Weekend Weather: Rain through Thursday could trigger landslides

Heavy rain through Thursday could trigger dangerous landslides along steep terrain as well as flooding along small streams of the Inland Northwest.

The National Weather Service in Spokane has issued a flood warning for a wide swath of the region. The warning is in effect until Thursday afternoon.

Already saturated terrain in the mountains and along steep slopes could give way under heavy rain.

Last weekend’s rains have already caused landslides across the region, forecasters said.

The mid-week runoff may push small streams over their banks, creating water hazards along roadways, forecasters said.

In addition, low-lying areas may see ponding from water that is slow to drain away.

The flood warning area includes portions of North Idaho, counties to the north of Spokane, the eastern slopes of the Cascades, the Okanogan region, the Waterville Plateau and the middle and upper Yakima Valley.

Forecasters advised against trying to drive through water-covered roads.

Areas hit by fire in the past two years could be vulnerable to rock and mudslides caused by the weight of accumulating rainfall and the lack of vegetation to hold back the downward force created by the heavy rain, forecasters said.

A wet storm system that is carrying subtropical moisture has moved into the Pacific Northwest and should continue to bring rain and high mountain snow through Thursday afternoon.

Up to an inch of rain was expected in many locations along with heavy snow in the mountains. Snowfall levels were expected to rise to between 4,000 and 5,000 feet in elevation, forecasters said.

In the Spokane area, forecasters said that up to an inch of rain is likely by this afternoon.

Rain is expected to continue periodically through this weekend under an active Pacific storm track.

The storms during the latter part of an El Nino winter have been strong enough to reach Southern California and northern Mexico.

Locally, high temperatures at lower elevations are likely to be in the low 50s with lows in the upper 30s to lower 40s.