Click the link to read the release on the Colorado State University website:

May 14, 2024

Editor’s note: This story was adapted from a press release originally published by Stanford University.

The huge, long-lasting wildfires that have become increasingly common in recent years can cause changes in soil chemistry that affect water contamination, air quality and plant growth. These changes, however, are poorly monitored and rarely factor into post-fire recovery efforts or risk assessments, according to a CSU-led article published May 14 in Nature Reviews Earth & Environment.

The literature review, initiated and led by Thomas Borch, a soil chemist and professor in CSU’s Department of Soil and Crop Sciences, found that better techniques are needed to monitor fire-induced changes in soil chemistry. This enhanced monitoring could inform decisions on how to treat drinking water sourced from burned areas, support reforestation, and protect workers against toxins during post-fire cleanup, rebuilding or revegetation.

The work was conducted in collaboration with researchers at Stanford University. CSU doctoral student Jacob VanderRoest and postdoctoral researcher Holly Roth also contributed to the review article.

“A better understanding of the molecular mechanisms in soil can help explain, for instance, why drinking water from a forest fire-impacted watershed is suddenly more toxic, or why a forest is not coming back,” said Borch, a senior author of the study.

“In our study, we mesh organic and inorganic chemistry together, whereas a lot of fire research will typically just consider one subject area,” said Claudia Avila, a soil biogeochemist who co-led the study with Alandra Lopez while both researchers were postdoctoral scholars in the lab of Stanford Doerr School of Sustainability Professor Scott Fendorf.

The review highlights evidence from recent studies suggesting wildfires may release more planet-warming carbon dioxide into the atmosphere than anticipated. Charcoal-like remnants of burned wood and other organic materials, known as black carbon, may not trap carbon dioxide for as long as scientists had hoped.

“Carbon that’s gone through forest fires and becomes black carbon can actually turn more readily into carbon dioxide by microbes than previously thought,” said Fendorf, the Terry Huffington Professor at Stanford.

“From a climate perspective, we still have a poor understanding of how much of the carbon that is left after a fire has the potential to be transformed into greenhouse gasses, such as carbon dioxide,” said Borch, who worked in Fendorf’s lab as a postdoctoral fellow 20 years ago.

Wildfires can have many benefits for ecosystems, the authors note. For example, some fires can increase the nitrogen content in soil organic matter and augment the water solubility of soil organic carbon, setting the stage for regrowth. However, recovery depends on the presence of other chemicals. For instance, certain types of organic molecules formed in soil during fires, called karrikins, are needed for many seeds to germinate. If the local soil chemistry and fire conditions do not produce enough of these karrikins, revegetation may be stunted.

Other research included in the new review has shown that wildfires can double the soil concentration of a group of toxic chemicals known as polycyclic aromatic hydrocarbons, which can induce chemical reactions that inhibit revegetation. These molecular-scale effects could well explain the mystery of vast areas where trees have struggled to reestablish after wildfires in the Rocky Mountains, Borch said.

Wildfires can also alter the chemical properties of inorganic materials such as metals within soils. Fire can change the metals into dangerous forms that readily move through the environment, ending up in the air or nearby water, the authors explained. The collaborators from Stanford University had previously documented high levels of a hazardous form of the metal chromium at wildfire sites resulting from heat-induced transformation of naturally occurring, benign forms of chromium. At sites where extremely hot, long-lasting fires cooked soils to high temperatures for extended periods, chromium persisted for many months until the next large rain event.

Other research on chromium indicates that after lower-intensity fires, remnant plant and animal tissue in soil can allow the toxic form of chromium to return to its inert form. Taken together, these studies illustrate the broader reality that wildfire impacts on soil chemistry depend on the intricate nature of the fire and landscape, including fire duration and temperature.

Predicting and mitigating wildfire risks

Broader surveillance and modeling could inform wildfire management decisions and strategies for protecting lives, property and natural resources. Avila offers an example of how this approach to informed stewardship could help prevent the leaching of metals into drinking water supplies.

“By identifying an area that has a high potential for, say, chromium release, we can call for prescribed burns that are lower intensity and reduce the potential for high-intensity, toxin-releasing fires,” said Avila, who is now an assistant professor of environmental and ocean sciences at the University of San Diego.

“If we can grasp the complexity of the intertwined processes that are happening both on the organic and the inorganic side, then that helps give us the ability to predict outcomes for different fire, landscape and geological conditions,” Fendorf said.

Summers of Smoke

For decades, Colorado State University has been at the forefront of fire science, earning its reputation as one of the leading institutions studying wildfires. Explore other stories on wildfire research at CSU.

Click the link to read the guest column on the Colorado Newsline website (Becky Edwards and Jen Clanahan):

May 15, 2024

As Mamas, we are constantly seeking balance, whether it is managing our responsibilities at work and home, finding time for our own interests, budgeting or, quite literally, when we are teaching our children to ride bikes or trek across a log over a stream. Balance keeps things in check and benefits all of us.

