Click here to read the report. Here’s the executive summary:

Rivers are crucial to supporting biodiversity and providing ecosystem services such as clean drinking water and recreation opportunities, offering far more value to people, wildlife, and ecosystems than might be expected given their small global footprint. Yet rivers are under increasing threat as the climate warms and our populations grow, placing greater stress and demand on freshwater resources. Despite their life-giving importance, few rivers and streams are currently protected from human impacts to their integrity and flow. We have the opportunity now to protect more of these waterways in the United States through a variety of mechanisms.

We offer a rigorous assessment of wild rivers that are currently unprotected and, using various criteria for evaluating their ecological value, quantify and highlight those that are most ecologically important to protect. We focused in particular on identifying rivers and streams throughout Colorado with the highest potential for Outstanding National Resource Water (ONRW) designation, although we anticipate the data provided to be valuable for supporting river protection through other mechanisms, such as the federal Wild and Scenic Rivers Act. Here, we connect designation criteria to statewide data to identify rivers with the greatest potential to achieve formal protection via ONRW designation. We summarize our key findings and map these rivers statewide to help visualize the “best of the best” river segments and other ecologically important places to seek new protections.

Our assessment shows that, of the 15,221 miles considered, rivers and streams with the highest ONRW potential are distributed widely across western Colorado, while most rivers east of the Front Range do not achieve sufficient water quality to be considered further for ONRW designation. In all, 662 river miles demonstrate outstanding overall value in that they score in the top 25% of all rivers statewide for every ONRW criterion, including water quality, ecological significance, recreational value, and absence of human modification, attributes that do not coincide as strongly elsewhere. It is important to note that Colorado requires water quality data for potential designation; unmeasured rivers and streams were excluded from consideration. Colorado’s rivers support a variety of aquatic species identified by the state as Species of Greatest Conservation Need (SGCN); 1,881 river miles are within the ranges of at least five aquatic SGCN. An impressive 12,600 river miles across western Colorado have sufficient water quality to support all beneficial uses, including drinking water; protection of any of these waters would help to maintain provision of this vital ecosystem service for generations to come. At the watershed level, the headwaters of the Dolores River are extraordinary in representing the greatest total river miles with high ONRW potential in a single watershed.

In short, thousands of river miles across Colorado—western Colorado, in particular—possess a wide range of ecological values and ecosystem services worthy of protection, whether through state-level designations, federal Wild & Scenic designation, or other available mechanisms. This assessment and the data accompanying it offer scientifically grounded support for identification of the values associated with rivers, streams, and watersheds across Colorado that can inform and support efforts to ensure those values persist.

From The Colorado Sun (Olivia Prentzel):

At least 54% of the state now is experiencing drought conditions, compared to 100% this time last year. But record-breaking heat and a dry winter could mean conditions worsen, a climatologist says.

As drought loosened its grip across nearly half Colorado in the past year, parts of Colorado could see conditions worsen in the coming months due to an autumn and winter that experts say will be hotter and drier than normal.

About 52% of the state’s geographic area now faces some type of drought — ranging from abnormally dry to exceptional drought. This time last year, the entire state was plagued by the lack of rain, according to the U.S. Drought Monitor. While the drought was somewhat eased by the summer monsoon season, already punishing drought conditions have begun to worsen, with the most severe impacts hitting the Western Slope.

Record-breaking heat coupled with a dry winter forecast could mean that drought in Colorado will likely get worse in the coming months, according to Peter Goble, a climatologist with the Colorado Climate Center at Colorado State University.

“The outlook is not encouraging,” Goble said. “It looks like summer is going to hang on here for a little while and as we look forward to winter, (we’re) looking at a high probability of another La Nina year,” he said, the second La Nina winter in a row…

“In recent history, those double-dip La Nina years — or years we have it come back a second time — have been quite dry across the center of the country and only really wet in the northwest and northeast corners,” Goble said. “If that pattern were to resurface, we could see drought conditions worsen over the next three to nine months.”

[…]

Colorado also saw its fourth warmest June through August period on record, Goble said…

Now, about 15% of the state is seeing conditions of the severity recorded last September, maps show.

Despite the decrease, Goble said he’s still concerned about the state’s current drought conditions and for what’s to come.

“The biggest thing that concerns me is, as good as the precipitation was in western Colorado over the summer, we didn’t see that big of a recovery to the overall water supply system or our lakes, streams and reservoirs,” he said…

In the east, worsening drought conditions also raise concerns regarding the winter wheat planting season. Without a layer of moisture in the top level of soil, it becomes harder for seeds to stay put and can affect how much grows, he said.

Xubin Zeng, University of Arizona

Extreme rainfall and flooding have left paths of destruction through communities around the world this summer. In New York City, remnants of Hurricane Ida flooded streets and subway lines as more than 3.15 inches of rain fell in an hour and more than 7 inches fell in all on Sept. 1-2, 2021. A week earlier in Tennessee, a record-shattering 17 inches of rain fell in 24 hours, turning creeks into rivers that flooded hundreds of homes and killed 20 people.

A lot of people are asking: Was it climate change? Answering that question isn’t so simple.

There has always been extreme weather, but human-caused global warming can increase extreme weather’s frequency and severity. For example, research shows that human activities such as burning fossil fuels are unequivocally warming the planet, and we know from basic physics that warm air can hold more moisture.

A decade ago, scientists weren’t able to confidently connect any individual weather event to climate change, even though the broader climate change trends were clear. Today, attribution studies can show whether extreme events were affected by climate change and whether they can be explained by natural variability alone. With rapid advances from research and increasing computing power, extreme event attribution has become a burgeoning new branch of climate science.

