07/18/14 Idaho DEQ Smoke Forecast

Updated 0900 MDT Friday, July 18, 2014

Valid through Noon MDT Monday, July 21, 2014

Smoke Outlook

Garden Valley continues to see impacts from the Whiskey Complex.  Overnight values were consistent with what has been observed the past 2 nights in Garden Valley with slightly lower readings in Idaho City.  The Boise area was elevated overnight compared to previous nights.  Idaho City was in the Unhealthy category yesterday while Garden Valley and Boise were both in the Unhealthy for Sensitive Groups yesterday.  North Idaho from St. Maries north experienced moderate level impacts from the fires in Washington; however, by mid-morning, the entire state was experiencing impacts to a varying degree except for the region south of a line running from Twin Falls-Driggs.  Afternoon heating allowed the smoke to rise and disperse.   

The weather will be similar to yesterday with west-northwest winds aloft and warm and dry conditions across the state.  There is a slight chance for thunder along the Nevada-Idaho border this afternoon.  Expect locally breezy winds this afternoon with gusts from 15-25 mph across the Snake River Plain and 10-17 mph north of the Clearwater.  A red flag warning for the Middle and Upper Snake River Plain has been issued for this afternoon.  Mixing heights will range from 4,000-9,000ft AGL with lower heights in the northern portion of the state.

Late Sunday, the upper level wind pattern shifts to a southwest flow, which will move smoke north of the Snake River Plain and allow monsoon moisture back into southern Idaho.  Warm conditions will persist through Sunday with a chance for showers late Sunday/early Monday in southern Idaho. 

In north Idaho, this weekend will start with higher humidity levels as subtropical moisture is transported into the area ahead of a Saturday cold front.  This front will create dry conditions for Sunday with a chance for an upper level shortwave to impact on Monday; however, this system is tracking along the border and is trending to move northeast rather than east. 

Smoke impacts today will be high near fires in the Central Mountains.  Transport of smoke from fires burning in Oregon and Washington will be the primary contributors today.  A very consistent pattern has developed over the last 18 hours in the models indicating clear zonal advection of smoke.  Expect all areas of Idaho to be hazy except a swath running along a line from McCall-Bannock Pass and Lewiston-Lolo Pass.  The Whiskey Complex is planning a burnout if weather and fireline work is conducive.

This weekend may see a slight reprieve in northern Idaho as wetter conditions may limit fire activity in Washington.  The wind shift to southwest on Sunday will likely introduce smoke from the Oregon fires into the Clearwater while fire in the Boise National Forest will advect smoke towards the Salmon-Challis region.  The timing of this wind shift will determine the strength of these impacts as an afternoon wind shift will keep the smoke aloft while an evening or nighttime shift may bring the smoke overhead just as heights lower and temperatures drop.

View DEQ near-real time monitoring at:  http://airquality.deq.idaho.gov/

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