It is in the spirit of balance that the new Bureau of Land Management Public Lands Rule was penned. Previously, the management of these public lands has focused on other uses, while conservation has been left out of the equation. Drilling, grazing, ranching and recreation were taken into consideration, but not conservation and land preservation.

Until now.

Recently, the Department of the Interior announced a final rule to guide the BLM on managing resilient ecosystems that will weather a changing climate, protect existing landscapes that provide critical wildlife habitat, clean air and water, and take into consideration how communities are impacted by a changing world. These decisions will be made based on science, data and Indigenous knowledge.

While the Federal Land Policy and Management Act, the act that supplied the BLM with its modern mission, does require the BLM to protect public lands, the Public Lands Rule provides guidance and resources to achieve it.

It will give land managers tools to protect, restore and maintain our public lands and waters. In Colorado, the BLM manages more than 8.3 million acres of our public lands.

This rule could not have come at a more crucial time. Our public lands are feeling the strain of climate change and increased use. Recognizing that we are at a pivotal point in time where we must preserve, protect and properly manage our public lands, the new rule will bring balance to today’s activities, which will also determine the state in which we pass these treasured lands to future generations.

Our public lands are the backbone of our way of life in the Western states. They are where we teach our kids to fish, camp and hike. They are where we go ourselves to find solitude, recreate, and slow down from our busy lives.

Communities situated near these lands and waters are changing too. Some are experiencing the benefits of booming economies, while others scramble to maintain their way of life as once-sleepy towns get busier. About 4.3 million jobs are created across the U.S. through outdoor recreation, like wildlife watching, boating and hiking, on public lands. These activities contribute about $11.4 billion to the national economy, especially impacting gateway communities to these areas. Now, there will be new opportunities for people to engage in decision-making when it comes to issues that are close to home.

We are grateful that we are able to enjoy these varied and vast lands with our families. We believe it is our responsibility to care for them during our time here and maintain them for our kids, and theirs. This new rule will help ensure that these treasured lands remain healthy and ready to welcome future generations.

We would like to thank BLM Director Tracy Stone-Manning for her leadership on the rule and  Colorado’s Sens. Michael Bennet and John Hickenlooper for their support, and Montana Sen. Jon Tester.

Click the link to read the release on the University of Southern California website:

Airborne sounding radars can perform comprehensive mapping within a few hours compared to existing in-situ methods that would take a few years

May 16, 2024

Water shortages are expanding across the Earth. This is particularly acute in desert areas of the Middle East that are subject to both drought and extreme conditions such as flooding. As a result of these uncertainties, there is an increasing reliance on shallow aquifers to mitigate these shortages. However, the characteristics of these aquifers remain poorly understood due to the reliance on sporadic well logs for their management.

To address this challenge a team of researchers at the USC Viterbi School of Engineering Ming Hsieh Department of Electrical and Computer Engineering along with collaborators at Metric Systems Corporation, Caltech, Institute of Flight System Dynamics at the Technical University of Munich, the Department of Electrical Engineering at Qatar University, the Qatar Environment and Energy Research Institute at Hamad Bin Khalifa University, Bin Omran Trading & Telecommunications, the Earth and Life Institute at Catholic University of Louvain, the Department of Civil and Environmental Engineering at University of Hawai’i at Manoa, and The Aerospace Corporation, developed a new prototype for what the team is calling an  “Airborne Sounding Radar for Desert Subsurface Exploration of Aquifers,” nicknamed “Desert-SEA.” The new technique will map the top of the aquifer, called the “water table,” spanning areas as large as hundreds of kilometers using a radar mounted on a high-altitude aircraft. According to the researchers, Desert-SEA will measure, for the first time, the variabilities in the depth of the water table on a large scale, allowing water scientists to assess the sustainability of these aquifers without the limitations associated with in-situ mapping in harsh and inaccessible environments.

“Understanding how shallow groundwater moves horizontally and vertically is our primary objective as it helps us answer several questions about its origin and evolution in the vast and harsh deserts. These are questions that remain unanswered to this day,” says Heggy, a research scientist at USC who specializes in radar remote sensing of deserts and the lead author of the paper outlining the technology in IEEE-Geoscience Remote Sensing magazine.

How it works:
The technique uses low-frequency radar to probe the ground. The radar sends a series of pulsed waves into the ground, which are reflected when interacting with the water-saturated layer. From the reflected signal, and using an array of advanced antennas combined with computational techniques, the water table can be mapped with relatively high vertical and spatial resolution.

Water shortages are expanding across the Earth. This is particularly acute in desert areas of the Middle East that are subject to both drought and extreme conditions such as flooding. As a result of these uncertainties, there is an increasing reliance on shallow aquifers to mitigate these shortages. However, the characteristics of these aquifers remain poorly understood due to the reliance on sporadic well logs for their management.

