Red Flag Warnings issued Thursday for areas in Oregon, Utah, Wyoming, and Colorado
Moderate amounts of lightning occurred Wednesday in Southern Oregon, Northern California and Central Nevada, while larger numbers of strikes were detected in New Mexico and Arizona. Most areas where the lightning occurred in Oregon, California, and Nevada received light rain but many locations in Arizona and New Mexico saw heavier precipitation along with the lightning.
Here is a summary from the Northwest Geographic Area Coordination Center issued Thursday at 6:57 a.m. PDT:
Thunderstorms moved north across the Pacific Northwest spreading moderate lightning from the California border to the Puget Sound. Pockets of lightning occurred in South Central Oregon, the Oregon and southern Washington Cascades, and Western Oregon and southwest Washington, with scattered light precipitation. Isolated lightning strikes in Eastern Washington and Northeast Oregon. Light initial attack occurred with the largest fire reported in Central Washington for approximately 100 acres.
Thunderstorms were prevalent in the Northwest United States on Friday with many areas receiving rain ranging from a trace to about half an inch in some locations in Northwest California and Southwest Oregon.
Thunderstorms apparently affected the route of Air Tanker 911, a DC-10, as it ferried from Moses Lake, Washington to Sacramento McClellan Friday night, lengthening the planned 600-mile flight to 749 miles.
Some rain will continue on Saturday across Washington, Montana, and Northern Idaho.
The threat of thunderstorms, lightning, gusty winds, or dry fuels have triggered Red Flag Warnings across six states
Thousands of lighting strikes hit Montana, Idaho, Washington, and Oregon Thursday and Thursday night. Much of the area also received at least a little precipitation over the last 48 hours, which could reduce, but not eliminate, the threat of new wildfires.
Researchers have found that about a quarter of the fires caused by lightning that grow to more than 4 km² (988 acres) are reported more than a week after they are ignited.
A paper published in the Fire Open Access Journal describes how the National Lightning Detection Network (NLDN) and U.S. Forest Service fire data were used to determine the correlation between lightning strikes and the reported location of lightning-caused wildfires.
The NLDN, which has been used operationally for several decades, consists of 113 sensors across the continental United States and has a reported flash detection efficiency of cloud to ground flashes between 90–95%, with spatial errors that are typically less than 500 meters for the flash data used in the study.
The researchers found, of lightning-caused fires that grew to more than 4 km² (988 acres):
50% reported the same day 71% reported within 3 days 73% reported within 5 days 77% reported within 7 days
Holdover fires that are not reported for days or weeks after the lightning occurs can be problematic for land managers. Shortly after a thunderstorm has left the area, fire detection efforts are often ramped up and may continue in that mode for a few days. Fires that smolder in duff or under snow and suddenly grow can be unexpected. Firefighting resources that may have been staged in anticipation of emerging fires could be released or assigned to active incidents, complicating efforts at quick initial attack with overwhelming force.
Authors of the paper: Christopher J. Schultz, Nicholas J. Nauslar, J. Brent Wachter, Christopher R. Hain, and Jordan R. Bell.