0.52 inches here, 1 to 1.5 inches on the CDO upper watershed; will it run?

May take Jake Horse out to see if the Sutherland Wash is running, anyway, if the CDO is not running here in Catalina.

Thunderstorms (at least 4 separate ones yesterday), with hail, graupel, wind, rain;  what a nice day for Catalinans and our environs.  Lightning was still visible as of 7:52 PM last evening, and close enough that  thunder could be heard, technically meaning a thunderstorm is in progress in weather parlance.  Here’s some pea-sized hail for you, sent by a listener, “Dave”, in Sutherland Heights:cropped IMG_20130308_104705_630

Was awakened by a moderate rainshower just before 3 AM.  Dropped 0.03 inches in a few minutes, to bring the total to 0.40.  Another shower followed within half an hour, but bucket didn’t tip for even 0.01 inch.  May have to jiggle it to get that extra 0.01 inch that I KNOW fell. Hahahah.

In the meantime, exulting over the large amounts, so well foretold by the U of AZ Beowulf Cluster run from 24 h ago.  Truly amazing!  Our total here was also well=predicted by that model; amounts in this storm increase northward reaching 0.87 inches at Oracle State Park, 0.55 inches at the NE corner of Saddlebrooke.  We SO needed a good rain.  Here’s where the totals are:

201303091030_pptreport

Here are some mind-boggling statewide totals from the USGS, some approaching two and a half inches of water content at Sunflower near Payson!  How great is that?!  Really, this has been a billion dollar storm in dropped water and snow. Maybe it should have a name now.

2013030911_AZ pcp USgS Sheet1

You will can also access rainfall data from the U of AZ rainlog.org network here, and from CoCoRahs national network for Arizona here.  As always, its necessary to point out that in the rainlog network, the measurements reported this morning will be assigned to yesterday’s date, while the ones in the CoCoRahs system will be assigned to today, March 9th.

Since its unlikely to rain for at least 10 days, I thought I would overdo the precipitation data for our billion dollar storm.

Sadly, as you will see in this Pima County ALERT gauge totals above,  we in the north end of the County really got the nice rain; most of the county did not.  We were lucky we were that bit farther north because it wasn’t the wind direction helping us out in most of the storm; that “help” is taking place now because the wind is more from the west at cloud levels.   Going into yesterday yesterday evening the wind at cloud/mountain top levels was from the south-southwest rather than from the west, and normally that more southerly flow helps the south facing sides of the Catalinas, as much as us.  So, it was more to do with cloud top temperatures and those clouds being a bit too warm to the south, while northward and to the northwest (perpendicular to our jet stream), the temperatures decreased rapidly at the same level in the atmosphere, and that in turn, allowed cloud tops to deepen more as they went nortward.  Make any sense?  Here’s a map of temperatures aloft for yesterday, two graphics to try to explain this:

A 500 millibar map at 5 PM AST. Center of coldest air is to the northwest of us at that time, gets colder over you as you take Highway 79 to Florence and beyond. Cloud tops do, too.
A 500 millibar map at 5 PM AST. Center of coldest air is to the northwest of us at that time, gets colder over you as you take Highway 79 to Florence and beyond. Cloud tops do, too.  The full loop is here.

 

Mapm for the same time with colors showing temperatures getting colder to the NW of us. More likely to have deeper clouds and thunderstorms as you go NW.
Mapm for the same time with colors showing temperatures getting colder to the NW of us. More likely to have deeper clouds and thunderstorms as you go NW.  Full loop is here.

First, here’s last evening’s TUS sounding, as rendered by the Cowboys of Wyoming.  Its got some writing on it:

The Tucson sounding at 5 PM AST, yesterday, March 8th.
The Tucson sounding at 5 PM AST, yesterday, March 8th.  Cloud tops marked by asterisks to represent ice crystals, and bottom by little “o’s”.  The arrows in roughly an “R” shape is an attempt at replicating the thunderstorm sign used by NOAA.  Even though the clouds were topping out at less than 25,000 feet, they still contained enough ingredients such as hail and updrafts to generate enough static electricity for lightning.

