Tag: weather

Wildfire potential, December 2012 through March 2013

Monthly wildfire outlook, December, 2012

The Predictive Services section at the National Interagency Fire Center has issued their National Wildland Fire Potential Outlook for December, 2012 through March, 2013:

Significant Fire Potential

For December above normal significant wildland fire potential only exists across a portion of the west central U.S. stretching from Nebraska and Wyoming south through Colorado, Kansas and Oklahoma into Texas and New Mexico. Small portions of the Hawaiian Islands also show above normal significant wildland fire potential. By the January through March timeframe no above normal significant fire potential is expected in the U.S.
Below normal significant fire potential is expected across much of the southeastern U.S. for the entire forecast period.
Elsewhere expect near normal significant fire potential to exist. In many areas of the western U.S. this indicates fall and winter conditions that are generally considered out of fire season.

Climate and Drought Conditions

El Niño/Southern Oscillation (ENSO): Equatorial Pacific sea surface temperatures continue to indicate a neutral ENSO pattern.
Drought: Most of the nation had less than 50 percent of normal precipitation for November with only parts of the northwestern U.S. receiving normal to above normal rain and snow. Severe to exceptional drought continued over most of the central and western U.S. with pockets in the Southeast.
Fuel Conditions: Generally fuel conditions across the areas of most concern this time of year are better than normal. However, a trend of continued dryness across much of the central U.S. especially into Colorado and New Mexico indicate the possibility of seeing an early onset of fire season in these areas, though that should be later in the outlook period.
Weather Outlook: Current climate projections by the Climate Prediction Center favor a continuing neutral pattern. For December, long range models indicated a high probability of above normal temperatures over much of the southern U.S. and northern Alaska while below temperatures settle over the northern Plains, the upper Midwest and southwestern Alaska. Precipitation projections indicate a high likelihood of below median precipitation for the mid-Mississippi and Ohio Valleys. Southeastern Alaska will likely be drier than normal.

For January through March, projections show higher probabilities for above normal temperatures across northern Alaska, most of the Southwest, the Great Basin, the central and southern Rockies, the central and southern Plains, and the lower Mississippi Valley. Below normal temperatures are probable over the far northern Plains and southern Alaska. Precipitation will be above median over the Ohio and mid-Mississippi Valleys and below median across California and the Southwest.

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Red Flag Warnings, December 2, 2012

On the second day of winter Red Flag Warnings for extreme wildfire danger are affecting portions of Colorado, Nebraska, Kansas, and and New Mexico.

One of the areas affects the Fern Lake Fire in Colorado where the warning will be in effect from noon Sunday until 6 a.m. Monday. The forecast the fire area for Sunday predicts southwest winds of 15 gusting to 24 mph, a high temperature of 51, sky cover of 49 percent, and a minimum relative humidity of 24 percent. However Sunday night will see the winds increasing to a maximum 41 with gusts to 62 along with a 22 percent chance of rain. The humidity will max out Sunday night at 75 percent.

The map was current as of 10:26 a.m. MT on Wednesday. Red Flag Warnings can change throughout the day as the dozens of National Weather Service offices around the country update and revise their forecasts. For the most current data, visit this NWS site.

Red Flag Warning weather

State of the global climate, 2012

The World Meteorological Orgnaization (WMO) has issued a “Provisional Statement on the State of Global Climate in 2012”. Some of their conclusions about the number of fires differ slightly from the stats we assembled on November 23, 2012.

The WMO’s document is lengthy, but below are some excerpts.

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Global average temperature anomaly. Credit WMO

Wildfires

Dry conditions, combined with the heat in the Northern Hemisphere during most of spring and summer 2012, contributed to devastating wildfires. Across the contiguous United States, the number of wildfires throughout the year was the least since 2000; however, the amount of acres burned per fire event during the same period was the largest on record.

Significant wildfires also developed in the Eurasian Continent. In Spain, over 184,000 hectares of land had been scorched by wildfires between January 1st and September 15th, the highest in a decade. The most notable wildfire ignited on September 24th in Valencia, forcing nearly 2,000 people to evacuate. In August 2012, southern parts of Bosnia and Herzegovina recorded a wildfire that burned nearly 5,000 hectares of land, causing nearly 83 million U.S. dollars in damage.

