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The Air Quality Index at 10 a.m. on
Thursday, Aug. 23, 2018. See the map
above for current conditions.
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Forecast issued: Aug. 23, 2018
Forecaster: James Miller, USDA Forest Service
The main story this morning is that
smoke has been slow to exit the Willamette Valley from Portland south to
Eugene. As of 10 a.m. on Thursday, Aug. 23, 2018, moderate air quality
prevailed over Eugene, unhealthy for sensitive groups air quality was
widespread in the Salem area, with unhealthy air common throughout the Portland
metro area. Despite the marine air arriving over Portland around sunset yesterday,
air quality indices actually increased overnight leading to some of the highest
pollution levels of the five-day smoke episode over Northwestern Oregon
observed this morning.
It appears that clearing is finally
underway to the west of Portland, signaling that the metro area should see
improving conditions throughout the afternoon hours. At the Sauvie Island
monitoring location northwest of downtown Portland, particulate matter levels
have lowered from 83 micrograms per cubic meter at 2 a.m. to 17 micrograms per
cubic meter at 10 a.m., resulting in an improvement of the air
quality index from unhealthy to moderate. Likewise, the Longview, WA monitor
located northwest of the Sauvie Island station has lowered from 68 micrograms
per cubic meter (unhealthy
air quality index) at midnight to 5 micrograms per cubic meter (good
air quality index).
The AIRPACT, Canadian FireWork and
High-Resolution Rapid Refresh smoke models each suggest that smoke should
finally exit the northern Willamette Valley by the late afternoon hours.
However, both the AIRPACT and Canadian FireWork model hint that smoke from
coastal British Columbia and the Olympic Peninsula may move over the Portland
metro area and Columbia Gorge after sunset today into Friday morning. The High-Resolution
Rapid Refresh model keeps smoke from the Olympic Peninsula mainly to the north
and east of Portland into Friday morning. It will be interesting to see the
next update of the HRRR model in the afternoon to see how it handles any
potential smoke entering the Portland metro from the north/northwest after
sunset.
In the southern Willamette Valley
(e.g. Eugene) contrary to the forecast made yesterday, moderate smoke levels will
likely stick around a little longer than in the northern portion of the valley.
The High-Resolution Rapid Refresh model still has smoke over the Eugene metro
area at 4 p.m. today. By tomorrow morning, the High-Resolution Rapid Refresh model
suggests the entire Willamette Valley will finally be free of wildfire smoke
leading to a return of good air quality indices.
The near-surface smoke forecast from the High-Resolution Rapid Refresh (HRRR) Model shows the entire Willamette Valley free of smoke by Friday, August 24, 2018 at 4 a.m.
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The High-Resolution
Rapid Refresh (HRRR) Model suggests the northern Willamette Valley will clear
out by Thursday, August 23, 2018 at 4 p.m.
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The
near-surface smoke forecast from the High-Resolution Rapid Refresh (HRRR) Model
shows the entire Willamette Valley free of smoke by Friday, August 24, 2018 at
4 a.m.
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Disclaimer: Forecasting weather,
fire behavior, and smoke transport and dispersion is challenging. While we
strive to bring you the most up-to-date and accurate forecasts, conditions can
and do change rapidly. Please take the appropriate action to protect yourself.