It's worth mentioning that the MJO, which stands for Madden-Julian Oscillation (now you know why it's usually abbreviated) is currently quite weak, as is the GWO, hence there's not much in the way of energy into what's sometimes called "forcing", which is essentially a mechanism by which longwave ridges are pushed northwards into the polar vortex, disrupting it and tending to shift the longwave pattern either to the west or east while, at the same time, weakening the vortex, thereby slowing the jet and encouraging it to become more meridional. There are preliminary indications that the MJO may increase in strength during February, and, possibly, shift into a phase which encourages northerly or easterly flows for the UK.
In conjunction with this, the stratospheric vortex appears to be undergoing a warming. When the stratospheric vortex warms, the windspeed drops, and this slowing of the upper stratospheric jet filters down to the tropospheric vortex (the one we normally refer to), slowing it and increasing the chances of forcing mechanisms (such as the MJO) affecting it, either shifting its core position across the Pole, or dividing it in two. This often dramatically changes the weather pattern in the mid-high latitudes, and, if preceded by a spell of zonal, mild Atlantic weather over the UK and western Europe can plunge us into colder weather. If this happens, and it is a huge IF), it could signal a cold spell during the second half of February.
In the shorter term, though, the situation outlined in my previous post remains the case.
