Lightning shows up, but not the rain

Another “awesome” display of lightning flashed over the Cat Mountains east of Catalina early last evening, accompanied by gusty northerly winds, but that fierce thunderstorm couldn’t make it over those mountains, but rather died on the way.  Only sprinkles occurred here, giving us yet another “trace” of rain day.  Kind of discouraging after the prior night’s nice little rain of 0.18 inches, one that also occurred after night fall.  But as we know, weather never repeats itself exactly.

———-Yesterday’s major cloud mystery———–

Many of you, I am sure noticed the remarkable cloud scene below, perhaps as you came out of the house, or during your lunch hour, and likely puzzled over it the rest of the day.  I, too, wondered how that little dot of cloud got so separated from its early Mt. Lemmon spawning grounds and brothers and sisters hovering over the mountain, trying to grow up.  Notice that it seems like a puff of cloud, ragged on the bottom, a little rounder on the top.  Could it be the top of a “smokestack” Cumulus that somehow we missed, whose connecting parts to Mt. Lemmon have evaporated?  Its an important question that we shall try to answer.

12:51 PM. Cumulus humilis and fractus begin gathering over Mt. Lemmon. Recall, btw, this scene began a little after 8 AM on the thundery day before, for perspective--we're late, not a good sign. But what in the world is that little cloud dot to the left and middle of the photo?
12:51 PM. Cumulus humilis and fractus begin gathering over Mt. Lemmon. Recall, btw, that this kind of cloud scene began a little after 8 AM on the thundery day before, for perspective–we’re late here, not a good sign of active rain day.)

 

To solve this mystery, Mr. (he’s not a doctor, nor does he have an advanced degree of any kind!) Cloud Maven Person went to the U of Arizona Department of Atmospheric Meteorology and looked at yesterday’s cloud movie.  These are top rated movies, and, if you’ve ever looked at them, you can understand why clouds and what the weather does can be hard to predict;  locations of storms missed, etc.  No computer model can see all the remarkable little cloud wiggles, sudden comings and goings, that you see in these movies, thus introducing slight errors that tend to degrade those model predictions over time.  And lots of the time, the locations of the clouds at the outset of the model run is even markedly off!   Below, yesterday’s complex cloud movie linked for you in the word, “Movie”:

Movie

You will barely be able to read the time of the day in the lower left hand corner, which adds further complexity in solving this problem, but if you look closely you will see that a minute or two BEFORE the shot above at 12:51 PM, and slender tower rose up from Ms. Lemmon, its trunk evaporating almost immediately, but the last thing to evaporate was the little puff above that sped westward toward Samaniego Ridge.

In conclusion, I think we have solved yesterday’s cloud mystery.

——————-end of cloud mystery module——————–

That such a cloud could shoot up and out from Mt. Lemmon like this one did was a sign that there was great environment for much larger clouds, at least in the fall of the temperature with height (lapse rate), but that more humidity was needed to keep them from evaporating as they tried to grow.  It wasn’t long before the hopeful sign of a Cumulonimbus calvus (anvil not formed yet) appeared beyond the Catalina Mountains, and the chance of evening rains, as the models had predicted, began to look better.

2:05 PM. Cumulonimbus calvus top makes its appearance, likely 70 miles or more away.
2:05 PM. Cumulonimbus calvus top makes its appearance to the SE, likely 70 miles or more, and hours away.

 

5:33 PM. Threatening clouds and thunderheads were now moving into the Oracle/Mammoth areas, and the chances of a significant rain here were growing by the minute as major radar echoes approached from the east.
5:33 PM. Threatening clouds and thunderheads were now moving into the Oracle/Mammoth areas, and the chances of a significant rain here were growing by the minute as major radar echoes approached from the east.  I remember thinking how how happy I was that such a dreadful Cumulus day over the Catalinas was now going to be reversed by this onslaught of storms as the U of AZ model had predicted.

 

7:05 PM. Thus far, only "debris" clouds from the thunderstorms upwind had crossed the Catalinas, spreading westward toward the setting sun. But those dark clouds did provide the contrast as the setting sun lit up the Catalinas for this great scene.
7:05 PM. Thus far, only “debris” clouds from the thunderstorms upwind had crossed the Catalinas, spreading westward toward the setting sun. But those dark clouds did provide the contrast as the setting sun lit up the Catalinas for this great scene.

 

7:22 PM. Multiple layers of clouds provide multiple sunset colors.
7:22 PM. Multiple layers of clouds provide multiple sunset colors.

 

7:32 PM. That extra brightness in the center of the photo, if you noticed it, is called a sun pillar. Its due to a fall of plate-like, hexagonal ice crystals that fall face down that allow the sun's light to be reflected toward us.
7:32 PM. That extra brightness in the center of the photo, if you noticed it, is called a “sun pillar”. Its due to a fall of plate-like, hexagonal ice crystals that fall face down and  that enhances the reflected toward us.  The sun set exactly below this bright spot.  For a bit more on sun pillars, go here.

 

What seems to be ahead…..

The U of AZ mod hasn’t been updated as of this hour….so, being in a hurry, we’ll do an “SOP” forecast (you have to see Bob for a good one.  I like Bob, too) but we have plenty of lower level humidity, and there appears to be a weak upper trough passing over us today, and that “should” help to collect storms into larger masses instead of just isolated ones.  Oops, let me not forget our TUS NWS computer forecast for the Catalina area, too.

So, today might be the last day for a reasonably good chance of a major rain here in Catalina.  After today, and for the next two weeks, the circulation pattern is not so great for summer storms, according to the NOAA spaghetti factory plots, seen here.

It seems more and more like we’re doomed to a drier than normal summer, darn it.  (Missed those first great storms, too, that started our summer rain season.)

That’s about it for my cloud world.  Camera will be ready for the black shafts of summer today!

 

 

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.