(Originally published at 9:12 a.m. MDT August 22, 2018)
When I saw the prediction from the Missoula National Weather Service office above, it got me thinking about how this cooler, possibly wetter weather is going to affect the dozens of large wildfires currently burning in the northwest United States. Two of the fires we have written about over the last couple of days, Watson Creek in Oregon and Howe Ridge in Montana, recently had small amounts of precipitation, certainly not enough to put them out, but it will absolutely slow their spread for a day or two.
No doubt other fires were also were affected, as you can see in the map below showing precipitation over the last 48 hours. But it looks like Washington, western Oregon, and most of northern California remained dry.
More rain is expected in the Northern Rockies into next week. Below is the forecast for precipitation on Monday afternoon, August 27. The “haze” shown in California and Oregon is presumably smoke from the Mendocino Complex of Fires.
Next are the predictions for precipitation and temperature August 27 through 31.
July in the state had the highest minimum temperature on record
Above: Credit Los Angeles Times
There are many ways that a warmer climate can influence wildfires, causing them to burn more intensely. Higher temperatures can lower the relative humidity, lower the amount of moisture in the vegetation (fuel), raise the temperature of the fuel itself, and cause more powerful thunderstorms with lightning. But one factor that we don’t think about very often is that the heat can persist through the night, influencing fire behavior.
When today’s senior firefighters began their careers, they could usually count on fires “laying down” at night. The intensity and rate of spread would decline to the point where night shift personnel could more easily and safely “go direct”, constructing fireline very close to the edge of the fire.
During the month of July in California, many of the large fires continued to grow rapidly at night, which often required firefighters to drop back to a safety zone and simply watch, since there is little that they could do without putting themselves in harms way.
No surprise that CA has been getting warmer, but particularly striking is accelerated pace of nighttime warming. Large implications for human health (harder for human body to cool off) & for #wildfires (fires don’t “lay down” when temps stay warm at night). #CAwx#CAfirehttps://t.co/ATnz7u1J3B
Of course it is too early to say that this will be a permanent change, but in the last month a new record was set for California’s average minimum temperature; it was the highest since records have been kept. And this was not just a one-month event. The trend has been increasing since the 1980s.
Many of those senior firefighters have been known to to lament the trend in the last couple of decades of incident management teams declining to have a night shift. The justification of the teams was that it was not safe to have firefighters working at night because of snags falling, steep terrain, and other issues. After observing the nighttime fire behavior in recent years, the senior firefighters might now be less inclined to argue strongly in favor of night shifts, at least in certain geographical areas and weather conditions.
(Originally published at 1:20 p.m. MDT August 1, 2018)
On August 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for August through November. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.
If their analysis is correct, in August and September firefighters will be busy in Washington, Oregon, Idaho, California, and northern Nevada.
An excerpt from the NIFC narrative report for the next several months;
NIFC’s monthly graphical outlooks;
NOAA’s three-month temperature and precipitation forecasts; and,
“August is the peak month for fire activity across the West. Given the amount of lightning received along with preexisting heavy fuel loading and dryness, a very active month is expected with Above Normal significant wildland fire potential likely across portions of the Pacific Northwest, Northern Rockies, northern Great Basin, and California. Typically, a weather event occurs by mid-September that brings moisture to regions experiencing significant fire activity which allows for the western fire season to begin to decrease in activity. Given ongoing trends that support a normal seasonal progression and given a transition from ENSO Neutral conditions to El Niño, such an event is expected. Most regions will exit the fire season at this point, but only a brief lull is expected across California before it enters its fall fire season by October and November. Given ongoing dryness in the fuels, the fall season may very well be robust across portions of the state.”
Above: Estimated precipitation July 4 to July 11, 2018. Intellicast
We have entered a relatively quiet period of wildfire activity in the western United States. On today’s national Situation Report, more fires decreased in size than increased. Of the fires that had changes of more than 100 acres, only three got larger, while five actually decreased. The reported size getting smaller is a result of more accurate mapping.
