Something in the sky to look at, Cirrus!  And more!

Some Cirrus, Cirrocumulus, Altocumulus clouds from the tropics have floated over in time for a nice sunrise presentation.  Some of these clouds should be around all day.  From this morning:

Also, let me reprise our June rain frequency chart for Catalina.  “Upon further review”, I have altered some text box wording to reflect a more accurate picture.  In reviewing some Tucson rain days in early June, where I had asserted that they were associated with “cold troughs”, I learned from an review of old weather maps that, while those rains were associated with troughs in the upper levels, they weren’t nearly so cold and strong as I had believed.  And those troughs had tapped the tropics for the rains that fell, and I had not indicated that.  It bugged me that I had got that wrong and so here is the corrected version of that chart.

Also with “only” 35 years of data here in Catalina, the “transition” zone below could be a statistical fluke.  In checking the Tucson 100 year plus record, there has been rain on days in this “transition” period, so its not impossible.  No rain is indicated during this period in the models right now, either, but there is a threat of rain developing.  More on that below.

Looking troughy enough for a rain threat in a few days

From our Canadian friends, this four panel prog chart for the afternoon of June 16th.  Note “trough” (upper left panel) extruding southward from Montana all the way down to Cabo San Lucas.  The models have had this figured out for many days, but the magnitude of the trough, the strength of the winds around it, and how much cool air it would contain way down here in the SW US,  has been subject to some wild variations.  Now it appears that the trough will be pretty weak, not much cold air in it, BUT, with the amplitude it has (how far south it extends) makes it possible to fetch us some tropical air.  None of the models have much in the way of moist air reaching us YET.  Take a look at the lower left panel for moisture at 700 millibars, or around 7,000 feet above the ground here in Catalina.  That blue shading shows that the moist plume drawn northward will mainly be in eastern NM and west TX, which will be good for them, but not us.  Still these kinds of things are dicey and one of those rare days with rain in mid-June is not out of the question.   What is life without hope?

The End.