Sunset, anyway, even if only a few drops of rain fell last evening. Nice lightning to the south, too, 9-10 PM.
However, yesterday afternoon, we had some examples of really “bad” cloud bases. They were trying to make me think we might have a repeat of the day before’s cloudburst by darkening themselves up. While Mr. Cloud Person (me) was almost fooled, he wasn’t really at all.
Lets replay yesterday afternoon…. Here in the summer, of course, we look to the east (NE through SE) and over the Cat mountains for guidance in storms, for prognostic purposes, not to the west during the summer rain season. This is especially true in the late afternoon and evening when our chance of rain is peaking. We often see the sky loading up with dark cloud bases somewhere over there. Its pretty darn neat, and can happen in only a few minutes. These are often storm complexes, clusters of Cumulonimbus clouds, that done sprung up over the White mountains or other terrain earlier in the day, and are being re-inforced/ are propagating westward by the outflow winds that accompanied them. Those winds near the surface shove the air above it upward creating new clouds. Sometimes we’ll see an especially low cloud on the more moist days, called an “arcus” cloud, a ribbon of cloud that rides above and near the front of the outflow wind.
OK, those clouds that feinted rain late yesterday for a time. First, we’ll start when you were getting really excited and running around telling the neighbors that, “Hay!” (a lot of them have horses), “It looks like it might rain again this evening! Look at those clouds over there over the Cat mountains!” You’re loud, but you’re not exactly screaming, since you are holding back a little; you know about those “fakery” cloud situations where the bases fall apart, don’t congeal into a large, solid mass. You’re holding back just that bit of excitement. I am proud of you. Here’s what got you going:
This is looking pretty damn good, but its not there yet. Why? First, while there is an OK, keep an eye on base over the Cats, its got some thin spots, some brighter areas near the darkest areas. Note the little bright spot in the middle of the closest larger base. Fakery right there. You know this cloud is not going anywhere in spite of its overall darkness underneath. Also, you really don’t see any sharp edged indicating newer) rainshafts. Blobs of smooth sky, even with rain, are associated with dying cloud masses, and if that’s what coming at you, you may not get ANY rain because it may have all fallen out before it gets to you with our slow summer winds up “top.”
The next photo is 20 minutes later. Its look that bit better, but in all that time, no rainshaft has dropped out of this stuff. Nor has the cloud complex gotten much closer. No rainshaft equals no cloud tops colder than -10 C (14 F) above that base (about 20,000 feet yesterday), and that means while dark, the clouds are not terribly deep.
Why aren’t they yet? Not enough push underneath, warmth, etc. This lack of progression is of some concern. Of course, this can change in a hurry, but increasing concern develops that this could go bad. A lot of time with not much happening is quite bad, really. The next photo is about 6:19 PM. While the cloud base is looking formidable, still pretty solid, a rainshaft has STILL not developed indicating cloud tops are going nowhere, man! Dammitall, to cuss that bit! Starting to get that “rejected” feeling: “Well, you thought I (that vaporous mass) was going to do this, but I’m not.” You think about the screaming you did at your neighbors… Could be embarrassing. In the last photo, ten more minutes later, its over, finished. The cloud base has shrunk in size, is starting to look raggedy, still no rainshaft, etc. etc. You begin thinking of this cloud fakery in terms of spheres of equestrian processed hay. But, you did hold back that bit, you didn’t go all out because you had seen this happen before. I am proud of you.