@NOAA: No ENSO? NOAA still issues Winter Outlook!

From NOAA (Mike Halpert):

While I’ve usually written this post in October, this year we decided to wait until a month before winter (December–February) starts. In past years, we’ve asked if El Niño (or La Niña) will play a role in the winter’s outcome. This year is different, however, as ENSO-neutral is present and expected to persist through the winter and into the spring. So what does NOAA’s Climate Prediction Center (CPC) base their winter outlook on when ENSO-neutral is in the cards? Read on to find out.

Other clues for seasonal prediction

Aside from ENSO, the recent trend in temperature and precipitation turns out to be the most skillful predictor on seasonal time scales. As Tom said in his post on the topic, “simply put, the trend is how temperatures and precipitation have changed over some length of time.” Trends are actually more skillful overall than ENSO for informing temperature forecasts, largely because of the patterns from global warming due to human-emitted greenhouse gases. However, ENSO trumps trends for precipitation. When El Niño or La Niña is a no-show, though, trends often become the primary consideration for both temperature and precipitation.

When CPC makes seasonal outlooks, predictions are always relative to the recent three decades (or “base period”). Right now, that base period is from 1981 to 2010, so, for example, the outlook is the chance that winter will be warmer or cooler than the average during 1981–2010. CPC utilizes trends by comparing the most recent 15 winters to the base period because studies have shown that this maximizes the skill in the forecasts. So for this upcoming winter of 2019–20, we compare the winter averages from 2004 through 2019 to the base period. Tom’s article has a lot more detail about how this 15-year idea, called the “Optimum Climate Normal,” was developed.

The climate trends, defined as the Optimum Climate Normals, for winter (December–February) temperatures across the United States. The trend is determined by taking the average winter temperatures over the last 15 years and subtracting the average winter temperatures from 1981-2010. NOAA Climate.gov image using data from the Climate Prediction Center.

The temperature trend map (1) shows that warmer-than-average winters have become more prevalent across the South and up the East Coast, with the largest trends in California, the Southeast and Florida. Interestingly, trends in much of the central and northern Plains and the Pacific Northwest are quite flat, with even a few regions in Nebraska, South Dakota, and Washington State trending colder during recent winters. This does not mean that global warming is making these regions colder—rather, recent winters have shown a large range of temperature changes, what we call “interannual (year-to-year) variability,” that are likely obscuring the influence of increasing greenhouse gases in these regions.

The climate trends, defined as the Optimum Climate Normals, for winter (December–February) precipitation amounts across the United States. The trend is determined by taking the average winter precipitation over the last 15 years and subtracting the average winter precipitation from 1981-2010. NOAA Climate.gov image using data from the Climate Prediction Center.

In a general sense, trends in rain, snow, and other forms of water falling from the sky (precipitation!) favor above-average across much of the northern part of the country, with trends toward drier-than-average conditions along the West Coast, the southern Plains and along the Atlantic South Coast. Both the temperature and precipitation trends share some resemblance to the patterns we would expect during La Niña (northward shift in the jet stream), although temperature trends are warmer compared to historical La Niña patterns, and precipitation trends are somewhat wetter (2).

CPC also uses computer model predictions for the forecasts, leaning on them more during ENSO-neutral times. In this case, the model forecasts (temperature, precipitation) are somewhat consistent with the trends, although most of the model forecasts are even warmer than what would be expected from the recent 15-year trend. The precipitation forecasts have a wide range of possible outcomes, although the average of all model forecasts generally favors wetter-than-average across the northern part of the country with drier-than-average conditions across parts of the South, so again—mostly consistent with trends.

To the outlook!

The temperature outlook favors above-average temperatures across the western, southern, and eastern parts of the nation, and Alaska and Hawaii (not shown here).

Places where the forecast odds favor a much colder than usual winter (blue colors) or much warmer than usual winter (red), or where the probability of a cold winter, a warm winter, or a near-normal winter are all equal (white). The darker the color, the stronger the chance of that outcome (not the bigger the departure from average). NOAA Climate.gov map, based on data from NOAA CPC. Seasonal temperature outlook through February 29, 2020 via CPC.