Drought

2012 began with severe to exceptional drought, as defined by the North American Drought Monitor (NADM), across the south central and southeastern contiguous United States and the northern half of Mexico. In the southern Plains of the U.S., the 2012 drought was a continuation of severe drought conditions which developed in 2011. Throughout 2012, drought conditions evolved across the United States, improving in some areas while deteriorating in others.
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Documented fire tornado

Fire Tornado documentation, Australia. Credit: research led by Rick McRae

Fire Tornado path, Australia. Credit: research led by Rick McRae

We have previously written about events described as “fire tornadoes”, but research led by Rick McRae in Australia has us convinced that those should be more accurately called fire whirls, not tornadoes. We were never very comfortable using the term “fire tornado” for those events, but it has become common and we were not aware, until now, that a phenomenon many times more powerful existed.

Mr. McRae documented what was unquestionably a real fire tornado that occurred near Chapman, ACT, Australia during the McIntyres Hut Fire January 18, 2003.

Researchers had speculated about the ability of a fire to produce a tornado, but this is the first documentation of the creation of a true tornado by the convection column of a large fire.

In a video interview (scroll down and view the second video) and in a paper published October, 2012 in the journal Natural Hazards, he described a fire tornado as occurring over a vegetation fire, a process now known as the phenomenon of “pyro-tornadogenesis”. Under certain conditions, a fire can cause a pyro-cumulus cloud to form, which is not in itself unusual over a large fire. If the cloud continues to build, it can generate lightning, rain, and hail, much like a conventional large thunderstorm. And large thunderstorms can sometimes propagate a tornado, which is what happened over the McIntyrres Hut Fire.

Mr. McRae’s research determined that the fire tornado was moving across the ground at 30 kph (19 mph), had horizontal winds of 250 kph (149 mph), and vertical winds of 150 kph (93 mph).

Fire tornado, broken-off trees — Aftermath of a fire tornado, showing 12-15 meter tall trees broken off 2-3 meters above the ground. From research led by Rick McRae.

Dr. Jason Sharples, also associated with the research, described the differences between a fire tornado and a fire whirl:

Tornadoes are associated with thunderstorms and as such they are anchored to a thundercloud above, and are able to sporadically lift off the ground. Fire whirls, on the other hand, are anchored to the ground and do not require the presence of a thunderstorm.

Rick McRae is a Special Risks Analyst at the ACT Emergency Services Agency.

Thanks go out to Chris

Australia Australian Capital Territory fire tornado firenado research weather

Red Flag Warnings, November 21 2012

The wildfire season is not over in some parts of the United States, as Red Flag Warnings have been posted for three areas:

Portions of southeast Wyoming and western Nebraska for late Wednesday morning and Wednesday afternoon; winds west 15 to 30 with gusts up to 45 mph across western Laramie County and up to 35 mph elsewhere; relative humidity as low as 10 percent
The southeast corner of Colorado, from 11 a.m. through 5 p.m. on Wednesday; winds southwest 15 to 25 mph with gusts up to 35 mph; relative humidity 7 to 12 percent.
The Florida Big Bend area, Red Flag Warning Wednesday afternoon for north to northwest winds 6 to 10 mph with gusts up to 15 mph; relative humidity 30 to 35 percent and lower on Thursday; Fire Weather Watch on Thursday for similar conditions.

There is no Red Flag Warning for central and western South Dakota, but the fire danger is elevated, with temperatures expected to be in the mid 60s and possibly low 70s on Wednesday. Relative humidity will be 15 to 20 percent with areas south of Interstate 90 likely seeing winds of 15 to 22 mph with gusts in the 25-30 mph range. Thursday will see 28 mph winds gusting at 35 to 40 with temperatures in the low 50s and relative humidity of 30 to 38 percent.

The map was current as of 9:28 a.m. MT on Wednesday. Red Flag Warnings can change throughout the day as the dozens of National Weather Service offices around the country update and revise their forecasts. For the most current data, visit this NWS site.

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Wildfire news, November 5, 2012

More than 100,000 lightning strikes in South Australia

Thunderstorms over the last couple of days have blasted South Australia with more than 100,000 lightning strikes. One report says 173,000 strikes left 80,000 residents without electrical power. Firefighters are working on over a dozen fires on the Eyre Peninsula, Kangaroo Island and Fleurieu Peninsula.

