NWS Issues Rare Particularly Dangerous Situation Red Flag Warning Across Eastern Washington and Oregon

The National Weather Service issued a rare Particularly Dangerous Situation (PDS) Red Flag Warning for large portions of eastern Washington and northeastern Oregon over the weekend, triggering a dramatic escalation in fire activity that resulted in the ignition and explosive growth of multiple large fires — including the three that devastated Spokane County.

What Is a PDS Red Flag Warning?

A standard Red Flag Warning alerts fire managers and the public to elevated fire weather conditions. A Particularly Dangerous Situation designation is issued only in the most extreme cases — when a combination of exceptionally high winds, critically low humidity, and dry fuels is expected to cause any new or existing fires to grow rapidly and potentially catastrophically out of control.

NWS meteorologists reserve the PDS designation for situations where the combination of conditions is so severe that fire behavior is expected to be extreme and potentially unsurvivable for anyone caught in the fire path. Such warnings are issued relatively rarely in the Pacific Northwest.

Conditions That Triggered the Warning

The warning was prompted by a convergence of multiple dangerous factors:

Wind gusts to 45 mph east of the Cascade crest, driven by a frontal passage and strong pressure gradient
Relative humidity as low as 4-15% across eastern Washington and northeastern Oregon — critically low values that accelerate fire spread
Critically dry fuels following an exceptionally warm and dry spring and summer across the inland Pacific Northwest
High temperatures exceeding 100°F at lower elevations prior to the frontal passage

The PDS warning was in effect for Saturday afternoon and evening across central and eastern Oregon and large portions of eastern Washington, including the Spokane and Pendleton areas.

The Result: Explosive Fire Growth

The PDS conditions proved devastating. The Old Trails, Autumn Lane, and Fairview fires near Spokane all ignited or exploded in size during the warning period, driven by the strong, erratic winds into residential neighborhoods. Multiple other fires across eastern Oregon and Washington also made significant runs during the warning period.

Current and Forecast Conditions

As of August 3, the NWS reports that a weakening cold front has stalled in the central Great Basin, bringing breezy west winds with gusts of 25-35 mph and relative humidity between 4-15% to parts of the Northwest. Conditions have moderated somewhat from the PDS event, but fire weather remains elevated across much of the region.

Temperatures are cooler than average across the Inland Northwest and Northern Rockies, providing some relief from the peak heat. However, NIFC notes that north winds in the Okanogan Valley of Washington could create locally challenging conditions for fire crews.

August Fire Weather Outlook

The NIFC monthly fire weather outlook, issued August 1, forecasts above-normal significant fire potential across the entire northwestern United States through the end of the month. The combination of record-dry fuels, persistent below-normal precipitation, and recurring heat and wind events is expected to keep fire danger at critical or very high levels across the region for the remainder of August.