Catalina-Smog before the storm

Those of us awaking this morning were literally a-palled by the amount of smoke around.  Not even Twin Peaks was visible, some 10 miles to the SW. See examples of smog in the photos below.

Where did it come from?  Back trajectories, ones that end in Tucson as of this morning at 5 AM shown below, suggest the smog came from the SE of us (red and blue lines.  The green line for air around 12,000 feet, represents where the air came from  that air came from the off the California coast ; it was too high to be involved in our smog episode.  Best guess, could be smog from El Paso and/or from burning in northern Mexico, that in the presence of light winds,  has kind of muddled around and drifted N into Tucson.

Note the pooling of smoke in the low valley ahead in the Golder Ranch area in the first photo.  Probably the result of wood-burning stoves used in the small housing development back there.  What it shows you is the persistent nighttime inversion that forms in that bowl, the flat top of the smoke indicating a temperature inversion. You then see a “clear slot” of little smog and then the overall deeper smog layer above that, also very laminar in appearance.   With the sun’s rise over the mountain, that kind of structure/separation is soon removed as bubbles of warmer surface air float upward and are replaced by downward moving blobs, mixing all the structure you see in the first photo out.   In the last photo, a few tiny cumulus fractus clouds composed of droplets have formed over the Catalina Mountains.  The droplets in those clouds are probably 10 microns in diameter (about 1/10 the size of a human hair).   These droplets are about 100-1000 times bigger than the aerosol particles making up the smog.   This makes the clouds to tell from transparent haze blobs because the smog particles are too small to scatter much light while the cloud particles even in small clouds, prevent you from seeing through them.  Well something like that.

Hang on to your hat tomorrow; windy, thinking momentary gusts here in “Catalina Heights” will hit 30-50 mph by late afternoon and overnight before a very strong cold front rolls through around dawn tomorrow.  This is an unusually strong upper level AND lower level system with a deep low expected to form over southern Nevada during the day tomorrow.   Looks like the rain could change to snow above  3,000 feet after the front goes through, too.  That would be terrific!  The clearing after the front goes by will probably be late in the day with passing light showers possible until early Friday morning.  The ones later in the day and overnight, are likely to be snow flurries above 3,000 feet .  Don’t expect the temperature to do much tomorrow. And, the amounts of precip are likely to be substantial putting us at or above normal for the month.  Yay!   Well, this what it looks like to me; check the NWS for the official forecast!