Researcher uses radar data to make three-dimensional maps of smoke plumes
Radar rendering of smoke plume over the Creek Fire. By Neil Lareau, University of Nevada Reno.
The extreme heat caused by a large high pressure system in the West has led to an unusual number of fire tornados.
An article in the Washington Post by Matthew Cappucci explains how Neil Lareau, a professor of atmospheric sciences in the department of physics at the University of Nevada at Reno, used detailed weather radar data to make three-dimensional maps of smoke plumes over fires. While it is unusual to have a fire tornado anytime, the data indicates that on at least three fires this year fire tornados have been detected by radar. One was photographed on the Loyalton Fire August 15 about 12 miles northwest of Reno, Nevada. National Weather Service meteorologists who spotted it on radar issued the agency’s first-ever fire tornado warning.
Fire tornado on the Loyalton Fire, by @DVRockJockey August 15, 2020.
Fire tornados and huge smoke plumes topped by massive pyrocumulus clouds are indicators of extreme fire behavior. There is absolutely nothing firefighters or aircraft can do to slow a blaze under those conditions — and those pyrocumulus clouds seem to be occurring more frequently this year.
Creek Fire September 5, 2020. IMT photo.
The day after the Creek Fire started, its smoke plume grew to 55,000 feet, taller than the tornadic thunderstorms seen in Oklahoma and Kansas in the the spring.
From the Post:
“Anecdotally, this is the deepest that I’ve seen,” said Lareau, who was shocked by the height achieved by the smoke plume. “It’s about a solid 10,000 feet higher than we’re typically seeing with the highest of these plumes.”
Before 2020, only a few fires had ever produced documented fire tornadoes in the United States; now we’re seeing them every week or two. Lareau says the tremendous heights of the wildfires’ clouds, combined with more concerted and astute observation, are factors in the numerous fire tornadoes that have been reported this year. He thinks there may also be some truth to the apparent increase.
“We have a ton of eyes on every fire, looking at every frame, but still, we weren’t seeing these before,” he said. “And we’re seeing all too much of it right now. It’s rather worrying.”
Red Flag Warnings and Fire Weather Watches September 5, 2020.
Hot, dry and in some cases windy weather will bring elevated wildfire danger to many of the western states through the Labor Day weekend.
Southern California
Extreme heat in southern California could set all-time high temperature records with the possibility of rolling power blackouts and more wildfires. Some of the inland cities could have temperatures 10 to 20 degrees above normal through Monday. The hottest days will be Saturday and Sunday, with slightly lower temperatures Monday. Riverside could see highs of 116 on Saturday and 118 on Sunday.
Red Flag Warnings and Fire Weather Watches in southern California, September 5, 2020.
Red Flag Warnings are in effect Saturday for portions of Riverside and San Diego Counties through Sunday at 6 p.m. Forecasters expect east winds of 15 to 20 mph with gusts of 25 to 35 mph, with single-digit humidities in the afternoons.
Weather forecast for Riverside, California, September 5, 2020.
A Fire Weather Watch for the Los Angeles, Ventura County, and Santa Barbara mountains for Monday evening through Tuesday evening will probably be turned into a Red Flag Warning for gusty sundowner winds from the north or northeast at 15 to 25 mph with local gusts up to 40 mph Saturday, increasing to 15 to 30 mph with local gusts up to 45 mph Sunday evening and Monday evening. The strongest winds will be in the western portions of the Santa Ynez mountains and Santa Barbara south coast.
The National Weather Service did not mince any words in describing the forecast:
The very hot and unstable conditions will bring a significant threat of large plume dominated fires across the region through Labor Day.
Northwestern United States
A strong high pressure ridge centered across the western Great Basin Saturday will bring continued hot and dry conditions through the afternoon and early evening, with temperatures in the 90s and humidities below 15 percent, contributing to potentially extreme fire behavior given the very dry fuel conditions. In central Idaho and western Montana winds are expected to exceed 20-25 mph for several hours Saturday afternoon.
Smoke
Near surface smoke at 11 p.m. PDT September 5, 2020.
The National Significant Wildland Fire Potential Outlook issued September 1 by the Predictive Services section at the National Interagency Fire Center for September through December predicts that most of the forested areas of the western states, with the exception of Montana, will have above normal potential in September. In October and November that is expected to shift to California and the southeast.