The latest attribution study, released Aug. 23, 2021, looked at the rainfall from the European storm that killed more than 220 people when floods swept through Germany, Belgium, Luxembourg and the Netherlands in July 2021.

A team of climate scientists with the group World Weather Attribution analyzed the record-breaking storm, dubbed Bernd, focusing on two of the most severely affected areas. Their analysis found that human-induced climate change made a storm of that severity between 1.2 and nine times more likely than it would have been in a world 1.2 degrees Celsius (2.1 F) cooler. The planet has warmed just over 1 C since the industrial era began.

Similar studies haven’t yet been conducted on Hurricane Ida’s rainfall or the Tennessee storm, but they likely will be.

So, how do scientists figure this out? As an atmospheric scientist, I have been involved in attribution studies. Here’s how the process works:

How do attribution studies work?

Attribution studies usually involve four steps.

The first step is to define the event’s magnitude and frequency based on observational data. For example, the July rainfall in Germany and Belgium broke records by large margins. The scientists determined that in today’s climate, a storm like that would occur on average every 400 years in the wider region.

The second step is to use computers to run climate models and compare those models’ results with observational data. To have confidence in a climate model’s results, the model needs to be able to realistically simulate such extreme events in the past and accurately represent the physical factors that help these events occur.

The third step is to define the baseline environment without climate change – essentially create a virtual world of Earth as it would be if no human activities had warmed the planet. Then run the same climate models again.

The differences between the second and third steps represent the impact of human-caused climate change. The last step is to quantify these differences in the magnitude and frequency of the extreme event, using statistical methods.

For instance, we analyzed how Hurricane Harvey in August 2017 and a unique weather pattern interacted with each other to produce the record-breaking rainstorm in Texas. Two attribution studies found that human-caused climate change increased the probability of such an event by roughly a factor of three, and increased Harvey’s rainfall by 15%.

Another study determined that the western North American extreme heat in late June 2021 would have been virtually impossible without human-caused climate change.

How good are attribution studies?

The accuracy of attribution studies is affected by uncertainties associated with each of the above four steps.

Some types of events lend themselves to attribution studies better than others. For instance, among long-term measurements, temperature data is most reliable. We understand how human-caused climate change affects heat waves better than other extreme events. Climate models are also usually skillful in simulating heat waves.

Even for heat waves, the impact of human-caused climate change on the magnitude and frequency could be quite different, such as the case of the extraordinary heat wave across western Russia in 2010. Climate change was found to have had minimal impact on the magnitude but substantial impact on the frequency.

There can also be legitimate differences in the methods underpinning different attribution studies.

However, people can make decisions for the future without knowing everything with certainty. Even when planning a backyard barbecue, one does not have to have all the weather information.

Read more:
The water cycle is intensifying as the climate warms, IPCC report warns – that means more intense storms and flooding

This article was updated Sept. 2, 2021, with the New York City flooding.

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Xubin Zeng, Professor of Atmospheric Sciences and Director of the Climate Dynamics and Hydrometeorolgy Center, University of Arizona

This article is republished from The Conversation under a Creative Commons license. Read the original article.

From NOAA (Jessica Merzdorf Evans):

Seasonal summer rains have done little to offset drought conditions gripping the western United States, with California and Nevada seeing record July heat and moderate-to-exceptional drought according to the National Oceanic and Atmospheric Administration (NOAA). Now, new NASA research is showing how drought in the region is expected to change in the future, providing stakeholders with crucial information for decision making.

The study, published in the peer-reviewed journal, Earth’s Future, was led by scientists at NASA’s Goddard Institute for Space Studies (GISS) and funded by NOAA’s Climate Program Office and NASA’s Modeling, Analysis and Prediction (MAP) Program. It found that the western United States is headed for prolonged drought conditions whether greenhouse gas emissions continue to climb or are aggressively reined in.

However, the study also showed that the severity of acute, extreme drought events and the overall severity of prolonged drought conditions can be reduced with emissions-curbing efforts compared to a high-emissions future. This is important information for decision-makers considering two tools they can use to reduce climate impacts: Adaptation and mitigation.

Adaptation is a term used by the scientific community and policymakers to describe policies that address impacts that will occur or are already occurring. For example, adaptation to rising sea levels might include relocating low-lying infrastructure. By contrast, mitigation – efforts to reduce the amount of greenhouse gases in the atmosphere – can limit the severity of future impacts or even prevent them from happening by limiting how much the climate changes. Switching to cleaner energy sources and reducing greenhouse warming-driven ice melt are examples of mitigation to sea level rise.

Rather than representing competing options, adaptation and mitigation can both be used to address climate impacts. This new research shows how the two can complement each other when it comes to drought.

“Mitigation has clear benefits for reducing the frequency and severity of single-year droughts,” said lead author Ben Cook, a research scientist at GISS and an adjunct associate research scientist at Columbia University. “We may have more of these 20-year drought periods, but if we can avoid the really sharp, short-term, extreme spikes, then that may be something that’s easier to adapt to.”

Turning to the Past to Understand the Future

Both acute single-year and prolonged multi-year droughts occur naturally due to variations in ocean currents, precipitation and other factors. But climate change is turning up the heat in addition to these natural variations, causing even more water to evaporate from plants and soil, resulting in increased dryness even in the absence of major precipitation deficits.

