Quite a good example of tropical forcing right now. Strong convection is centred just west of the Dateline which equates to a strong MJO Phase 7 projection for end January into February.
http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR/m.3d.html
Compare the composites for this phase:
http://raleighwx.easternuswx.com/MJO/FebruaryPhase7500mb.gif
(remember this is a composite of just 16 days - how can the weather be chaotic and generate composites like this ?)
.... with GFS and GEM ensemble means day centred on day 8:
http://raleighwx.easternuswx.com/models/gfsensemble/00zGFSEnsembles500mbHeightAnomalyNH192.gif
http://raleighwx.easternuswx.com/models/cmcensemble/00zGGEMEnsembles500mbHeightAnomalyNH192.gif
The Global Wind Oscillation orbiting phases 1-4 is also reasonably supportive of this longwave pattern.
The northern-most extension of the ridge will be defined by (a) how far the tropical convective signal moves east across the Dateline and (B) the immediate impacts of sharply downwelling waves associated with warming of the atmopshere.
Both the tropical convection and downwelling waves have limited shelf lives so we should expect to see the core of the high shift towards the UK and then Europe in time. Both GFS and GEM ensembles agree and want to bring the high towards the UK days 11-15. Whether this is a touch progressive remains to be seen, but a lot of dry and more settled weather to come I think.
If tropical convection shifts just east of its current position, then there is more inclination towards the high being shifted further north allowing more a north-easterly component. Beyond that, when the convective signal retreats towards the Indian Ocean (or fades), on current analysis, there is a strong signal for high pressure being dominant and gradually drifting south and eastwards which is not conducive to upper cold.
The return of stratospheric temps to above normal should only be felt in the longer term well into February, probably more so March such are the timescales for these things beyond immediate fast propagation. We have the legacy of a lagged impact of a sustained cold stratosphere to work through just yet, allied to a low angular momentum which are not going to help with high latitude blocking in February.
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