Met Office - Why was the start of spring so cold

[Methuselah]

The thing that really gets my goat is the fact any unusual weather event is being linked to the lack of Arctic ice, Greenland blocking in Summer, blocking in the winter, persistent cold at lower latitudes all being blamed on lack of Arctic ice yet the reason why they are probably saying this is because the retreating Arctic ice is down to warming of the globe. 

 

Perhaps just perhaps its just natural variation and if conditions in the upper stratosphere like SSW are favorable then some sort of blocking is likely to occur no matter how much sea ice there is! 

 

Personally I think its embarrassing that a few years of cold, we are all going down the route winters are likely to be more snowy and blocked because of global warming yet I remember being told that make the most of the snow now because its going become harder to get snow in this country due to global warming. 

 

You can't have it both ways and all it tells me that long range weather forecasting will ALWAYS be difficult, who knows what effect on weather patterns an ice free Arctic will have, it may not even alter the weather patterns all that much at all.

Fair point. But melting Arctic ice is not the only 'cause' that gets aired; it could be Solar? Then again it might have no cause at all, save from the atmosphere doing its level-best to even itself out? It really could be all down to natural variation...

[The PIT]

All down to global warning

[phil nw.]

Which only begs the question why was it so -ve. Most of the discussion was about the NAO, why did those factors cause the AO to be so -ve, more so than the NAO. According to NOAA, the NAO for March 2013 was less -ve than March 2005 but the AO was the most -ve on record for March. Which says to me that the AO had more impact than the NAO as with regards to last month.

Why is the question I'm asking.

I would say the -ve AO has come from the SSW in early January Mr.D.

reversing the upper westerlies and the time lag of the downwelling took us well into Spring hence the lowest point of the -AO index came at the end of Winter into March.

This released the Arctic airmass to mid-latitudes when it was just about at it`s coldest-at the end of the Polar night.

Only now can we see the zonal mean winds just starting to return to westerly at the lower levels if you refer to the first image.

[Interitus]

I would say the -ve AO has come from the SSW in early January Mr.D.

heit_u_nh.gif30mb9065.gif

reversing the upper westerlies and the time lag of the downwelling took us well into Spring hence the lowest point of the -AO index came at the end of Winter into March.

This released the Arctic airmass to mid-latitudes when it was just about at it`s coldest-at the end of the Polar night.

Only now can we see the zonal mean winds just starting to return to westerly at the lower levels if you refer to the first image.

 

Interestingly this is one feature where comparison with 1962 falls down as there was no SSW that winter

[Guest pjl20101]

Thanks very much Phil and I can quite believe what you've said my friend and yes the westerly QBO is starting to get to work now. Although April may come out cooler than average at least it will have redeemable qualities about it.

[chionomaniac]

I would say the -ve AO has come from the SSW in early January Mr.D.

heit_u_nh.gif30mb9065.gif

reversing the upper westerlies and the time lag of the downwelling took us well into Spring hence the lowest point of the -AO index came at the end of Winter into March.

This released the Arctic airmass to mid-latitudes when it was just about at it`s coldest-at the end of the Polar night.

Only now can we see the zonal mean winds just starting to return to westerly at the lower levels if you refer to the first image.

Just to add to this, Phil. The mean zonal winds were about to turn westerly at the end of Feb, but the easterly vectors were 'recharged' by an increase in wave 1 activity at that time rebounding into the stratosphere - it is this that I suspect was responsible for keeping and prolonging the lower strat negative mean zonal wind anomalies. Ordinarily, that wave 1 activity in a strong westerly regime may not have had such a pronounced effect on the tropospheric AO, however, with the lower strat already 'primed' by January's SSW then the effect was quite dramatic and can be seen by the upsurge in tropospheric easterlies during March in your first graph.

 

As ever, timing is everything, and the when the stratospheric conditions are aligned to the MJO for March, then conditions were perfect for strong northern blocking to occur in our sector:

 

[cooling climate]

The wave 1 activity was due to a very large mountain torque over Asia  and subsequent

warming in the stratosphere.The animation that was posted in the strat thread of this event

shows just how pronounced it was.

Several posters and certainly myself were still expecting to see much more in the way of

northern blocking (-AO and NAO) from the SSW which occurred during early Jan manifest

itself in the troposphere but had it not been for this mountain torque and wave 1 activity

then this may well have not been the case.

As far as the stratosphere and the MJO are concerned it is extremely hard to determine

whether one leads the other( chicken and egg scenario) or whether they are inextricably

linked and work in tandem.

Another point and I do not know whether this is purely coincedental is the phase of the  

QBO when the extreme blocking occurred in December 2010 and  March 2013.

In both events the QBO was transitioning from a easterly phase to a westerly phase in the

lower stratosphere. I wonder does this atmospheric state allow for better propagation, blocking

etc.

[syed2878]

@the pit. I do agree with u there it is down to globle warming and give it a few years and i'm sure parts of the u.k will become like the tropics, cors globle warming.

[Radiating Dendrite]

@the pit. I do agree with u there it is down to globle warming and give it a few years and i'm sure parts of the u.k will become like the tropics, cors globle warming.

The Pit was being fascicious

The chance of anywhere in the UK becoming like the t tropics in the next few years is around 0.0000000001% (in my opinion).

[syed2878]

i knew that its y i replied. Anyway the less said about gw from me the better it is.