To understand the southwest’s vulnerability and tendency towards drought and the factors that contribute to it, the team selected the severe single-year drought of 2002 and the extended drought of 2000 to 2020 as examples of acute and prolonged droughts respectively. They then looked at how common these acute and prolonged droughts were, not only during the period of instrumental records, but also using reconstructed drought conditions stretching back more than a thousand years and state-of-the-art supercomputer simulations of the future.

The team reconstructed soil moisture from the years 800 to 1900 using tree ring data from the region. The thickness of tree rings varies due to the wetness or dryness of each year, providing scientists with a reliable way of estimating how much rain fell in a given year. For years after 1900, they used directly measured soil moisture values. To look at a range of possible futures, the team used data from the latest version of the Coupled Model Intercomparison Project, or CMIP6. CMIP6 is an ensemble of climate model simulations that provide climate change projections depending on a range of possible greenhouse gas emission scenarios, allowing scientists and policymakers to directly compare the impacts of different emissions policies. And under different emissions scenarios, drought behaves differently.

The southwestern United States has been prone to drought for millennia. But warming temperatures dry the soil further, and the region’s natural aridity becomes the backdrop for a higher risk of severe and prolonged droughts if greenhouse gas emissions continue to climb, said Kate Marvel, a research scientist at GISS and Columbia University.

“The paleoclimate record shows that this region is prone to drought,” she said. “There have been really, really severe droughts in the past: For instance, we know there were megadroughts in the 13th century. But against the backdrop of natural climate variability — the things the climate would do even without human influence — we are confident increases in greenhouse gases make the temperature rise, and we’re fairly confident that increases drought risk in this region.”

A Future Not Yet Set in Stone

Understanding that some amount of increased drought can be expected under high and low emission scenarios alike has implications for adaptation strategies like rationing water usage and changing agricultural practices. At the same time, the study’s finding that greenhouse emissions reductions still matter for extreme drought underscores the value of mitigation.

“The ongoing southwestern drought highlights the profound effects dry conditions have on people and the economy,” said Ko Barrett, senior advisor for climate in NOAA’s Office of Research and vice-chair of the Intergovernmental Panel on Climate Change’s Sixth Assessment Report. “The study clearly highlights the impact that greenhouse gas mitigation could have on the occurrence and severity of Southwestern drought. It is not too late to act and blunt impacts like severe Southwestern drought periods and short-term drought events.”

Marvel agreed. “There’s going to be a new normal regardless,” she said. “There’s going to have to be some adaptation to a drier regional climate. But the degree of that adaptation – how often these droughts happen, what happens to the drought risk – that’s basically under our control.”

Click here to read the summary. Here’s an intro from email:

A continued active monsoon pattern has resulted in further improvements to drought conditions over western Colorado while short-term abnormally dry spots have popped up over eastern Colorado.

Overall, August 2021 was what we typically expect to see, especially in recent years – hot temperatures, dry conditions, the occasional spotty shower. And similar to many of our recent years, the month ended warmer and drier than average.

For western Colorado, summer 2021 was HOT! In fact, this makes 7 summers out of the last 10 years that have been warmer than average. This was the second hottest summer in the record, going back 127 years. The hottest summer was 2018.

From Circle of Blue (Laura Gersony):

The climate crisis will jeopardize key sources of fresh water and make extreme weather events more severe. But experts say there’s still time to prevent the worst outcomes.

Extreme droughts affecting agriculture and ecosystems are already more frequent and intense than they were last century. This trend will continue as glacial melting, decreased rainfall, and a “thirstier” atmosphere jeopardize sources of freshwater in some parts of the globe.

Heavy rainfall will also become more common and more powerful.

There are a handful of high-impact “tipping points” that could drastically change global or regional water cycles. These events are unlikely in our current climate—but the warmer Earth gets, the bigger the risk becomes.

With swift, drastic action, warming could still be limited to 1.5 or 2 degrees Celsius, avoiding the worst-case scenarios for freshwater.

William R. Cotton, Colorado State University

Wildfires burn millions of acres of land every year, leaving changed landscapes that are prone to flooding. Less well known is that these already vulnerable regions can also intensify and in some cases initiate thunderstorms.

Wildfire burn scars are often left with little vegetation and with a darker soil surface that tends to repel rather than absorb water. These changes in vegetation and soil properties leave the land more susceptible to flooding and erosion, so less rainfall is necessary to produce a devastating flood and debris flow than in an undisturbed environment.

Burn scars can also initiate or invigorate thunderstorms, raising the risk both of flooding and of lightning that could spark more fires in surrounding areas, as my research with fellow atmospheric scientist Elizabeth Page has shown.

Factors contributing to thunderstorms

Three things contribute to the potential for burn scars to fuel thunderstorms: lack of vegetation, reduced soil moisture and lower surface albedo – essentially how well it reflects sunlight. When burned soil is darker, it absorbs more energy from the sun.

These factors contribute to higher surface temperatures over the burn scar area relative to unburned areas nearby. The temperature difference can drive air currents, causing convection – the motion of warmer air rising and cooler air sinking. When that rising warm air draws in more humid air from surrounding areas, it can produce cumulonimbus clouds and even thunderstorms that can trigger rain and flooding.

In an analysis of a flash flood that occurred on burn scars in Australia in 2003, scientists found that the soil’s moisture was low and its albedo in the burn area had fallen from 0.2 to 0.08. To put that into perspective, charcoal has an albedo of about 0.04 and fresh snow is nearly the maximum of 1. When the scientists simulated those changes in a computer model, they found that if the land hadn’t been burned, just over a tenth of an inch of rain would have fallen. Instead, those changes led to 1.25 inches and severe flooding.

