Aircraft meteorological systems may revolutionize incident meterology

By TRACI WEAVER

Imagine being able to get real-time, exact weather readings from directly over a fire instead of relying on a forecast from a National Weather Service office 100 or more miles away. Incident meteorologists would immediately know if weather conditions were not as forecast, and firefighters could be quickly warned if unpredicted winds were materializing. That may soon be a reality, thanks in part to the vision of Paul Witsaman, aviation and fire meteorologist for the National Weather Service Southern Region.

"Firefighters understand the relationship of fire and weather," Witsaman says. "We've [traditionally] relied on the information ground personnel provide us, [along] with belt weather kit readings, to keep us informed of what the weather is actually doing at the site.

I wondered what it would be like if we could get accurate readings from 10,000 or 15,000 feet above the fire. If we knew exactly what the wind, humidity and pressure were at that level, it would help draw a three-dimensional weather picture for a fire or other all-risk incident."

PHOTOS JAN AMEN An AT-402 equipped with AIMMS flies over a prescribed fire to test the system while ascending to 13,000 feet and back down to 1,000 feet.

Finding the Technology
Witsaman wrote an abstract on the subject, detailing how valuable it would be to have the capability to monitor weather from aircraft flying over fires.

"I really didn't even know if the technology existed, but it just made sense, especially since aircraft are so prevalently used on a fire," he says.

The technology did exist. In fact, Canadian-based Aventech Research Inc. had developed a product called an Aircraft Integrated Meteorological Measurement System (AIMMS-20).

"AIMMS technology began with the [design of the] AIMMS-10 in 1997, after extensive input from forest protection professionals in Canada and the United States," says Stephen Foster, director of marketing and sales for Aventech Research. "They highlighted the benefits of representative upper-air data given the critical influence of site-specific meteorology on wildfire behavior and aerial spraying."

Aventech just happened to have an AT-402 equipped with AIMMS as part of an aerial pesticide study at the USDA Agricultural Research Station (ARS) in College Station, Texas. "We were interested in trying to reduce the amount of chemical that gets off target when doing aerial pesticide application for agriculture," says Hal Tom, a pilot with the ARS Areawide Pest Management Research Unit. "Wind is obviously the biggest factor in causing drift, which not only results in wasted chemical, but can be a liability issue if the chemical lands on someone else's property."

Bradley K. Fritz, agricultural engineer with ARS, and Tom lent their assistance with AIMMS to the National Weather Service and the Texas Forest Service, which conducted a small, prescribed fire near Bastrop to test what has now become known as the

"HI-RISE project," Hazardous Incident — Rapid In-Flight Support Effort.

The AT-402 flew over the prescribed fire to record wind speed and direction, dew point, temperature and air pressure while ascending to 13,000 feet and back down to 1,000 feet. The data was sent via satellite to Aventech. Ten minutes later, incident meteorologists (IMETs) stationed at the incident command post near Bastrop received the information.

AIMMS technology can provide real-time weather readings from 10,000 to 15,000 feet above the fire.

"The data came across to us via a wireless Internet [connection]," says IMET Greg Murdoch. "We were able to digest the data and make some immediate decisions. Because of the flight, we adjusted our forecast. Based on the inversion, we decreased the chance of thunderstorms and increased the minimum relative humidity forecast from 50 to 57 percent."

Sensors on a plane equipped with the AIMMS record wind speed and direction, dew point, temperature, and air pressure.

Data is sent via satellite to the command post, allowing incident commanders to make immediate decisions based on weather conditions.

Murdoch explains that the technology could revolutionize incident meteorology, especially when it comes to accuracy and confidence in an incident meteorologist's forecast.

"What we see in the upper atmosphere at 10 a.m. will mix down by 3 p.m., giving us a true picture of what the weather will do that day," Murdoch adds. "That will really help in determining trigger points and giving incident personnel lead time for making operational decisions."

Improving Firefighter Safety
The HI-RISE project is welcome news to firefighters as well. According to Rich Gray, Texas Forest Service burn boss during the test flight, the technology could be another positive step in incident safety.

"Anything the National Weather Service can do to more accurately forecast when fronts will pass or other weather  [conditions will change] translates to safer operational decisions for firefighters," he says. "The trigger points for pulling firefighters off the line are based primarily on wind speed and relative humidity. With real-time, accurate information and the ability to track changes in the weather and fire behavior, we'll know in advance if those trigger points are going to be met.

"Weather has been a factor in many firefighter deaths," Gray adds. "The direct result of this [technology] is improved firefighter safety."

Those involved with the HI-RISE project hope to see it become a regularly used tool on incidents. Agriculture applicators also hope the technology becomes commonplace in their industry. The cost of outfitting a plane with an AIMMS unit is around $30,000. The unit has to be calibrated for the type of plane to account for the aerodynamic influence of the aircraft itself on the wind measurements.

San Antonio-area meteorologist Monte Oaks, who was also part of the HI-RISE project, said it is in line with the National Weather Service's mission. "By testing this new data source on a variety of applications, NWS meteorologists will also better understand the value we can provide future customers as we expand fire weather services into an ‘all-hazards' meteorological support role," he says.  

More test flights using AIMMS may be conducted in Texas and Idaho this summer.

Traci Weaver is a fire-prevention specialist and an information officer with the Texas Forest Service. Contact her at tweaver@tfs.tamu.edu.