Global Discussion : The Story Of The Tricky Secondary LowAdded : Wednesday at 14:45 One of the first things you learn in met is that during winter, we tend to see snow on the Northern edge of low pressure areas and rain on the South. Stands to reason to be honest, after all, the colder air is to the North and the precipitation is falling through polar air.
But sometimes, things aren't quite as they seem...
The weather system on Friday has been causing a few headaches for meteorologists. After all, if the system runs along the channel, then you would expect snow across Southern England right? OK, here is what's happening...
Here is the low pressure system in question :-
You can see the central circulation just off the coast of Brest and to the North we have high pressure and residual colder air which has been brought South behind the low pressure system affecting the UK today :-
But, if you take a look at the GFS ► precipitype forecast then you can see the heaviest of the precipitation stays to the South of the UK across the Channel :-
Not just that, but the low pressure slows down as it approaches the UK and drags in warmer air into the circulation to the East and Northeast of the system.
Secondary lows always warrant careful attention from meteorologists as they tend to be fast moving and models are notorious on shifting the track a few miles North and South in the run up to the event.
At present though, decent agreement from all the global models as well as mesoscale models such as the DWD ICON which takes the system to the South of the UK :-
Had it been 150 miles further North and moved in a little quicker then it would have been a totally different scenario. But shows why we monitor these features until we get good model consensus and why the secondary lows always keep us on our toes.
METEOROLOGIST : MARSH |