ndscott50
Well-Known Member
The developing 2026–27 El Niño is starting to look like something we may have not seen before.
The latest Niño 3.4 reading is around +2.7°C, which is a record value for August. Even more remarkable, NOAA data show the warmest subsurface water anomalies yet observed in the eastern equatorial Pacific, locally 10–11°C above normal at roughly 100 meters depth. That enormous reservoir of warm water is one reason models continue to intensify the event.
The model guidance updated August 19 is somewhat nuts. The latest forecasts are clustering around an El Niño that could peak above +3°C, with some guidance approaching +3.5°C. Earlier model analysis put the median near +3.6°C, roughly 0.8°C beyond the previous record on a comparable basis. Even NOAA's more conservative official forecast now gives a 69% chance of the relative ENSO index exceeding +2.5°C.
There has even been discussion of whether an event of the magnitude being modeled might be something on the order of a multi-century, potentially 600-year, event statistically. There are still a lot of questions about that but the the ocean and model guidance are moving well outside the range of El Niño events we have directly observed.
So what could this mean for Lake Powell?
A record El Niño does not guarantee a huge Upper Colorado snowpack. Historically, El Niño's strongest precipitation signal is farther south than many of Powell's most productive headwaters.
But the strength and location of this event make the Pacific storm track something to watch. If the enhanced subtropical jet repeatedly directs Pacific storms into California and the Southwest and then across the southern and central Rockies, the San Juans and southern Colorado River Basin could have an extremely productive winter. If that storm track occasionally migrates north into the central and northern headwaters as well, that's the setup where things could get really interesting for basin-wide snowpack and ultimately Powell inflow.
Conversely, if the jet locks too far south or persistent ridging develops over the interior West, a historically strong El Niño could still produce a fairly ordinary Powell runoff year.
We're still months away from knowing which way this goes. The tropical Pacific is currently doing things we haven't seen in the modern observational record, and given the condition of Lake Powell and the Colorado River system, the evolution of the Pacific jet this fall and winter is going to be really interesting to watch.
The latest Niño 3.4 reading is around +2.7°C, which is a record value for August. Even more remarkable, NOAA data show the warmest subsurface water anomalies yet observed in the eastern equatorial Pacific, locally 10–11°C above normal at roughly 100 meters depth. That enormous reservoir of warm water is one reason models continue to intensify the event.
The model guidance updated August 19 is somewhat nuts. The latest forecasts are clustering around an El Niño that could peak above +3°C, with some guidance approaching +3.5°C. Earlier model analysis put the median near +3.6°C, roughly 0.8°C beyond the previous record on a comparable basis. Even NOAA's more conservative official forecast now gives a 69% chance of the relative ENSO index exceeding +2.5°C.
There has even been discussion of whether an event of the magnitude being modeled might be something on the order of a multi-century, potentially 600-year, event statistically. There are still a lot of questions about that but the the ocean and model guidance are moving well outside the range of El Niño events we have directly observed.
So what could this mean for Lake Powell?
A record El Niño does not guarantee a huge Upper Colorado snowpack. Historically, El Niño's strongest precipitation signal is farther south than many of Powell's most productive headwaters.
But the strength and location of this event make the Pacific storm track something to watch. If the enhanced subtropical jet repeatedly directs Pacific storms into California and the Southwest and then across the southern and central Rockies, the San Juans and southern Colorado River Basin could have an extremely productive winter. If that storm track occasionally migrates north into the central and northern headwaters as well, that's the setup where things could get really interesting for basin-wide snowpack and ultimately Powell inflow.
Conversely, if the jet locks too far south or persistent ridging develops over the interior West, a historically strong El Niño could still produce a fairly ordinary Powell runoff year.
We're still months away from knowing which way this goes. The tropical Pacific is currently doing things we haven't seen in the modern observational record, and given the condition of Lake Powell and the Colorado River system, the evolution of the Pacific jet this fall and winter is going to be really interesting to watch.
(I sure hope so!)