The data from NIFC shown here represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.
Below:
An excerpt from the NIFC narrative report for the next several months;
More of NIFC’s monthly graphical outlooks;
NOAA’s three-month temperature and precipitation forecasts;
Drought Monitor;
Keetch-Byram Drought Index.
“A continuation of peak season activity into September is expected across much of the West as drought conditions continue to take hold. Most western regions will experience areas of above normal significant large fire potential as shown on the maps to the left. By mid-month, however, the seasonal transition to fall will begin. Cold fronts brining winds but also precipitation will begin providing relief to the critically dry fuels. Fire activity will begin to diminish as fuel moistures begin to recover. As the days get shorter, overnight humidity recoveries will become greater. This will add further relief to fuels, especially the finer fuels.
“Following a brief pause in activity in California and a cessation of seasonal activity elsewhere across the West, large fire potential is expected to increase in October and November in wind prone areas across the state. The expectation of drier than average conditions and a higher probability of more frequent Foehn Wind events suggests that significant large fire potential will be elevated until winter sets in during December. The fall fire season across the East is expected to be near average but above average across much of the Southern Area due to drier than average conditions associated with a developing La Niña.”
Temperature and precipitation outlook, Sept., Oct., & Nov, 2020. Forecast made August 20, 2020.
August 23 through 24, partly due to the possibility of dry lightning
Storm Prediction Center’s Fire Weather Outlook for dry lightning August 23, 2020. SCTDRYT is scattered dry thunderstorms. ISODRYT is isolated dry thunderstorms. The colors of the labels apply to the same colors of the shaded areas.
The chance of lightning with little or no rain Sunday and Monday combined with high temperatures and low humidities has led to predictions of elevated fire danger.
Storm Prediction Center’s Fire Weather Outlook for dry lightning August 24, 2020. SCTDRYT is scattered dry thunderstorms. ISODRYT is isolated dry thunderstorms. The colors of the labels apply to the same colors of the shaded areas.
Red Flag Warnings are in effect for the northern half of California Sunday and Monday. The highest threat of dry lightning is Sunday afternoon through Monday morning.
Red Flag Warnings August 23, 2020
Thunderstorms with little or no rain is what started over 500 fires earlier last week. On Monday scattered or isolated dry thunderstorms could hit northern California and portions of Nevada, Utah, Wyoming, and Colorado. The storms are expected to move farther north Monday.
Nick Nauslar, a Fire Meteorologist at the National Interagency Fire Center in Boise wrote about the forecast in a tweet at 11:30 p.m. Saturday, saying, “Hundreds of new fires are likely if this event pans out.”
The Hot Dry Windy Index (HDW) predicts higher than normal fire danger for the area of the Hennessey Fire in the Bay Area Sunday through Tuesday. On Sunday it is above the 90th percentile compared to the average for the date. The HDW is a fairly new tool developed for firefighters to predict weather conditions which can affect the spread of wildfires. It is relatively simple and only considers the atmospheric factors of heat, moisture, and wind. To be more precise, it is a multiplication of the maximum wind speed and maximum vapor pressure deficit (VPD) in the lowest 50 or so millibars in the atmosphere. The HDW only only uses weather information – fuels and topography are not considered by HDW at all. If the fuels are wet or have a high live or dead moisture content it will not be reflected in the data.
Hennessey Fire 13 miles north of Napa, California, August 17, 2020. Screenshot from the video below. This shows the smoke after the wind shift.
A time-lapse camera at Atlas Peak in Napa County, California recorded the moment a wind shift caused by a passing thunderstorm August 17, 2020 suddenly changed the direction the Hennessey Fire was spreading.
If firefighters find themselves in a situation where thunderstorms could influence the wind direction on a fire, they should ensure they are in a safe location. A passing thunderstorm changed the wind direction on the Yarnell Hill Fire June 30, 2013 entrapping and killing 19 firefighters.
(To see all of the articles on Wildfire Today about the lightning-caused wildfires in California, including the most recent, click HERE.)
As of August 18 the Hennessey Fire has burned 2,700 acres; 205 structures are threatened and evacuation orders are in place. Three structures have been destroyed.
At least five tornado-strength/scale vortices are likely to have occurred in the fire Saturday
August 16, 2020 | 5:04 p.m. PDT
Fire tornado on the Loyalton Fire, by @DVRockJockey August 15, 2020.
