Virga anyone?

Mr. Cloudmaven person foretold certain cloud types would occur yesterday in conjunction with “storm” 3 yesterday (which was really only the passage of an upper level trough over us–see map for 5PM yesterday).  Let’s see how he did, that is, whether he is an actual “cloudmaven”:

(0=not observed, 1 observed, -1, cloud observed, not predicted:

Cirrocumulus,  0

Altocumulus floccus virgae,  0

Cirrus,  1

Cumulus fractus, -1

Cumulus humilis, -1

Cumulus mediocris, -1

Stratocumulus, -1

Stratocumulus virgae, -1

Cloud score:  -4  =s bad cloudmaven; credentials suspect.

Here are some of the cloud sights from yesterday in case you miseed them and want to fill in some entries in your cloud diary:   1) 4:42 PM, 2) 5:26 PM, 3) 5:53 PM, has band of cirrus with trough passage, and 4) 6:12 PM, with some virga/ice fallout showing (darkish veils below clouds).























However, I did opine that there might be a sprinkle with this trough (see map again for example of yesterday’s “trough.”  (Sounds like the stockmarket in ’09.)  Having been specially trained to recognize virga and precipitation when a forecast of precipitation is on the line, I found it easy to recognize just how close I came to getting that sprinkle as evidenced by some virga trailing down from some of the patches of Stratocumulus clouds.  See above hills in photo at left.

You now know, if you have been reading this blog and thinking about it all day,  that ice formed in these clouds because they had crossed a temperature threshold, had gotten cold enough to form ice.  That “virga” was, if you flew through it, snow flurries.   Where it melted into raindrops closer to the ground is not visible.  However, it is unlikely that virga of this magnitude reached the ground.

You might now even guess the temperature which the tops of the clouds reached.  My guesstimate from the TUS sounding at 5 PM yesterday is somewhere between -15 to -20 C, a threshold for ice (precip) formation in shallow clouds such as these.  Estimated depth of the thicker clouds seen here? About 2000 feet or so is all.

BTW, if you noticed these very subtle virga/ice in these Stratocumulus clouds that began to show up late in the afternoon, you are a cloud observer supreme!

Yesterday’s weather map:

The end.