When Models Need HumansAdded : Sunday at 8:02 Numerical weather models are great! You know how much we use them and rely on them, but there are some days when the models can't see what a human meteorologist can see. Take a look at the TAF (Terminal Aerodrome Forecast) for London Heathrow Airport for today :-
This is suggesting the risk of FU from 8pm tonight to 2am and a risk of BR from 2am to 5am and MIFG from 4am to 9am.
If you didn't know where some of these abbreviations came from then the answer is down to the World Meteorological Organisation in Switzerland which devised the standard for their use. These ones in particular come from French words with FU coming from the French word Fumee (for Smoke), BR coming from the French word Brume (for Mist) and MIFG which is a part translation for MI which comes from the French word Mince (meaning Shallow) and FG which is errr Fog.
But we digress... If you take a look at the model forecast for 2am it shows this :-
Hang on?! Where is all this smoke and mist and shallow fog which you are talking about? The reason, is that the human forecasters know that tonight is Bonfire Night in the UK and as a result factor this into the TAF forecasts for pilots.
They will look at surface conditions for things like wind speed, proximity of known bonfire displays and population areas and then factor these in. The reason for the mist and fog risk is down to whether the smoke particulates create conditions where cooled air later this evening can condense and latch onto the particulates and give rise the development of mist and fog.
One model which does factor in these particulates is the Finnish HIRLAM model. You can see the cloud forecast for 3am on this model :-
The reason? The Finnish FMI agency have also developed a smoke/particulate model called SILAS which understands that on November 5th the UK have a desire to set fire to damp wood and release fireworks and factor this into the main HIRLAM model.
But even so, you can't beat human forecasters when it comes to knowing a few local quirks and habits.
METEOROLOGIST : MARSH |