Hi TRT,
I´m not working, where bigger sandstorms happen...
But still, we have thunderstorms, showers and so on.
First, wheather check - today with internet - easily done and a must!
(If you working where no infrasructure is - you should have a satellite-telephone, so that you can call one who can do the weather for you)
Second, if your sandstorms make only 60 km/h - any decent helicopter does at least 100 kts - thats 180 km/h and speed enough to fly around / past a more or less local weatherphenomena.
Becomes hard, if the thuderstorms you want to evade are frontal thundersorms.
Ones was lucky, that radar could give me a clue where to get through - but was a more than 120 nm detour....
Greetings Flying Bull