El Niño: “The fact of the matter is it’s always unpredictable” — Nolan Doesken

Average influence of El Niño on US temperature and precipitation
Average influence of El Niño on US temperature and precipitation

From the Fort Collins Coloradoan (Jacy Marmaduke):

…there’s another factor at play this season to complicate an already inexact science regarding El Nino. And it’s leaving even seasoned forecasters unsure what this winter will look like.

It’s called the Pacific Decadal Oscillation, and it only happens about every two decades. The combination of the PDO with a historic El Nino means the normal El Nino pattern might be thrown off course.

“In my 27 years, I don’t know if I’ve ever seen anything like this,” said Mike Baker, meteorologist and climate service focal point with the National Weather Service in Boulder…

The last two big-time El Ninos took place in 1997-98 and 1982-83. Both periods started out warmer and drier than usual for Northern Colorado but were punctuated by a small number of heavy snowfalls in the area.

Fort Collins averages 15 inches of rain and 47 inches of snow a year. Looking at each of the four years individually, those years brought above to well-above rain and two well-above average, one average and one below average snowfall. The most rain was in 1997, when Fort Collins last experienced a major flood, with 25.24 inches. That year also saw 75.9 inches of snow, second in those years only to 1983’s total of 81.7 inches.

A Christmas Eve blizzard in 1982 dropped about 24 inches of snow on Denver, although Fort Collins only received about 4 inches. A late October snowstorm in 1997 slammed Denver with more than 24 inches of snow and Fort Collins with about 18 inches.

Northern Colorado is less affected by El Nino than southern and southwestern Colorado, and even Denver. That’s because it’s further from the storm track, or the Pacific jet stream —a river of wind in the upper atmosphere that picks up storms.

“These little weather disturbances are carried along like leaves in a river, and these little disturbances when they move across an area produce the weather,” Baker said. “That’s why we don’t see weather all the time. We have to wait for one of those little leaves of energy to come by in the jet stream.”

The Pacific jet stream sets itself up along the coast where the water is relatively warmer, which is why storms come from the south during El Nino years.

Here’s where things get weird, though. Remember the Pacific Decadal Oscillation, the thing that happens every 20 years? It causes warmer water in the northern part of the Pacific, all the way from the Pacific Northwest up to Alaska.

So right now, the entire Pacific coast is warm and there’s no temperature gradient, which means the jet stream is wandering around like an awkward party guest, unsure where to sit down.

Whether Fort Collins gets any big snows depends on where the jet stream eventually finds a seat.

“We always tell the media, if the jet stream sags 50 miles, we’re gonna see nothing here along the Front Range,” Baker said. “If it sags a little farther north, we’re gonna get clobbered.”

Forecasters say the precipitation outlook for the next three months is indeterminable. The jet stream’s location might be farther north than normal for an El Nino period, its movement toward the U.S. might be delayed, or it may not set up at all.

“The fact of the matter is it’s always unpredictable,” said Nolan Doesken, state climatologist at the Colorado Climate Center. “People get all excited about a strong El Nino as if this will absolutely predict the rest of the late fall and winter … But it’s just one modifier of the otherwise beautiful and complex atmospheric-oceanic circulation system.”


CWCB: September 2015 Drought Update

Click here to read the current update. Here’s an excerpt:

Warm dry conditions have continued across much of eastern Colorado, while the mountains have seen near average precipitation so far this month. Drier conditions have resulted in declining soil moisture levels, but overall evapotranspiration rates are below average for the season, and pasture conditions and harvest yields are reportedly good. Water providers are also reporting increased demands during August and September, however system-wide storage levels remain above average and providers have no immediate concerns.

The abnormally dry conditions along the eastern plains and Front Range are not serious enough to require action.

