Re: 2023 snowpack, official numbers in history
Posted: Thu Apr 27, 2023 11:30 am
Aren't those streamflow values in acre feet, and not in actual water level? I'm not sure how you measure something flowing in acre feet, though. How does this convert to cfs?Wandering Daisy wrote: ↑Fri Apr 14, 2023 9:26 pm With the snow comes runoff. I just looked at today's CDEC 50% probability of peak 1-day snowmelt flows. I am not 100% I am reading this correctly. Correct me if I am wrong.
the numbers below are: 50% probability peak flows date/depth I am not quite sure exactly what "50%" means. At any rate here are a few examples. The most probable case is about 2 weeks earlier for peak flows.
Merced River at Happy Isles 6/4 9.9 feet (note that flood stage is 8.0 feet)
Merced River at Pohono Bridge 6/1 19.6 feet (note that flood stage is 10.0 feet)
Lake Elenore inflow 5/7 5.8 feet
Cherry Creek 5/28 9.2 feet
SF American at Kyburz 6/3 7.9 feet
Rubicon at Hell Hole 5/24 8.4 feet
Kaweah at Lake Kaweah 5/30 13.5 feet
Kings at Pine Flat 5/29 57.3
Kern at Lk Isabella 5/29 24.2
I did not look up all the flood stages. If the melt is at 50/50 probability, it looks like first week in June is the 50/50 probable peak flow. The 9.6 feet over flood stage at Pohono Bridge in Yosemite likely means that the road will be flooded and no access to the valley.
I think the CDEC projections are updated frequently. This is something interesting to keep an eye on. Also, once peak flow is reached it takes time for levels to come down.
https://www.cnrfc.noaa.gov/awipsProducts/RNOHFSSPK.php
"DATA REPRESENTS STREAMFLOW VOLUMES ENDING AT 1200 UTC FOR EACH DAY
STREAMFLOW VOLUMES ARE IN 1000 ACRE-FEET"
EDIT: There is a conversion. You take the numbers on that chart linked in Daisy's post, and divide by 1.983 to get the max cfs at that gage. From there, you can look up a chart to estimate the flood stage. For Pohono in Yosemite, that's just under 12 feet for the 50% probability flow estimate. Please correct me if I'm wrong!