Get ready now.
Because by the time the ember storm hits, you won’t have time.
That’s the message that emerged from a sobering webinar on preparing your home for a wildfire, put on by the University of Arizona Extension recently.
“It’s going to swirl up and go into eddies in the lee side of your building and create piles of embers,” said moderator Chris Jones of the ember storm created by even the close approach of a wildfire. “That’s where they can start a small fire and the fire gets bigger and they’re able to destroy the home.”
The warning comes as Arizona heads into one of the most dangerous fire seasons in history, based on the condition of fuels, projected temperatures and the severe to exceptional drought that grips most of the West — and virtually all of Arizona.
Last year, wildfires burned nearly a million acres in Arizona — and that followed the first relatively normal winter snowfall in years. This year, most areas got less than half the normal snow and spring has turned hot and dry — despite the brief arrival of cool, wet conditions last weekend.
A megafire can throw softball sized embers up to a mile ahead of the fire line. Mostly the embers rain down as small chunks of glowing wood — or flurries of sparks.
“If they’re able to get lodged into places, they can ignite the house,” said Jones. “An ember can be a small spark like you see coming out of a campfire — or they can be much larger. Even small sizes can be enough to set a house on fire.”
Mostly, the webinar focused on steps homeowners can take to protect their homes from such an ember storm — both long before the fire starts and as the flames approach.
“A hot fire can loft material up — much larger pieces of material that are burning. It can carry these materials a mile away — certainly a quarter of a mile,” said Jones. “It is the most common way that houses catch on fire during wildfires — from the embers rather than a flaming front from a burning forest.”
Such an ember storm can easily set several homes on fire at once, quickly overwhelming fire departments. For instance, in Rim Country even a single house fire draws in units from multiple departments. If two or three houses ignite at once under the rain of embers, the fire department will lack the resources to respond.
Once one house on a block catches fire, the flames can spread readily to neighboring houses. Repeated analysis of wildfire flame patterns in residential neighborhoods show that the ember storm starts the process — but flames then spread from house to house until the whole block is gone.
Preparing for that ember storm not only can save your home, it can save the whole block. Unfortunately, you still face potential disaster if a neighbor hasn’t taken those precautions or left thickets of brush against the house and between homes.
Cities and counties can reduce this risk by adopting Firewise codes, which require homeowners to keep dangerous concentrations of brush cleared — protecting both their own home and the neighborhood.
Ultimately, protection from an approaching ember storm requires cities and counties to embrace fire-adapted building codes. These codes don’t add much to the cost of a new home, but do incorporate protective designs for things like porches, attics, roofs, building materials and other weak points when the ember storm hits.
Kevin McCully, the fuels management officer for the Payson Fire Department participated in the webinar and stressed the value of a wildland-urban interface building code in reducing the potential catastrophe of an ember storm — at least for new construction.
“The WUI code is valuable in getting those weak spots in the structure — siding, roofing, especially when building a new house — you can engineer a lot of that safety into the house.”