Other than over Hawaii and western Alaska, probabilities are all between 33-50%, indicating the confidence of this outlook is less than for other winter outlooks. This lower confidence is partly due to the absence of ENSO’s influence.

Places where the forecast odds favor a much drier than usual winter (brown colors) or much wetter than usual winter (blue-green), or where the probability of a dry winter, a wet winter, or a near-normal winter are all equal (white). The darker the color, the stronger the chance of that outcome (not the bigger the departure from average). NOAA Climate.gov map, based on data from NOAA CPC. Seasonal precipitation outlook through February 29, 2020 via CPC.

The precipitation outlook shows that wetter-than-average conditions are favored over much of the northern part of the country, as well as Hawaii and Alaska (not shown). Below-average precipitation is only favored over central and southern California and southern Arizona and in parts of the southern Plains. Again, confidence is quite modest, with probabilities only exceeding 50% over Hawaii and southwestern Alaska.

Both maps include blank regions where neither above-, near- nor below-normal is favored. These areas (shown in white and labeled EC for “equal chances”), have the same chance for above, near, or below-normal (33.33%). This doesn’t mean that near-average temperature or precipitation is favored this winter in those regions, but rather that there’s no tilt in the odds toward any outcome.

And I would be remiss if I didn’t again provide a reminder that these forecasts are probabilities (% chance) for below-, near-, or above-average outcomes with the maps showing only the most likely outcome (3). Because the probabilities shown are less than 100% (of course), there is no guarantee you will see temperature or precipitation departures that match the color on the map. As we’ve explained in earlier blog posts, even when one outcome is more likely than another, there is still always a chance that a less favored outcome will occur (last winter’s forecast for the northern Plains and Pacific Northwest are a good example of the less likely outcome occurring).

CPC issues probabilistic seasonal temperature and precipitation forecasts so users can understand risk and opportunities in order to make informed climate-sensitive decisions. However, the nature of a probabilistic forecast means that other outcomes are always possible, just less likely. In fact, for our probabilities to be “reliable,” the less likely outcomes will and must occur from time-to-time.

Footnotes
(1) These maps show temperature and precipitation trends in standard deviation, which is a way of showing the change relative to the usual range.

(2) Our own Nat Johnson speculated on why the global temperature and precipitation trends resemble La Niña: sea surface temperature trends over the past decades are La Niña-like, with overall somewhat cooler-than-average trends in the central and eastern tropical Pacific, and so the trends over North America are likely to reflect, in part, decadal to multidecadal La Niña-like sea surface temperature variability. Global warming interacts with this La Niña-ish trend, leading to a warming pattern mostly where La Niña-like and global warming effects add together, and small changes to temperature patterns where they are opposite. The global warming precipitation signal is generally similar to the La Niña pattern, with more precipitation north and less south, so perhaps the La Niña pattern and global warming are working together in this case.

(3) The terciles, technically, are the 33.33 and 66.67 percentile positions in the distribution. In other words, they are the boundaries between the lower and middle thirds of the distribution, and between the middle and upper thirds. These two boundaries define three categories: below-normal, near-normal and above-normal. The CPC forecasts show the probability of the favored category only when there is a favored category; otherwise, they show EC (“equal chances”). In the maps, the probability is shown only for the favored category, but not for the other two categories. Often, the near-normal category remains at 33.33, and the category opposite the favored one is below 33.33 by the same amount that the favored category is above 33.33. When the probability of the favored category becomes very large, such as 70% (which is very rare for a seasonal outlook), this rule for assigning the probabilities for the two non-favored categories becomes different.

Happy Thanksgiving

It only takes one voice, at the right pitch, to start an avalanche ~Dianna Hardy (Wolf Conservation Center)

This year I am thankful for so much but especially the young people (particularly Greta Thunberg) that are calling out climate deniers and the folks that are dragging their feet about the climate crisis. It’s your future and it’s about damn time for the world to listen.

From Cool Green Science (Joe Fargione):

This time of year always reminds me that we have so much to be thankful for. But we also have a lot to be concerned about. Climate change, for example.

