Wildfire smoke and fire danger, August 31 and September 1, 2016

wildfire  smoke forecast
Wildfire smoke forecast for 5 p.m. MDT August 31, 2016.

NOAA’s Earth System Research Laboratory, as part of an experimental program (above), has produced a smoke forecast for 5 p.m. on Wednesday, August 31, showing that many areas in the western U.S. are affected by smoke from wildfires.

Below is their forecast for 5 p.m. MDT on Thursday, September 1, 2016.

Wildfire smoke forecast
Wildfire smoke forecast for 5 p.m. MDT September 1, 2016.

The last map, below, predicts elevated wildfire danger on September 1 in parts of California, Nevada, Utah, Idaho, and Montana. Isolated dry thunderstorms could be in the cards for areas in Nevada, Idaho, Montana, Utah, and Wyoming.

Wildfire danger for September 1
Wildfire danger for September 1, 2016.

Pioneer Fire in Idaho is one of 5 fires in US with over 1,000 firefighters assigned

The Pioneer Fire was very active Monday and Tuesday.

Above: Pioneer Fire. Uncredited/undated InciWeb photo.

On Tuesday the Pioneer Fire in central Idaho continued its march to the north, adding another 16,000 acres to bring the total to over 157,000 acres. Burning 32 miles northeast of Boise and 23 miles west of Stanley, it has been creating huge convection columns rising 30,000 feet into the atmosphere for the last two days.

Map Pioneer Fire
Map of the Pioneer Fire at 8 p.m. MDT August 30, 2016.

Most of the growth on Tuesday was on the north side while it was pushed by an 8 to 12 mph wind gusting at 18 to 24 that was variable, but mostly out of the south. As we write this at 2:50 p.m. on Wednesday, the wind so far today has been out of the west and northwest at 4 to 10 mph with gusts of 16 to 24. The smoke being pushed to the east will probably make the air quality rather unpleasant in Stanley, due east of the fire.

The fire was very active late into Tuesday night due to the low relative humidity which ranged from 24 to 30 percent during the night at the White Hawk weather station at 8,344 feet elevation. At 2:33 p.m on Wednesday it was 66 degrees with 21 percent humidity.

Map Pioneer Fire
Map of the Pioneer Fire August 30, 2016. The black line is completed fireline. The red is uncontrolled fire edge.

The Pioneer Fire is one of five currently active fires in the United States that are staffed by more than 1,000 personnel.

Fire NameStatePersonnelAcresCost to date, millions

As of Tuesday evening the total number of resources assigned to fires in the US included 444 hand crews, 1,060 engines, 147 helicopters, and 19,064 personnel. When the number of crews approaches 500 and there are almost 20,000 personnel committed, you know things are getting busy.

Impressive convection column on Pioneer Fire is being studied by researchers

Above: The photo above was taken from the research aircraft August 30 by Nick Guy of the University of Wyoming’s Atmospheric Science department.

The Fire Weather Research Laboratory from San Jose State University is conducting research from an aircraft flying over the Pioneer Fire in central Idaho. Today using N2UW, a twin engine 1977 Beech 200T King Air, they flew for over three hours at 27,000 feet studying the fire for the RaDFire project.

The aircraft is outfitted with a ton of instruments including Doppler radar. Craig Clements, Associate Professor in the Meteorology Dept. at SJSU, described it for us:

The radar is called the Wyoming Cloud Radar (WCR). It’s on the aircraft, points up, down, and down-forward to get horizontal winds and vertical winds. The goal of the RadFIRE (Rapid Deployments to Wildfires Campaign) is to get data on plume dynamics from ground based mobile Doppler Lidar. But we were awarded 10 flight hours to test the WCR to see if it works in smoke plumes. And it does so well, more than we can imagine!

The group has been known to fly through the convection column. I’ve done that a few times and it’s an interesting experience — it can get a little turbulent, as you might expect.

On Monday they said the top of the pyrocumulus cloud over the fire topped out above 30,000 feet. In Tuesday’s photos it was at about 25,000 feet but toward the end of the day the top got up to at least 32,000 feet, Mr. Clements said.

The project is sponsored by the National Science Foundation and it’s being led by San Jose State University. Other collaborators on the project are David Kingsmill at the University of Colorado Boulder, and the University of Wyoming King Air team.

Since it started on July 18 the Pioneer Fire has burned over 140,000 acres.

This last photo of the convection column was not taken by the researchers. It was shot by Steve Botti in Stanley on August 29, more than 20 miles away from the fire.

Pioneer Fire
Pioneer Fire, as seen from Stanley August 29, 2016. Via Mike Warren.

South entrance to Yellowstone opens after being closed by the Berry Fire

The Maple Fire in Yellowstone spreads closer to West Yellowstone and Hwy. 191

The video above was uploaded Monday August 29 the day before Highway 89 opened.

The south entrance to Yellowstone National Park opened Tuesday morning after having been closed for the last week after the Berry Fire burned across U.S. Highway 89 at the north end of Jackson Lake in Grand Teton National Park.

The fire was active Monday on the northeast, south, and west sides and has burned about 13,200 acres. A large smoke column actually assisted firefighters working on the east side of the highway Monday by shading the fire on that side of the lake, slowing the spread.

Fires Yellowstone and Grand Teton National Parks
Fires in Yellowstone and Grand Teton National Parks, August 30, 2016. The green lines are the boundaries of the two parks. The white line is the Wyoming/Montana boundary.