To address this challenge a team of researchers at the USC Viterbi School of Engineering Ming Hsieh Department of Electrical and Computer Engineering along with collaborators at Metric Systems Corporation, Caltech, Institute of Flight System Dynamics at the Technical University of Munich, the Department of Electrical Engineering at Qatar University, the Qatar Environment and Energy Research Institute at Hamad Bin Khalifa University, Bin Omran Trading & Telecommunications, the Earth and Life Institute at Catholic University of Louvain, the Department of Civil and Environmental Engineering at University of Hawai’i at Manoa, and The Aerospace Corporation, developed a new prototype for what the team is calling an  “Airborne Sounding Radar for Desert Subsurface Exploration of Aquifers,” nicknamed “Desert-SEA.” The new technique will map the top of the aquifer, called the “water table,” spanning areas as large as hundreds of kilometers using a radar mounted on a high-altitude aircraft. According to the researchers, Desert-SEA will measure, for the first time, the variabilities in the depth of the water table on a large scale, allowing water scientists to assess the sustainability of these aquifers without the limitations associated with in-situ mapping in harsh and inaccessible environments.

“Understanding how shallow groundwater moves horizontally and vertically is our primary objective as it helps us answer several questions about its origin and evolution in the vast and harsh deserts. These are questions that remain unanswered to this day,” says Heggy, a research scientist at USC who specializes in radar remote sensing of deserts and the lead author of the paper outlining the technology in IEEE-Geoscience Remote Sensing magazine.

How it works:
The technique uses low-frequency radar to probe the ground. The radar sends a series of pulsed waves into the ground, which are reflected when interacting with the water-saturated layer. From the reflected signal, and using an array of advanced antennas combined with computational techniques, the water table can be mapped with relatively high vertical and spatial resolution.

When imaged, a stable water table usually appears as flat reflector as the amounts of water withdrawn and the amount of water that enters the system (its “recharge”) are nearly equal. However, if there is any imbalance, this will be reflected in the resulting image showing an upward or downward deflection in shape of the water table.

A similar technique is widely used for probing ice in the Antarctic and planetary bodies; however, adapting it to sense shallow aquifers in the deserts required resolving several challenges in the radar design that took three years of hard work with industry partners in Carlsbad, CA, to resolve it.

“In particular, we had to resolve the blind zone near the surface. The highly radar-attenuating ground, unquantified sources of noise, and complex clutter can mask the detection of shallow aquifers. Our system’s probing and surveying capabilities surpass those of commercial ground penetrating radars, whether surface or drone-mounted. Our system transmits stronger signals, has more sensitive receivers, and operates faster by several orders of magnitude,” says Heggy.

Current shallow groundwater maps in several parts of arid deserts, such as the Sahara, rely on data from wells that are tens, hundreds, and sometimes even thousands of miles apart, which could lead to inaccurate estimates of their volume and dynamics. Heggy suggests that this would be like finding out data about groundwater in the entire United States solely by looking at data from a well in New Jersey. (The desert area of North Africa and the Arabian Peninsula is twice the size of the continental United States). Thus, well logs alone cannot give a proper assessment of their rapid evolution, cautions Heggy.

According to the researchers, Desert-SEA’s capability to transmit high-power signals and use advanced onboard processing can fill the gaps in the data presented by well logs’ geographical distribution.

With this new prototype, Heggy predicts that even with a small airplane flying at two hundred miles per hour, the team could  cover in an hour what researchers would normally cover in a year from well log data.

Co-author Bill Brown was the lead engineer on the project. Brown says, “The Desert Sea Radar represents a significant advancement in airborne sensing and environmental engineering. By integrating high-frequency radar with AI technologies, it can generate real-time, three-dimensional mappings of subterranean water sources. This capability is crucial for securing sustainable water management in arid regions.”

While this technology will be tested in the Middle East, it has wide application to other places that are subject to extended droughts, notably in central Asia and Australia, and even in US deserts.

This technology works best in very dry areas like sand and its particular importance goes beyond understanding the current water supply. It can also be deployed for repeated assessments to understand sustainability for agriculture and, consequently, for ensuring food security for inhabitants of these extreme environments.

“Having the ability to peer more than 100 feet deep through dry sand, across vast deserts and in record time, is going to allow us to answer fundamental questions about the ebb and flow of groundwater in these regions and how we can use it in a more sustainable way,” said Elizabeth Palmer, a Fulbright Fellow working on the project.

“I am always glad to participate in airborne research missions. However, because the Desert-SEA mission will have a humanitarian impact on relieving water stress, it gives me unique feelings of motivation and pride,” Akram Amin Abdellatif, a researcher at the Technical University of Munich (TUM) noted.”

The next step for the research team is to take this designed prototype and build a flight model to be implemented on helicopters and fixed-wing aircraft.

