Extensive cloud coverage remains over most of the US, with exception to the Southwest (top, left - MODIS Aqua RGB). In terms of air quality, as can be seen in AIRNow's animation below (right), moderate levels of PM2.5 (code yellow) was observed in central California, as well as in its border with Oregon. Moderate levels also in the Plain States, Great Lakes and Southeast region of the US. Code orange was observed in Northeastern Idaho, Southwestern Montana and Northern California.
On Dec 26th the volcano San Cristobal in Nicaragua began spewing gas and ash, prompting evacuation of about 300 families that live nearby, according to Huffington Post which also shows some nice images of the volcanic activity. The tracks of ash originated from this activity was seen on MODIS Aqua image of Dec 26th and Dec 27th (below, left). OMI satellite also observed traces of SO2 (below, right) on Dec 26th offshore the western coast of Nicaragua, where the plume was observed by MODIS.