Climate change can be difficult to talk about, especially with family and friends. In fact researchers have found that roughly 6 in 10 Americans rarely, if ever talk about climate change with their friends or family. And it can be hard to know where to start. Thankfully, The Nature Conservancy has developed a set of resources, including a handy guide that you can download with tips for how to approach the conversation for best results.

In addition to arming yourself with the right approach to the conversation, it helps to have good information. Here are the four essential things that everyone should know about climate change. And they’re simple enough that you can explain them while you’re passing the gravy, even if your little niece or nephew is throwing peas at you from across the table.

It’s Warming.

The Earth has already warmed by 1.7 degrees Fahrenheit (0.98 degrees C), continuing the warming trend we’ve seen since the industrial revolution. It is now warmer than it has been in the past 125,000 years.

It’s Us.

In theory, things other than human emissions of greenhouse gases could have caused changes in the temperature of the planet. Scientists have already studied all of these things. The conclusion is clear: only greenhouse gas emissions — mostly carbon dioxide emissions from burning fossil fuels — can explain the warming that we see, even after taking into account the effect of volcanoes, sun spots, Earth’s orbit, ozone, and aerosols. (Check out this cool interactive graph that shows the effects of all these things independently and combined.)

It’s Bad.

We have already seen significant impacts from climate change. Increased flooding, fires, and heat waves are all linked to climate change. Natural disasters are already a big problem — they displaced 17 million people in 2018 and they cause $100 billion in damages every year in the United States alone. With so many people already in harm’s way, we can little afford the significant increases in natural disasters that unchecked climate change would bring.

If we keep burning fossil fuels at a reckless pace, the Earth will warm by 5 to 9 degrees F by the year 2100 (2.6 to 4.8 degrees C). This may not sound like much, but note that when it was only 7 degrees F colder than it is now, we were in the last ice age.

A 5 or 9 degree warmer planet would be a completely different world than the one we currently live in, with more flooding, crop failures, hurricanes, and sea level rise than we’ve ever seen. We would lose coral reefs, as bleaching events become more intense and frequent, leaving reefs no time to recover. And one in six species would be threatened with extinction due to climate change.

The impacts on human societies are less certain. Can society afford to pay for the economic damages from more floods, droughts, fires, and heat waves without breaking down? The sea level is projected to rise by 1 to 2 feet (11 to 22 inches) by 2050, and up to 5 feet by 2100 if melting causes ice sheets collapse the way some scientists think they will.

Just 1 to 3 feet of sea level rise will cause the dislocation of 250 million people. Could our societies withstand this disruption?

For my children’s sake, I hope we never find out the answer to these questions. It’s not too late to make some the investments needed to insure against the worst impacts of climate. But we have to act decisively. Now.

Comasche Solar Farm near Pueblo April 6, 2016. Photo credit: Reuters via The Climate Reality Project

We Can Fix It.

The future will be powered by wind and solar with electric vehicles, and it will be much more efficient. Not only will these technologies help solve climate change, they will eliminate the more than 600,00 premature deaths per year that occur globally due to our current polluting forms of land transportation and power generation. These gains will make our whole society more productive and wealthier.

We will also need to invest more in natural climate solutions — protecting nature, planting trees, and building healthy soil — to help remove carbon from the atmosphere. A common worry is that it would cost too much to solve climate change. But most people don’t realize how affordable wind and solar, energy storage, electric cars, and even electric airplanes have already become.

The only question is whether we will transition to this better world in time to avoid the most damaging and destabilizing effects of climate change.

Aspen moves ahead with integrated water plan and moving its conditional storage rights — @AspenJournalism

Aspen’s iconic Maroon Bells are visible from the site where the city of Aspen had proposed building a dam and reservoir. The city has hired an engineering firm to help figure out where to move its conditional water-storage rights after a water court judge in June ruled out the possibility of building dams or reservoirs on upper Maroon or Castle creek. Photo credit: Brent Gardner-Smith/Aspen Journalism

From Aspen Journalism (Heather Sackett):

With the clock ticking on moving its conditional water-storage rights, the city of Aspen is taking steps toward developing a water integrated resource plan, or IRP.