How far will it fall in the coming La Nina? If El Nino/La Nina average is ~1.5C, given Earth’s energy imbalance, we are now passing thru 1.5C, for practical purposes. See MayRpt – https://mailchi.mp/caa/comments-on-global-warming-acceleration-sulfur-emissions-observations

Click the link to read the blog post on the Colorado Climate Center website (Russ Schumacher):

May 16, 2024

The midwest and south have been very active with severe weather lately, but it’s been relatively quiet here in Colorado so far. But we’ve reached the middle of May, which is the time of year when the threat for severe thunderstorms and tornadoes in Colorado rises rapidly. In this blog post, we’ll walk through some of the interesting aspects of Colorado’s severe weather climatology, and what history shows about what we could expect in the coming months. (If you like to explore data on your own, you can jump right over to the set of severe weather maps and graphs on our website.)

Where does severe weather tend to happen in Colorado?

First, let’s look at where severe weather happens in Colorado. (Below is a static map, but do check out the interactive map on the website where you can zoom in, select specific hazard types, etc.) The first thing you likely notice from this map is that severe storms happen a lot more frequently in eastern Colorado than on the western slope. This probably isn’t a huge surprise. There are four ingredients required to get severe thunderstorms: moisture and instability in the atmosphere, a mechanism to lift the air, and vertical wind shear (the change in wind speed and/or direction as you go up in height). Those ingredients are in place a lot more often in eastern Colorado than to the west — especially the moisture and instability. It’s tough to get enough moisture for really intense thunderstorms up in the high country.

Now, if you look even closer at the map of reports, you might notice some other interesting patterns. For example, in southeast Colorado, can you pick out Highway 50? Your eye might also be drawn to clusters along the Front Range urban corridor, or even other roads. There’s not any reason to believe that hail falls more frequently on highways than in open fields: instead, this demonstrates that the primary source of severe weather data is reports made by people, so there are more reports where people tend to be! (More of them in cities and on roadways, fewer in rural areas away from towns and major roads.)

When does severe weather tend to happen in Colorado?

Next, we can take a look at when during the year that severe weather reports tend to happen. The black lines in these graphs show a smoothed version of the average number of reports per day. For tornadoes, the frequency ramps up through May and reaches a peak in early June, with a slow decline through the summer and into the fall. The graph for severe hail looks similar, but shifted a little later: the peak is in mid-June. The graph for severe wind reports looks a little strange, though, with a big spike on a particular day. That spike comes from the unusual derecho that swept across the country on June 6, 2020. Just in Colorado, there were 137 reports of severe thunderstorm winds (58 mph or stronger) and 36 reports of winds exceeding 75 mph on that one day, far more than any other day in Colorado records.¹ That single storm system was able to alter what the severe weather climatology looks like in Colorado!

Another way to look at the data, which smooths out the effect of individual rare events, is “severe weather days”: the number of days that had one or more report of a particular hazard. The tornado and hail graphs look pretty similar to the ones above, but now the wind graph is better behaved. It shows that severe thunderstorm wind gusts are more frequent later in the summer, with a peak in early to mid-July. (An important note is that this only considers wind gusts produced by thunderstorms. Other types of intense wind tend to happen in the winter and spring.)

2023 was a very active year

We’re still awaiting the final compilation of data from NOAA for 2023, but we know that it was one of the most active years for Colorado severe weather in recent times. You might remember the Red Rocks hailstorm, the historic number of tornadoes in northeast Colorado on June 21, the unusual late-night hailstorm on June 28, or the Yuma County tornado on August 8 that was rated EF-3. Later in the evening of August 8, a new state record hailstone, 5.25 inches in diameter, was collected in Yuma County by a storm chaser.

Especially when it comes to hail, 2023 was a year for the record books, with the largest number of reports on record across every size category. (Keep in mind, though, that hailstorms have not been consistently recorded over time, and population has grown, so it’s tough to look at trends of hail reports over the long term. The 2023 data are also still awaiting final confirmation.)

How to get severe weather warnings; how to submit reports

If severe weather is in the forecast, it’s important to have more than one way to get warnings from the National Weather Service. Make sure that Wireless Emergency Alerts (WEA) are active on your phone. Get a NOAA Weather Radio, especially for times when you might be outside of cell service, like when camping. Follow your local broadcast meteorologists and your local National Weather Service office. Think about the safe place where you, your family, and your pets can go if a warning is issued.

If severe weather happens to occur in your area, you can also help by reporting what happened to the National Weather Service. They accept reports over social media, or if you’re especially dedicated you can get trained to be a Skywarn spotter, submit reports on your phone using mPING, or join the Community Collaborative Rain, Hail, and Snow (CoCoRaHS) network where you can submit detailed information about hail, heavy rain, and other hazardous weather. All of these reports are useful both for knowing what is happening while storms are ongoing, and for researchers to understand how to make better forecasts and warnings in the future.

In future posts, we’ll take a deeper dive into some of the most unusual and highest-impact storms that have occurred in Colorado in its history, and other interesting aspects of the severe weather climatology.

