Weather Effects
View factsheet.
While inconvenient for your average hiker or boater, major shifts in the weather can be deadly for firefighters. Longer and more intense fire seasons make accurate and timely weather predictions crucial to firefighter safety. To answer this need, the Fire Weather Alert System (FWAS) was developed by Jason Forthofer, Research Mechanical Engineer, and Natalie Wagenbrenner, Research Meteorologist, both from the Rocky Mountain Research Station’s Missoula Fire Sciences Laboratory. The FWAS is a mobile app that gathers weather data from many sources into a single convenient space and provides firefighters with individualized, easy-to-use, and timely weather alerts on their phones.
View recording (53:53).
Okay. Let me go back. Okay. So let’s go back to not even a year ago, August eighth two thousand twenty three. You know, large wildfires hit western and central Maui, and, it killed at least a hundred people and resulted in three to six billion dollars of damage, mainly in the area of of the historic town of Lahaina.
And and this here’s a picture right here of just a portion of Lahaina. This one famous house survived. We could talk about that maybe. But we’re looking in this picture towards the towards the east. These are the West Maui mountains there. You can see some of the some of the grassy areas that that would that burned there and here’s the town.
View article.
Large forest fires have far-reaching impacts on the environment, human health, infrastructure and the economy. Forest fires become large when all forest types across a landscape are dry enough to burn. Mesic forests are the slowest to dry and can act as a barrier to fire growth when they are too wet to burn. Therefore, identifying the factors influencing fire occurrence in mesic forests is important for gauging fire risk across large landscapes. We quantified the key factors influencing the likelihood that an active wildfire would propagate through mesic forest. We analyzed 35 large forest fires (> 2500 ha) that occurred in Victoria, Australia where mesic and drier eucalypt forests are interspersed across mountainous terrain. We used a random forest model to evaluate 15 meteorological, topographic and disturbance variables as potential predictors of fire occurrence. These variables were extracted for points within burnt and unburnt patches of mesic forest. The likelihood of an active wildfire spreading through mesic forest increased by 65 % as vapor pressure deficit (VPD, i.e., atmospheric dryness) rose from 2.5 to 7 kPa. Other variables had substantially less influence (< 20 % change in fire occurrence) and their effects were further reduced when VPD was very high (> 6.5 kPa). Mesic forests were less likely to burn in areas with lower aridity, shallower slopes, and more sheltered topographic positions. Mesic forests 13–15 years following stand-replacing disturbance had 6 % higher chance of burning than long undisturbed forests (50 years post-disturbance). Overall, we show that topography and disturbance history cannot substantially counter the effects of high VPD. Therefore, the effectiveness of mesic forest as a barrier to the development of large forest fires is weakening as the climate warms. Our analysis also identifies areas less likely to burn, even under high VPD conditions. These areas could be prioritized as wildfire refugia.
World of Wildland Fire brings you short videos on fire weather and fire behavior relationships.
Webinar registration.
Join Nevada’s Living with Fire on Thursday, May 9th via Zoom for our online webinar, “Fire Weather” This short online session will delve into what fire weather is and what are its factors. Guest speaker Edan Lindaman, senior meteorologist and fire weather program leader for the National Weather Service in Reno, Nevada, will be sharing fire predictions for this upcoming summer. Learn about fire weather and how it relates to your local ecosystem.
View article.
We examined the hourly diurnal cycle of 23,557 fires and identified 1,095 overnight burning events (OBEs, each defined as a night when a fire burned through the night) in North America during 2017–2020 using geostationary satellite data and terrestrial fire records. A total of 99% of OBEs were associated with large fires (>1,000 ha) and at least one OBE was identified in 20% of these large fires. OBEs were early onset after ignition and OBE frequency was positively correlated with fire size. Although warming is weakening the climatological barrier to night-time fires6, we found that the main driver of recent OBEs in large fires was the accumulated fuel dryness and availability (that is, drought conditions), which tended to lead to consecutive OBEs in a single wildfire for several days and even weeks. Critically, we show that daytime drought indicators can predict whether an OBE will occur the following night, which could facilitate early detection and management of night-time fires. We also observed increases in fire weather conditions conducive to OBEs over recent decades, suggesting an accelerated disruption of the diurnal fire cycle.
View article.
The Great Basin of the western United States is experiencing dramatic increases in wildfire and Bromus species invasion that potentially accelerate wind erosion and plant community change. We used a wind erosion model parameterized for rangelands and standard ecological monitoring data sets collected at 10,779 locations from 2011 to 2019 to characterize potential wind erosion in the Great Basin, assess relationships between factors affecting wind erosion, and quantify effects of wildfire and invasive Bromus species on aeolian horizontal sediment flux, Q. There were 403 monitoring plots (∼3.7% of plots) with Q > 100 g m⁻¹ d⁻¹. Median values for the highest Q category (>100) ranged from 196.5 to 308.5 g m⁻¹ d⁻¹. Locations with Q > 100 g m⁻¹ d⁻¹ were associated with dry, low elevation areas of the Great Basin with low perennial grass and perennial forb cover, and with large bare gaps between plants. Areas with high perennial grass, perennial forb, and shrub cover had small Q (≤10 g m⁻¹ d⁻¹). Substantial wind erosion was predicted in areas that have experienced wildfires, but areas with multiple wildfires had a lower predicted probability of Q particularly as invasive Bromus species cover increased. Modeled Q was up to two orders of magnitude higher post‐wildfire (median 44.2 g m⁻¹ d⁻¹) than in intact or annual grass‐invaded regions of the Great Basin (median 0.4 g m⁻¹ d⁻¹). Our results reveal the complex interplay among plant community composition, wildfire, and the amount of bare ground controlling wind erosion on Great Basin rangelands.
View synthesis.
This paper provides a synthesis of the key laboratory- and field-based observational studies focused on wildland fire and atmospheric turbulence connections that have been conducted from the early 1900s through 2021. Included in the synthesis are reports of anecdotal turbulence observations, direct measurements of ambient and fire-induced turbulent flow in laboratory and wildland environments, and remote sensing measurements of fire-induced turbulent plume dynamics. Although considerable progress has been made in advancing our understanding of the connections between atmospheric turbulence and wildland fire behavior and smoke dispersion, gaps in that understanding still exist and are discussed to conclude the synthesis.
View article.
Focus on wind changes and mid-tropospheric properties may be counterproductive or distracting when one is concerned about major growth events on very large fires.
View article.
Here, we investigated the effects of seasonal weather and plant associations, related to abiotic characteristics, on herbaceous production dynamics across 44 intact, representative sagebrush steppe sites across eastern Oregon from 2003 to 2012. We tested for the effects of sampling year, lagged precipitation, and potential evapotranspiration predictors, as well as prior year biomass and plant association on production of major herbaceous functional groups. We also tested for synchrony across functional groups and plant associations. We found that spring precipitation was the most consistent predictor of production. However, several other variables including prior year weather significantly affected production. Production sensitivity to weather was combined with high synchrony across functional groups and associations, suggesting low potential for production stability associated with these factors in sagebrush steppe in the northern Great Basin.