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chionomaniac

Stratosphere Temperature Watch

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yes much better, lets hope the forecasts and signs prove to be reliable, i have everything crossed for a warming event. sure, what would a cold december and january be without a cold feb?

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I have been waiting for the New Year NCEP updates and will just show the current zonal mean wind anomalies.

post-4523-1231192276_thumb.png

Two things of note, even though it may seem that there is not much data to look at. First the orange and yellow colours at the top of the stratosphere are very indicative of the strong upper stratospheric vortex that has developed over the North Pole. Secondly, the light green colours of the negative zonal mean winds, below 70hPa and into the troposphere, are reducing rapidly leaving an average, neutral zonal mean wind flow. Are these signals, with the La nina induced, flat Pacific jet, influencing the current models pattern change?

post-4523-1231192551_thumb.png

c

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we will have to wait and see I suppose C

looking at that 200mb hemispheric flow reminds me I've not been keeping those for some months, not sure why as they were yet another 'tool' in trying to figure out the mysteries of an lrf!

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Latest update.

Firstly tonight a look at the position and strength of the stratosphere polar vortex at a 30hPa level.

post-4523-1231449237.gif

This shows a fairly strong, centrally placed vortex.

Looking at the temperature of the stratosphere we can see that the temperatures are below average and these lower temperatures are filtering down to the troposphere layer (below 100hPa).

post-4523-1231449540_thumb.png

Next a look at the stratospheric zonal wind anomalies. Firstly if we look at the tropospheric anomalies we see that the negative anomaly has ended and we are now in a slightly positive anomaly at the tropospheric level.

post-4523-1231450192_thumb.png

Looking upwards there are positive wind anomalies at the upper end of the stratosphere. These are over 30m/s greater than average (orange colour) at the top and even the winds greater than 20m/s lower down are showing signs of propagating lower down. If this continues then I suspect that their full effects will be felt in the troposphere during the last third of January. The positive anomalies represent increased westerly winds so the eventual result that could be deduced is a stronger tropospheric vortex with increased westerlies at this time. Only time will tell but the signs aren't great.

The stratospheric forecasts for the zonal wind anomalies suggest a further increase before a drop.

post-4523-1231450561_thumb.png

The stratospheric temperature forecast doesn't look great . After a few days of flirting with possible temperature rises, today the forecast is for further upper level reductions around 16th Jan. Perhaps that warming event has just been delayed!

post-4523-1231450817_thumb.png

And finally one thing of interest is that the stratospheric vortex is forecast by the NCEP to elongate with two centres at the end of the forecast period. I am trying to find out what effects this may have further down the line.

post-4523-1231451073.gif

c

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Latest update

c

Thank you for the update. A grim outlook!

Karyo

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Thank you for the update. A grim outlook!

Karyo

But it can change quickly and I suspect it will in the next few days.

c

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Guest North Sea Snow Convection
The shape of the vortex is forecast to change with warmer anomalies filtering through at this level

From this

post-4523-1231496793_thumb.png

to this

post-4523-1231496821_thumb.png

Yes, a stengthened vortex with a tighter gradient. However, I still believe the effects at surface level will produce a colder type of mobile pattern that last winter :D

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Worth noting that despite the falling temperature anomalies at 30 hPa, the zonal winds are forecast to decline considerably:

http://strat-www.met.fu-berlin.de/cgi-bin/...xes&alert=1

This is a direct result of fluxing of heat and (probably) ozone between layers. This forecast reduction takes us to 'acceptable' zonal wind anomalies in the 25-30m/s mean value. This reduction in zonals has potential implication for upwelling (as opposed to downwelling when the QBO is rising) to occur within the troposphere, especially as the westerly QBO has now peaked and is likely heading into decay.

It will also be interesting to see what happens to a vortex which is impacted by cooling midway through the season rather than at the beginning (aka most recent years). During 1963 I think the second half of the winter had a cooler 30hPa layer.

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Worth noting that despite the falling temperature anomalies at 30 hPa, the zonal winds are forecast to decline considerably:

http://strat-www.met.fu-berlin.de/cgi-bin/...xes&alert=1

That's some good news and hopefully the first signs of a warming event that many of us are hoping/praying for! It doesn't even have to be a major one, just to edge the temperature upwards a bit closer to average for the time of year. This can be enough to slow the jet a bit and open the door for the latter part of February and March.

Karyo

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That's some good news and hopefully the first signs of a warming event that many of us are hoping/praying for! It doesn't even have to be a major one, just to edge the temperature upwards a bit closer to average for the time of year. This can be enough to slow the jet a bit and open the door for the latter part of February and March.

Karyo

or possibly the second half of feb.