Further reading

For further reading, check out this paper by former CSU PhD student Sam Childs:
Childs, S. J., and R. S. Schumacher, 2019: An Updated Severe Hail and Tornado Climatology for Eastern Colorado. J. Appl. Meteor. Climatol., 58, 2273–2293, https://doi.org/10.1175/JAMC-D-19-0098.1.

1. The previous highest number of thunderstorm wind reports on a day was 30 severe reports (58+ mph), and 7 “significant” (75+mph) severe reports. ↩︎

Click a thumbnail graphic to view a gallery of drought data from the US Drought Monitor website.

Click the link to go to the US Drought Monitor website. Here’s an excerpt:

This Week’s Drought Summary

Heavy precipitation fell across the Rocky Mountains of Montana, Wyoming and Colorado, as well as a large part of the South and southern Midwest. This brought widespread improvements to much of the South and Midwest, with scattered or widespread improvements in the Great Plains and Midwest. Heavy precipitation falling over the Southeast brought improvements from central Alabama into the southern Appalachian Mountains, as well as the area surrounding the convergence of the Ohio, Mississippi, and Tennessee rivers. A small area of the Mid-Atlantic region missed out on much of the precipitation, leading to minor degradations. Very dry weather for the past few months led to increased fire danger in parts of the Florida Peninsula, and short-term moderate drought and abnormal dryness expanded in coverage. Texas saw isolated degradations in the panhandle and south – where record breaking temperatures converged with the lack of precipitation. The High Plains were a mixture of light to moderate precipitation, which greatly influenced where improvements or degradations were made. Kansas, Colorado and Wyoming saw improvements where measurable precipitation fell. Degradations occurred in western Kansas and eastern Wyoming, where trace amounts of precipitation fell. Montana saw heavy precipitation, which improved conditions across much of the state. Isolated storms in western Oregon and Washington brought widespread improvements in Oregon, which continued into southwestern Washington. Central Washington, meanwhile, missed out on the precipitation and saw further expansion of abnormal dryness…

High Plains

The High Plains was a mixed bag of light to moderate precipitation, as well as improvements and degradations. Wyoming and Colorado saw improvements and degradations closely aligning with areas of moderate and light precipitation respectively. Northern and central Wyoming saw improvements, which were a continuation of improvements made in Montana and South Dakota. However, degradations occurred in areas that received trace amounts of precipitation along the eastern and southeastern part of these states into northern Colorado. Northeastern Colorado also saw a slight introduction of abnormally dry (D0) conditions as overflow from adjoining area of western Nebraska, where precipitation was low. Slight improvements occurred in south and northeast areas of Kansas that received precipitation. Elsewhere, conditions in central and western Kansas continued to degrade as streamflows, soil moisture, and groundwater continued to deteriorate. Southeast Nebraska saw slight improvements from continuous moisture over the past few weeks…

West

Temperatures across the northern and Pacific coast of the West saw temperatures of 2 to 6 degrees above normal. Areas in northern California, northwest Oregon, south and central Washington and northeastern Montana experienced temperatures 6 to 8 degrees above normal. Little to no measurable precipitation fell over much of the West, except for Montana where 1 to 3 inches of precipitation fell. Conditions improved through most of central and western Montana with slivers of improvement in the parts where the short-term dryness from the weeks past have shown improvement. There were some isolated areas in western and southern Montana that saw degradations. Oregon saw widespread improvements in part due to the isolated precipitation and improved streamflow and soil moisture. These conditions were also seen in southern Washington where improvements were made. Central Washington, however, missed out on any meaningful precipitation and saw temperatures of 4 to 8 degrees above normal, leading to abnormal dryness (D0) expansion…

South

The South saw a mixture of improvements in the north and degradation in the western and southern parts of the region. Western Texas, central Arkansas and northern Mississippi saw trace amounts of precipitation, while central and eastern Texas, Louisiana, and central and southern Mississippi saw between 2 to 5 inches of precipitation. Precipitation helped alleviate conditions in northern, western and southern Oklahoma. Following the precipitation, further improvements occurred across northern Arkansas and western and eastern Tennessee.

The Texas panhandle and southern parts of Texas saw expansion of existing abnormal dryness – and a small sliver of moderate drought (D1) in far south Texas – with a lack of measurable precipitation and above-normal temperatures. Southern Texas saw temperatures of 6 to 8 degrees above normal with Brownsville (124°F), Harlingen (125°F), and McAllen (122°F) breaking May temperature records of 115°F (5/4/1999), 121°F (5/26/1973), and 119°F (5/13/1995) respectively. A small area around the Missouri Bootheel also saw moderate drought (D1) expansion…

Looking Ahead

Over the next five days (May 16-21), heavy precipitation of2 to 5 inches is expected to continue to fall in the far South from central Texas to western Georgia, with 1 to 2 inches of rain expected in surrounding areas into the southern Midwest and Mid-Atlantic coast. The rest of the central and eastern United States will see some light precipitation. Much of the West will miss out on this precipitation.