———begin tedious stream of consciousness again, probably worth skipping——–

Graupeling hard here at 3:38 AM!  Third shower since getting up!  Pounding roof.  Very small, like rice grains.   Just quit, like someone turned a light off at 3:41 AM.   Tells me its a new cell that just formed with narrow strands of precip/graupel.   Investigating…no echo at 3:36 AM nearby… waiting for next 6 min sweep…    2:42 AM:  No echo!  I have not seen this happen before.  Could it have developed and died in less than 5 min?  Did not tip bucket!  Its just like yesterday, we had no less than four hail/graupel episodes and I was beside myself thinking of those balls of ice bouncing OUT of my rain gauge collector!  I was being short-changed in the amount of precip I could report.   I think I am going to have to add to my rain total, maybe 0.03 inches due hail balls that bounced out

——————–end of tedious stream———————-

OK, now up to 0.13 inches in rain that has fallen since about 3 AM.  This is great, because now the total amount in the storm is 0.50 inches here!

Yesterday’s clouds

After a few sprinkles-its-not-drizzle amid brief sunbreaks yesterday morning, the first thunderstorm rumbled across Marana and the Oro Valley at 9:30 AM.

9:55 AM. Thunderstorm with hail and heavy rain moves into Oro Valley.
9:55 AM. Thunderstorm with hail and heavy rain moves into Oro Valley.
10:21 AM. Looking upwind toward Pusch Ridge at the bases of a line of rapidly moving Cumulus congestus clouds.
10:21 AM. Looking upwind toward Pusch Ridge at the bases of a line of rapidly moving Cumulus congestus clouds.
10:25 AM. Hail-producing cloud has passed by, but shaft increases in size and visibility. This is a time when tremendous amounts of ice is forming in the cloud, ultimately leading to its demise as a fluffy area looking area of only ice crystals. Without the liquid droplets, that disappear during this stage where ice forms explosively, no graupel or hail can form. Its a normal life cycle event for cells like this.
10:25 AM. Hail-producing cloud has passed by, but shaft increases in size and visibility. This is a time when tremendous amounts of ice is forming in the cloud, ultimately leading to its demise as a fluffy area looking area of only ice crystals. Without the liquid droplets, that disappear during this stage where ice forms explosively, no graupel or hail can form.
Its a normal life cycle event for cells like this.
12:12 PM. Another line of young Cumulonimbus clouds races toward Catalina and Sutherland Heights, a recurring theme yesterday.
12:12 PM. Another line of young Cumulonimbus clouds races toward Catalina and Sutherland Heights, a recurring theme yesterday.
12:23 PM. Passage of that complex of Cumulonimbus clouds shown in the prior shot resulted in this hail shaft trail on the foothills of Samaniego Ridge. Hail shafts are very narrow. If it had been snow, there would have been much greater coverage.
12:23 PM. Passage of that complex of Cumulonimbus clouds shown in the prior shot resulted in this hail shaft trail on the foothills of Samaniego Ridge. Hail shafts are very narrow. If it had been snow, there would have been much greater coverage.
2:30 PM. But the day wasn't done then, was it? Here something in the way of an arcus cloud rolled across Oro Valley and onto the Catalinas. Thought maybe a tube might form.
2:30 PM. But the day wasn’t done then, was it? Here something in the way of an arcus cloud rolled across Oro Valley and onto the Catalinas. Thought maybe a tube might form.
4:55 PM. Just kept on giving. Here yet another line of developing Cumulus congestus, just reaching the precip stage a little upwind of Catalina, dropped a few more graupel particles while going on to dump heavily farther north.
4:55 PM. Just kept on giving. Here yet another line of developing Cumulus congestus, just reaching the precip stage a little upwind of Catalina, dropped a few more graupel particles while going on to dump heavily farther north.  This recurring pattern of clouds developing,  able to become deeper with colder cloud tops is the primary reason the north part of Pima County did so well yesterday and this morning,

Today’s clouds

These early morning stratiform (flat) clouds will disperse into Cumulus and Stratocumulus in clumps. They’ll be cold enough at cloud tops for ice and virga, but clouds likely will be too shallow for more than a hundredth or two in the heaviest precip areas around Catalina. Things dry out later in the day, the Cu becoming smaller, so the best chance of measurable rain is before, say, 2 PM.

Get camera out fast, too. THere was a huge dump of hail or snow on Charoleau Gap last night or this morning I suspect, and it looks spectacular even now at 6:53 AM. Its local, because its not seen at the same elevations to the south on Samaniego Ridge. But, it will just be gorgeous with those deep blue skies and white Cumulus clouds all around.

The End, finally, I think.

Author: 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.