In the midst of one of the worst cold snaps in years, it might be hard to think about spring flooding.
But it’s on the minds of the state’s climate experts.
David Pearson, service hydrologist at the National Weather Service in Omaha, put out his first spring flood outlook of the season Thursday.
Despite all the snow and the extremely low temperatures that have iced up rivers, the risk for flooding in the spring is nowhere near as high as it was the past two years.
In fact, according to the forecast, the risk is normal or even below-normal in most places.
“The overall flood risk for this spring is generally normal,” Pearson said in the presentation, which was posted on the website for the weather service’s Omaha office.
This year’s conditions seem to mirror those of two years ago, when flooding inundated eastern Nebraska and caused more than $1 billion in damage.
Snowfall totals have been well above average, and colder-than-normal temperatures in February have led to heavy icing on some rivers.
However, there were some important conditions present two years ago that are missing now.
In 2019, the state was in the midst of several years with above-average precipitation, leaving the ground saturated with moisture. This year, most of the state remains in a drought that started last year.
Also, though it has been snowy in Nebraska, areas farther west and north that feed rivers here have not seen as much snow.
Martha Shulski, the state climatologist, said the 2018-2019 season presented a “worst-case risk scenario, with frozen and saturated soils, a significant snowpack and substantial river ice after a very cold February.”
In addition, there was a intense storm in March that added moisture at a time when existing snow and ice was rapidly melting.
Shulski said many of those same ingredients that fueled the 2019 floods are not present now.
For example, because of drought conditions, soil moisture levels are much lower. Also, until February, this winter was much warmer, meaning ground temperatures are warmer. Those two factors mean snowmelt can be absorbed, leading to less runoff.
“As far as widespread spring snowmelt flooding, the ingredients are not all in play as (they were) in 2019,” she said. But that doesn’t mean there isn’t risk for flooding in some areas.
Shulski said the bitterly cold temperatures this month will lead to ice buildup on rivers, increasing the risk for localized flooding from ice jams.
The weather service agrees.
“There is an above-normal risk for ice jam flooding along ice jam-prone rivers,” it said in its flood risk assessment.
The weather service said the biggest risk is the Platte River downstream of Columbus, which already has seen some flooding.
Last month, the weather service issued a flood warning on the river from Fremont to Ashland after some lowland flooding occurred in areas in and around Fremont.
Other areas about which the weather service expressed concern are the Loup River near where it flows into the Platte River and the Niobrara River from Verdel upstream to U.S. 281.
Though flooding could occur in those areas because of ice melting, it could be exacerbated by heavy precipitation events.
“Flooding this spring will be largely dependent on the location and intensity of additional precipitation and thunderstorms,” the weather service presentation said.
Most people living along the Missouri River face a below-normal flood risk. Only on the southern portion of the river in Nebraska, from Plattsmouth to Rulo, is the risk considered to be normal.
The flooding risk is normal on the Platte River west of Columbus, as well as on the Elkhorn River. All other major creeks and rivers in the eastern part of the state, including Salt Creek, have either a normal or below-normal risk of flooding.
Of course, it’s early in the season, and things could change. More snow or rain, combined with a rapid warmup, could lead to increased flooding chances.
“Flood risk is something we should continue to track as conditions develop over the next few months,” Shulski said.
FLOOD OF 2019: THE AFTERMATH AND THE RECOVERY
Reach the writer at 402-473-2647 or firstname.lastname@example.org.
On Twitter @LincolnBizBuzz.