Studies have found that the intensity of this effect of burn scars on storm potential decreases over time, but the risk remains until the vegetation regrows.

Riding the thermals

When I used to pilot sailplanes, also known as gliders, I often rode the thermals – upward currents of warm air – in the Santa Catalina Mountains near Tucson and in Colorado’s Front Range. The best locations for catching thermals were on the south and southwest slopes of rugged terrain, where the thermals became chutes of rapidly rising air.

A wildfire in one of these locations would burn more intensely because of the swift air currents, leaving a dark, water-repelling surface with little vegetation behind. With moisture from the Southwest Monsoon that arrives in the region in late summer, these thermal chutes, intensified by burn scars, are prime locations for initiating or intensifying storm-producing cumulonimbus clouds and flooding.

In these arid regions, plant recovery may take three to five years or more, particularly in locations where intense fires burned on south- and west-facing slopes where sunlight is more intense. Many of the record-breaking 2020 wildfires in Colorado and Arizona occurred in mountainous terrain where flash flooding on burn scars has been deadly in the past. These areas will continue to be of particular concern over the next few years.

The effects can linger

How long burn scars will continue to fuel storms depends on how arid the region is and how quickly vegetation recovers.

Forecasters, emergency responders and people living in and near wildfire burn scars need to be aware that these areas are at risk both for potential major flooding and debris flows, and for invigorated storms with a potential for heavy precipitation.

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William R. Cotton, Professor Emeritus of Meteorology, Colorado State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

From NOAA:

During meteorological summer (June-August), the average temperature for the Lower 48 was 74.0°F, 2.6°F above average, nominally eclipsing the extreme heat of the Dust Bowl in 1936 by nearly 0.01°F and essentially tying 1936 for the warmest summer on record. A record 18.4 percent of the contiguous U.S. experienced record-warm temperatures for this season. For August, the contiguous U.S. average temperature was also 74.0°F, 1.9°F above the 20th-century average and ranked as the 14th-warmest August on record. For the year to date, the contiguous U.S. temperature was 55.6°F, 1.8°F above the 20th-century average, ranking 13th warmest in the January-August record.

The summer precipitation total across the Lower 48 was 9.48 inches, 1.16 inches above average, ranking eighth wettest in the historical record. The August precipitation total for the contiguous U.S. was 3.09 inches, 0.47 inch above average, ranking 14th wettest in the 127-year period of record. The year-to-date precipitation total across the contiguous U.S. was 21.19 inches, 0.48 inch above the long-term average, ranking in the middle third of the January-August record.

Devastating flash flooding and fatalities resulted from multiple events during August including Tropical Storm Fred in western North Carolina, convective flooding from a complex of storms across middle Tennessee, Hurricane Ida across Louisiana and portions of the Northeast in early September and from Tropical Storm Henri, also across parts of the Northeast. With 35 fatalities accounted for during August*, it was the deadliest month for flooding across the U.S. since Hurricane Harvey in 2017.

Wildfires continued to spread across the western U.S. during August as the Dixie Fire in north-central California became the second-largest fire in the state’s history. The Caldor Fire also in California grew rapidly during August, threatening South Lake Tahoe communities. Air quality remained a concern across the U.S. as ash and fine particulates from the many wildfires obscured the skies.

*The remnants of Hurricane Ida impacted the Northeast in early September, raising the 2021 fatality count outside of the August observation period.

This monthly summary from NOAA National Centers for Environmental Information is part of the suite of climate services NOAA provides to government, business, academia and the public to support informed decision-making.

August
Temperature

August temperatures were above average across the West Coast, Southwest and from the Plains to the East Coast. Vermont and New Hampshire both had their warmest August on record while Maine and Massachusetts ranked second warmest. Much of the above-average warmth can be attributed to warm overnight temperatures. Temperatures were near to below average across much of the northern Rockies and the southern Plains.

The Alaska average August temperature was 49.4°F, 0.1°F below the long-term mean, ranking in the middle third of the 97-year period of record for the state. Temperatures were above average across portions of the Southeast Interior, Panhandle and Aleutian regions. Temperatures were cooler than average across the North Slope, Northeast Interior, northern West Coast and parts of Bristol Bay. A persistent cold low-pressure system over the northern Chukchi-Beaufort Seas during August contributed to the cooler-than-average temperatures and the largest observed sea ice extent over the Chukchi Sea since 2006.

Precipitation

Precipitation was above average across portions of the central and northern Rockies, the northern Plains, Great Lakes and from the Deep South to southern New England. Mississippi ranked fourth wettest while Tennessee had its fifth-wettest August on record. The Southwest monsoon continued to be active in August, eliminating much of the year-to-date precipitation deficit across the region. Tucson, Arizona, had its wettest August and second-wettest summer on record. Precipitation was below average across portions of the West, southern Rockies, central Plains, Midwest, northern Great Lakes and northern New England.

Statewide precipitation for Alaska was above average for August, but varied by region. Precipitation was below average across the Aleutians, Bristol Bay and Northwest Gulf regions while the interior regions, Northeast Gulf and Panhandle regions experienced above-average precipitation for the month.

According to the August 31 U.S. Drought Monitor report, approximately 46.6 percent of the contiguous U.S. was in drought, slightly more than the coverage at the beginning of August. Drought conditions expanded or intensified across the Northern Tier, the Pacific Northwest and portions of California. Drought coverage and/or intensity lessened across parts of the Four Corners region, the Midwest, Hawaii and Puerto Rico and was eliminated in Alaska.

