Models Push Back EasterlyAdded : Tuesday at 13:10 When the global models started hinting at an Easterly scenario a couple of weeks back, the initial cold was expected around the start of this week. That then got nudged back to this coming weekend and now the general consensus is for the real cold to approach from the East at the start of next week.
Here is the current synoptic chart :-
This is the high pressure area which is basically the catalyst for the whole event. You can see it to the West of the UK this morning and by the end of the week it has migrated to the Northeast of us and develops into a rather impressive Scandinavian high :-
The issues come around the incredibly complex synoptic setup across Siberia. Just take a look at this chart for a second :-
The problem is that weather models are simply number crunchers. They obey the laws of physics and move air around depending on atmospheric pressure. The problem with very cold dense air is that it forms surface high pressure areas due to the weight of the cold air when in fact you might have a complex upper air pattern with low pressure systems. It's this reason why the colder air stays locked further East thanks to low level systems which keep the colder air there before high pressure develops at all levels across Scandinavia over the weekend :-
Into next week though and the Easterly develops, properly :-
Full scale retrogression across the Atlantic is something which we haven't seen for a while across the UK and contingency planners should now actively be preparing for this event.
It's worth bearing in mind that the 6z GFS ► is a cold outlier, in fact, most of the operational runs have erred on the colder side of the ensemble output, but a colder week next week for all parts of the UK regardless.
METEOROLOGIST : MARSH |