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Worth noting that despite the falling temperature anomalies at 30 hPa, the zonal winds are forecast to decline considerably:

http://strat-www.met.fu-berlin.de/cgi-bin/...xes&alert=1

This is a direct result of fluxing of heat and (probably) ozone between layers. This forecast reduction takes us to 'acceptable' zonal wind anomalies in the 25-30m/s mean value. This reduction in zonals has potential implication for upwelling (as opposed to downwelling when the QBO is rising) to occur within the troposphere, especially as the westerly QBO has now peaked and is likely heading into decay.

It will also be interesting to see what happens to a vortex which is impacted by cooling midway through the season rather than at the beginning (aka most recent years). During 1963 I think the second half of the winter had a cooler 30hPa layer.

I see the temperature forecasts have changed as well since yesterday. Rather than drop to a record low as forecast yesterday, a slight rise is now forecast which I see Jim H is still thinking that these will rise to above average.

GP do you know if the shape of the stratospheric vortex has a direct influence on the troposphere below or is the shape solely important at the lower stratospheric levels? Yesterday a figure 8 vortex was forecast at T+240 but already this is less pronounced today. Is there also anywhere where weekly QBO figures are published so that I can monitor any forecast weakening?

Thanks

c

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Nice to see the stratopheric zonal winds expected to reduce considerably hopefully signalling a further recovery of the stratopheric temperatures.

Karyo

if this happens soon, then perhaps the second half of february is where we should be looking.

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when was there a significant warming?..and what effect did it have on the northern hemisphere and or the uk?..answers on a postcard please

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when was there a significant warming?..and what effect did it have on the northern hemisphere and or the uk?..answers on a postcard please

Last February, there were a series of sharp warming spikes and during the second half of March and April, we had a couple of wintry outbreaks and northern blocking was more prevalent.

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Last February, there were a series of sharp warming spikes and during the second half of March and April, we had a couple of wintry outbreaks and northern blocking was more prevalent.

And here it is:

post-4523-1231693799_thumb.png

And compare to the Jan warming 1985!

post-4523-1231693828_thumb.png

CET Jan 85 0.8ºC, Feb 85 2.1ºC

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And here it is:

post-4523-1231693799_thumb.png

And compare to the Jan warming 1985!

post-4523-1231693828_thumb.png

CET Jan 85 0.8ºC, Feb 85 2.1ºC

but wasnt jan 85 already cold before the warming event..if memory serves me right the 1st 2 weeks were very cold..but february is warmer?

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but wasnt jan 85 already cold before the warming event..if memory serves me right the 1st 2 weeks were very cold..but february is warmer?

The warming event date is officially given as 01 Jan 1985. But looking at that chart the warming filtered through to the troposphere almost immediately.

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The warming event date is officially given as 01 Jan 1985. But looking at that chart the warming filtered through to the troposphere almost immediately.

did it..i always thought it was around 6 weeks...so which is right????..because that warming dosnt fit the cet does it?

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did it..i always thought it was around 6 weeks...so which is right????..because that warming dosnt fit the cet does it?

It's not a hard and fast rule though. The CET fits in with the propagation of the warm anomaly into the troposphere.

Here is another example. The official date of MWW is 23rd Jan 1987, but in fact the warming started earlier than that. If you look carefully then the warm anomaly enters through into the troposphere (say at approx 100hPa level) before the official date. Now remembering that the WMO definition of a MWW is reversal of zonal mean winds at 60ºN and 10 hPa then the event may be already progressing before this occurs. In this instance these are the dates when polar air ( I use <-10ºC at 850 level as a rule) that this occurred:11-15/1/87,15-19/2/87,23-24/2/87.

post-4523-1231698203_thumb.png

Note the stratosphere was warm at the end of 1986 as well so this may explain the early Jan dates. But there is a lot I don't know and can't answer and I am sure there are still many unknowns regarding the stratosphere - troposphere interface that are still to surface.

c

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It's not a hard and fast rule though. The CET fits in with the propagation of the warm anomaly into the troposphere.

Here is another example. The official date of MWW is 23rd Jan 1987, but in fact the warming started earlier than that. If you look carefully then the warm anomaly enters through into the troposphere (say at approx 100hPa level) before the official date. Now remembering that the WMO definition of a MWW is reversal of zonal mean winds at 60ºN and 10 hPa then the event may be already progressing before this occurs. In this instance these are the dates when polar air ( I use <-10ºC at 850 level as a rule) that this occurred:11-15/1/87,15-19/2/87,23-24/2/87.

post-4523-1231698203_thumb.png

Note the stratosphere was warm at the end of 1986 as well so this may explain the early Jan dates. But there is a lot I don't know and can't answer and I am sure there are still many unknowns regarding the stratosphere - troposphere interface that are still to surface.

c

looking at the 1987 chart..was warm through out november and december..but followed by a mild december and january 1988

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