WILDFIRE SMOKE FORECAST
OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE
1:30 PM PDT MON AUG 4, 2014
SIGNIFICANT FIRE INFORMATION:
Numerous wildfires extend across mainly southern, central and eastern Oregon.
For updated “Significant Fire” details, visit ODF’s fire blog at http://wildfireoregondeptofforestry.blogspot.com/ or the Northwest Interagency Coordination Center (NWCC) at http://www.nwccweb.us/index.aspx.
A “Significant Fire Potential” map, for ODF protected lands, is available at (http://nfdrs.smkmgt.com/ODF_Significant_Fire_Potential.png).
DEQ smoke monitoring sensors are indicating generally “good” air quality west of the Cascades and “moderate” air quality east of the Cascades.
Statewide air quality index readings are available at http://www.deq.state.or.us/aqi/index.aspx
SMOKE DISPERSION FORECAST:
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.
Upper level ridge remains over the region and to the east leaving the state under light south to southwesterly flow aloft. This upper level flow has been transporting wildfire smoke from southwest Oregon and northern California over most of the state. However, most of the smoke is aloft with some particulate settling out and degrading surface air quality a little. This pattern will remain through today with continued hazy skies in most regions from the wildfire smoke. Air mass is destabilizing during the afternoon but with generally light NW to N wind flow at low levels, expect little change in air quality today or tonight.
Upper level ridge only weakens slightly, and air mass stability and wind flow change little, so expect little change in air quality over most of the central and eastern part of the state. Upper level flow should turn a little more SW’erly giving less hazy conditions over most of the western part of the state.
Ridge flattens Wednesday through Friday bringing in slightly cooler and more onshore flow over the state. This should slowly clear much of the smoke aloft and near the surface through most of the state except the extreme south and those areas downwind of active burning east of the Cascades. Air mass will remain generally stable except for better mixing during the afternoon hours. Wind flow at low and higher levels with range from WSW to NNW.
Current weather forecasts from the Portland, Medford, and Pendleton National Weather Service offices are available at: http://www.wrh.noaa.gov/pqr/, http://www.wrh.noaa.gov/mfr/, and http://www.wrh.noaa.gov/pdt/ respectively.
This bulletin is also available on the web at
ODF Smoke Management Meteorologist