... Would the water levels be significantly higher if I started 1-2 hours later from WP, at first light? What do people think is the time of the day/night when water levels are at their lowest? I get that they're likely at their worst/highest in the afternoons after the day time melt. But it's not clear to me that 4am vs 6am would make a big difference. Any thoughts? Thanks in advance for everyone's collective wisdom!
Think about the physics of this problem and Hydrology 101. There is a slight delay between the peak sunshine at noon, the peak temperature in mid afternoon, and peak flow from snowmelt because it takes time for the snow to warm and melt water to percolate through the snowpack. The snowmelt delay is a minor delay, and a lot of the melt occurs around the edges and bottom of the snowpack where it doesn't need to percolate anyway. So peak melt is sometime in the afternoon, with several hours of high temps this time of year. The next delay is for the water to accumulate in tributaries and converge into main stream/creek/river. This "time of concentration" effect can be the most significant and depends on the size of the watershed, terrain surface, and slope. Whitney area here is very steep and rocky so this delay is probably just a few hours, maybe 1-3? The other significant delay is the time it takes for the water to flow down the main creek to your particular crossing, which depends on the distance from the snowpack and slope of the creek/river. We're pretty close to the melt here, so that's maybe an hour. I'm thinking 2-4 hrs is a good guess, which puts the peak at around 5-7pm roughly. Caveat: if there is a lake or lakes between the snowpack and creek crossing, the reservoir(s) will attenuate the peak and create another delay in arrival time downstream, perhaps another hour or few (depending on size of the lake).
In any case, the "peak" for snowmelt is broad curve that changes slowly over hours. This is very different from a typical large rainfall event where the peak is usually a large spike in flow that rises and falls quickly and then tapers off gradually.
For the low flow that you've asked about, the snowpack cools all evening and may refreeze. Low temp is around 4-5am, and minimum flow might be around 5am-8am and stay low until the snow starts to melt seriously in mid-morning and work its way down to the crossing.
Alas, for this situation at high elevation, steep slopes, and rocky terrain paths, I think you'll see very little difference in creek flow between 4am and 6am, but you'll have daylight at 6am. How's that for a convoluted answer?
