure cells further south.

A repeat again of Atlantic ridge building north and linking with block to north is a good bet I

think, with a more east northeasterly flow there after.

I agree with this synoptic development. The jetstream will be shoved well south again come Feb after a temporary buckle last week of Jan due to the magnetic disturbances of the sun. This will see AZH ridge north and get absorbed into GHP/Arctic HP and I thin N to NE'ly winds will dominate first 10days+ of Feb before a migration east of the HP cell to Scandi. It is correct to not need a SSW/MMW that propogates downward to bring cold setup. As has been pointed out we have had sever cold this winter without one.

BFTP

[Methuselah]

I agree with this synoptic development. The jetstream will be shoved well south again come Feb after a temporary buckle last week of Jan due to the magnetic disturbances of the sun. This will see AZH ridge north and get absorbed into GHP/Arctic HP and I thin N to NE'ly winds will dominate first 10days+ of Feb before a migration east of the HP cell to Scandi. It is correct to not need a SSW/MMW that propogates downward to bring cold setup. As has been pointed out we have had sever cold this winter without one.

BFTP

Can you explain those, Fred?

[chionomaniac]

I agree with this synoptic development. The jetstream will be shoved well south again come Feb after a temporary buckle last week of Jan due to the magnetic disturbances of the sun. This will see AZH ridge north and get absorbed into GHP/Arctic HP and I thin N to NE'ly winds will dominate first 10days+ of Feb before a migration east of the HP cell to Scandi. It is correct to not need a SSW/MMW that propogates downward to bring cold setup. As has been pointed out we have had sever cold this winter without one.

BFTP

That may be the case but at this part of winter we may just need one to keep the chance of cold throughout February. Certainly one can see from last year's mean zonal wind analysis how November's warm stratospheric conditions led to a weaker vortex which influenced the troposphere in December and early January.

The same find of help in February would be great.

[mountain shadow]

That may be the case but at this part of winter we may just need one to keep the chance of cold throughout February. Certainly one can see from last year's mean zonal wind analysis how November's warm stratospheric conditions led to a weaker vortex which influenced the troposphere in December and early January.

The same find of help in February would be great.

Quick question. Is the projected warming over the pole? or elsewhere? might help give a clue as to impact on us.

[chionomaniac]

Quick question. Is the projected warming over the pole? or elsewhere? might help give a clue as to impact on us.

It is not quite as simple as that. The warming tends to wrap around the periphery of the vortex helping to create an area of higher pressure that eventually displaces the vortex which gets engulfed by the warming and the vortex disintergrates. The 5 hPa sequence of charts probably show this as well as any.

http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html

It is the breakdown of the vortex that hopefully will eventually affect us but it is too early to say whether it will or not.

Edited January 20, 2010 by chionomaniac

[Uncle_Barty]

The sun has been geomagmetically very quiet - the planetary A-index has not exceeded a value of 10 since the end of October.

Personally I dont at all buy the theory that sunspot activity has much (if any) of an influence on our synoptic patterns. I can point to plenty of occasions when we have had all sorts of synoptic patterns with all sorts of sunspot and geomagnetic activity levels (the winter of 1981/2 occurred at a time of high sunspot activity and magnetic storms).

Anyway, that's going a bit off-topic for this thread so I shall stop there!

[brogdale]

It is not quite as simple as that. The warming tends to wrap around the periphery of the vortex helping to create an area of higher pressure that eventually displaces the vortex which gets engulfed by the warming and the vortex disintergrates. The 5 hPa sequence of charts probably show this as well as any.

http://www.geo.fu-be...tics/index.html

It is the breakdown of the vortex that hopefully will eventually affect us but it is too early to say whether it will or not.

Apologies if this has been posted before, but it seemed an appropriate complement to Chiono's explanation above:-

[chionomaniac]

The GFS has not quite forecast a MMW at T+240, however, with a warming like this forecast at that time it won't be long before these winds are fully reversed at the 10 hPA level!

[Richard Lake]

The GFS has not quite forecast a MMW at T+240, however, with a warming like this forecast at that time it won't be long before these winds are fully reversed at the 10 hPA level!

SSW = Sudden Stratospheric Warming?

If this is the case then my friend Wikipedia makes for interesting reading; even if I don't understand most of it

http://en.wikipedia.org/wiki/Sudden_stratospheric_warming

Will be interesting to read what the usual suspects make of this over the coming days; I will be reading intently!

Edited January 21, 2010 by rikki

[Guest North Sea Snow Convection]

Central warming date back on the agenda in about a weeks time. In fact zonal wind reversal is forecasted to just about be achieved at both 10mb and 30mb level

[chionomaniac]

The ECM forecasts have fluctuated slightly about whether we have a MMW or not. I think that this is purely a technicality issue as the results of the warming will be by and largely the same whether it is classified as a major or minor one. Surely it is splitting hairs if we are getting hung up on whether or not the zonal winds reverse at 59ºN instead of 61ºN at the 10 hPa level? I know that last year I was getting hung up about it!

The fact is is that there will be a large section of negative mean zonal winds in the upper layers of the stratosphere within a couple of days. If any thing it looks like these reversed winds have encouraged an area of positive mean zonal winds to get propagated to the lower levels of the stratosphere and the troposphere which will probably lead to a +AO period. In order to get the negative mean zonal winds to be propagated down to the troposphere we may need to see the PV rebuild again at the upper layers of the stratosphere to give the negative mean zonal winds a propagative push down to lower levels and this may take a couple of weeks.

In the meantime the lower stratospheric profiles are suggesting that the displaced lower polar vortex is dropping into Scandinavia, a very favourable area to get a northerly form which is why this scenario has been on many models agenda. We just need the weak vortex area over Newfoundland to reduce or move to allow heights to rebuild over Greenland to help with this scenario.

c

[Weather-history]

This winter has been pretty blocked thus far, it makes you wonder if any stratospheric warming is just going to enhance the blocking.

[karyo]

This winter has been pretty blocked thus far, it makes you wonder if any stratospheric warming is just going to enhance the blocking.

It could take a few weeks to see the effects of the current stratospheric warming. Mid February maybe?

Mind you, last winter was quite blocked and cold, until the stratospheric warming occured and then we had mild weather for the second half of February and an uneventful start to spring!

Karyo

[cooling climate]

I posted this in the model thread but I thought that it would be relevant in here as well

as it gives an insight into the possible northern hemisphere pattern during February.

http://www.accuweather.com/mt-news-blogs.asp?partner=accuweather&blog=Anderson&pgurl=/mtweb/content/Anderson/archives/2010/01/february_looking_busy_for_me_1.asp