  • The Colorado Drought Mitigation and Response Plan was formally deactivated by Governor Hickenlooper on September 15, 2015 due to improved conditions. Additional information on this can be found at http://cwcb.state.co.us/water-management/drought/Pages/DroughtResponse.aspx
  • Statewide water year-to-date precipitation is 94 percent of average, a slight decline since last month. Statewide August received only 62 percent of average precipitation while September to-date have seen only 71 percent of average. Generally, the west slope has seen greater precipitation than the eastern plains.
  • August temperatures were above average by 1.6 degrees Fahrenheit, with the warmest temperatures along the southern Front Range. September to-date has seen slightly above average temperatures on the west slope and well above average temperatures on the eastern plains. Warmer temperatures typically drive up demand for irrigation water during the growing season.
  • Reservoir Storage statewide is at 115 percent of average as of September 1st. The Arkansas has the highest levels in the state at 145 percent of average. The Upper Rio Grande has the lowest storage levels at 92 percent of average, this is also the only basin with below average storage. However, the Rio Grande levels are 31 percent greater now than this time last year.
  • The Surface Water Supply Index (SWSI) is highly variable across much of the state. The majority of the sub-basins remain near normal, however most have seen declines over the last month. Portions of the South Platte and Arkansas have abundant supplies due largely to reservoir storage levels. The greatest declines have been in the Colorado and Yampa River basins.
  • The state has recently complete an automation tool for the SWSI index and a revised detailed monthly report can be found at http://water.state.co.us/DWRDocs/Reports/Pages/SWSIReport.aspx
  • El Niño has gained strength over the last few months and continues to be forecasted as a strong event, which is likely to persist through winter. Strong El Niño events typically result in above average precipitation in the fall, but not necessarily in the winter, with the highest risk of a dry winter for the northern and central mountains. The best combination would be for the El Niño to weaken over the winter, and then come back strong in spring.
  • #ColoradoRiver District Annual Seminar recap: El Niño looks promising for southwest Colorado


    From The Grand Junction Daily Sentinel (Dennis Webb):

    Western Coloradans might consider keeping an umbrella handy this fall thanks to the development of a strong El Niño weather system.

    Less clear is the degree to which snow-sport enthusiasts and those concerned with the adequacy of water supplies should count on a heavier-than-average overall snowpack this winter. But the weather trend is inspiring optimism among some.

    “It looks like we’re going to have a heavier-than-normal snowfall this year, is what we’re hoping,” said Dusti Reimer, a Powderhorn Mountain Resort spokeswoman who noted that cooler-than-normal temperatures also are in the forecast.

    “We’re definitely excited with those possibilities to make this pretty much an epic ski year.”

    Klaus Wolter is a research scientist in Boulder with the National Oceanic and Atmospheric Administration’s Earth Systems Research Laboratory Physical Sciences Division. He said that while chances are good in western Colorado for above-average precipitation this fall thanks to El Niño, mid-winter is likely to be drier than normal in Colorado’s central and northern mountains. Southern Colorado, by contrast, is more likely to continue benefiting in mid-winter from the moisture El Niños typically deliver to the southwestern United States.

    “Basically if you want to have a lot of snow this winter the San Juans (San Juan Mountains in southwest Colorado) are the place to go,” Wolter said recently at the Colorado River District’s Annual Water Seminar in Grand Junction.

    For western Colorado as a whole, whether it can finish the snowpack season with net above-average precipitation depends on whether there’s a wet enough spring, he said. The good news is that El Niños typically boost spring snowfall levels, and the fact that the current one is a strong one increases the likelihood it will still be around by spring, Wolter said.

    It was late-season moisture during another strong El Niño season, in 1982-83, that threatened to cause Lake Powell to overfill that spring.

    Jim Pokrandt, a spokesman with the Colorado River District, said that from everything he hears from Wolter and other experts, “Colorado is kind of a no-man’s land” when it comes to El Niño winters. El Niños tend to be a strong predictor of above-average snow in southwest Colorado, while only sporadically providing benefits farther north, he said.

    “We’ve seen El Niños produce good winters and we’ve seen El Niños leaving people saying, ‘Hey, what happened?’ It’s just not as sure-fire a thing as it is for other parts of the country,” Pokrandt said.

    Given the concern over the adequacy of snowpack levels in the Colorado River Basin in recent years, Pokrandt would be happy to see El Niño at least produce average snows in coming months, even if it doesn’t deliver a whopper of a winter.

    “The way things are going, 100 percent of average would look like a good year and act like a good year. I’ll take average,” Pokrandt said.

    “… I hope as skiers and water managers we get at least an average year, if not better.”

    El Niños are associated with warmer-than-average surface water temperatures in the eastern equatorial Pacific Ocean. Data to date suggests the current one could be one of the strongest since 1950.

    For California and the Southwest, it should provide relief from drought, although possibly with negative side effects such as mudslides. El Niños also tend to result in below-average moisture for the Northwest and northern Rockies — making the current one bad news for places such as Washington state that already have been coping with wildfires and other effects of drought.