City Council last month approved spending $81,674 to hire Broomfield-based Carollo Engineers as a consultant for the first phase of the IRP. A main goal of the plan will be to decide where to move the city’s conditional water-storage rights after a water court judge in June approved the city’s settlement with opposing parties in two water court cases. The decrees issued by the judge in those cases rule out the possibility of the city building dams or reservoirs on upper Castle or Maroon creeks.

The city has six years to finalize a plan to move the water rights and associated storage to new locations. That and the increasing effects of a hotter, drier climate, which means less water in streams, have the city feeling a sense of urgency when it comes to figuring out its water supply.

“We do have a sense of urgency, but we also recognize we are only going to get one chance to make such a large change to our system,” said Margaret Medellin, Aspen’s utilities resource manager. “We want to do it right.”

The site on Maroon Creek where the city of Aspen had proposed building a dam and reservoir on a snowy day in spring 2019. The city has hired an engineering firm to help figure out where to move its conditional water-storage rights after a water court judge in June ruled out the possibility of building dams or reservoirs on upper Maroon or Castle creek. Photo credit: Brent Gardner-Smith/Aspen Journalism

Conditional water rights

All 10 parties who settled with the city in water court, one of which was environmental group American Rivers, agreed not to oppose the city’s efforts to change its conditional water-storage rights to different sites.

Instead of flooding two pristine valleys to create reservoirs, the city has identified five other locations to where it could possibly store water. Those sites are the city golf course; the Maroon Creek Club golf course; the city’s Cozy Point open space; the Woody Creek gravel pit; and a 63-acre parcel of land next to the gravel pit, which the city bought in 2018.

“We don’t have any issue with Aspen’s plan to move forward with those conditional water rights,” said Matt Rice, director of American Rivers’ Colorado Basin Program. “That’s a decision for them and local stakeholders to make.”

Carollo Engineers was one of five firms that responded to the city’s summer request for proposals. The more than $81,000 that the City Council approved will pay for Carollo to complete only Phase 1 of the IRP, which will define goals and develop a detailed scope of work. Phase 2 would create the IRP using community input.

“Normally, when we do an IRP, we are looking at what the future looks like in terms of water needs and trying to characterize those and predict them out several decades,” said John Rehring, senior project manager and vice president of Carollo Engineers.

The city of Aspen has identified this 63-acre parcel of land it bought in 2018 next to the gravel pit in Woody Creek as a potential site of water storage. The city has hired an engineering firm to help figure out where to move its conditional water-storage rights after a water court judge in June ruled out the possibility of building dams or reservoirs on upper Maroon or Castle creek. Photo credit: Brent Gardner-Smith/Aspen Journalism

Storage needed?

City officials maintain that a lack of reservoir storage is a problem.

Medellin said the lack of water-storage facilities is a big weakness in the city’s water system and that it is controversial to build dams and reservoirs “because every valley up here is beautiful.”

But, Medellin said, climate change may increase the need for water storage.

“We’ve acknowledged these storage rights are very important to the future of Aspen, especially as we start to see climate-change implications,” she said.

Carollo Engineers agrees with that assessment.

“Clearly, the city of Aspen’s system lacks the water storage it needs to reliably meet demands through a range of supply-and-demand conditions even now — before the impacts of climate change have fully taken hold,” the proposal reads.

The issue of storage came to the forefront in the Aspen community in 2012 when news broke that the city was contemplating using its conditional water-storage rights to build dams and reservoirs in Castle and Maroon valleys.

Consultants have come to different conclusions about how much water storage the city actually needs. A 2017 report by Deere and Ault Consultants, which was based on conclusions in a risk analysis by Headwaters Corporation, said Aspen needs 8,500 acre-feet of water storage. But a 2016 study by Wilson Water concluded Aspen does not need any storage.

Two other areas that the IRP will address is the vulnerability of Aspen’s water supply to natural disasters such as 2018’s Lake Christine Fire and last winter’s historic avalanches in Castle and Maroon valleys, as well as how to decrease customers’ demand for water. Even though Aspen has taken steps to reduce the use of water for outdoor irrigation through a landscape ordinance, those gains could be wiped out because in a warmer future, there will be less water flowing in local streams.

“It’s almost like you are playing this game where you, on one hand, lower the level of demand but, on the other side of the equation, climate change is decreasing our supply,” Medellin said.

