March showers for spring flowers; the bloom is on, the rain is here

This is so great, today’s badly needed substantial rain for our Cal pops and other wildflowers, now beginning to bloom.  You may have seen some poppies along North Oracle Road in the past week.

Here is the current radar and cloud situation from IPS MeteoStar (loop is here).  You can see three rain bands, very similar in configuration to the historic snowstorm of February 20th that also had three bands.  What’s potent and interesting is that the lead band with precip just to the west of us (passing over Ajo at this time).   That cloud band is usually just that, composed of thick, middle and high clouds (Alstostratus/Cirrus/Altocumulus) without any precip or just virga.   And its usually also followed by the “clearing before the storm”, the ones that lead on many occasions to those super spectacular sunsets before the surge of low clouds and precip. You can see that “clearing before the storm” aspect in southwest AZ in the image below.

But, as you can see, THIS cloud band “before the storm”, has developed some rain.   So, in this case, we have a chance to pick up some light rain before the  major bands arrive later in the day. You can also follow the progress of the storm on those great WunderMaps here.  Might be on this site ALL DAY.

4:10 AM combination satellite and radar, the best on the web IMO.
4:10 AM combination satellite and radar, the best on the web IMO.

Here, too, is the University of Washington’s 500 mb map for 5 AM AST this morning showing the flow at about 18,000 feet above sea level.  You can see the three bands here, too, and a fourth taking shape in the center of the low, now off southern California.201303081200_500mb  You will see that the strongest winds at this level are over Tucson now, meaning rain is imminent, and it is.  Already had a trace, a few drops fell at 4:06 AM.  Expect lightning in AZ today, maybe around here, too, with the second or third bands.


Here’s the loop U of AZ weather department’s mod output from last night’s 11 PM run, which gives you an hour by hour account of the storm over the next two days.  While the main bang is today, a lobe of cold air aloft follows it and scattered light showers continue into tomorrow. What will help Catalina’s rainfall is that the wind will be more westerly rather than southerly at cloud levels during and after the storm, which means they will pile up on this side of the Catalina Mountains the best, and which should do better than other areas.  The U of AZ mod knows something of this, and you can see the precip in the panel below extending from the Catalinas toward the west and over us.  Its due to this frequent occurrence during and following storms that really boosts our winter precip totals over surrounding areas of similar elevation.

There are a lot of parameters available from this output.  You can look at the whole range of them here.

Valid for 3 AM AST tomorrow morning, March 9th.
Valid for 3 AM AST tomorrow morning, March 9th.


Yesterday’s clouds

It was asserted yesterday that there would be some Cumulus and Cirrus by Mr. Cloud Maven person.

Here they are:

4:16 PM.  Forecast of Cumulus cloud(s) verifies!
4:16 PM. Forecast of Cumulus cloud(s) verifies!  It was small, but great.
6:10 PM.  Cirrus creep underway from the west.
6:10 PM. Cirrus creep underway from the west.

Sure, it was clear practically the whole day, and some people might complain that they got eye strain looking for Cirrus and Cumulus clouds during the day….  But then, you can find people who will complain about anything.

Enjoy this day!

The End



By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.