The news in recent weeks has included a deluge of headlines reflecting what millions of people across the country are wondering about (and hoping for):
Have the astonishing storms that have swept across the West since mid-December vanquished the drought at last?
The answer, of course, is complex. Yes and no. But, in fact, it is far more “no” than “yes.” Drought is a long-term condition that doesn’t… ahem… evaporate in a matter of a few very wet weeks.
For some well-informed perspective on the recent spate of “atmospheric rivers” that have pounded the West Coast and contributed to record snowfall in places like Flagstaff, ADWR Water News turned to two of the Southwest’s most reputable experts on weather conditions and forecasting.
Both Mark O’Malley, lead forecaster for the National Weather Service, and Arizona State Climatologist Erinanne Saffell provide expert analysis twice annually for the Arizona Drought Interagency Coordinating Group, which makes biannual recommendations to Arizona’s Governor about whether to declare a statewide drought emergency.
ADWR News asked O’Malley mostly for some perspective regarding the recent series of storms and about their potential long-term impact on moisture conditions in the Southwest, especially the Colorado River system. Our questions for Dr. Saffell, meanwhile, focused primarily on the effect of the storms in Arizona specifically.
Following is ADWR Water News’ discussion of overall current moisture conditions in the Colorado River Basin with NWS Lead Meteorologist O’Malley.
Next week: Dr. Erinanne Saffell, Arizona State Climatologist, discusses the impact of the recent storms on Arizona’s drought conditions.
ADWR Water News: While the recent storms appear to be helping to stabilize California drought conditions, what impacts, if any, are these "atmospheric rivers" having farther east? Are snowpack conditions in the Colorado Basin dramatically improved, too?
O’Malley: The series of storms that pummeled California helped bring beneficial moisture inland across Arizona and the Colorado Basin. Snow water equivalent (SWE) ranges from 125-150 percent of normal for this part of the winter in the headwaters of the Colorado River to as much as 250 percent of normal in northern Arizona.
It must be noted, we're still only heading into the middle of winter, and additional snowfall will be needed the next couple months to ensure heightened spring runoff.
ADWR Water News: Even if snowpack is above average, what factors may affect runoff? In the recent past, hot, dry and windy conditions, as well as the early advent of spring, have combined to drastically reduce runoff on the Colorado River watershed. Is that still a threat to runoff projections?
O’Malley: In the past several years, inconsistent snowfall over the entire winter, unusually warm spring months with rapid snow melt, and persistent dryness to deep soil moisture profiles have hampered spring runoff below what would otherwise be expected.
There are early indications (based on better summer and fall 2022 rainfall aiding soil moisture, and a more extensive snowpack) that runoff this season may not be as detrimentally affected as the past couple years. However, it's still only mid-winter and it remains to be seen how additional precipitation and spring warming affect the runoff season.
Even if conditions remain favorable and above-average spring runoff occurs throughout the Colorado Basin, storage levels on the larger reservoirs are so low (that) this year's runoff contribution will only be a small dent in the long-term deficit.
ADWR Water News: How do in-state moisture levels strike you at this point in the winter season? We're guessing things are looking good, but don't the same mitigating factors apply in Arizona as they do in the Colorado River watershed?
O’Malley: Overall precipitation and moisture in Arizona have been above normal so far this winter. Early season storm systems consisted mostly of rainfall. However, much colder storms since mid-December have resulted in more beneficial snowfall creating a favorable snowpack.
Even in the early season rain events, runoff into state reservoirs was better than the past couple years, so we're optimistic that spring runoff totals will be very beneficial to local central Arizona reservoirs.
ADWR Water News: Last fall, you predicted that the “La Nina” condition would ebb in the early months of 2023 and that appears to be what's happening. What do you foresee may be the result this spring of that turn to more of a “neutral” or “El Nino” condition?
O’Malley: While La Nina conditions are still evident in the Pacific basin, there are strong indications that we will be entering a neutral state in the spring and summer. This winter has been a good example that not all La Nina years always produce drier than normal weather in the Southwest. While the majority of La Nina's are dry for the Lower Colorado, there are a small handful (including this year) that result in normal to above normal precipitation.
The forecast for the spring suggests a small increase in odds that warmer than normal temperatures will occur, but no real tilt in odds regarding precipitation. Beyond the spring and summer, it's a little too early to accurately predict the El Nino/La Nina state, however another La Nina next fall and winter is the least likely outcome.
ADWR Water News: Regarding current conditions in the Colorado River watershed, are these average-to-better-than-average conditions spread evenly? Or are some parts of the system still experiencing abnormally dry conditions? In the recent past, the southern slopes of the Rockies often were considerably drier than in the north.
O’Malley: Some of the headwater regions of Utah are still experiencing Severe and Extreme Drought conditions given the prolonged deficits. However, much of the Colorado headwaters have fallen out of drought depiction (as has the majority of Arizona). However, the Colorado headwaters snowpack is somewhat lower (as compared to normal) versus the rest of the basin – albeit, still a healthy 125-150 percent of normal. All told, this is much better than the past two winters, though the peak runoff doesn't occur for a few more months.