The National Weather Service Climate Prediction Center’s 6-10 day outlook heavily favors above-normal temperatures from New Mexico to Wisconsin, Maine, and down into Florida, with the greatest possibility being in southern Texas. The Southwest and High Plains are expected to be near normal temperature and everything to the west is likely going to be cooler than normal. Hawaii and northern Alaska are likely going to be warmer than normal, whereas parts central and western Alaska are leaning towards below-normal temperatures. For precipitation, much of the country is leaning towards above-normal precipitation. New Mexico and central and southern Texas are leaning toward below-normal precipitation, with the western and eastern coasts likely to be around normal. The Big Island of Hawaii is likely to see above-normal precipitation, along with central and northern Alaska. Southern Alaska is leaning toward below-normal precipitation.

At the end of April, 38.82% of Canada was in #drought (D1-D4), 14.32% of the US, and 68.06% of Mexico was in drought.

Click the link to read the article on the KUER website (David Condos). Here’s an excerpt:

May 13, 2024

Runoff from mountain snowpack is particularly precious in Utah. It provides 95% of the state’s water supply. In recent years, however, getting above-average snowpack hasn’t necessarily led to above-average runoff. Historically, water managers could count on those numbers to more-or-less match, said Colorado River Authority of Utah Chair Gene Shawcroft. This discrepancy — and the uncertainty it brings — makes the already tricky job of managing water in the West even harder, he said.

“That’s part of the challenge we have with everything we do in the water world. Not only are we pressured to make sure there’s water for the future. We’re also wrestling with, ‘What happens if our water supply is less than what we’ve anticipated?’”

When snowpack peaked in the Colorado River’s Upper Basin in early April, it was 112% of its historical normal. But the actual runoff for April was just 99% of normal. As of May 10, snowpack was still above average at 107% of normal. The most recent streamflow forecast for May-July, however, predicts runoff to only be 87% of normal. Localized examples of this gap show up in southern Utah, too. In the southwestern region, which includes St. George and Kanab, snowpack levels hit 101% of normal on May 1. But the May-July streamflow forecast expects runoff to be just 60% of normal. The Escalante-Paria basin from Bryce Canyon National Park to the southern edges of Lake Powell had snowpack levels that were 262% of normal on May 1, but the latest streamflow forecast anticipates runoff to be 101% of normal…

So, why is this happening? One big factor is how parched the ground is. Soil moisture and groundwater levels are still trying to claw their way back from the extreme drought Utah had between 2020 and 2022, said Utah Snow Survey Program Supervisor Jordan Clayton. The ground became so dried out, that it soaked up a disproportionate amount of snowmelt in the subsequent runoff seasons. Even during the past two years, the ground beneath some of that snow has remained on the dry side…

Another factor is how fast the snowpack melts. If it goes quickly, the ground will likely stay saturated and a much larger percentage of the water will make it downstream. If it happens in fits and starts, however, the ground has more chances to dry out between melting periods and could absorb more of that water…

Where the snow falls also matters. As Clayton looked at Utah’s snow conditions this winter, he noticed that the middle and lower-elevation mountains had especially high snowpack levels compared to their historical normals. The problem is that most of Utah’s water doesn’t come from those lower elevations, but from sites with an altitude of around 10,000 feet.

Click the link to read the release on the NRCS website:

As of May 1^st, 2024, Colorado’s snowpack exhibits a distinct north-south divide and is at 90% of median. The northern basins display persistent snowpack levels from 95% of median in the combined Yampa-White-Little Snake basins to 105% in the South Platte. In stark contrast, the southern basins are below median ranging from 57% in the Upper Rio Grande to 84% in the Arkansas. Statewide precipitation has reached 105% of median for the water year to date (WYTD), while April’s drier conditions have resulted in 88% of median precipitation. This monthly subnormal statewide median, when disaggregated, reveals a stark contrast in precipitation distribution, particularly with southern basins ranging from 54% to 68% and northern basins ranging from 82% to 102%. Southern basins have not only received less precipitation compared to the state’s median but also when set against their historical medians. The combined San Miguel-Dolores-Animas-San Juan (SMDASJ) basins are at 88% WYTD, dipping further to 68% for April totals. 

Streamflow projections echo snowpack and precipitation variances, with the state averaging forecasts at 95% of median. A closer look reveals 34 of 86 streamflow stations predicting above median flows. The Yampa-White-Little Snake forecast an above median flow at 109%, reflecting sustained snowpack levels. Conversely, the combined SMDASJ basins, experiencing reduced snowpack at 72%, project streamflow at 73% of median. Specific sites like Navajo Reservoir inflow and the Animas River at Durango are anticipating below median streamflow at 440 cubic feet per second (CFS) and 279 CFS, respectively. 

