Models And Upper AirAdded : Friday at 13:55 Numerical weather models are pretty clever things, but when you get under the bonnet of some of them then you can see just how impressively complex they are.
Most of us experience the weather at pretty much one layer in the atmosphere on a day to day basis. That level is 2 metres. After all, that's the approximate height of most of us and it's why temperature and wind information models tend to be around this level too.
But, to forecast the weather for the air near your face next Wednesday needs the models to forecast the weather for a few more layers. The GFS ► has 64 layers in the atmosphere it forecasts for, whilst the ECMWF ► has 137 vertical layers. They aren't forecast just in case you fancy going for a ride in a hot air balloon to 4,000ft, but they are there to forecast the fluid motion of the atmosphere and know whether the air is rising, falling, moving from South to North (V component) or West to East (U component).
This allows us to see whether high pressure or low pressure areas are building or deepening as well as the vertical buoyancy of the atmosphere for things like showers/thunderstorms etc.
The polar vortex at around 10mb is currently facing a bit of a battering from warming across Alaska in the upper level atmosphere :-
As a result, the models are really struggling with how this couples and in turn is reflected in the lower troposphere. A good example of this is the ECMWF ► run with an Easterly and colder air hanging on for the week after next :-
The GFS ► though keeps the ridge in the Atlantic stronger and keeps low pressure further North :-
Normally, we would overlook the whole thing, but some big differences in the ECMWF ► and GFS ► at the moment. This isn't normally the case in a bog standard weather situation, but when such impressive happenings are occurring in the top level of the atmosphere then we can give you 73 good reasons why the ECMWF ► has the upper hand in scenarios like this...
METEOROLOGIST : MARSH |