The Mid-Atlantic States, Great Lakes Region, Midwest, and parts of the West Coast in and around Northern California have been experiencing Moderate to Unhealthy AQIs (EPA AirNow Combined Loop, top left). These Unhealthy AQIs peaked near Reno, California a few hours after sunrise, presumably from active fires around the area. Air quality in the Midwest is also being affected by smoke combined with a mixture of dust, sulfates, and NO₂. The MODIS AOD image (top right) shows elevated AOD over the Northern Plains States, in agreement with the Moderate AQIs in the area. Light smoke is starting to cross the US border, blowing north from burns in Southern Mexico and Central America. The NAAPS Aerosol Model (bottom left) predicts the smoke surface concentration over the fire sites south of the border to reach 128 µg/m³. The model also predicts dust to reach 10.24 mg/m³ in and around Arizona.

Large concentrations of NO₂ can be seen over the Great Lakes Region and the East Coast (OMI NRT Total NO₂, bottom right). The model notes sulfates to also be affecting air quality in the East as well as in the Midwest, in agreement with Moderate AQIs in these areas. The sulfate surface concentration is predicted to have reached 8 µg/m³ over Pennsylvania, which could be the reason behind USG AQIs in central Pennsylvania.

Pretty simple air quality situation over the US on Saturday. There is moderate AQI for particulates pretty much everywhere east of the Mississippi. However, there are also clouds pretty much everywhere east of the Mississippi. Very little information is added from spaceborne observations today.

The EPA AQI loop below left shows Unhealthy AQI in central California,
as well as areas of Moderate AQI stretching along the east coast and
onto the Gulf coast. The OMI tropospheric NO₂ image below
right indicates that nitrates may be the cause of the elevated AQIs
in the Mid-Atlantic.

The NPS webcam image below left shows the effect of the elevated AQIs
in central California on visibility at Joshua Tree National Park; at
right are clear and hazy images from the same location for comparison.

The graphic below shows measured PM_2.5 concentrations in
southern California and shows several stations approaching the
Unhealthy line.

After what's been one of the snowiest and coldest winters in awhile, even parts of the deep-south are feeling the chill. The snowfall footprint stretches from the valleys of California to the nation's Capital, with measured snowfall also across the southern contiguous U.S. (Arizona, New Mexico, Texas, Louisiana, Mississippi, Alabama, and Georgia) (top left, courtesy WSI). In terms of air quality, elevated, Code Yellow, Moderate AQIs, were scattered throughout the Pacific North and Southwest, Mid-West, Plains, Great Lakes, Mississippi Valley, Mid-Atlantic and Northeast states (top right). Satellite retrieval of aerosol optical depth (AOD) within these regions was obstructed today, due to immense cloud cover (bottom left); however if you look closely, you can see the spines of the Appalachians peeking through the image as the result of clear skies and a swath of snow cover. Finally, a Code Red, Very Unhealthy AQI, was reported in northeast California. After investigating further, it is unclear if this is an actual measurement of elevated PM2.5 or an artifact from instrument error (bottom right).

The VIIRS AOD image, below left, shows low values of AOD across the country for today. There does appear to be scattered increases in AOD near the Pacific coast of southern California. There is also an increase in AOD near the northwest corner of Oregon. The KNMI OMI NRT NO2 product below right, shows increases in NO2 throughout the troposphere. There appears to be an increase in the Pacific Northwest and southern California regions. For this reason, there may be some increased nitrate aerosol and particulate formation that will affect air quality at the surface.

Below, left. the GEOS Chem model shows an increase in total AOD for the southeast and Gulf regions of the U.S. The heaviest concentrations appear to be north eastward of the concentrated fire region in the southeast region. Below right, courtesy EPA AIRNOW, shows the code red for eastern southern California. This was most likely due to residential wood burning in the region due to very cold temperatures.

Air quality is pretty clear today except for some areas of Moderate to USG, growing and dispersing in the course of hours with most of the Moderate AQI's residing on the East coast (EPA AirNow, top left). Large concentrations of NO₂ through the total column can be seen off the coast of the Mid-Atlantic States (OMI, top right), resulting in elevated AOD's specifically offshore from Maryland (MODIS, bottom left). Sulfates are also predicted to have an effect on air quality off the coast, especially Maryland, predicted to reach 8 μg/m³ (NAAPS, bottom right). The model also predicts dust to reach 5.12 mg/m³ over the border of Arizona and New Mexico. HMS has noted dust/sand kicked up in the Pacific Southwest, carried Southwest by winds from Nevada into California. The AirNow loop shows Unhealthy AQI's growing during the day in Southern California, presumably the noted dust/sand from Nevada. Small plumes of smoke from burns in the Pacific Northwest also seem to be affecting air quality on the West Coast, where spots of USG can be seen popping up throughout the course of the day.

A few fires in the southeast continue, as seen on the MODIS Aqua image
and the HMS fire and smoke product shown below (top left and top
right, respectively). Fortunately, they seem to be having a limited
effect on air quality, as shown in the EPA AQI loop at the bottom right.
The NWS issued a red flag warnings in this area due to low humidity.

The San Joaquin Valley and Los Angeles have declared air action days
due to Unhealthy levels of fine particulate matter, seen in the image
of the EPA air monitoring network above at the bottom left. The NPS
webcam image from Joshua tree National Park, shown below left, seems
to show the effects of this; at the right are clear and hazy images
for comparison.