Campers spending the afternoon of September 17 in Boise National Forest should not expect the approach of rain clouds to lower the wildfire risk. In a Red Flag Warning issued at 4:31 a.m. Mountain Daylight Time (MDT) that day, the NWS Boise forecast office said rainfall would be limited, lightning would be frequent, and thunderstorm outflow gusts could reach 50 mph. The Idaho areas are in effect from noon to 9 p.m. on the 17th.
This alert was upgraded from a stage that had been monitoring the potential for wildfire. The NWS explained that newly ignited fires can spread quickly and advised against outdoor burning. For camping plans, that means limiting activities that create embers, such as campfires or outdoor cooking, and deciding in advance where to go indoors as soon as thunder is heard.
Areas Affected
In Idaho, the affected areas include northern and southern Boise National Forest, western Sawtooth National Forest, and Camas Prairie. In Oregon, they include the Burns BLM district, Steens Mountain, northwestern Vale BLM district, and Baker Valley. The Oregon alert is in effect from 11 a.m. to 8 p.m. Pacific Daylight Time (PDT). Travelers moving between the two states should note that the same alert is displayed at different times depending on the time zone.
The NWS forecast discussion at 5:33 a.m. on the 17th expected thunderstorms to develop over the high terrain of southwestern Idaho and the Blue Mountains of Oregon’s Harney and Baker counties, with some becoming strong in the afternoon. Fast-moving thunderstorms may not leave enough rain, particularly in southeastern Oregon. The forecast indicated that brief heavy rain could occur in some places while other areas receive little total rainfall relative to the lightning.
The same forecast discussion also reported a 59 mph wind gust near Twin Falls around 12:30 a.m. on the 17th. This was a separate, already observed event and does not mean that the same winds occurred at every campground. The afternoon warning’s 50 mph figure refers to thunderstorm gusts that may occur later. This weather warning alone also cannot determine whether individual national forest roads or campgrounds are closed, so reservation holders should separately check operating notices from the agency managing their destination.
What RV Travelers Need to Know
Plan an evacuation route first so you do not remain outside for a long time trying to pack up camp after lightning moves close. NWS lightning safety guidance says to move indoors when thunder is heard and remain in a safe location for at least 30 minutes after the last thunder. A sturdy building with a roof and walls or a metal-roofed vehicle with its windows closed qualifies; open shelters and tents should not be used as shelter.
NWS camping safety guidance recommends identifying shelter before camping and preparing a way to receive alerts, such as through a weather radio or mobile-phone emergency alerts. Simply having parked an RV is not a reason to continue nearby activities. If companions are out fishing or walking, it is better to decide where to shelter together and when to return before afternoon thunderstorms develop.
The NWS outlook is that showers and some thunderstorms may continue on Friday the 18th. Do not treat the warning’s end time on the night of the 17th as confirmation that next day’s mountain plans are safe. Immediately before traveling, check the latest forecasts and warnings for the destination again, and decide whether to use fire based on restrictions from the agency managing the site.
Photo: NOAA/NWS Boise / Original photo page (Public domain)