Friday, 20 April 2018

Wildfires amid hot and dry conditions in US Southwest


Anyone recall Guy McPherson referring to the SE as the “dust bowl that never end”?
Southwest fire threat called 'extreme to historic' amid brutally hot and dry conditions



MSN,
19 April, 2018


The air is dry and the winds are strong over a large portion of the Central and Southern U.S., on Tuesday. The vegetation is bone dry and the U.S. Drought Monitor says the region is in “exceptional” drought. All of this combined is stoking wildfires that ignited late last week and increasing the chances of new fires on Tuesday.

A particularly dangerous situation is expected to develop with extreme fire weather and very dry fuels [trees, shrubs and grass] across western Oklahoma and parts of northern Oklahoma on April 17,” the National Weather Service wrote on Tuesday.

The Weather Service issued an “extremely critical” fire weather outlook for a giant swath of the South that covers parts of Kansas, Colorado, New Mexico, Oklahoma and Texas. “Extremely critical,” is as bad as it gets, and it’s the second time the Weather Service has had to use it in the past week.

If new fires ignite on Tuesday, the Weather Service expects them to “exhibit erratic behavior and rapid spread rates,” do to strong winds. On top of that, a wind shift is expected this evening as a cold front passes through, which will make it even more difficult for firefighters to control the blazes.

Two major wildfires are burning in Oklahoma this week, the 34 Complex and the Rhea megafire. “Megafire” is a term the National Interagency Fire Center defines as a wildfire that has consumed more than 100,000 acres.

The 34 Complex is burning in Woodward County and has crossed into southwest Kansas, but was nearly-half contained as of Monday. The extreme conditions on Tuesday could put that containment to the test. As of Tuesday morning the 34 Complex had burned nearly 68,000 acres.

The Rhea Fire, which started April 12, has burned nearly 250,000 acres as of Tuesday. According to the Oklahoma Forestry Service, the fire was only 3 percent contained and its cause is unknown.

The Rhea Fire is Oklahoma’s third megafire in three years. Last year in March, the Northwest Oklahoma Fire Complex consumed more than 800,000 acres. In March 2016, it was the Anderson Creek Fire, which raced across the Oklahoma/Kansas border and torched a total of nearly 400,000 acres. (Even though only part of the fire was in Kansas, it still qualified as that state’s largest on record.)

March 2017 brought the even-more-massive Northwest Oklahoma fire complex, which devoured more than 830,000 acres. In 2016, the Anderson Creek Fire started in Oklahoma and spread to Kansas, where it became the largest wildfire on record. The Anderson Creek Fire burned more than 400,000 acres.

In an excellent post on the fires, Weather Underground’s Bob Henson tried to make sense of why fire danger in Oklahoma is becoming more extreme. He boils it down to two major players: climate change and a change in land use:

Echoing a global trend that’s associated with human-produced climate change, Oklahoma has seen signs of a ramp-up in hydrologic extremes over the past few years.

May 2015 was the state’s wettest single month on record, and 2015 was its wettest year. “The November-December 2015 period was the wettest on record as well, and the sixth warmest. So the growing season extended into winter to some extent that year,” said [Oklahoma state climatologist Gary McManus]. The result was an unusually lush landscape going into the first part of 2016 that dried out quickly in the weeks leading up to the Anderson Creek fire.

The same thing happened in 2017, which was dry up until August — right when the state’s normal wildfire activity would cut back on the vegetation.

On top of that, the landscape is changing in Oklahoma with the addition of vast swaths of redcedar trees, which used to only grow in rocky terrain that was less prone to wildfires.



Trends in land ownership and management, especially in recent years, have allowed eastern cedar to spread more widely across the landscape. A state brochure noted that infestations of at least 50 redcedars per acre grew fourfold in the second half of the 20th century. It added: “The effects that the exploding populations of redcedar is having on the state might be compared to the soil erosion that occurred during the ‘Dust Bowl’ era of the 1930s-40s. It is becoming a problem in almost all coun­ties, and will take years and millions of dollars to bring the spread of cedars under control.”


To make matters worse, the juniper trees are sappy — it’s what gives them such a lovely smell, but it also lights up like a kerosine torch.


Cooler temperatures are coming behind a cold front that’s slated to arrive in Oklahoma on Tuesday night, but the region is not going to get much rain. Drought conditions



No comments:

Post a Comment