On August 15 meteorologists with the National Weather Service in Reno observed on radar a very rare fire tornado in real time at the Loyalton Fire about 12 miles northwest of the city. They used emergency warning systems to get the word out as quickly as possible to firefighters and the general public. It is believed that this is the first time a real time warning for this type of event has ever happened, at least in the United States.
They also sent out tweets, of course:
Map of the Loyalton Fire the morning of August 16, 2020, time uncertain, but possibly about 2 a.m.
The Loyalton Fire started at about 4:30 p.m. August 14 east of the town of Loyalton and southwest of Mount Ina Coolbrith. It burned north and east adjacent to the areas of Beckwourth Pass and Hallelujah Junction. Early Sunday morning it was estimated at 29,829 acres. More information about the Loyalton fire on Wildfire Today.
A fire tornado is just like it sounds — a large column of rotating air over a vegetation fire. Inside it and around it are extremely strong winds, very high temperatures, and flying debris.
On July 26, 2018 a firefighter was killed as a fire tornado burned and scoured a mile-long path as the Carr Fire moved into Redding, California. A Redding Fire Department Inspector was burned over in his truck and died on Buenaventura Boulevard. Three dozer operators were entrapped and one of them was also killed.
According to a Green Sheet report by CAL FIRE the conditions that resulted in the entrapment of three dozers and the Redding Fire Department Fire Inspector that day were due to the fire tornado — a large rotating fire plume that was roughly 1,000 feet in diameter. The winds at the base were 136-165 mph (EF-3 tornado strength), as indicated by wind damage to large oak trees, scouring of the ground surface, damage to roofs of houses, and lofting of large steel power line support towers, vehicles, and a steel marine shipping container. Multiple fire vehicles had their windows blown out and their bodies damaged by flying debris.
The strong winds caused the fire to burn all live vegetation less than 1 inch in diameter. Peak temperatures likely exceeded 2,700 °F.
Here is an excerpt from an article in the Washington Post about the fire tornados yesterday:
Fire tornadoes in and of themselves are rare; being able to detect them in real time on radar is something new. Wendell Hohmann is the meteorologist at the Reno office who issued the precedent-setting warning. He described it as a “once-in-a-lifetime, career event.”
“We were just trying to get the message out of the extreme fire behavior from this fire given the rotation and the tornadic potential,” Hohmann said. “We figured we could do a severe [thunderstorm warning], but we decided to do a tornado warning to get [the emergency alert system] and [wireless emergency alerts] to activate.”
Matthew Cappucci believes at least five tornado-strength/vortices are likely to have occurred on the Loyalton Fire August 15.
For those wondering about the #FireTornado that occurred in #California earlier on, here’s a brief explainer about what the heck happened.
The news media sometimes calls any little fire whirl a “fire tornado”, or even a “firenado”. These and related terms (except for “firenado”) were, if not founded, at least documented and defined in 1978 by a researcher for the National Weather Service in Missoula, David W. Goens. He grouped fire whirls into four classes:
Fire Devils. They are a natural part of fire turbulence with little influence on fire behavior or spread. They are usually on the order of 3 to 33 feet in diameter and have rotational velocities less than 22 MPH.
Fire Whirls. A meld of the fire, topograph, and meteorological factors. These play a significant role in fire spread and hazard to control personnel. The average size of this class is usually 33 to 100 feet, with rotational velocities of 22 to 67 MPH.
Fire Tornadoes. These systems begin to dominate the large scale fire dynamics. They lead to extreme hazard and control problems. In size, they average 100 to 1,000 feet in diameter and have rotational velocities up to 90 MPH.
Fire Storm. Fire behavior is extremely violent. Diameters have been observed to be from 1,000 to 10,000 feet and winds estimated in excess of 110 MPH. This is a rare phenomenon and hopefully one that is so unlikely in the forest environment that it can be disregarded.”
It was just two days ago that I wrote extreme fire behavior and massive pyrocumulus are becoming much more frequent. If we are going to see more fire tornados, that is a scary thought. The west coast is expected to have very high temperatures this week.
Is it just me, or recently have there been more wildfires than usual exhibiting extreme fire behavior and with MASSIVE pyrocumulus. It only took the #LakeFire 29 minutes from its first report. Some will say the increase started 15-20 years ago. But lately, wow!