An additional note on Hurricane Ida precipitation and temperature implications: As is typical with very heavy rainfall events, localized bands of very heavy rain may not be completely captured by the gauge-based observing network, which is the basis for this analysis. This circumstance can lead to an underrepresentation of actual rainfall totals. The issue can be compounded by disruptions to the observers’ ability to report values during or following a severe event and, in this case, several of our reporting stations posted missing data for both temperature and precipitation during this event. Additionally, quality assurance routines may flag large valid precipitation values as erroneous, resulting in underestimated values. NCEI is working to ensure all reports are indeed validated. As a result, a more complete accounting of the temperature statistics and precipitation across Louisiana during August will be available with the September report.

Summer (June-August)
Temperature

Summer temperatures were above average to record warmest from the West Coast to the Great Lakes and into the Northeast as well as across portions of the Mid-Atlantic and Gulf Coast. California, Nevada, Utah, Oregon and Idaho each reported their warmest June-August on record. Sixteen additional states had a top-five warmest summer on record. No state ranked below average for the summer season. Temperatures were below average across portions of the southern Plains and Southeast. Warm overnight temperatures heavily influenced the warm summer temperatures, especially across portions of the Southeast, where daytime temperatures were below average for the season.

The Alaska statewide average temperature for the summer was 51.4°F, 1.0°F above average and ranked in the warmest one-third of the 97-year record. Temperatures were warmer than average across much of the eastern half of the state as well as across the Aleutians and near average for much of the rest of the state.

Precipitation

Precipitation was above average across portions of the Great Basin and Southwest, from the southern Plains to the Great Lakes and across much of the eastern U.S. Mississippi had its wettest summer on record with Alabama, Michigan, New York and Massachusetts ranking among their five wettest summers on record. Precipitation was below average from the Northwest to the western Great Lakes and into the central Plains. Minnesota had its seventh-driest summer on record.

Precipitation in Alaska was above average across much of the northern half of the state as well as across portions of the Northeast Gulf and Panhandle regions. Precipitation was below average in the southwestern portion of the state. Kotzebue had its wettest summer on record, reporting 9.21 inches and besting the previous record, set in 1963, by nearly an inch. The wildfire season was well-below average with only 254,000 acres consumed — less than half of the median value.

Year-to-date (January-August)
Temperature

Year-to-date temperatures were above average from the West Coast to the Great Lakes and into the Northeast as well as across parts of the Mid-Atlantic and Southeast. California and Maine each reported their third-warmest January-August on record. Sixteen additional states had a top-ten warmest year-to-date period. Temperatures were below average across much of the southern Plains and lower Mississippi Valley.

Year-to-date temperatures across Alaska were near average with above-average temperatures observed across the southwestern portion of the state. Much of the rest of the state experienced near average temperatures for this period.

Precipitation

January-August precipitation was above average from the Deep South to the Midwest, across the Southeast and portions of the Northeast. Mississippi had its third-wettest such year-to-date period on record. Precipitation was below average from the West Coast to the western Great Lakes and across portions of northern New England. Montana ranked fifth driest while three additional states ranked among the driest 10 January-August periods on record.

For Alaska, January-August precipitation was above average across the West Coast, North Slope and from the Central Interior to the Panhandle. Precipitation was below average in parts of the Cook Inlet region.

For more detailed climate information, check out our comprehensive August 2021 U.S. Climate report scheduled for release on September 14, 2021.

Good News, Bad News

Good: Improvements in MN/IA and parts of the Northern/Central Plains after good rainfall

Bad: WA is back to 100% short/very short. MT at 93%

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

US Drought Monitor map September 7, 2021.

High Plains Drought Monitor map September 7, 2021.

West Drought Monitor map September 7, 2021.

Colorado Drought Monitor map September 7, 2021.

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

This Week’s Drought Summary

This U.S. Drought Monitor (USDM) week saw continued improvement in conditions across drought-stricken areas of the Central and Northern Plains states as well as in Iowa and Minnesota where light-to-moderate rainfall accumulations were observed. Despite recent precipitation in the Northern Plains, hay shortages and the associated costs of purchasing and transporting supplemental feed are forcing some ranchers to sell livestock. In response to the emerging situation, the U.S. Department of Agriculture (USDA) announced expansion of emergency assistance through the ELAP program to help cover feed transportation costs for drought-impacted ranchers. In the Northeast, the remnants of Hurricane Ida brought intense, heavy rains (5 to 10+ inches) and devastating flooding to areas of Pennsylvania, New Jersey, New York, and Connecticut. In the Southeast, short-term dryness (past 30- to 60-day period) and declining soil moisture and streamflow levels led to degradation on the map in portions of the Carolinas. In the South, short-term precipitation shortfalls and declining soil moisture levels led to some degradation of conditions in areas of Arkansas and Oklahoma that have largely missed out on recent rainfall events. Out West, dry conditions prevailed across most of the region this week. However, some beneficial rainfall was observed across isolated areas of the Southwest in association with the remnants of Hurricane Nora…

High Plains

On this week’s map, areas of the region—including eastern portions of North Dakota, South Dakota, Nebraska, and Kansas—saw isolated improvements in response to continued rainfall activity. The heaviest rainfall in the region was observed in eastern Kansas where accumulations ranged from 2 to 7 inches, while areas further to the north in Nebraska and the Dakotas received 1-to-4-inch accumulations in isolated areas. For the last 30-day period, the percentage of normal precipitation has ranged from 100 to 300% of normal across a widespread area of the Central and Northern Plains. However, isolated pockets of dryness have persisted—particularly in western portions of the region that have not benefited from the recent rainfall events. According to the USDA for the week ending September 5, the percentage of topsoil in North Dakota rated short to very short was 63%, while neighboring South Dakota was rated 66% short to very short…

