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Radar valid at 430 pm PDT, Aug 9th 2017

alert legend

WAZ001-503-504-506-507-509>517-555-556-558-559-567>569-092330-
San Juan County-Western Whatcom County-Southwest Interior-
Western Skagit County-Everett and Vicinity-Tacoma Area-
Admiralty Inlet Area-Hood Canal Area-Lower Chehalis Valley Area-
Olympics-Eastern Strait of Juan de Fuca-
Western Strait of Juan De Fuca-North Coast-Central Coast-
East Puget Sound Lowlands-Bellevue and Vicinity-
Seattle and Vicinity-Bremerton and Vicinity-
Cascades of Whatcom and Skagit Counties-
Cascades of Snohomish and King Counties-
Cascades of Pierce and Lewis Counties-
945 PM PDT Tue Aug 8 2017

...AN AIR QUALITY ALERT EXTENDED FOR WESTERN WASHINGTON THROUGH
NOON FRIDAY...

The air quality alert that was in effect until noon Thursday has
been extended until noon Friday.

A strong upper level ridge will keep a dry stable air mass over
Western Washington into Thursday. In the lower levels, weak
onshore flow has resulted in some improvement in air quality along
the coast and areas near the Strait of Juan de Fuca. In the
interior the low level flow is not strong enough to improve the
air quality and with the winds right off the ground a bit
northerly, conditions deteriorated during the day on Tuesday. Many
places in the interior from Seattle southward were reporting air
in the unhealthy category Tuesday evening.

Northerly flow aloft will continue to transport smoke into
Western Washington from wildfires in British Columbia through at
early Thursday. In addition, atmospheric ventilation in the
interior lowlands of Western Washington will remain poor. Weak low
level onshore flow will continue to bring better air quality to
the coast and areas along the Strait of Juan de Fuca.

The smoke and hazy skies will continue to plague Western
Washington for the next few days. A change to southwest flow
aloft will begin late Thursday and continue into Friday. Initially
the flow aloft will be light so it will take some time for
improvements to occur. The increase in onshore flow at the lower
levels will also take time to develop. For these reasons the air
quality alert has been extended to noon Friday.

People with respiratory ailments like asthma can find more
information, including current air quality, at the following
websites...

wasmoke.blogspot.com
airnow.gov

Additional regional information...

Puget Sound area...pscleanair.org
Southwest Washington...swcleanair.org
Olympic region...orcaa.org
Northwest region...nwcleanairwa.gov

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