Fire jumps Interstate 15 in Cajon Pass

A fire that started near Interstate 15 in Cajon Pass in southern California jumped the interstate and burned 350 acres at the last report. The Devore Fire began at 10:55 a.m. and was 5 percent contained by late afternoon, with full containment expected by 6 p.m. Tuesday. The fire is being fought by 450 personnel and required the evacuation in the Matthew’s Ranch area. More information is available at InciWeb.

Fuel filter being recalled after starting fires

A fuel filter used on diesel engines is being recalled after failures of the unit caused two fires. The California Air Resources Board announced that that the LongMile diesel particulate filter made by Cleaire Advanced Emission Controls is being voluntarily recalled after a second fire attributed to the device. The most recent fire burned three acres on August 4, but in September of 2011 another fire blackened 3,600 acres in Washington and cost $5.2 million to suppress. The initial attack on that fire was made by a group of nuns using buckets of water.

Australia California South Australia weather

Wildfire potential, November through February

The Predictive Services section at the National Interagency Fire Center has issued their National Wildland Fire Potential Outlook for November, 2012 through February, 2013. As we get closer to winter, there are no areas identified as having above normal wildfire potential for that period.

Here is an excerpt from the report:

Significant Fire Potential

For November above normal significant fire potential only remains across small portions of the Hawaiian Islands. By the December through February timeframe no above normal significant fire potential is expected in the U.S.
Below normal significant fire potential is expected across much of the southeastern U.S. for the entire forecast period
Elsewhere expect near normal significant fire potential to exist. In many areas of the western U.S. this indicates fall and winter conditions that are generally considered out of fire season.

potential weather

Firefighters prepositioned in southern California for Santa Ana winds

Red Flag Warnings, 8:26 a.m. PT, October 27, 2012

Firefighting resources have been prepositioned in southern California for the last two days in order to be ready for any wildfires that break out during the predicted strong Santa Ana winds. There has been “light initial attack” fire activity over the last couple of days, according to the Southern California Geographic Area Coordination Center, but no large fires so far. Maybe this can be credited not only to the not-quite-as-strong-as-expected winds, but to aggressive initial attack by the fire agencies. One fire near Fontana burned a few hundred acres before firefighters put it out. Photos of that fire by tjvphoto can be found HERE.

The Red Flag Warning is still in effect through Saturday evening. While the winds have been fairly strong, the predicted northeast winds of 20 to 30 mph gusting at 50 to 60 mph have not quite materialized in most areas. The effect of the Santa Ana condition has been quite variable in southern California, but the Chilao weather station on the Angeles National Forest has been recording some of the highest wind speeds. Since 12:53 a.m. on Saturday it has seen sustained winds in the 30s with gusts above 40 mph; the strongest gust was 49 mph.

The forecast is for northeast winds of 25 to 30 mph gusting up to 30 on Saturday, but the relative humidities will be very low, in some areas going down to 5 percent during the afternoon. The winds will decrease in the late afternoon when the pressure gradient relaxes as the surface high over the Great Basin shifts.

California weather

Red Flag Warning for southern California

Red Flag Warnings for extreme fire weather are in effect for most of the forested and brush-covered lands in southern California. The pattern along the Colorado River is interesting, and indicates that the weather forecasters put some thought into this, rather than simply using state boundaries as has been done in some cases previously.

The weather forecasts vary from one location to another in southern California, but they generally call for strong northeast winds of 20 to 30 mph gusting at 50 to 60 mph, along with very low humidities. The Red Flag Warnings mostly begin late on Thursday and continue into Saturday.

The map was current as of 9:25 a.m. MT. Red Flag Warnings can change throughout the day as the dozens of National Weather Service offices around the country update and revise their forecasts. For the most current data, visit this NWS site.

Thanks go out to Ken

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Red Flag Warnings, October 17, 2012

Red Flag Warnings, 949 am MT, October 17, 2012

Red Flag Warnings for extreme fire weather are in effect for much of the central United States, plus portions of northern California.

The map was current as of 9:49 a.m. MT. Red Flag Warnings can change throughout the day as the dozens of National Weather Service offices around the country update and revise their forecasts. For the most current data, visit this NWS site.

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