Ignoring The Models!Added : Thursday at 13:50 If you take a look at the GFS ► forecast in the 6z run for next weekend :-
And now, take a look at what the model forecast for the previous run for the same time :-
They're poles apart! One has a classic Easterly developing, whilst the other continues with the Atlantic influence on the weather.
Now, you might be thinking "Come on! Be fair Metcheck, this is is T+228 and a long way out for any numerical model?" And you would be right, but usually we tend to find the global models having a decent handle on overarching patterns at this sort of range.
The issue comes down to the forecast split in the polar vortex later this week which tends to be something which happens as we approach the end of meteorological winter in the Northern hemisphere.
You can see the GFS ► forecast for the stratosphere for this coming weekend here :-
Pretty impressive warming which the GFS ► then propagates down to the surface during the longer range parts of the model run.
The problem is, that all the global models struggle when these sort of events happen. They are pretty good at handling the vortex, they are pretty good at handling the downward propagation and eventual blocking patterns which develop after the event, but they struggle like anything with regards to where the blocking occurs.
As a result, you can expect some rather strange charts in the medium to longer range of the GFS ► at the moment (say, T+180 onward) with big fluctuations from run to run and model to model over the next few days as it resolves where and how any propagation could occur.
We call this model volatility and at the moment pretty much all of the global models are showing this uncertainty beyond 180 hours. Even the ensembles aren't immune to this. Check out the GEFS ensemble post stamps at T+300 :-
×View All GFS ► PostStamp Ensembles Images
In short, the models are all over the place right now, more so than you would expect at this sort of range. We expect this volatility to calm down over the next week or so but the skill of the meteorologists being tested at the moment is not finding patterns in the models, but knowing when to ignore them.
METEOROLOGIST : IGNORINGMODELSATTHEMOMENT |