A new fire in Yellowstone National Park is named the Central Fire, probably because it is in the center of the park. It is 9 miles west of the Lake developed area and 2 miles south of Hayden Valley. The fire is just northwest of the 2015 Spruce fire which is expected to block the fire’s growth to the east. Currently it is burning in mature lodgepole pine.

The Maple Fire has spread considerably over the last several days and is within about 2 miles of Highway 191 north of West Yellowstone, Montana, and about 3.5 miles from the community. It has crossed from Wyoming into Montana and on the south side is burning along the Madison River very close to the West Entrance Road (Highway 20). It has reached the east side of the Boundary Fire that spread on its west side to within a quarter mile of Highway 191.

The staff at Yellowstone wants visitors to know that all entrances and roads within the park are open. Visitor facilities and businesses in the park and surrounding communities are not impacted by the fires and remain open.

The Buffalo Fire is in the north-central part of Yellowstone about 2 miles north of the Northeast Entrance Road (Highway 212). The fire has burned about 4,000 acres, a few of which may be just across the state line in Montana.

Above: the Maple Fire burns along the Madison River in Yellowstone National Park August 29, 2016. Video by Jeremy Weber of the West Yellowstone News.

Where does the moisture in a pyrocumulus cloud come from?

Above: CNN Meteorologist Chad Myers explains pyrocumulus clouds. This is a screenshot from Mr. Myers’ 52-second video. The Weather Channel has a similar explanatory video.

Cumulus clouds are puffy clouds, usually having a somewhat flat base but with some vertical development that gives them rounded towers on top. They can form when the sun heats the earth, which then heats the air above it causing the warmer air to rise. Rising air cools and the relative humidity increases. If it reaches 100 percent, water vapor condenses forming a visible cloud.

Above: time-lapse video of pyrocumulus over the King Fire in California.

Clouds can also form over vegetation fires. In some cases a very intense fire can produce enough heat that the air rises very quickly. If it is not dispersed laterally by wind it can rise high enough that a cloud forms. This can look like a cumulus cloud, but when they form over a fire they are called pyrocumulus clouds.

Occasionally these clouds will produce rain or even lightning. Water requires a non-gaseous surface to make the transition from a vapor to a liquid. Smoke helps out by contributing very small particles that are used as condensation nuclei on which water droplets form, to create clouds or rain.

If pyrocumulus clouds grow large they resemble cumulonimbus, thunderstorm clouds. What goes up must come down, and if not disturbed by a strong wind during the dissipating stage the updrafts can reverse and become downdrafts. This is sometimes called a “collapsing column”. When that descending air hits the ground it spreads out, sometimes in all directions, and can quickly and drastically change the wind direction at a given point on a fire. This can be fatal if firefighters find themselves in the wrong location at the wrong time.

I had always assumed that much of the moisture that formed a pyrocumulus came from a byproduct of combustion — water vapor — something that many burning fuels create. (Some TV meteorologists also make the assumption about the sources of the moisture.) A great deal of water vapor is produced when vegetation burns, and the higher the fuel moisture the more water vapor is created.

But I wanted to confirm that assumption before I wrote this article, and it turns out I was wrong. I found two research papers that were devoted to the subject and they were mostly in agreement. As the byproducts of combustion rise above a fire the water vapor is rapidly diluted before it reaches the condensation level, or what becomes the base of the pyrocumulus. One group of researchers in Germany calculated that 10% of the moisture in a pyrocumulus comes from the fire.

Others with the Bushfire & Natural Hazards CRC in Melbourne, Victoria, Australia determined that the contribution of water vapor from the fire is negligible since it is diluted before it reaches the height of the cloud:

Fire plumes entrain large amounts of environmental air as they ascend, which greatly dilutes the plume gases, including the fire moisture. Figure 3 shows the fire moisture dilution for the moist fire simulation(right panels of Fig. 2). The lightening shades of blue with height demonstrate the fire moisture dilution. When the plume reaches the condensation level (4.5 km) there is barely any fire moisture evident to contribute to cloud development. The dilution rate may be sensitive to fire size and intensity.

pyrocumulus moisture
From research by the Bushfire & Natural Hazards CRC, Melbourne, Victoria.

Continue reading “Where does the moisture in a pyrocumulus cloud come from?”

Wildland fire potential in the lower 48 states

The U.S. Forest Service produced this map showing wildfire potential in the lower 48 states. Higher resolution versions are available.

Here is how the USFS describes this map:

“The wildland fire potential (WFP) map is a raster geospatial product produced by the USDA Forest Service, Fire Modeling Institute that is intended to be used in analyses of wildfire risk or hazardous fuels prioritization at large landscapes (100s of square miles) up through regional or national scales. The WFP map builds upon, and integrates, estimates of burn probability (BP) and conditional probabilities of fire intensity levels (FILs) generated for the national interagency Fire Program Analysis system (FPA) using a simulation modeling system called the Large Fire Simulator (FSim; Finney et al. 2011).

The specific objective of the 2012 WFP map is to depict the relative potential for wildfire that would be difficult for suppression resources to contain, based on past fire occurrence, 2008 fuels data from LANDFIRE, and 2012 estimates of wildfire likelihood and intensity from FSim. Areas with higher WFP values, therefore, represent fuels with a higher probability of experiencing high-intensity fire with torching, crowning, and other forms of extreme fire behavior under conducive weather conditions.

Using the FPA FSim products as inputs, as well as spatial data for vegetation and fuels characteristics from LANDFIRE and point locations of fire occurrence from FPA (ca. 1992 – 2010), we used a logical series of geospatial processing steps to produce an index of WFP for all of the conterminous United States at 270 meter resolution.”