This map showing cumulative precipitation over the 10-day period ending May 29 helps explain some of the recent widespread flooding in the middle of the country. It looks like a few areas had more than 12 inches. Many locations had more than 6.
(I don’t know why data for those five western states does not show up.)
At the International Association of Wildland Fire’s Fuels conference currently underway in Albuquerque, Research Ecologist Matt Jolly’s presentation on “Mapping extreme fire weather and its impact on firefighter safety” was very interesting. In his allotted 20 minutes he began by talking about the rollout that is nearly complete of the third revision of the National Fire Danger Rating System.
Mr. Jolly described the development and evaluation of an extreme fire weather metric called the Severe Fire Weather Potential Index. The Index is strongly correlated to wildland fire occurrence and intensity detected by the MODIS satellite and is a strong predictor of wildland firefighter entrapments and fatalities from 1979 to 2017.
Mr. Jolly said some firefighters have told him that the WildfireSafe app which has been in the prototype stage for the last three years is a useful tool for accurately predicting the fire danger at the local level.
These images were snapped with a cell phone during Mr. Jolly’s presentation.
If NIFC’s analysis is correct, wildfire activity along the west coast will grow substantially into the summer
Continue readingThe NWS may one day issue watches and warnings based on the predicted spread of a dangerous wildfire.
Continue reading
Researchers have developed a fancy graphic presentation that explores the relationship between precipitation and the annual area burned in the Western United States. You should check it out.
They concluded that weather conditions DURING the fire season, humidity and rain, have far more effect on total acres burned than winter snow.
The figures and text (below) here are excerpts from the document.
“Wildfires have been increasing: but why? Is it the effect of increasing temperatures? Declining snowpack? Decreasing precipitation? In their recent paper, “Decreasing fire season precipitation increased recent western US forest wildfire activity,” Zachary Holden and his co-authors explore the relative influence of these factors. They first identified the variables related to temperature, snow, and precipitation that best predicted area burned:
“Temperature: vapor pressure deficit [VPD] (the difference between the maximum amount of water the air can hold and the amount it actually holds)
“Snow: maximum annual snow water equivalent [SWE], and
“Precipitation: wetting rain days [WRD], days with more than 1/10 inch of rain, in the months of May through September.”
The outlook predicts above normal potential for western Washington and northwest Oregon
Continue readingIf NIFC’s analysis is correct, wildfire activity should begin to increase in Eastern New Mexico and Western Texas in April.
Continue readingIn a comment on the earlier post about the Hot-Dry-Windy Index (HDW), Brian Potter, a research meteorologist with the U.S. Forest Service, offered to provide some preliminary results looking at how HDW performed during the 2017 Chetco Bar Fire in Oregon, as well as how the Haines index performed during that fire.
The HDW is a new tool developed for firefighters to predict weather conditions which can affect the spread of wildfires. It is described as being very simple and only considers the atmospheric factors of heat, moisture, and wind.
Mr. Potter has provided three figures showing the weather indices computed from the National Weather Service’s NAM model analyses. Because they use a different model from the HDW website, he does not have historic percentile values for HDW, but they are illustrative, nonetheless. These are preliminary data and have not been through peer review or evaluation.
Here is a graph of HDW values compared to growth on the Chetco Bar Fire:
Here are the Haines Index values for the mid-elevation version of the Index:
And the high elevation version of the Haines Index:
Mr. Potter said he has some thoughts about the graphs, but is interested in hearing what others take away from them.
The Chetco Bar Fire in southwest Oregon started July 12, 2017 and burned over 191,000 acres.
Wildfire potential in United States is expected be normal or below normal in most areas during the coming four months
Continue readingThe east should be cooler, while the Drought Monitor shows Severe to Exceptional drought in the Four Corners area.
Continue reading