West

For the week, most of the region continued to experience dry conditions, although some residual moisture from Hurricane Nora worked its way into the Southwest leading to some isolated shower activity. On this week’s map, improvements were made in isolated areas of Arizona, New Mexico, and Utah where recent monsoonal rainfall has continued to improve drought conditions on a shorter-term basis. For the monsoon season (to date), some impressive rainfall totals have been observed in areas of southern and central Arizona and New Mexico as well as in areas of Utah. In Arizona, Tucson is currently having its 3rd wettest monsoon season on record with 12.41 inches (as of September 7), Flagstaff 10.35 inches (4th wettest), Payson 13.06 inches (2nd wettest), and Las Cruces, New Mexico 5.06 inches (3rd wettest). Elsewhere in the region, much of California, western Great Basin, Pacific Northwest, and the Northern Rockies have experienced drier-than-normal conditions during the past 90-day period. In Washington, drought and associated precipitation deficits dating back to the springtime, combined with extreme summer heat, have severely impacted the state’s wheat crop which is reportedly had its lowest output since 1973. According to the USDA, the percentage of topsoil rated short to very is as follows: Washington 100%, Oregon 89%, Idaho 75%, Montana 93%, Wyoming 70%, and California 85%. According to the Natural Resources Conservation Service (Sept 1), reservoir storage levels were below normal across all the western states except for Washington state (data not yet available for Montana)…

South

After the passing of Hurricane Ida, the region experienced some drying out this week as compared to the previous week’s deluge. For the past 30-day period, above-normal precipitation levels (130 to 300% of normal) have been observed across southeastern Louisiana, Mississippi, and much of Tennessee. Conversely, precipitation has been below normal across much of Arkansas, Texas, and Oklahoma during the past month, leading to expansion of areas of Abnormally Dry (D0). This includes around Tulsa, Oklahoma, which observed only 0.85 inches (normal 3.64 inches) for the month of August and no precipitation to date for September. Elsewhere, some minor improvements were made in an area of Moderate Drought (D1) in the Trans-Pecos region in the vicinity of Big Bend National Park where the Chisos Basin observing station reported 10.42 inches of rain (340% of normal) for the month of August. Likewise, the Pine Springs Guadalupe National Park observing station in the Trans-Pecos logged 8.98 inches (560% of normal) during August 2021. For the week, average temperatures were above normal (3 to 9 deg F) across Texas, Oklahoma, and western portions of Louisiana and Arkansas while areas to the east were 1 to 6 deg F below normal…

Looking Ahead

The NWS WPC 7-Day Quantitative Precipitation Forecast (QPF) calls for moderate-to-heavy rainfall accumulations ranging from 2 to 5+ inches along the Gulf Coast of Texas, Louisiana, Florida Panhandle, and areas of southern Georgia. Across the Mid-Atlantic and the Northeast, light rainfall accumulations (generally < 1 inch) are expected; except for coastal areas of Massachusetts and Maine where accumulations of approximately 2 inches are predicted. In the Midwest, light precipitation accumulations (generally < 1 inch) are forecasted across the eastern half of the region, while areas in the western extent will be drier over the coming week. From the Plains to the West Coast, mainly dry conditions will prevail with the exception of areas of isolated, light precipitation possible across the Central and Southern Rockies and the northern Great Basin, while slightly greater accumulations (generally around 1 inch) are expected in the Northern Rockies. The CPC 6-10-day Outlooks are for a moderate-to-high probability of above-normal temperatures across the northern half of the conterminous United States as well as along the Eastern Seaboard extending into New England. Across much of the Pacific Northwest, North Dakota, and the Upper Midwest, normal temperatures are expected. In terms of precipitation, there is a low-to-moderate probability of above-normal precipitation across New England, the Midwest, the South, and the eastern half of Texas. Below-normal precipitation is expected across most of the Western U.S.

Just for grins, here’s a gallery of early September US Drought Monitor maps for the past several years.

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A new State of the Climate report confirmed that 2020 was among the three warmest years in records dating to the mid-1800s, even with a cooling La Niña influence in the second half of the year. New high temperature records were set across the globe. The report found that the major indicators of climate change continued to reflect trends consistent with a warming planet. Several markers such as sea level, ocean heat content, and permafrost once again broke records set just one year prior. Notably, carbon dioxide (CO2) levels in the atmosphere also reached record highs in 2020, even with an estimated 6%–7% reduction of CO2 emissions due to the economic slowdown from the global pandemic.

These key findings and others are available from the State of the Climate in 2020 report released online today [August 25, 2021] by the American Meteorological Society (AMS).

The 31st annual issuance of the report, led by NOAA National Centers for Environmental Information, is based on contributions from more than 530 scientists from over 60 countries around the world and reflects tens of thousands of measurements from multiple independent datasets (full report). It provides a detailed update on global climate indicators, notable weather events and other data collected by environmental monitoring stations and instruments located on land, water, ice and in space.

The report’s climate indicators show patterns, changes and trends of the global climate system. Examples of the indicators include various types of greenhouse gases; temperatures throughout the atmosphere, ocean, and land; cloud cover; sea level; ocean salinity; sea ice extent and snow cover.

