[Rasp] Several RASP days not updates since yesterday

[Ian]

There was one run which failed to converge. Ie the model got into a loop 
where instead of each step getting closer to a solution the results 
started to diverge again. This leads to a model crash.

It is caused by an anomaly in the input data - often associated with 
unusual weather events like "cut off lows" (but that was not the cause 
of recent crashes). This coupled with compromises made when the model 
was constructed makes the model run crash. It happens on a handful of 
runs a year.

In order to avoid this, the model would have to have smaller "time step" 
intervals and/or a smaller "resolution ratio" ie 12km -> 4km -> 1.3km. 
That would make it run slower and use more computer time and electric 
power. The parameters selected were a compromise that work most of the time.

When this happens I have seen the same date forecast crash on subsequent 
forecasts runs, ie 1 day ahead, night before etc.

If you see this, have a look at the alternate model legacy vs beta. It 
is possible one crashes when the other manages to resolve.

Regards

Ian


On 4/8/26 20:40, AirSchool Paragliding wrote:
> Greetings all
>
> Just noticed that a few of the RASP days haven't been updated since 
> yesterday e.g. RASP 1.3km d0 and d2, RASP 2km d4 and d5
>
> Many thanks
> Ria
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