20 Spring 2012 Applegater
Burning answers
BY roB BuDGE
Have you seen the Gater’s online
calendar? www.applegater.org
This time of year, I get lots of
questions about prescribed burning from
members of the public. Three of the most
frequent are: “Why is the weather forecast
that the Forest Service (FS)/Bureau of
Land Management (BLM) use sometimes
different from the one posted on the
National Weather Service’s website?”; “How
does the FS/BLM get clearance to burn?”;
and “How come the FS/BLM are allowed
to burn when there is an air stagnation
advisory?” Hopefully, the following
explanations of the smoke management
process will help answer these questions.
Weather forecast
When the FS/BLM wants to conduct
a prescribed burn (whether it be the
burning of slash piles or a low underburn
on the forest floor), the first thing we
do is consult the weather forecast that is
produced by the National Weather Service
(NWS). The state of Oregon is divided
into 32 distinct fire weather forecast zones.
Every morning at about 6 am a weather
forecast is issued for each zone for that day
and several days into the future.
After consulting the forecast, the
Burn Boss (the person in charge of
the prescribed burn) determines if the
predicted weather matches what is required
in the Prescribed Fire Burn Plan (a
document that describes the project in
detail, including goals, objectives, required
weather parameters, volume and type of
vegetation to be burned, maps, required
personnel and equipment, etc.). The goal
is a safe, clean burn with minimal smoke
impacts, so particulars such as the altitude
and aspect of the burn site and the dryness
and makeup of the fuels are all compared
with the weather forecast.
If the predicted weather is favorable,
the process of notifying cooperators and
members of the public that a prescribed
burn will take place begins.
On the day of the burn, the Burn Boss
will often request a “Spot” weather forecast
from the NWS for the specific burn site
to make sure that conditions are still good
to go. The Spot forecast is explicit to the
specific burn unit at that time, rather than
for the larger fire weather zone. Because
it uses current, site-specific weather
observations and takes into account local
terrain features and microclimates, the
Spot forecast can be significantly different
from the forecast for the fire weather zone
that was issued the previous day. Usually,
the Burn Boss receives the finished Spot
weather forecast from the NWS about an
hour after it is requested.
Clearance to burn
The State of Oregon requires that
Smoke Management Rules be followed for
the “prescribed burning of forest fuels for
forest management purposes.” This is the
law, and federal land management agencies
must follow it like anyone else. The state
also has a Smoke Management Plan,
which is designed to protect air quality.
In support of this effort, the Oregon
Department of Forestry operates a Smoke
Forecast Office, which is located in Salem.
Just like the NWS, the state uses
fire weather zones for its smoke forecasts
and instructions. Every day between 2-3
pm during the spring and fall prescribed
burning seasons, a smoke management
forecast is issued for the following day.
The forecast contains instructions specific
to each fire weather zone. Based on the
predicted “mixing height” (the height
the smoke needs to rise above the ground
before it disperses into the atmosphere)
and the “transport wind flow” (the wind
that blows the smoke out of the area),
prescribed burning within a zone may
have varying restrictions applied in order
for the prescribed burn to meet air-quality
standards. Restrictions might be placed
on tonnage (the amount of material to
be burned), spacing (distance between
burn units), time, and distance to smoke-
sensitive areas.
If the forecast calls for no burning,
or if it limits the amount of tonnage that
can be burned, the FS/BLM can request
an exception. Often an exception is
requested because, from experience and
local knowledge, the Burn Boss suspects
that the smoke forecast may not accurately
reflect actual conditions at the burn site.
(After all, Salem isn’t exactly right around
the corner.) Depending on the location
of the unit, e.g., high elevation, distance
to homes or recreation areas, etc., as well
as the type and amount of vegetation
being burned, it is sometimes possible to
conduct a successful prescribed burn with
no appreciable impact to air quality from
smoke, even if the initial zone forecast did
restrict burning.
To request an exception, the FS/BLM
Burn Boss calls the Smoke Forecaster by
phone, provides a legal description of the
project area, and describes the amount
and type of vegetation to be burned. The
Forecaster then focuses on the specific area
and can grant permission to burn based on
the current conditions at that site.
Sometimes the Forecaster grants
permission to proceed with a prescribed
burn because the smoke forecast (which
was produced the previous day) doesn’t
match the actual conditions on the
ground. The Burn Boss can also negotiate
with the Forecaster to get permission
to burn a portion of the unit or a lesser
amount of material (fewer tons) while
still meeting air-quality requirements.
And sometimes, after talking with the
Burn Boss, the Forecaster sticks with his
initial determination and will not grant
permission to burn based on air-quality
concerns. The Smoke Forecasters are fully
aware of the importance of prescribed
burning as a land management tool and
make every effort to not restrict prescribed
burning unless it is necessary to maintain
air quality.
Air Stagnation Advisories (ASAs)
During the winter months, ASAs
may be issued by the NWS for the Rogue
Valley. These advisories warn of weather
conditions in which air pollutants get
trapped in the valley and do not clear out
as they typically would. This can result in
serious air-quality issues in the valley.
When an ASA is issued, residents are
asked to limit their driving and the use
of wood-burning stoves. However, most
federal prescribed burning takes place
outside of the Rogue Valley proper, and
is usually at higher elevations. Therefore,
an ASA does not necessarily constitute a
ban for prescribed burning in or near the
advisory area.
While members of the public might
express concern that the FS/BLM is
burning during an ASA, it’s important
for people to understand that an ASA is
usually issued for the general public in the
populated areas (typically in the valleys).
During an ASA, our rules mandate
that prescribed burning be closely
controlled in such a manner that smoke
from the burn will not further degrade
air quality in the ASA area. Prescribed
burning may be allowed if the smoke will
vent away from or above the ASA area, so
in these cases we rigorously check wind
conditions to get it right. After all, we are
residents of the Rogue Valley, too.
Rob Budge • 541-618-2102
Deputy Fire Staff, Fuels
Rogue River-Siskiyou National Forest
NOTE: See online article, “Federal forecast
predicts fewer wildfires in West this year.”
Spot weather reports and burning early in the day can help keep smoke
from moving down into valleys or residential areas. Photo by Sandy Shaffer.