Yeah, in my experience a lot of people from the eastern half of the country don’t fully understand just how snowmelt dominated the western water climate is. The water volumes involved are far greater than those that come during the monsoon or any tropical systems. Something like 95% of water in the western US comes from snowpack.
Put it this way. A best case scenario for Mead in Hilary might have been a track further east and maybe up to 4-5 inches max of rain over southern NV/northwest AZ/southern UT. And even then, not all of that area would get that much rain, as a lot of it tends to come in showers and thunderstorms that are hit or miss. This is especially true when you’re talking about regular monsoon season thunderstorms - even in a very active monsoon year with a lot of big storms, your location might just have enough bad luck with where the cells track that you miss out on a lot of it. Spring snowmelt involves much more water being melted from a much bigger area. As far as Lake Mead is concerned, every year you melt maybe 15-20 inches of water equivalent snowpack from basically every mountain in western CO, eastern UT, most of western WY, northwest NM, northern AZ, and southern NV.
Tropical events and monsoon thunderstorms get all the attention because they drop a lot of rain in one specific place in a very short time, which of course causes all kinds of flooding and damage - especially because it is quite difficult to forecast the intricacies of where the storm cells happen to form more than a few hours out, so there often isn’t much you can do to prepare. Snowmelt is a more gradual process, and while the biggest years can have a lot of snowmelt flooding, it’s a lot easier to prepare for and the damage is often less eye-catching. There was plenty of flooding this spring, but everyone knew it was coming just from one look at how much snow was in the mountains, so there was plenty of time to make preparations.
