Map, showing the approximate location of the planned prescribed fire at Devils Tower (300 acres in white) and the 56 acres (in red) that escaped beyond the planned perimeter. Image from Google Earth. Perimeters by Wildfire Today. (click to enlarge)
Yesterday after Wildfire Today made inquiries about reports that may have been completed regarding the escaped prescribed fire on May 8, 2013 at Devils Tower National Monument in Wyoming, the National Park Service released the official review of the incident.
The NPS ignited the 300-acre unit on May 7, 2013. Several spot fires occurred outside the planned perimeter that were contained the first day. But during mopup at 12:50 p.m. on May 8 fire became established again at one of the spot fire locations on the southwest side of the project. At that time the cooperating U.S. Forest Service resources present the day before had been released. Some of the remaining firefighters were concentrating on the previous day’s spot fires at another location, but most of the firefighters were attending an After Action Review of a non-injury tipover of a Utility Task Vehicle (UTV) that occurred the day before. The 56 acres burning outside the burn unit were mostly stopped at the Monument boundary, but a few acres crossed over onto private land leased by Wyoming state Senator Ogden Driskill, but no structures were damaged.
Devils Tower Rx fire, May 7, 2013. NPS photo.
In the interest of full disclosure, Devils Tower was one of the seven National Parks for which I was the Area Fire Management Officer, from 1998 until 2003.
The review pointed out several times that one of the primary issues related to the escape was that in computing the fine dead fuel moisture, it was assumed that the fire would be shaded by the smoke column. However, some of the area was not shaded, and for two hours each day on May 7 and 8, at those locations the fine dead fuel moisture dropped below the 4 to 10 percent allowed in the prescription, down to 3 percent.
Other than how the weather affected the fuel moisture, the review barely mentioned the weather conditions and the forecast. Two spot weather forecasts were issued before the escape — one at 7:57 a.m. MDT on May 7 and another at 9:29 a.m. on May 8, the day of the escape. For May 8, both forecasts predicted fairly strong northeast winds, of 7 to 15 mph and 8 to 14 mph.
The Remote Automatic Weather Station at Devils Tower is very close to the location of the prescribed fire, in a low-lying area partially sheltered by trees from winds from all directions (see map above). Northwest, north, and northeast winds are additionally partially blocked by higher ground and the Devils Tower itself. Below are the weather observations from the weather station between 17:23 on May 7 through 17:23 on May 8. They show mild sustained wind speeds, with gusts around mid-day to late afternoon on May 8 of 13 to 22 mph. If the weather station was in a more exposed location the recorded speeds would have been higher.
Devils Tower weather, May 7 and 8, 2013
The NPS committed four people to the facilitated learning analysis of the non-injury slow tip over of the UTV, and three to the review of the escaped prescribed fire.
Photo from the FLA for the UTV tip over, that presumably shows a UTV in the approximate location of the accident. NPS photo.
We initially covered the prescribed in 2013 fire HERE and HERE.