Check this map out below from the University of Washington Huskies Weather Department. The whole 24 h series of sea level pressure maps is here and watch how things change in the SW and western Arizona just in that time. You rarely see lows of this magnitude in our area as we have right now, and this much change in just 24 h in a sea level pressure map. As you can see from the low center centered over Ajo, AZ, (below) the air is going in counterclockwise circles in our State. Well, of course, friction caused by cactus and mountains turns the air toward that low center, trying to get rid of it. But, the forces producing it so far are stronger so far and so it has a very low pressure (less than 1004 millibars) for this time of year over AZ.
Note, too, that all the clouds and precip (shown here) and by those white areas on the map below, are to the west and north of the center. But that will change as the upper air low center (second map) spins back to the southwest a bit and the air over us changes in direction from the southwest, as it is now on this upper level map, to a more southerly direction in the hours ahead.
In the meantime, Pacific air should be gaining a presence over the interior of Baja and begin circulating from there up toward us. Clouds should literally start appearing out of the clear skies to the southwest of us in satellite imagery today (such as here) and then those clouds will work their way up this way, likely increasing in depth and coverage as they do.
Another exciting prospect is that this same process, clouds appearing out of the blue, will likely start happening over us as the day progresses, and maybe, in view of the strong winds aloft, some nice “flying saucer” clouds, namely, Altocumulus lenticularis, flat, lens shaped clouds that hover over mountains will show up over the Catalinas.
These are great days ahead for weather folk, and I hope in spite of any inconveniences caused by quite wonderful inclement weather, you will enjoy this dynamo of a weather day. Of course, you wanna go here, to the NWS, for all the great details.
Rain? Supposed to begin in these parts between around 4 PM and 6 PM today (you can see this here from the U of WA model). Interestingly, this model has a rather thin band of precip sitting over us for more than 12 h. Good grief! Too good to be true I suppose, since we might get well over half an inch, and would certainly, if it happens, push our wildflower prospects for this spring up in view of our 1.83 inches here in Catalina in November.
Also this; a nice satellite view of the US where you can see the night lights of the cities, if you’re up early enough and haven’t seen it before.
The End for now.