Karl Wetlaufer, a hydrologist with the NRCS Water and Climate Center, highlights the impact of recent weather patterns on streamflow projections: “The month of April brought above normal temperatures and below normal precipitation across the Upper Colorado and the Rio Grande basins. These conditions contributed to rapid snowmelt in most of the basins and above normal monthly streamflow in many sub-basins. All of these contributing factors led to a drop in total seasonal (April-July) volumetric forecasts since April 1st in most sub-basins with the exception of the Colorado Headwaters where forecasts remained most similar to last month.”

“The rapid onset of warmer temperatures in late April accelerated snowmelt rates, particularly in the Upper Colorado and Gunnison basins, highlights a potential for early peak streamflow,” comments Nagam Gill, NRCS hydrologist. SNOTEL data at the Schofield Pass and Red Mountain Pass sites in the Gunnison basin, show that snow water equivalent (SWE) was reduced to 75% and 90% of the seasonal peak, respectively, by early May. This trend is also observed at the Upper Taylor SNOTEL, where the snow water equivalent decreased to 48% of its peak by the same time, earlier than the historical median melt-out dates. Despite the past peak in SWE, ongoing weather patterns into May and June can still influence streamflow. Late spring rains, although not as impactful as winter snowpack, can help sustain streamflow and top up reservoirs levels before the drier summer months set in.

As of the end of April, reservoir storage across Colorado is at 97% of median an improvement from 86% observed this time last year. Most basins are reporting near to above median, ranging from 106% in the South Platte to 124% in the Colorado Headwaters. The combined SMDASJ basins are the exception at 84% of median slightly above last year’s 82% at this time. Despite less robust snowpack conditions this year, reservoir levels have benefited from last year’s abundant snowpack, which has helped maintain relatively high-water storage levels.

<sup>* San Miguel-Dolores-Animas-San Juan River basin
* *For more detailed information about April mountain snowpack refer to the  May1st, 2024 Colorado Water Supply Outlook Report. For the most up to date information about Colorado snowpack and water supply related information, refer to the Colorado Snow Survey website.</sup> 

Click the link to read the article on the KUNC website (Alex Hager):

May 10, 2024

This story is part of ongoing coverage of the Colorado River, produced by KUNC in Colorado and supported by the Walton Family Foundation. KUNC is solely responsible for its editorial coverage.

A team of researchers has been hard at work in the Rocky Mountains to solve a mystery. Snow is vanishing into thin air.

Now, for the first time, a new study explains how much is getting lost , and when, exactly, it’s disappearing . Their findings have to do with snow sublimation, a process that happens when snow evaporates before it has a chance to melt.

Perhaps most critical in the new findings is the fact that most snow evaporation happens in the spring, after snow totals have reached their peak. This could help water managers around the West know when to make changes to the amount of water they take from rivers and reservoirs.

“This lets us make much better decisions and understand processes that there was not data available to understand before,” said Jessica Lundquist, the study’s author. “These data are absolutely critical.”

Researchers across the western U.S. have been producing increasingly granular data about snow over the past two decades. Eighty-five percent of the Colorado River starts as high-altitude snow in the mountains of Colorado and Wyoming. As climate change and steady demand are putting a strain on the river’s supplies, scientists have sought to develop a better understanding of how snow behaves and give policymakers a more nuanced idea of how to manage reservoirs.

Water managers often see a gap between the amount of water they expect to melt into rivers and streams each year and the amount that actually does. A number of climate factors are to blame, such as dry, thirsty soil that soaks up snow melt on its way downhill.

This new data, published in the Bulletin of the American Meteorological Society, helps explain how sublimation also contributes to that gap.

Lundquist said it will help make snow prediction models more accurate. This winter, models projected that 30 %-40% of snow would be lost to sublimation. She and her students found that about 10% of snow was actually lost to sublimation, less than models predicted.

“Before this study, there was no place you could get enough measurements to evaluate whether your model was getting all of the different processes right,” Lundquist said.

In March 2023, KUNC visited the research site to watch data collection in progress. It involved a network of more than 100 high-tech sensors, plus a small crew of hardy PhD students trekking through the snow with shovels and old-school hardware to gather measurements.

Those researchers found that wind is a major driver of snow sublimation during colder months, and heat from the sun is a major driver during the spring.

Colorado Snow Survey supervisor Brian Domonkos, who was not involved in the study, said he hopes to see more research like this carried out over a wider geographic range.

“One spot is a great start,” he said. “A study of this depth and this breadth, with all of the sensors that they deployed , is a spectacular start. Ideally, we would love to see this same study, sensors and whatnot, distributed across a number of sites in many locations across Colorado.”

The initial study was carried out in Gothic, Colorado, near Crested Butte. Gothic, a once-abandoned 1800s mining town, has long hosted the Rocky Mountain Biological Laboratory. Each year, legions of scientists live in its cabins and study the natural world.

The site, Domonkos said, experiences a wide range of conditions throughout the winter and is a reasonably good representation of other places in Colorado’s mountains.

Lundquist, the study’s author and an engineering professor at the University of Washington, also wants to see more research on the matter going forward, especially during the spring months.

