Vog in the forecast

[MyManao]

http://weather.hawaii.edu/vmap/new/

Wow, the end of the forecasting period on that model has us drowning in the stuff.. yikes.. 

I wonder how they forecast amount of vog? Bigger eruption, smaller, none, just after, years without, all make a lot of difference. Even in this eruption itself.. it erupted, lots of gas output, then paused, and during the pause the erupted lava drained back into the system. And then it erupted again but with much less gas.. as the lava that had been erupted and drained back erupted again, but already gas depleted.. all make for variations on the theme. And that model projects so many days ahead.. I wonder what it relies on for volume of gas over time?