    Predicting the impacts on Colorado is made difficult because of its location, somewhat on the border between the Southwest and the northern Rockies. While Interstate 70 is sometimes referred to as a typical rough dividing line between areas of above-average and lesser moisture during El Niños, Wolter more specifically puts it around Crested Butte and the Elk Mountains area.

    If nothing else, the current El Niño looks promising for southwest Colorado, an area that has been particularly dry in several recent years.

    “If this outlook pans out, that will be really good for the water supply situation in southwest Colorado,” said Jim Pringle, a warning-coordination meteorologist with the National Weather Service in Grand Junction.

    Wolter said that even if the mid-winter is drier in the central mountains, ski areas may benefit from having good conditions to open their seasons, and hopefully also good conditions come spring. That might bode well for spring break business and offer the possibility for pushing off their closing dates if the economics warrant staying open longer, he said.

    Reimer said Powderhorn is scheduled to open Dec. 17 and close April 3, but those dates could be reconsidered if conditions warrant an earlier opening or later closing. She said the resort will further benefit from work this summer to expand its snowmaking coverage from 25 acres to 42 acres.

    California Drought Monitor September 22, 2015
    California Drought Monitor September 22, 2015

    From The Grand Junction Daily Sentinel (Dennis Webb):

    California’s water-supply problem is by default the problem of the entire Colorado River Basin, and basin states ignore it at their own peril, two speakers warned Thursday.

    “You have to keep track of what’s going on in California. California affects the Colorado River and vice versa,” Jennifer Gimbel, principal deputy secretary for water and science at the U.S. Department of Interior, said during the Colorado River District’s annual water seminar in Grand Junction.

    Pat Mulroy, retired general manager of the Southern Nevada Water Authority, warned that Lake Mead is dropping ever closer to a point at which it would no longer be capable of releasing water for downstream uses. That will lead to panic and irrational behavior, she predicted, and federalization of a river system under which water is now governed and allocated by interstate compact.

    “We will have all-out chaos,” said Mulroy, now senior fellow for climate adaptation and environmental policy at the University of Nevada, Las Vegas’ law school.

    California is coping with a severe drought, the effects of which have been amplified by the inability of varying interests there to build flexibility into water management, store water in wet years and otherwise prepare for dry times, Mulroy said.

    “The story of California is the story of missed opportunities, and of the inability, the human inability, to find solutions,” she said.

    Gimbel, former director of the Colorado Water Conservation Board, said part of California’s problem is a lack of sufficient in-state water storage capability to help it prepare for dry years, as opposed to the high-capacity storage provided by Lake Mead and Lake Powell on the Colorado.

    “It’s quite honestly what’s saved our bacon over these last 15 years of the drought,” Gimbel said.

    She said the heavy precipitation during what’s being called the “Miracle May” earlier this year helped stabilize water levels in Lake Powell. That has provided some breathing room for dealing with what’s an ongoing drought, and efforts to deal with it must continue, Gimbel said.

    She said Lower Basin states have had “difficult discussions” in this regard, “and when things get bad people tend to go back to their positions.”

    “… I think that we have to do better on this river. We cannot give up, and it means that when we get scared we cannot retreat to our corners and close the door. We can’t do it alone.”

    She hopes that Colorado learns from California’s experience “about drawing lines in the sand, litigating and being unable to move forward.” She said as work began on Colorado’s state water plan, she worried about the rhetoric she was hearing, and about people falling back to their standard positions.

    “You can protect what you want to protect, go after what you want to go after,” but everyone has to work together, said Gimbel, who praised the progress that since has been made on the plan.

    Said Mulroy, “It is not easy to try to find a new balance point, it is not easy to try to understand your adversary’s position or your fellow stakeholder’s position.”

    That is something that has yet to occur in California, she said.

    Mulroy sees a need for people to view themselves as citizens of the Colorado River Basin. Everyone has to conserve water and participate in the management of the system, and water needs to be viewed not just as a right but a responsibility, she said.

    “If we each take a little bit less in times when we can … and we set limits on how far we’re comfortable letting the system drop before we start recharging the system, then we won’t be sitting in front of dry reservoirs,” Mulroy said.

    Asked about concern on the Front Range that conservation measures could mean fewer green lawns and reduced property values, she talked about the initial resistance in the Las Vegas area to efforts to have homeowners convert to more desert landscaping, before they realized it could be beautiful and also end the need to mow lawns.

