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Thursday, August 8, 2013

Wildfire smoke forecast - Aug. 8, 2013

2 P.M. PDT THURSDAY, AUG. 8, 2013


Air quality is generally moderate to good across most of the state, consistent with the trend observed over the last several days. The notable exception continues to be extreme southwest OR including Grants Pass, Shady Grove, Cave Junction and Medford, where air quality remains “unhealthy” for many communities, especially locations in proximity and downwind of local wind flows in active wildfire zones. Some wildfire smoke is also continuing to affect portions of central (including Bend and Sisters)and northeastern Oregon.

Statewide air quality index readings are available at


Wildfire smoke dispersion depends on the stability of the atmosphere as well as wind direction and speed. A stable atmosphere holds smoke to the ground and an unstable atmosphere allows smoke to rise and dissipate. Smoke is typically mixed to higher altitudes during the afternoon, when daytime heating destabilizes the air mass. Conversely, smoke tends to settle near the ground and in drainages during the overnight and early morning hours.

The upper-level closed low pressure system continues to slowly approach western Oregon from the southwest, resulting in cooler conditions with partly to mostly cloudy skies over much of south central and southwest OR. Also, scattered light showers have developed over south central OR, including activity east of Klamath Falls that is slowly moving to the NNW. Some lightning activity has also occurred in the last hour over Deschutes Co. within developing showers. Showers and thunderstorms are expected to develop across southwestern and south central OR during the remainder of today. No organized surface wind pattern is in place, and local wind circulations are currently dominating the pattern.

Air quality should generally remain good-to-moderate for most of the state today as large-scale transport of smoke has continued to decrease. Lack of organized surface winds and only moderate mixing will cause persistence of surface smoke in those communities in the proximity of the major fires burning in SW Oregon. Those areas lucky enough to see rain showers today will see some improvement in air quality. Otherwise no major changes are imminent.

There is potential for some dry lightning development over southwestern and south-central OR this afternoon and evening away from existing showers; the new storms will initially be fairly dry and could cause brief gusty surface winds, potentially fanning wildfire smoke out in any direction. They also bring an increased potential for new fire starts. Showers that develop later today over far southwestern OR and near the CA border in south central OR could also bring beneficial local rainfall late.

The upper-level trough will move very slowly north-northeastward during this period, and likely be centered over southwestern OR by Saturday. Generally this will provide a favorable scenario for improved air quality over southwestern OR. Low-level winds should generally remain unorganized, which will likely continue to confine surface smoke to those communities in proximity of active wildfires. Showers and thunderstorms are likely to increase in coverage Friday afternoon and evening for southwest and west central OR, and potentially into central OR on Friday night. This trend should persist through Saturday with some areas of western OR receiving significant rainfall at times. Areas that do receive rain will see improved air quality. Highest chances of beneficial rains appear to be the southern and central portions of the Cascade Range.

Chances for significant rain also increase for northwestern OR and the northern portion of the Cascades by late Saturday. The general trend will continue to be towards wet thunderstorms as the Saturday/Sunday time periods arrive for western OR. However, the thundershowers will have progressively less moisture to the east (over eastern OR) to work with, and this scenario also applies to the early stages of thunderstorms over central OR. For these areas the potential is significant for more wildfire starts as the storms initiate. The same applies across NE Oregon if the storms develop in that region.

By Sunday, shower and thunderstorm activity should begin to decrease over the state from the south.

Current weather forecasts from the Portland, Medford, and Pendleton National Weather Service offices are available at:,, and respectively.

This bulletin is also available on the web at

For more information, contact DEQ’s Brian Finneran at 503-229-6278 or
ODF Smoke Management Meteorologist

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The purpose of this blog is to provide breaking news about wildfire activity on the forestlands protected by the Oregon Department of Forestry. We invite you to post questions or comments about current wildfires. Please keep your posts civil and free of profanity.

Current wildfire info

National weather forecasters predictions that Oregon would see above average temperatures and below average rainfall in the summer of 2018 proved true. Almost all of Oregon was abnormally dry this summer, with a majority of the state in moderate to severe drought. Many areas posted record high temperatures or record strings of hot days. These conditions set the stage for potentially large, fast-moving wildfires.

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Protection jurisdiction
The Oregon Dept. of Forestry protects 16 million acres of private and public forestlands from wildfire. This includes all private forestlands in Oregon as well as state and local government-owned forests, along with 2.8 million acres of federal Bureau of Land Management lands in the western part of the state. In total there are about 30.4 million acres of forest in Oregon.

Fire suppression policy
The department fights fire aggressively, seeking to put out most fires at 10 acres or smaller. This approach minimizes damage to the timber resource and fish and wildlife habitat, and protects lives and property. It also saves money. While suppressing large fires can cost millions of dollars, economic and environmental damage from wildfires can be many times greater.


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Oregon Dept. of Forestry's public information officers in Salem, Ore., maintain this blog. During the wildfire season, we spend much of our time reporting on fires and firefighting to news media and the public.