The seasonal monsoonal flow has been bringing precipitation to not only the Southwest, but it has been pushing north into parts of Nevada, Utah, and Colorado. And the typical July thunderstorms have been affecting other areas as well.
As a reminder, the National Interagency Fire Center predicted July 1 that fire activity would increase this month in parts of California, Nevada, Utah, Washington, Oregon and Idaho. California has had some large fires, Utah has had several, and the Martin Fire in Northern Nevada has burned almost 440,000 acres. We’ll see what happens during the second half of the month.
The updated precipitation and temperature outlooks for the next six to ten days predict higher than normal temperatures in the far west and dry conditions in the Northwest and Northern Rockies.
Wildland firefighters have enough to worry about, but Thursday a tornado briefly touched down just south of the Weston Pass Fire, then while receding back into the cloud it moved directly over the fire.
Tornadoes are very rare in this part of the country. According to the National Weather Service office in Boulder, it was the 6th confirmed tornado in Park County since records began in 1950.
Chief Meteorologist/Climatologist for 11 News in Colorado Springs, said “No, this isn’t a firewhirl, it is a legit tornado produced by a thunderstorm that moved across the Weston Pass Fire.”
The Weston Pass Fire has burned about 13,000 acres 9 miles southwest of Fairplay, Colorado.
Thanks and a tip of the hat go out to Jason. Typos or errors, report them HERE.
(Originally published at 11:55 a.m. MDT July 2, 2018)
On July 1 the Predictive Services section at the National Interagency Fire Center issued their Wildland Fire Potential Outlook for July through October. The data represents the cumulative forecasts of the ten Geographic Area Predictive Services Units and the National Predictive Services Unit.
If their analysis is correct, in July the areas with the highest potential will move from the Southwest to Washington, Oregon, Idaho, Utah, California, and northern Nevada.
The highlights of the NIFC narrative report for the next several months;
NIFC’s monthly graphical outlooks;
NOAA’s three-month temperature and precipitation forecasts; and,
“Abnormally dry conditions along the West Coast allowed for a northward expansion of drought into western Oregon and Washington in June. Some improvement was noted across the southern Great Plains while drought emergence was observed across the Lower Mississippi River Valley. Preexisting drought conditions and continued drier than average conditions across the Southwest allowed for a normal progression of the fire season across the Four Corners Region until mid-month when the remnants of Hurricane Bud moved north from Mexico and produced widespread wetting rainfall that reduced the elevated large fire potential in that area. While rainfall amounts that were greater than 200% of average were received across Arizona, New Mexico, and portions of southwestern Colorado, the Great Basin and California remained very dry receiving less than 10% of average precipitation. Temperatures across the West were near average for the month from the Pacific Coast east to the Continental Divide. East of the Divide, temperatures were near average.
“The southwestern monsoon is expected to arrive in early July and should reduce fire activity across the Southwest. A normal refocusing of fire activity north into the Great Basin and west into California is expected. The existence of a continuous grass from this year along with carryover of fine fuels from 2017 should lead to Above Normal Significant Large Fire Potential in these areas. By late July, fire activity is expected to increase across Oregon and Washington. Entry into the Western Fire Season will be delayed slightly across most of the Northern Rockies due to the persistent wet systems that impacted the region through… However, precipitation data shows an area of below average precipitation for June across extreme northwestern Montana and northern Idaho. As a result, both areas could experience an early entry into the fire. In Alaska, the fire season will gradually come to an end in July as precipitation events become more frequent.
“August is the peak of the Western fire season. Seasonal transitions focus the fire activity over the northwestern quarter of the country, though California also continues to experience significant activity. With significant carryover of fine fuels from last year and an average grass crop growth this year, elevated fire potential is expected August through early September in this region from California and the Central Great Basin north to the Canadian Border. Higher elevations in the mountains may also see elevated fire potential as well should warmer and drier than average conditions develop as expected.