I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.
We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.
Ignore the 18z GFS at least everything in the stratosphere is looking good
Ironically the GFS stratospheric outlook is looking especially good, unlike its mood swinging tropospheric sibling
That's a pretty good description of it, I must say.
I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.
We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.
I think the problem is that we know that the NAO can be a law unto itself, behaving in a set patterned away and not responding to other drivers in the way that it might.
We have seen this before, notably in winters earlier this century and that is again looking where we are headed for February in spite of everything else.
The sustained process of destroying the polar votex continues to grow with every passing day. Looking to the ECM forcast now for yet another spike in temperatures. GFS stratosphere forecasts already indicating this, courtesy of the latest MT I have been speaking about
Meanwhile the next pulse of warming anomalies are making their way to the troposphere - and they underpin further the prospects for February with a new entrenched -AO/NAO pattern and strongly question any suggestion of attempts to return to zonality. Of all the options available as far as the UK is concerned, this is the least likely to occur. So easterly, then north/north easterly as blocking retrogresses to the NW?
The refreshed and newly updated ECM 32 dayer which has stayed consistent for several roll-outs now, looks very good value for money
The NAO can operate in disconnect to the AO, at least for a time, but as far as winter is concerned seasonal wavelengths dictate that this usually happens early in the season - late November and December. However during the second half of the winter there is an increased coupling of the two during January and most especially February.
However the key part of this is that the relationship cannot operate indefinitely de-coupled. Despite the gyrations and contrary signals coming from the models atm, that are leading people to believe what they are saying at face value, nothing has changed in terms of the outlook in terms of February for an entrenched -AO pattern in direct contrast to first half of the winter.
On that basis any suggestions by the models to over strengthen the northern arm of the jet should be taken (imo) with a pinch of salt. Especially kee jerk reactions to the ebbs and flows of daily model forecasts. It seems wiser to take an overview imo over a couple of days or so to get a wider picture.
The present complication in terms of jet energy to the north is a residual parcel of vortex close to the North Pole and the modelling of this has been chopping and changing for some time. But when seen in the context of the overall pattern and expectations of stratospheric forecasts this is not a long term situation with further downwelling of warmer layers expected through the first week of Feb that should further change, and improve the polar profile. I'm not sure that the models have read this signal yet properly.
Irrespective of what happens next week, easterly or not - that is why I am taking model projections into the new month with a pinch of salt.
Edit: chionomaniac on NW has given a much more technical answer to the overall situation than I ever could in my own simple lay language - but the gist is more or less the same in terms of the prognosis for February. As he states in terms of the vortex - longer term changes should be expected in the context of the present messy and uncertain situation
Edited by user
26 January 2012 12:00:34
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