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Wildfire Smoke Update
for
Thursday, September 13, 2012 2:18 PM

Satellite Photos | Locations and Smoke Conditions


Today's Report and Forecast Today's Summary
With very stable air in place under a ridge of high pressure, air quality has begun to worsen today. Smoke production across Idaho and western Montana was not very extreme yesterday, but it was enough to create smoky areas. Overnight, inversions developed, and smoke spread out across southwestern Montana and filled the valleys. Most locations didn’t have a large quantity of smoke to deal with, but with the stable and suppressive air in place, even a little bit of smoke was enough to impact air quality and visibility near the ground. As atmospheric winds change direction as well, the smoky region spread out. Cumulative smoke concentrations are MODERATE in Helena, Bozeman, and West Yellowstone as the smoke that was once contained to far southwestern Montana spreads north and east. Particulate concentrations have been rising to levels that are UNHEALTHY FOR SENSITIVE GROUPS in Butte and Missoula, and UNHEALTHY in Hamilton. Cumulative smoke concentrations in Hamilton and down the Bitterroot Valley are still VERY UNHEALTHY. Air quality is GOOD in far northwestern Montana and in the plains, but a haze is visible in the sky across eastern Montana.

For the rest of the night and even into the weekend, atmospheric winds will generally blow from the west. With the given locations of the major fires in Idaho and Montana, we can expect the smokiest areas across the state to be the southern half of Montana. Red Flag Warnings are in effect for parts of eastern Montana, as well as central Idaho where most of the large wildfires are burning. Dangerous fire weather is expected on Friday as the ridge of high pressure brings very warm temperatures, dry air, and some gusty wind to the region. It has been under these conditions that we have seen very large smoke plumes on satellite images, so it can be expected that we will see similar conditions tomorrow evening. On Saturday, a cold front will start to drop down from the north/northwest in the afternoon. Strong winds and a wind shift are expected with this front, but no precipitation. This can also prove to be dangerous for active wildfires. Winds at the surface will come from the north/northwest behind the cold front, but by Sunday, high atmospheric winds will also start to come from the north/northwest. We similar conditions yesterday (Wednesday) where these kinds of winds helped to clear the air in most places (except the Bitterroot and the extreme southwest). If the forecast holds together, we may be looking at a break from the smoke by the beginning of next week.
Cumulative smoke concentrations are MODERATE in Helena, Bozeman, and West Yellowstone as the smoke that was once contained to far southwestern Montana spreads north and east. Particulate concentrations have been rising to levels that are UNHEALTHY FOR SENSITIVE GROUPS in Butte and Missoula, and UNHEALTHY in Hamilton. Cumulative smoke concentrations in Hamilton and down the Bitterroot Valley are still VERY UNHEALTHY. Air quality is GOOD in far northwestern Montana and in the plains, but a haze is visible in the sky across eastern Montana.
Residents near active fires and under plumes aloft need to remain aware of current conditions and use the visibility guidelines to guide their activity decisions as the situation changes.

Air Quality Bureau
Montana Department of Environmental Quality
Phone: (406) 444-3490
Email: DEQMTSmoke@mt.gov




This is the visible satellite image from 1:30 this afternoon. Smoke plumes are not visible at this hour, but smoke that has settled into the valleys of western Montana and especially eastern Idaho is very visible. 

This is the visible satellite image from 1:30 this afternoon. Smoke plumes are not visible at this hour, but smoke that has settled into the valleys of western Montana and especially eastern Idaho is very visible.


 
This webcam is at the Gates of the Mountains and looks south across the Helena Valley. I posted an image from the same webcam yesterday when conditions were very clear. Today, however, you can see the smoke that has returned to the area. You can also see how the smoke is near to the ground and that there is a definite line where the smoke ends. This is very characteristic of smoke conditions under a strong ridge of high pressure. Under a high pressure ridge, the air is very suppressive and actually sinks toward the ground. The result is this, where the air near the ground cannot mix with the rest of the atmosphere, and so you can get this buildup of pollution (in this case, wildfire smoke) in the lowest levels of the atmosphere.

This webcam is at the Gates of the Mountains and looks south across the Helena Valley. I posted an image from the same webcam yesterday when conditions were very clear. Today, however, you can see the smoke that has returned to the area. You can also see how the smoke is near to the ground and that there is a definite line where the smoke ends. This is very characteristic of smoke conditions under a strong ridge of high pressure. Under a high pressure ridge, the air is very suppressive and actually sinks toward the ground. The result is this, where the air near the ground cannot mix with the rest of the atmosphere, and so you can get this buildup of pollution (in this case, wildfire smoke) in the lowest levels of the atmosphere.


This morning’s analysis from NOAA’s satellite services division shows the active fires in Montana and the smoke plumes combining and spreading downwind (the analyzed smoke is based on yesterday’s satellite coverage, the fire detects are based on last nights satellite coverage).

This morning’s analysis from NOAA’s satellite services division shows the active fires in Montana and the smoke plumes combining and spreading downwind (the analyzed smoke is based on yesterday’s satellite coverage, the fire detects are based on last nights satellite coverage).

Red indicates hot spot detected. Green represents thin smoke, yellow is moderate smoke, and purple is dense smoke. Fire size is exaggerated for visibility at this scale. To identify individual fires on graphic above go here: http://activefiremaps.fs.fed.us/lg_fire2.php 

It looks to be another relatively clear day in Big Sky despite the smoke that some areas are seeing in southwestern Montana. However, some smoke is visible in the sky on the horizon, and the details of Lone Peak are starting to become “fuzzy.”

It looks to be another relatively clear day in Big Sky despite the smoke that some areas are seeing in southwestern Montana. However, some smoke is visible in the sky on the horizon, and the details of Lone Peak are starting to become “fuzzy.”

Real time particulate information is currently available in most of the larger urban areas from MTDEQ's Today's Air website.

Today's particulate report below compares particulate levels received from DEQ's
reporting stations with MTDEQ’s Health Effect Categories.

Locations and severity of PM 2.5 particulate values over the past 24 hours from the time above.
Health Effects Categories City
  Hazardous  
  Very Unhealthy  Hamilton B24, B8
  Unhealthy  
  Unhealthy for Sensitive Groups  Missoula B1(1)
Frenchtown B1(1)
Butte B24, B8
  Moderate

 Helena B8
West Yellowstone B24, B8
Bozeman B24, B8, B1
 

  Good

 Libby
Flathead Valley
Seeley Lake
Sidney
Billings
Great Falls
 

B1(x) One-hour BAM value (number of values)
B8(x) Eight-hour average BAM
B24 24 hour  average BAM value
Local impacts in areas immediately adjacent to active fires are expected to exceed some or all of the advisory levels.  DEQ recommends the use of local visibility guidelines to evaluate possible health risks and make informed activity decisions.