“Dancing Rainshafts”; the movie

While we here in Catalinaland only received a “trace” of rain again from a thunderstorm that sudddenly formed just before 3 PM to our SE-S, there were some tremendous rains in the area yesterday afternoon and evening.  Some examples:

Pima County ALERT precip, max observation:  2.09 inches, Brawley Wash at Highway 86

U of AZ rain map, maximum, as of 7 AM (more reports will filter in during the day): 0.90 inches, N Tucson, see this dump in the movies.

Cocorahs, Pima County max, as of 7 AM (more reports will filter in during the day): 0.64 inches, 2.5 WNW Tucson

USGS, Statewide max 1.2 inches, JD Cabin near Williams.

NWS regional roundup for yesterday; available after 9 AM…

In the meantime, here’s a nice map of radar-derived rainfall, ending at 5 AM today, from the folks at WSI Intellicast:

The most exciting, predictive aspect of the day, that is, how unstable the air over us was, how ready the atmosphere was to allow plumes of cloudy air to shoot upward,  is shown in this U of AZ Weather Department action-packed movie which I shall name;  “Dancing Rainshafts”, because they do kind of twist around each other in this movie in the late afternoon.  One of those is responsible for that 0.90 inches rain in north Tucson around Sky Line Ave.   This is one of the most interesting videos I’ve seen.  Nothing much happens until late morning, and then, “Pow!”

If you noticed at the beginning of the day, when Cumulus started to form on the Catalinas, you saw these incredible, tall, thin clouds, something akin to smoke stacks, plumes from geyers, rising off them.   It was a sure sign the atmosphere would do something special yesterday.  You’ll have to see those tall thin clouds in the U of AZ movie; while I did “document” them in a sense, there was no memory flash card in the camera again, the tiny font alerting me to this fact too small for normal vision.

Still, thanks to the U of AZ Cats, who won their football game on Saturday, you can see it here,  to repeat.

OK. now on to the local cloudscape yesterday….

Here’s what I thought was a surprise, this sequence where a modest cloud glaciated.  Suddenly, after a period of remission in Cumulus activity, this moderately large cloud welled up SE of the house (first photo).

2:49 PM. So-so Cumulus congestus arises to the SE. Am hopeful something will happen, but it doesn’t look so well organized; base a little broken up.  I decided to go into the house and think about something else.

2:58 PM. Amazing! That modest guy has glaciated at the top! I am somewhat shocked. As you know, this means a bunch of snow/rain/graupel-soft hail has formed up there. Fantastic! The next two shots illustrate that this happens, most of the time here anyway, just BEFORE rain falls out the bottom.













Also at 2:58 PM looking at cloud base of the glaciating top (far right) to see if there was yet any sign of a filament of rain, though a few very large and sparse drops might have ejected from it by now (under the far right).
2:58 PM. As part of a photographic burst, here’s a better view of the bottom of that cloud with the glaciating top. No shafts. Here’s an example where, in a burst of converational meteorology you can amaze your friends by telling them, “There’ll be a heckuva shaft of rain coming out of this cloud in about five to ten minutes.”  You’ll be seen as some kind of weather guru. Perhaps you’ll be invited to the next neighborhood party as a result of your new status.
3:03 PM. Shaft emerges. There are striations in the cloud above the bottom if you can make them out. That’s all that precip up there finally being unloaded.
3:08 PM. The shaft at right, such as it is, is fully developed from that modest Cumulonimbus cloud. Other shafts have developed more rapidly.
3:16 PM. The original shaft is just about gone, but look at this coming out! This intensification tells you that a turret had shot upward to far higher levels than the one that started this whole thing off.  The shower has drifted  to the east, too.



























The weather ahead….

More of the same every day for the foreseeable future, which is about a week now. Check here. They have a lightning icon in every 12 h period! Fantastic!

But, with all those percentage chances of rain over that whole given in 12 h increments, what IS the chance of measurable rain here in Catalina at some time during that FIVE days?  IF I have calculated it correctly from an example given to me by Mark Albright, Research Meteorologist at the U of WA, it is…drum roll… 96%!