08/14/2015 Idaho DEQ Smoke Forecast

Updated 1200 Noon MDT Friday, August 14, 2015

Valid through: Noon MDT Monday, August 17, 2015

Smoke Outlook

Air quality is currently ranging from Moderate to Unhealthy across northern Idaho and in southwest Idaho north to Garden Valley and McCall.  Air quality is forecast to remain in the Moderate to Unhealthy category for the 24hr standard across the northern Idaho.  Impacts are from regional fires burning in Washington State, California, Oregon, and a multitude of local fires that started this week in the Clearwater drainage.

Nez Perce Reservation:  24-hour monitor readings range from Moderate to Unhealthy.  Hourly readings are fluctuating from Moderate to Hazardous, depending on location and wind direction.  The Nez Perce Tribe will continue their Air Quality Advisory.  Please contact the Nez Perce Tribe for more information: airquality@nezperce.org.

An upper level low pressure system will move through Oregon and Washington today bringing a vigorous cold front through Idaho this morning and afternoon.  This will allow for a persistent chance of lightning and thunderstorms this afternoon.  Surface winds will be strong today and generally from the south-southwest today (Northwest within the Treasure Valley and Lewiston-Clarkston Valley) with speeds ranging from 5-15mph across southern Idaho and 10-20 mph across northern Idaho with gusts up to 40 mph as the front passes.  Mixing heights are expected to be range from 3,000-9,000 ft AGL this afternoon which should promote vertical mixing.  Saturday looks to be an unsettled day-minus the convective activity-across all of Idaho before a flat ridge develops within a zonal flow regime on Sunday.  Surface winds will range from 10-15 mph across all of Idaho on Saturday before dropping into the 5-10 mph range on Sunday.  Some slight warming will occur Sunday and Monday as a flat ridge develops within a zonal flow pattern aloft. The wind direction also looks to change on Sunday with northerly flow in northern Idaho and southwest flow across southern and central Idaho with southeast flow within the Treasure Valley.

The strongest smoke impacts are occurring across the Clearwater drainages, the Idaho Panhandle and southwest Idaho.  This will continue into the afternoon and especially this evening as northerly flow develops within the Purcell Trench and westerly winds bring smoke from fires in Oregon into Hells Canyon which then enters the Clearwater Drainage.  Expect to experience impacts from the Canadian Border south to Coeur d’Alene and along the low spots to Lewiston and east essentially to within the Lochsa Drainage.  The highest impacts are expected to be within the drainages into Camas and Weippe Prairies, as well as down to the Lewiston-Clarkston Valley.  In southern Idaho, impacts will be greatest-although less than the impacts across northern Idaho- within the Treasure Valley, from Boise, west into Oregon, and north to McCall and Garden Valley and east to Twin Falls within the Snake River Plain.  Nocturnal drainage flow will contribute to greater impacts in southwestern Idaho tonight.  Impacts are expected across the Treasure Valley and as far east as Salmon as a southwest flow pattern develops tomorrow afternoon across southern Idaho.  Some impacts should once again be expected on Sunday across the southwestern portion of the state.  Essentially, the only regions not experiencing or expected to experience impacts through this weekend are the Upper Snake River Plain and the Eastern and Southeast Highlands.

DEQ Air Quality Advisories:

Idaho DEQ has issued a Stage 1 Forecast and Caution for the following areas:

·                     Latah, Nez Perce, Lewis, Clearwater, Idaho Counties, river corridors and surrounding areas (off the Nez Perce Reservation) effective  through 10:00am PDT August 17, 2015, at which time is will be re-evaluated and either extended or lifted.

Smoke forecasts are dependent on predicted fire growth and weather.  If conditions change unexpectedly, impacts could occur.  When visibility starts to go below 5 miles, sensitive groups should minimize outdoor activities.  Everyone else should minimize prolonged or physical activity outdoors.  Refer to the Smoke and Health Tab on the Idaho Smoke Information Blog for additional health information. 

Your eyes are your best tools to determine if it’s safe to be outside.  Even if you smell smoke, the air quality may still be good. 

AQI Category	Visibility (miles)
Good	11+
Moderate	6-10
Unhealthy for Sensitive Groups	3-5
Unhealthy	1½  -2¾
Very Unhealthy	1-1¼
Hazardous	Less than 1

How to estimate air quality based on visibility for areas without an air quality monitor or airport visibility estimate:

a. Face away from the sun.

b. Determine the limit of your visible range by looking for targets at known distances (miles).

c. Visible range is when an object you can easily see in the distance disappears.

d. Use the visibility values above to determine the local wildfire smoke category.