From The Colorado Springs Gazette (Liz Forster):
…reservoirs are filling, and the generous snowfall has nearly eliminated a drought that hydrologists said in January would take years for recovery.
“I don’t see how you could order something better than what we got after a year like last,” said Greg Smith, a senior hydrologist with the National Oceanic and Atmospheric Administration. “This is exactly what we needed.”
…this March was the third wettest in the Upper San Juan River Basin, with about 14.1 inches of snow water equivalent, Smith said. The record was set in 1979 with 17.3 inches, and the average is 6.1 inches…
Colorado’s snow water equivalent dropped below its median peak of 16.8 inches for the first time April 28, 18 days later than usual. (The median is the midpoint between the highest and lowest.) But a storm at the end of April boosted the snowpack above peak — and the snow hasn’t stopped. Flakes fell again last week across the state, though not enough to surpass the median apex again.
The contrast in Colorado snow levels year to year are remarkable at 15.4 inches versus 4.
Encouraging conditions are widespread in the Upper Colorado River Basin and across the Southwest, Smith said…
“Even in areas like the Yampa and Green rivers, which were running a bit below average to start, they caught up in the second half of spring,” he said.
The drought that ushered in severe wildfires and dismally low reservoir levels is almost history, with about 84% of the state sated, according to the U.S. Drought Monitor, compared with 82% in need of a soak one year ago.
Since the U.S. Drought Monitor was established in 1999, the state always had some abnormally dry areas. Now, only 15.28% of the state is abnormally dry, and less than 1% is in a moderate drought…
Becky Bolinger, a climatologist with the Colorado Climate Center, said the state needed enough snow to fill three “buckets”: soil, rivers and streams, and reservoirs.
“When the snowpack first started to accumulate, we thought, ‘This is good, but will it be good enough to really recover the entire hydrological system?’ But once the snow and cold came in February and March, it became more likely that we could see recovery in all of those buckets,” Bolinger said.
Besides cooler, wetter conditions throughout the Southwest, the wind has blown in less dust, which can accelerate melting because of its darker color, a measurement known as albedo.
So far this year, three events have blown dust onto the 11 mountain passes tracked by the Colorado Center for Snow and Avalanche. By May 14, 2018, the research institute had reported eight.
“Our melt rate is going steady, and there’s nothing too much to be concerned about,” said Russ Schumacher, state climatologist and director of the Colorado Climate Center.
The wet, cool cycle appears to be continuing into late spring and summer, forecasts show. NOAA predicted a 50% chance of above average precipitation for most of Colorado through July, average temperatures for central Colorado, below average for the eastern plains and slightly above average on the Western Slope.
From The Denver Post (Chris Bianchi):
The key as far as possible stream and river flooding, though, is just how quickly that snow will melt. If temperatures quickly spike, for example, rivers and streams could be quickly overwhelmed by a sudden influx of high water.
“The mountains have been getting snow and they’re going to get more (this week),” said Jim Kalina, a meteorologist with the National Weather Service office in Boulder. “The first concern for flooding would be from the melting snowpack. If the pattern changes and we suddenly get warm, that’s probably the biggest concern for the rivers. There’s a potential since we have such a high snowpack.”
Of course, the melting snow will provide a huge positive boost to Colorado in the form of valuable water for state reservoirs. At the end of April, statewide reservoirs were running at 90 percent of average. That said, the lowest reservoir capacity levels were mainly in the southwestern part of the state, and that’s where the most snow remains to melt. The melting snow will likely help fill reservoirs that were largely depleted by last year’s drought…
…long-range outlooks produced by the Climate Prediction Center (CPC), which cites a familiar culprit for the wetter than average long-range outlook: El Nino. There are a number of factors in play, but the key is the continued presence of a weak El Nino pattern in the tropical Pacific Ocean. The meteorological domino effect of warmer-than-average central Pacific waters influences global weather, including an influx of energy into the United States’ subtropical jet stream. While it’s not always the case, that El Nino-driven boost of jet stream energy can often translate to extra moisture along the Front Range.
“Typically, El Nino leads to a bit of wetter years over our area here in eastern Colorado,” Kalina said. “There seems to be a bit more moisture available. There seems to be more fuel for added precipitation.”
While the effect of soil moisture on summer showers and storms isn’t entirely clear, there is also a possible natural link between added snow levels and increased rainfall. In short, melting snow increases the amount of water in the ground, and that water has to evaporate. That evaporated water can add moisture to the air, therefore increasing chances for afternoon showers and storms…
Summer and fall rain, however, typically comes from a different source: the annual monsoon. The monsoon is a seasonal reversal of typical wind patterns, leading to extra showers and thunderstorms for the southwestern United States. This usually starts to flare up in July, with August and early September the typical prime time for monsoonal moisture. While Denver and most of the Front Range is typically tends to feel only fringe impacts from the monsoon, showers and storms generated by the monsoon can lead to extra rain and storms.
Predicting the monsoon’s strength and precise impacts, however, is a bit of a shot in the dark.
“The main thing is the monsoon sets up. It’s really difficult to predict that,” Kalina said. “Some years you have a weak monsoon, sometimes you have a strong one. It all depends on where it sets up and how strong it is.”
At least in the near term, chances are overall trending toward a wet late spring, summer and early fall. And in case you’ve been stuck in a windowless basement the last few weeks, it’s been a wet start to May, with more moisture likely en route this week and next.
From The Mohave Daily News (Saul A. Flores):
According to the BOR, the snowpack in the Upper Basin is nearly 140% above average as of April 15 and it forecasts that seasonal inflow to Lake Powell will be at 128% of average.
“We are pleased to see the above average snowpack conditions in the Upper Basin and the improvement in the inflow forecast for Lake Powell,” said Brent Rhees, BOR’s Upper Colorado regional director. “Significant risks and uncertainty persist and storage at Lake Powell remains essential to the overall well being of the basin.”
The BOR, based on April’s 24-month study, projected Lake Powell to release up to 9 million acre-feet in water year 2019. Lake Powell’s elevation at the end of the calendar year is projected to be 3,607.49 feet above sea level.
“These developments may lessen the chance of shortage in 2020,” Terry Fulp, BOR’s Lower Colorado regional director, said in a prepared statement. “However, one near or even above average year will not end the ongoing extended drought experienced in the Colorado River Basin and does not substantially reduce the risks facing the basin.”
In the same 24-month study, the BOR stated that Lake Mead’s elevation at the end of the 2019 calendar year is projected to be at 1,084.72 feet above sea level, nearly 10 feet above the shortage determination trigger of 1,075 feet.
The BOR said that operating tiers for Lake Powell in the water year 2020 and operating condition for Lake Mead in the calendar year 2020 will be determined based on the projected conditions on Jan. 1, 2020, as reported in this coming August’s 24-month study.