Report highlights include these indications of a warming planet:

• Greenhouse gases were the highest on record. As they do each year, and again in the midst of a global pandemic that slowed economic activity around the world, the major greenhouse gas concentrations, including CO2, methane (CH4) and nitrous oxide, rose to new record high values during 2020. The global annual average atmospheric CO2 concentration was 412.5 parts per million.

  

  This was 2.5 parts per million greater than 2019 amounts and was the highest in the modern 62-year measurement record and in ice core records dating back as far as 800,000 years. The year over year increase of methane (14.8 parts per billion) was the highest such increase since systematic measurements began.

• Global surface temperature was near-record high. Annual global surface temperatures were 0.97°–1.12°F (0.54°–0.62°C above the 1981–2010 average, depending upon the dataset used). This places 2020 among the three warmest years since records began in the mid- to late 1800s.

  

  This was the warmest year on record without the presence of El Niño. The seven warmest years on record have all occurred in the past seven years, since 2014. The global average surface temperature has increased at an average rate of 0.14°F (0.08°C) per decade since the start of the record; since 1981, the rate of increase has been more than twice as high.

• Upper atmospheric temperatures were record or near-record setting. In the region of the atmosphere just above Earth’s surface, the globally averaged annual lower troposphere temperature equaled the record high of 2016. In the layer above that, the lower stratosphere temperature continued to decline, as expected in a warming world.
• Sea surface temperatures were near-record high. The globally averaged 2020 sea surface temperature was the third highest on record, surpassed only by 2016 and 2019, both of which were associated with El Niño conditions.
• Global upper ocean heat content was record high. Globally, upper ocean heat content reached record highs in 2020 in the upper layer measured from the surface to 2,300 feet (700 meters), according to four of the five datasets analyzed in the report. This record heat reflects the continuing accumulation of thermal energy in the top 2,300 feet of the ocean.

Ocean heat content was also record high in the deeper layer beneath, from 700 to 2,000 meter depth, according to all five datasets. Oceans absorb more than 90% of Earth’s excess heat from global warming. The warmer upper ocean waters can drive stronger hurricanes and increase melting rates of ice sheet glaciers around Greenland and Antarctica.

• Global sea level was highest on record. For the ninth consecutive year, global average sea level rose to a new record high and was about 3.6 inches (91.3 millimeter) higher than the 1993 average, the year that marks the beginning of the satellite altimeter record.

Global sea level is rising at an average rate of 1.2 inches (3.0 centimeter) per decade due to changes in climate. Melting of glaciers and ice sheets, along with warming oceans, account for the trend in rising global mean sea level.

• Oceans absorbed a record amount of CO2. The ocean absorbed about 3.0 billion metric tons more CO2 than it released in 2020. This is the highest amount since the start of the record in 1982 and almost 30% higher than the average of the past two decades. More CO2 stored in the ocean means less remains in the atmosphere, but this also leads to increasing acidification of the waters, which can greatly harm or shift ecosystems.

The report also documents key regional climate and climate-related events.

• The Arctic continued to warm; minimum sea ice extent was near-record low. The annual mean surface air temperature for the Arctic land areas was the highest in the 121-year record, at 3.8°F (2.1°C) above the 1981–2010 average. This was the seventh straight year with an annual temperature more than 1°C higher than the 1981–2010 average. On June 20, a temperature of 38°C was observed at Verkhoyansk, Russia (67.6°N), provisionally the highest temperature ever measured within the Arctic Circle. The Arctic continues to warm at a faster pace than lower latitudes. With the warmth came fires. The Arctic experienced its highest fire year in terms of the amount of carbon released into the atmosphere, surpassing the record set in 2019 by 34%. The majority of the fires occurred in northeastern Siberia where abnormally high temperatures also occurred.

In March, when sea ice reached its annual maximum extent, thin, first-year ice comprised ~70% of the ice; the thickest ice—usually more than four years old—had declined by more than 86% since 1985 to make up just 2% of total ice in 2020. When the minimum sea ice extent was reached in September, it was the second smallest in the 42-year satellite record, behind 2012.

The Northern Sea Route along the Siberian coast was open for about 2.5 months, from late July through mid-October, compared to less than a month typically.

• Antarctica saw extreme heat and a record-long ozone hole. Extreme warmth was observed across parts of Antarctica during austral summer, contributing to a major heat wave. On February 6, Esperanza Station reached 64.9°F (18.3°C), the highest temperature ever recorded on the continent, surpassing the previous record set in 2015 by 2.0°F (1.1°C). The warmth also led to the largest late-summer surface melt event in the 43-year record, affecting more than 50% of the Antarctic Peninsula and impacting elevations as high as 1,700 meters.Later in the year, the Antarctic polar vortex was unusually strong and persistent, with polar temperatures in the stratosphere at record low levels throughout November and December. This strong vortex was linked to the longest-lived ozone hole over the Antarctic region, which lasted to the end of December. Record-low ozone values in late austral spring and early summer led to unusually high levels of UV radiation across the Antarctic region.

• Tropical cyclones were well-above average overall. There were 102 named tropical storms during the Northern and Southern Hemisphere storm seasons, well above the 1981–2010 average of 85. Three tropical cyclones reached Saffir–Simpson scale Category 5 intensity. The North Atlantic hurricane basin recorded a record 30 named storms, surpassing the previous record of 28 in 2005. Seven of those storms became major hurricanes, matching 2005 for a record number. Major Hurricanes Eta and Iota made landfall along the eastern coast of Nicaragua in nearly the same location within a two-week period, impacting over seven million people across Central America. In the western North Pacific, Super Typhoon Goni was the strongest tropical cyclone to make landfall in the historical record and led to the evacuation of almost one million people in the Philippines. Very Severe Cyclonic Storm Gati made landfall over Somalia, the first storm of such intensity to do so.