    “It is a real cultural shift, but people need to understand there is a need to conserve,” Mulroy said.

    She said that in considering the challenges river basin states face in the years ahead, it’s important to keep in mind the “amazing transformation” that has occurred in connection with the Colorado River’s management over the last 20 years. Parties in Colorado and other states have overcome acrimony and finger-pointing to forge agreements that have drawn attention from people in other parts of the world who have river systems facing similar challenges.

    “We need to look at the successes in order to keep the challenges that we face in perspective and not perceive them as insurmountable,” Mulroy said.

    El Niño: One of Nature’s Biggest Weather Makers — Weather-Ready Nation

    El Niño has arrived, according to forecasters with NOAA’s Climate Prediction Center, and it’s making big news. But why? It simply comes down to the extensive impact El Niño has on the world’s weather patterns.

    Average influence of El Niño on US temperature and precipitation
    Average influence of El Niño on US temperature and precipitation

    When an El Niño develops, it can start a chain reaction in the atmosphere influencing the weather in places much farther away from the tropical equatorial Pacific Ocean, including the United States. This means certain changes to the typical climate, or long-term average for temperature or precipitation, for folks in some parts of the U.S. Climate is like the tides. Just like the tides roll in and out, our climate warms during the summer and cools during the winter. El Niño’s would be like changing the level of those tides in some places. Perhaps they come in a little higher or earlier now, getting you wet before you have a chance to move your blanket back.

    The map above highlights areas of the U.S. that experience temperature or precipitation conditions that may be different from normal when an El Niño is present. Impacts from El Niño are most noticeable during the late fall through early spring months. During late spring and summer, climate patterns may not be affected at all.

    Not every El Niño event leads to the same climate conditions, however, and the strength of the El Niño event can have an impact on just how warm, cool, dry, or wet the affected areas become. As of summer 2015, the current El Niño has strengthened over the past few months, with a strong event currently favored during the late fall and early winter, according to the latest report from the Climate Prediction Center.

    In instances when a strong El Niño occurs, there can be large impacts to communities and the U.S. economy. Strong El Niños are often associated with heavy winter rains across California, which could bring much needed moisture to a region devastated by drought. Even if above normal precipitation falls across California, one season of above-normal rain and snow is very unlikely to erase four years of drought.

    Meanwhile, heavy rains in the southern half of the U.S. could lead to flooding causing widespread damage to towns and communities, lives and livelihoods. In addition, El Niño could elevate the risk for severe weather across the Southeast during winter. On the other hand, above-average late fall to winter temperatures across the northern tier of the U.S. might mean a milder winter and lower energy costs. It’s important to understand that a strong El Niño only favors these impacts, but doesn’t guarantee they will happen…

    For more information on El Niño, visit http://www.climate.gov/.

    #Drought news: 25% of #Colorado is abnormally dry

    From The Denver Post (Jesse Paul):

    The U.S. Drought Monitor report shows that the abnormal dryness is centered around Denver, and the state’s northeast and southeast.

    “We’ve been dry August and September,” said Bob Koopmeiners, a meteorologist with the National Weather Service in Boulder. “Way below normal.”

    The new dryness percentage follows a report last week in which only about 10 percent of Colorado was listed as abnormally dry.

    In July, a drought monitor report showed that Colorado was nearly free of the thirst that had affected the state — particularly the Western Slope and southeastern counties — for years.

    The dry conditions have led to open-burn bans across the Front Range, including in Jefferson, Boulder and Clear Creek counties.

    From KUSA via the Fort Collins Coloradan:

    Larimer County, parts of Boulder County, unincorporated Arapahoe County, unincorporated Jefferson County, Lincoln County and Gilpin County are under some level of fire ban. On Thursday afternoon, Clear Creek County became the latest one to impose fire restrictions.

    Along the western edge of the metro area, it is not hard to find evidence of just how dry it is…

    That sight repeated around the Colorado, where grass fires of varying sizes have broken out in the past few weeks. It is a far cry from what we saw earlier this spring and summer…

    Last week, the U.S. Drought Monitor map showed a state with a few abnormally dry spots. Fast forward to now and those dry conditions have grown, encompassing large swaths of the Eastern Plains and up and down the I-25 corridor. Firefighters say it’s evidence of a state that is rapidly drying out.