Really, when you do this kind of work (landscape photography) you have to take the weather as it comes. Make the most of the weather / light that you have. If it's possible to do the full time in Death Valley, do it. If not, you should have a Plan B. For me in that part of the US in February, Plan B would be Joshua Tree NP. Plan C would be Sedona AZ. Plan D would be the parks in southern AZ, especially Organ Pipe.
But it's all good. If you want it to be.
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