Aspen Journalism collaborates with The Aspen Times and other Swift Communications newspapers on coverage of water and rivers. This story appeared in the Nov. 26 edition of The Aspen Times.

@CWCB_DNR Governor’s Water Availability Task Force recap #cwcbwatf

From OutThereColorado.com (Mariane Goodland):

Members of the Colorado Water Availability Task Force talked happily about the snowstorm Tuesday, with high hopes that it will put Colorado above average for precipitation and snowpack for the water year that started on Oct. 1.

The 2019 water year saw three state weather records: largest hailstone (at 4.83 inches at Bethune), the hottest day (115 degrees at John Martin Reservoir), and the March bomb cyclone, which resulted in a record low barometric pressure reading near Lamar…

In the 2019 water year that ended on Sept. 30, the biggest snowfall of the season was 23 inches (which has already been substantially surpassed by Tuesday’s storm); the coldest temperature recorded in 2019 was minus 40 degrees at Taylor Park Reservoir in Gunnison County.

Colorado also experienced the warmest September in the 125 years tracked by the National Oceanic and Atmospheric Administration (NOAA). Assistant state climatologist Becky Bolinger said that it was warmer on average in September than it had been in June, the traditional start to the summer season. That was followed by one of the coldest Octobers on record, the fourth coldest in state history…

Colorado Drought Monitor November 26, 2019.

Colorado got out of drought for the first time in 20 years, briefly, but the state has returned to drought conditions as the summer ended, especially in southwestern Colorado.

Recent drought maps show three-quarters of the state back in drought, with the most severe in southwestern and western Colorado, which are in severe drought…

Reservoir percent of average October 31, 2019 via the NRCS.

Thanks to a good El Niño year in 2019, which produced above average rain and snowfall, almost all of Colorado’s reservoirs are in good shape, according to Karl Wetlaufer of the USDA’s Natural Resources Conservation Service. Statewide, reservoir storage is above average everywhere except for the Upper Rio Grande Basin, which includes the San Luis Valley. Reservoirs in the Upper Rio Grande are down to 25% of capacity.

Reservoirs in the Colorado River basin were at 81% of capacity at the end of October; in the Gunnison, home to the state’s largest at Blue Mesa, reservoirs were at 78% of capacity, also at the end of October.

Traditionally, a good October-November snowpack — which this year has allowed many ski areas to open early — portends a good water year. Colorado’s October-November snowpack in 2019 is only slightly below average and is likely to be above average when Tuesday’s storm is factored in, Bolinger said. Wetlaufer said statewide, snowpack is 90% of normal for October and November, and the state has received 17% of its normal snowfall accumulation, where it normally should be at 19% at this time of year.

Barefoot Dance In The Snow New York, New York March 8, 1916. Girls of the Marion Morgan School of Dance in Los Angeles perform barefoot in the snow in Central Park. Underwood Archives by Underwood Archives

“We could definitely make up water year deficits” with this storm, Bolinger said. “Cross your fingers and do your snow dances.”

Click here to go the CWCB website to view the slides. Click here to view the Twitter hash tag #cwcbwatf from the meeting.

#Drought news: The odds of reaching 100% of normal water year precipitation in Water Year 2020

Map shows the odds of reaching 100% of normal precipitation by the end of the water year based on how much precipitation has been observed so far this water year and how much has historically been observed during the remaining months in the water year. Credit: Center for Western Weather and Water Extremes / Scripps Institution of Oceanography via Wyoming Public Media

From Wyoming Public Media (Noah Glick):

According to the Center for Western Weather and Water Extremes, much of our region has about a 30% chance of seeing normal precipitation levels this water year. That primarily affects Nevada, Utah and Colorado.

McEvoy says recent winter storms throughout the region will help those odds improve when new numbers are released in December…

But this slow start isn’t necessarily a sign of things to come. According to the National Oceanic and Atmospheric Administration, the areas within our region most impacted by drought have a higher probability of seeing above average precipitation in early December. And it predicts minimal drought impacts for most of the region, with the exception of southeastern Colorado.

West Drought Monitor November 26, 2019.