A Stratocumulus Monday

Yesterday gave us “Catalonians” the perfect example of Stratocumulus clouds.   But why didn’t it rain from those dark clouds, save a few drops, maybe even a brief drizzle episode that mostly moved across Saddlebrooke around 9 AM?

Those Stratocumulus clouds were GENERALLY not cold enough at cloud top to have ice crystals form in them.   There were some very light showers, mostly east of us during the day, and THOSE clouds got cold enough at cloud top to have ice form in them.

How cold does a cloud top need to be in Arizona for ice to form in it?

Around 15 F (-10 C).

Here’s the TUS  5 AM AST sounding for yesterday from the Weather Cowboys at the University of Wyoming showing the tops are right around that (normal) ice-forming limit.  Where the lines split apart is close to where the cloud tops are, and the temperature lines slant downward to the left.

You may have also noticed that the clouds got markedly shallower here after about 3 PM, noticeable in the U of A movie after 3:30 PM AST.  That was also close to the time an upper level trough and the accompanying slight wind shift occurred.  To the rear of the trough, there is always a piston of downward moving, drier air that’s going to squash cloud tops.  By the evening TUS sounding, cloud tops were barely below freezing.

Some cloud shots from yesterday’s overcast:

Sharp-eye folks will detect a sprinkle over Charouleau Gap

The weather ahead

Still looking for rain here on the 22-23rd, HOWEVER, the last two model runs confined the rain to N of us! Not good.

Nor Cal rains/flooding episode begins overnight as a series of semi-tropical storms strike the coast.

Wish I could be there for surf and on the turf there, but I have my blog audience to think about. I don’t want to let both of them down by being gone for the 10 days of this great storm series, exploring the rain intensities in the coastal ranges of Cal.  Oh, well.

Still think total rains in the best coastal mountain spots over the next ten days will be 30 inches or more, actually not terribly unusual in the King Range and similarly exposed sites.