Rains may only delay forest fire danger

ByJo Zucker

Heavy, late rains in June may cause wild grasses to flourish, increasing fire hazard later in the summer.

According to Mike Carnahan of the Sisters Ranger District, "Rains have held things down at this point, and kept humidity high, so large fires have not been a factor yet because grasses are still green. But as the grasses dry out, the probability of fires increases."

Sisters area June precipitation from 1990-1996 ranged from .13 inches in 1994 to 2.64 inches in 1993. This year's June total of 1.07 inches was over the average, and included a torrential, day-long rainfall on the last day of the month.

"The more rain and moisture we get later in the season--later into June--the more of the grasses are created and the moisture allows them to grow bigger. They then become lighter fuels," said Carnahan.

Carnahan said that lighter fuels "are mostly grasses that come up with rain and dry out. Once lighter fuels get started, they cause the heavier stuff to burn."

As Rod Chaffee of the Central Oregon Interagency Dispatch Center explained, "The heavier, wet, spring conditions push the fire season back a little further. Instead of mid-June or the beginning of July, the fire season may begin around mid-July."

Chaffee said that the heavy, late rains "do not deter the fire season, they just delay it. The fire danger will still be there, it just doesn't come as soon as we normally see it."

Chaffee said, "It tends to have an effect on grasses, but then again, a lot of grasses depend on germination in the spring. If there is heavy rain, the grasses may not germinate. But this year there is that possibility because we had warmer weather in May that may have germinated the seeds. I am not sure whether there is an over-abundance of grass this year or not."

Carnahan detailed the combination of conditions that often lead to a harrowing fire season.

"When more grasses cure out in July and August, and there is a long hot spell with low humidity and without moisture, the combination of these things creates a severe fire hazard."

He said that factors like elevation and location also come into play.

The average amount of spring (April through June) precipitation in the Sisters area is as follows: 1991- .85"; 1992-1.04"; 1993-1.6 "; 1994-1.95"; 1995-3.71"; 1996-4.56"; 1997-3.26".