The ABCs of Drought
People in Orange County these days can usually tell you what a “Cat 3” means or can describe a storm surge. But what about the KBDI?
If you go to an Orange County Commissioners Court meeting these days, you’re likely to hear Emergency Management Director Jeff Kelley talking about the KBDI instead of a hurricane tracking chart. And that’s because the normally wet Southeast Texas is in a drought, even with the recent rains.
And the ever present “Burn Ban” that county commissioners talk about is based on the KBDI.
The Keevch-Byram Drought Index, named after its two creators, was developed in 1968 as a way to measure moisture in the soil and to determine droughts. That allows forecasters and scientists to set warnings for fires and the potential for spreading wildfires.
Drought maps and the KBDI are created once a week nationwide. Kelley on Monday gave commissioners maps that showed Orange County and most of Southeast Texas to be in a “moderate” drought category or the 400 to 500 level on the KBDI. The rains on Nov. 1 and 2 added moisture to the ground to temporarily help the conditions of the on-going drought.
And at this point, the National Weather Service in Lake Charles is forecasting that drought conditions will continue at least through January. That means that the long term effects will create a drought. Soaking rains can change the drought condition temporarily. On-going soaking rains can end a drought.
The Orange County Commissioners Court ended the burn ban because of the rain at the first of the month. Kelley, though, said drought conditions can return once more and another burn ban may be needed in the future.
At this time, the Texas Forest Service is reporting that the drought conditions for Southeast Texas are “moderate.” The rains improved the rating.
On the KBDI, Southeast Texas is at the 400-500 level this week. That level is typical of late summer and early fall because of “the lower litter and duff layers.” The level means the elements can combine to make a fire intensify and burn actively.
The highest level for fire conditions is a rating of 600 to 800.
High winds can make a fire spread and with November being the time of the year for cold fronts to come, the winds could contribute to fire hazards and bad fire conditions.
The Florida Department of Agriculture and Consumer Services Division of Forestry reports that the KBDI estimates the dryness of the soil and duff levels. The index increases for each day without rain and goes from a level of 0 up to 800.
“Prolonged drought influences fire intensity because more fuel is available for combustion,” the division reports. Low moisture from rain and humidity can dry organic matter and increase the KBDI.
A high KBDI means that conditions a favorable for “the occurrence or spread” of wildfires. A drought alone isn’t a prerequisite for a high rating on the KBDI.
Wikipedia reports that John Keetch and George Byram created the index for the U.S. Forest Service. The index “outlines mathematically the likelihood of wildfires based on soil conditions and other conditions related to drought.”
If rain continues to come only every few weeks, the letters KBDI may get more usage in Orange County.