Geographical Regional Highlights

North America

Mexico reported its warmest year in its 49-year record, tied with 2017 and 2019.

The contiguous United States reported its fifth-warmest year. Alaska reported its coolest year since 2012, although it was still warmer than its 1981–2010 average. The annual temperature for Alaska has increased at an average rate of 0.50°C per decade over the past half century.

Most of Mexico was drier than average in 2020 due to the late onset of a weak North American Monsoon and a lack of tropical cyclones on the Pacific side. The United States was dominated by warm, dry air in the West and an active storm track that brought wet conditions to much of the East. In Canada, the Avalon Peninsula in Newfoundland was hit by a strong blizzard with hurricane force winds in January. The storm contributed to the snowiest January on record for Saint John’s.

Central America and the Caribbean

The annual average temperature over the Caribbean basin was the second highest since the start of the record in 1891. Annual average maximum temperatures were record high for stations in The Bahamas, Dominica, and Trinidad and Tobago.

Powerful Category 4 Hurricanes Eta and Iota impacted Central America in November, making landfall along the eastern coast of Nicaragua in nearly the same location within a two-week period.

South America

Most of South America had above-average temperatures during the year. Central South America reported its second-warmest year for the region in its 61-year record, behind only 2015. During a strong heat wave in October, the city of São Paulo, Brazil, recorded four of its five all-time daily maximum temperatures.

The Bolivian lowlands suffered one of its most severe droughts on record during autumn. Drought also spanned the Chaco and Pantanal in Bolivia, Paraguay and southern Brazil. The Paraguay River shrank to its lowest levels in half a century. A decadal “mega drought” in south-central Chile continued through its 11th year, with extreme conditions in the most populated areas. Argentina reported its driest year since 1995.

Africa

Seychelles, an archipelago in the Indian Ocean off East Africa, observed its highest annual temperature in the record dating to 1972. In West Africa, Nuguru, Nigeria, observed about 80 days of maximum temperatures exceeding 104°F (40°C) in 2020, surpassing its previous record of 77 days in 2019.

Extremely heavy rains in April triggered widespread flooding and landslides in Ethiopia, Somalia, Rwanda and Burundi. The Lake Victoria region was the wettest in its 40-year record, and the lake itself rose more than three feet (one meter) due to the excessive rain.

Europe

The year 2020 was the warmest year on record for Europe, with all five of the warmest years occurring since 2014. Record warmth was reported for Belarus, Belgium, European Russia, Estonia, Finland, France, Kazakhstan, Lithuania, Luxembourg, the Netherlands, Norway, Poland, Spain, Sweden, Switzerland and Ukraine.

In February, almost all areas in Europe observed temperatures more than 5°F (3°C) higher than average. Biarritz in southern France reached a temperature of 80.0°F (26.6°C), which is higher than the monthly average for July and August.

The Middle East experienced an extreme drought during autumn, with most places reporting 0%–20% of their typical precipitation in September and no precipitation at all in October.

Asia

In 2020, Japan and Russia each observed their highest annual temperature on record. In northern Siberia, annual temperatures were more than 9°F (5°C) above average across vast territories. The average winter temperature for all of Russia was 5°C above normal. In East Asia, Hong Kong, China, reported 50 hot nights, where the daily minimum temperature did not dip below 82.4°F (28.0°C), and 47 very hot days, where the daily maximum temperature reached at least 91.4°F (33.0°C), both of which set new annual records.

The 2020 Southwest Asian Monsoon season (June–September) was the wettest since 1981, coincident with the emergence of La Niña. The Meiyu season (July–August), a typical rainy season over the Yangtze and Huaihe River Valleys of China, doubled its typical duration by two months in 2020. The May–October total rainfall averaged over the area was the most since the start of the record in 1961. Associated severe flooding affected about 45.5 million people.

As is typical, several tropical cyclones impacted Asia in 2020. Super Typhoon Goni was the strongest storm on record anywhere in the world to make landfall. More than one million people were evacuated from its path in the Philippines. Eight tropical cyclones directly affected Vietnam. Typhoon Molave was one of the most intense storms to reach the country in the past 20 years.

Oceania

Most locations across Micronesia were drier than average during the first half of 2020 and wetter than average at all locations in the second half. For the year, Kosrae was record wet, while Kapingamarangi and Saipan observed near-record low annual rainfall totals.

The last days of 2019 and first days of 2020 saw particularly hazardous fire weather in eastern Australia, where multiple fires had been burning since austral spring 2019. The emergence of La Niña was a welcome change for the Australian region, with this phase of ENSO contributing to increased rainfall over the continent, after a very significant 2019/20 fire season. Even with increased rainfall, this was Australia’s fourth-warmest year in its 111-year record. Both November and spring as a whole had record high temperatures.

Aotearoa, New Zealand, reported its seventh-warmest year since records began in 1909, in part due to its warmest winter on record. La Niña conditions contributed to higher temperatures in the latter part of the year. From late-December 2019 through February 2020, several areas across New Zealand observed record or near-record dry spells, that is, at least 15 consecutive days with less than one millimeter of rain each day. A 64-day dry spell, the longest on record, was reported in Blenheim, a town on the northern tip of the South Island.

The State of the Climate in 2020 is the 31st edition in a peer-reviewed series published annually as a special supplement to the Bulletin of the American Meteorological Society. The journal makes the full report openly available online.