The 2024 meltdown is well underway! The snowpack at the Upper San Juan Snotel site (USJSS) peaked 3 days early on April 11th with 25.8 inches of snow water equivalent (SWE). The snowpack reached 90% of normal or 3 inches shy of the 28.8-inch SWE peak that normally occurs on April 14th. Â
Daily high temperatures have climbed above 50 degrees at the USJSS for 10 out of the last 12 days, which is well above average for the site at 10,200 feet on Wolf Creek Pass. On top of that, the snow has multiple dust layers from strong wind events that carried dust from the Desert Southwest.
Above-average temperatures and solar absorption by our dirty snowpack have consistently generated twice as much streamflow in the San Juan River over the past 10 days. At the time of writing, the site has already lost 25% of the winter snowpack and the streamflow is at 1500 cfs and climbing.Â
The max temperature at the USJSS reached 56.5 F during the past 2 days and should be similar tomorrow. Runoff will slow and some snow will be replenished as cold, wet weather settles in from Thursday through Sunday. Â
Based on 88 years of record, we can normally expect the San Juan River to peak at 2450 cfs on May 24th. Only twice has the San Juan River peaked in April (2002 and 2012), and both years produced large wildfires (at least we thought they were large at the time). The upcoming cooler weather will most likely prevent an April peak, but above average temperatures and below-normal precipitation are predicted over the next 2 weeks so the river will peak earlier than normal. Â
The 2024 runoff appears to mirror 2022 due to similarly warm April temperatures and snowpack (both amount of snow and dust on snow). In 2022, we had slightly more snow (28.6 vs 25.8 inches of SWE), but an even dirtier snowpack. In 2022, the San Juan River peaked at 1970 cfs on May 8th when 1.3 inches of SWE remained at the (USJSS). Â
This year, I’m guessing that the river will peak on 5/13 at 1900 cfs. See you on the river! Â