Flood outlook along James River at normal levels of risk
The Climate Prediction Center has been calling for a warmer and drier-than-normal weather pattern beginning in June, according to Allen Schlag, hydrologist with the National Weather Service in Bismarck.
JAMESTOWN – The overall flood outlook along the James River is at historically normal levels of risk right now even with the amount of precipitation the Jamestown area has received, according to Allen Schlag, hydrologist with the National Weather Service in Bismarck.
“The reservoirs are full, the rivers are running,” he said. “ … We are going to be getting rains, but it looks more seasonally normal.”
The Climate Prediction Center has been calling for a warmer and drier-than-normal weather pattern beginning in June, Schlag said.
Jamestown received almost 4.5 inches of precipitation in April and about 3.9 inches of rain this month so far, according to measurements taken at the North Dakota State Hospital. Normal precipitation is about 1.5 inches for April and almost 2 inches in May.
“If we were looking to trying to get the rivers at major flood stage, this would be a rain event that everybody would recognize as problematic,” Schlag said. “We would be looking at widespread 3 to 4 and a half inches of rain and I just don’t see that happening right now.”
Currently, there are flood warnings for areas along the James River, but those are in South Dakota, he said. He said the James River is a very flat river in terms of its slope and really slow to drain.
“Right now I would say it is going to be primarily limited to South Dakota,” he said, referring to areas where flooding could occur along the James River. “It would take an extension of the misery of the rain that we’ve been receiving I think in order for it to start creating problems in North Dakota. That is just not something that we have in our forecast.”
The water levels at Jamestown and Pipestem reservoirs are climbing and water releases are increasing at each dam, said Bob Martin, interim Pipestem Dam manager for the U.S. Army Corps of Engineers.
Pipestem Reservoir was at 1,474 feet above mean sea level as of Tuesday afternoon, May 17. Martin said the groundwater is coming up but no seepage or unusual movements have been found during the dam safety surveillance, which was increased to weekly once the water level reached 1,470 feet AMSL.
Jamestown Reservoir has risen 16.5 feet since this winter and was at 1,442.5 feet AMSL as of Tuesday.
Combined releases at the two reservoirs were increased to 950 cfs on Wednesday, May 18. Releases at Pipestem Reservoir were increased from 100 cfs to 150 cfs on Wednesday, and releases at Jamestown Reservoir were increased from 650 cfs to 800 cfs on Tuesday.
Martin said he wouldn’t be surprised if there is another increase in the combined releases with more precipitation expected Thursday and possibly Friday, May 19-20.
About 850 cfs to 900 cfs from runoff and the James River is coming into Jamestown Reservoir as of Tuesday morning.
“If we get a couple blasts of rain that is going to bump that number up,” Martin said.
A relatively strong low-pressure system was expected to move into the state from the west Wednesday evening through Thursday, said Brandon Gale, a meteorologist with the National Weather Service in Bismarck. He said the NWS is expecting widespread precipitation across the state with the low-pressure system.
“While there could be some isolated thunderstorms, most of it will be a kind of general shower, rainfall so the precipitation rates won't be too heavy,” he said. “I think for the Jamestown area, we are forecasting 0.3 inch to a half inch of total rainfall from the system, so nothing too extreme rainfall wise. If you do get one of the isolated thunderstorms to move over any given location, you are going to have some higher totals, and those higher totals should be pretty isolated.”