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UPDATED: Heavy rain, possible flooding expected in Malheur County

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UPDATE: 5 p.m. Sunday –

The heaviest rain in 40 years is expected through Malheur County as the remnants of a hurricane move north on Monday, according to the National Weather Service.

The track of what was Tropical Storm Hilary in California on Sunday, Aug. 20, shifted to the west from what had been predicted earlier, with a path now straddling the Malheur-Harney county line.

A flood watch remains in effect through Monday evening.

“Expect record-setting rainfall today and Monday across the region associated with the remnants of Tropical Storm Hilary. This will likely produce flash flooding, rock slides and debris flows,” the National Weather Service in Boise said in a Sunday afternoon update to its flood watch.

Meantime, the Oregon Department of Geology and Mineral Industries on Sunday issued an alert for landslides and debris flows.

Read the full updated story HERE.

UPDATE: 3:30 p.m. Sunday – The Oregon Department of Geology and Mineral Industries issued an alert for debris flows and landslides if heavy rains develop as forecast in eastern Oregon.

“Debris flows are rapidly moving, extremely destructive landslides,” the agency said in a news release Sunday afternoon. “They can contain boulders and logs transported in a fast-moving soil and water slurry down steep hillsides and through narrow canyons. They can easily travel a mile or more. A debris flow moves faster than a person can run. People, structures, and roads located below steep slopes in canyons and near the mouths of canyons may be at serious risk.”

The agency provided advice:

•”Listen. Unusual sounds might indicate moving debris, such as trees cracking or boulders knocking together. A trickle of falling mud or debris may precede larger landslides. If you think there is danger of a landslide, leave immediately.

•”Watch the water. If water in a stream or creek suddenly turns muddy or the amount of water flowing suddenly decreases or increases, this is a warning that the flow has been affected upstream. You should immediately leave the area because a debris flow may soon be coming downstream.

•”Travel with extreme caution. Assume roads are not safe. Be alert when driving, especially at night. Embankments along roadsides may fail, sending rock and debris onto the road.”

UPDATE: 3 p.m. Sunday – The National Weather Service in Boise has revised its forecast for Malheur County to reduce the amount of rain expected in the Ontario area.

“The forecast track of Hilary has slowed slightly and also shifted slightly westward,” according to the Sunday afternoon forecast. “Record amounts of rainfall along with flash flooding are possible through Monday evening. The highest precipitation should occur Monday morning across Harney, Malheur and Baker counties in Oregon.”

Heavy rain is still forecast for the Ontario area, but rainfall amounts on Monday will be three-quarters to 1 inch of rain. Earlier forecasts anticipated up to 2” of rain.

Changes in the course of what is now called Tropical Storm Hilary could impact the forecasts. A tropical cyclone is classified as a hurricane with sustained ground winds of 74 mph or more. A tropical storm carries sustained winds of 39 to 74 mph.


“Rare” weather conditions are expected in Malheur County starting Sunday that could produce record rainfall, urban flooding and flash floods, according to the National Weather Service.

The weather service continued a flood watch for the area, and forecast that Ontario will get an inch of rain between midnight Sunday and noon Monday.

“We urge folks to monitor the forecast for updates for the next 48 hours,” the agency said in its forecast issued early Sunday, Aug. 20.

Forecasters are tracking Hurricane Hilary as it moves towards California, where catastrophic flooding is anticipated. The weather service expects the hurricane to develop into a tropical storm and then shear apart as it continues moving north to Oregon and Idaho.

“Remnants from Hurricane Hilary will bring record rainfall and strong winds to parts of southwest Idaho and southeast Oregon today through Monday. Flash flooding and debris flow are likely especially in the mountains,” the forecast said.

“Urban flooding is also likely to occur with rainfall rates of up to 4” an hour which could effect the Monday morning commute. These conditions are quite rare for this area with atmospheric moisture content expected to exceed any on record,” the forecast continued.

“At present, we are forecasting 1.09″ of rain from midnight to noon Monday in Ontario. That would be the 7th most rainfall ever for Ontario (since 1945). This amount of rainfall would likely cause urban and small stream flooding,” the forecast said.

“The heaviest rainfall is expected Monday when Hilary`s moisture interacts with an incoming Pacific upper trough, producing rainfall rates as high as 4 inches per hour,” the weather service said.

An Idaho Power spokesperson said the utility is monitoring the storm to anticipate potential outages.

“If any areas do see flooding with the incoming storms, we urge customers to stay away from flooded or submerged electrical equipment, such as the green boxes you often see in subdivisions or anything that has electric-hazard warning signs,” according to Annie Meyer, Idaho Power marketing specialist. “If customers notice flooded equipment or downed power lines, they should stay back and call Idaho Power at 1-800-488-6151 or 208-388-2323.”

This story will be updated throughout the day Sunday.

Useful links:

National Weather Service:

Ontario-area forecast

Local flood watch

Flood preparations

Hurricane Hilary updates

Oregon Department of Transportation:

Road conditions: Oregon Tripcheck

Idaho Power:

Outage tips

Food and Drug Administration:

Tips – preparing for floods

The National Weather Service Hurricane Center on Sunday, Aug. 20, forecast the Hurricane Hilary will degrade but still aim heavy rain and wind at Oregon.,

NOTE: The news team of the Enterprise will be on duty through the weekend to provide updates and alerts as warranted. Monitor our website and Facebook page.

HELP REPORT: If the weather turns severe as forecast, help the Enterprise by sending sharing photos or information about what’s happening your area. You can message the information via Facebook or email Editor Les Zaitz: [email protected]