How long can you leave powder in an closed powder measure on a press ( for me a Lee turret press) before it affects its performance/quality? I try to make sure it is no longer than 2 weekends. My press set-up is in my machine barn ( which I only heat when I need to work on my tractors/machinery ) and unfortunately it's snowing here in upstate N.Y. today. I'm concerned about the powder picking up moisture. Any suggestions/help would be greatly appreciated. Thank you for your time and expertise.