“Science is often led by the motivation of the scientists, and people love to go do research at places you can ski to in the winter, and places you can hike or drive to in the summer,” Lundquist said. “In the mud season, you can’t quite ski or hike or drive very well, and it’s a little bit harder to do. But that’s what we need to do to find the key answers to where the water’s going.”

A greater volume of data about snow could help hone forecasts with wide-reaching implications, as water managers as far away as Phoenix and Los Angeles turn to mountain snow data each year to more accurately plan how much water will be available for cities and farms around the Southwest.

Click the link to read the article on the ENSO blog (NOAA) website (Emily Becker):

May 9, 2024

El Niño weakened substantially over the past month, and we think a transition to neutral conditions is imminent. There’s a 69% chance that La Niña will develop by July–September (and nearly 50-50 odds by June-August). Let’s kick off the ENSO Blog’s tin anniversary with our 121^st ENSO outlook update!

Attention!

First things first: our beloved editor, Rebecca Lindsey, has trained us all very well, including being sure to acquaint our newer readers with the fundamentals of the El Niño/Southern Oscillation climate pattern, or ENSO. ENSO has two opposite phases, La Niña and El Niño, which change the ocean and atmospheric circulation in the tropics. Those changes start in the Pacific Ocean and affect global climate in known ways. El Niño and La Niña can be predicted many months in advance, giving us an early picture of potential upcoming temperature, rain, and snow patterns. When neither El Niño nor La Niña are present and conditions are more normal across the tropical Pacific, well, that’s ENSO-neutral conditions.

Hang 10

There was some discussion this week amongst our ENSO forecast team about whether El Niño, much weakened already early last month, is still present. El Niño is a coupled system, meaning the ocean and atmosphere both exhibit characteristic changes. The atmospheric half of El Niño is harder to detect this month; most of the standard equatorial Pacific atmospheric indicators (rain and clouds over the tropical Pacific, trade winds and upper-level winds) were pretty close to average.

However, the April average sea surface temperature in the tropical Pacific was still 0.8 °C above average according to the ERSSTv5 dataset (average = 1991–2020). The latest weekly measurement, which comes from the OISSTv2 dataset, was 0.5 °C above average. Given that the El Niño threshold is 0.5 °C, the team decided we’re right on the edge of the transition to neutral conditions.  We also can’t rule out some lingering El Niño impacts in other regions of the world. 

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Once this El Niño ends, it’s likely that our spell of neutral conditions won’t be a long one, with La Niña expected to develop by the late summer and last through the early winter at least.

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We’ve seen a quick switch from El Niño to La Niña several times before in our 1950–present record, especially after a strong El Niño. This tendency is one source of confidence in the prediction that La Niña will develop later this year.

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Other factors that provide confidence that La Niña is on the way include forecasts from computer climate models and cooler-than-average water under the surface of the tropical Pacific.

10-count

Even if the sea surface temperature in the tropical Pacific lingers near the El Niño threshold for a few weeks, it’s unlikely that there will be noticeable El Niño impacts on global climate conditions this coming summer. Nat looked at how the winter turned out in the US in his recent post, but El Niño causes changes in rain and temperature patterns all around the world, with related impacts on drought, food supplies, and flooding. You can look at El Niño and La Niña’s global patterns of temperature and rain/snow throughout the seasons here.

To get some insight into how this past winter turned out in other regions, I checked in with Steven Fuhrman of NOAA Climate Prediction Center’s International Desk (footnote). Steven had this to say about the effects from El Niño since December:

While many El Niño-related shifts in temperature and rain/snow are strongest during the Northern Hemisphere winter (December–February), some start earlier and last longer, especially in the tropics. One example is a tendency for drier and warmer conditions in central America and northern South America from September through March or April. Rebecca wrote about the impacts on the Amazon Rainforest back in the fall. Steven added this recap:

El Niño’s and La Niña’s shifts in temperature and rain impact communities around the world, including affecting global health and crop yields. This is why we spend so much time studying and predicting ENSO—it can provide an early heads-up of the possibility of severe impacts and allow people time to prepare.

Double digits

Speaking of so much time—who would have thought when we launched this blog back in May 2014 that we’d still have so much to say, 10 years later? In upcoming months, we’ll keep you posted on the ENSO forecast and discuss some of the climate shifts that can be expected during La Niña, including the likelihood of an active Atlantic hurricane season and drier winter conditions through the Southwest U.S. Also, I just checked our “ENSO Blog ideas” doc, which currently runs five pages long, so… here’s to another 10??

Footnote

Fun fact: For many years, Steven and I have regularly donated blood at our local hospital, along with some of our friends. There’s a national blood shortage in the U.S. right now—please consider visiting your local blood donor center!

22% of the Lower 48 is short/very short; 3% less than last week. Much of the US improved last week. Conditions declined in some states along the East Coast. Already dry soils dried out further in NM & CO.