EUGENE, Ore. -- When a wildfire starts, the first people on scene are typically firefighters and other first responders working hard to stop the flames from spreading as quickly as they can. But if a fire continues to spread, resources beyond just firefighters are needed to contain the blaze.
Weather plays a key role in wildfire behavior and spread. So much so that along with firefighters, meteorologists are sent to many fires to work directly with incident management teams. When the Holiday Farm Fire first started, National Weather Service meteorologist Tom Wright knew it was going to spread rapidly.
“I saw what it was doing. I’m sitting there in Medford watching this thing. And I thought oh my goodness this thing is really raging. I mean the way it’s going it could be down near Eugene within a couple days, and so I’m starting to watch it. I know that they’re going to need an IMET,” he said.
An IMET, or Incident Meteorologist, is a designated role within the National Weather Service, and all IMETs have the same common mission.
“My primary purpose out here is the safety of the firefighters and the public. Because we don’t want any weather to come up and bite you know that they weren’t expecting. A big wind shift or a thunderstorm comes up out of nowhere,” Wright said.
An Incident Meteorologist’s day starts early, as they brief firefighters on the weather every morning.
“Good morning, Tom Wright, Incident Meteorologist. The fire weather forecast is on page 22 of your IAP this morning, and you wouldn’t know it by standing here, but it’s pretty windy up on the ridgetops right now."
After the morning briefing, it’s time to monitor the current day’s weather and make any forecast adjustments. While there are many tools to make a forecast, Wright has found one tool that works best.
“I’d say one of the number one things is a sounding. Forecast soundings. I’ve gotten to the point on some fires, like in particular when I was on a fire in the Modoc forest, where I could tell what was going to happen just from looking at the sounding,” he said.
A forecast sounding is a vertical profile of the atmosphere, where variables such as temperature, dewpoint, and winds are displayed. All of this data is used to create weather forecasts, but there are a few weather parameters that are especially important to fire weather forecasting.
“The two most important things for fire are wind and humidity. The strong winds obviously can drive fire around. And the humidity determines what happens to the fuels. So, if it’s really humid the fine fuels like grasses will start take up water and be less able to burn," Wright said.
After the forecast is updated, it is important for an Incident Meteorologist to travel to the fire zone to analyze how previous weather has impacted the fire.
“This is a good example, we’re about two miles east of Blue River. And this is pretty close to where the fire started. These are good examples of the tree damage from the wind. You can see there’s at least three trees in view here that were uprooted. Those are probably a good one-foot in diameter trees that were uprooted by the wind," he said.
It can also be important to take weather observations in the field, as sometimes there aren’t any weather stations nearby.
“We have a lot of weather instruments we use in the field as Incident Meteorologists," Wright said. "One of those is this electronic Kestrel, gives us temperature, humidity, of course we can get the wind with this little propeller in here and wind direction using our compass. And this one is pretty advanced, it gives us altitude and probability of ignition. So, if embers were to hit something, what’s the probability they would ignite the thing, and of course that depends a little on fuels but this gives us a weather indication on how likely a fire is to ignite.”
Incident Meteorologists are a crucial part of a fire’s incident management team. Especially with the complex microclimates we have here in Western Oregon.