Flood potential still moderate for Carbon County

By David Louis

dlouis@rawlinstimes.com

RAWLINS — According to the National Oceanic and Atmospheric Administration (NOAA), mountain snowpack levels across Wyoming has been a bit of a mixed bag.

While generally trending down in Northern Wyoming since early April, Snow Water Equivalent (SWE) percentages have consistently notched upward across the drainage basins in southern Wyoming.

Currently, the SWE in the snowpack on the Upper North Platte is at 104 percent of normal, Lower North Platte 121 percent and the Little Snake River 108 percent. On April 11, the snowpack SWE were 97, 108, and 92 percent, respectively.

Those conditions are similar to 2010 and 2014 when there was spotty flooding reported across Carbon County.

SWE refers to the amount of water contained within the snowpack and can be thought of as the depth of water that would theoretically result if the entire snowpack melted instantaneously.

Snowpack SWEs were the highest across basins in southern Wyoming — varying between 98 to 124 percent of median. SWEs across basins in north and central Wyoming varied up to 96 percent of median.

SWEs at peak snowmelt runoff elevations — 8,500 to 10,000 feet — were the highest across the Laramie Basin at 120 to 125 percent of median.

Although Carbon County has experienced a bit of a Dr. Jekyll and Mr. Hyde weather pattern recently — shirtsleeves and sunscreen Friday and a mix of rain and snow during the weekend — long-range models indicate wet weather will persist during the next week to 10 days, said Jim Fahey, NOAA hydrologist.

“It’s always good news when you get water in Wyoming,” Fahey said. “But it’s yet to be determined how much is going to be rain and how much is going to be snow.”

While a mix of rain and snow is anticipated at lower elevation, there is a “pretty good bet” of snow above 8,000 feet.

“Every storm adds to the potential to increase the risk of flood,” Fahey said. “There again, it all matters how the snowpack comes off.”

The flood potential across the lower portions of the Laramie River Basin are currently anticipated to be moderate to high ,with moderate flood potential expected across sections of the Upper North Platte River and Little Snake River drainage basins.

“It’s all timing, and right now we’re still accumulating snow in the mountains,” Fahey said.

And the addition of rain Saturday and Sunday has had its affects on runoff already.

“The North Platte at Saratoga is just under six feet, a foot and a half below bank and two and a half feet below flood stage,” Fahey said. “But during the last couple of days there was a pretty good jump.”

For John Zeiger, Carbon County Emergency Management coordinator, it’s still a waiting game on if the area will see flooding this year.

“A lot of what will happen may depend on what’s gong to happen this week,” Zeiger said. “They are calling on up to 12-18 inches on the Snowy Range and Sierras. I think that could potentially boost us up, but I’m not a hydrologist. I know (NOAA) is a little more cautious now, moving us up a little bit with our flood potential.”

The area’s saving grace over the past weekend was that the rain fell at a constant rate. Had it not done so, Fahey added, it could have resulted in widespread heavy runoff.

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