A July day in the Western Ghats; replication ahead?

If you’ve ever been to Indian State of Kerala and the western Ghats, you know that yesterday, with the warmth, the thick, pounding rain with cloud bases at tree-top levels,  visibility a mile or two, and with little or no lightning, was a true sample of India in the summer, maybe a July day in the western Ghats.

Congratulations for having experienced India and a TRUE monsoon day without having to go anywhere1.

The totals?  4.48 inches at Our Garden on Columbus Avenue, wettest day in their 37 year record.  4.59 inches on Samaniego Peak.  The largest amount I could find was at Stewart Dam by the Salt River, 4.79 inches, all in 24 h, though most of these totals fell in less than 3 h.  Below a shot of the CDO wash at or near its peak at Wilds Road, the latter a “street” if I may, one that might now surpass in difficulty the Charoulou Gap for the 4-wheeler and ATV crowd judging from the way it looked yesterday.

BTW, the shots below are from a video taken by yours truly in the pounding rain as the total here in Sutherland Heights surpassed the 3 inch mark, on its way to 4.18 inches.  I was the only one there, except for Jessie, who runs Our Garden, who also showed up in the pounding rain right after I did, saying, “I thought I’d find you here.”  Huh.

bigger yet
10:55 AM. Rainfall in Sutherland Heights was now surpassing 3 inches when this was shot.

 

CDO at Wilds

11:00 AM at the Canada del Oro Wash at Wilds Road.
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11:00 AM at the Canada del Oro Wash at Wilds Road, looking upstream from near there.

 

This was twice as big and fast moving as anything I had seen in the prior seven summers, though doesn’t compare to the August 2003 flood in which the CDO wash at this location got all the the way to Lago del Oro Parkway, a hundred yards wider than this.

With yesterdays soaking wet air over us, it didn’t take much to send turrets spaceward, and it MAY have been that those car-floating rains in the Phoenix area had something to do with what happened.

A gust front moving this way was evident in the satellite and radar imagery as new echoes raced to the SE from that whopper after midnight.  The gust front appeared to dissipate before getting here, but then not long after the heavy rains began, the wind came up from the north after calm conditions marked the first inch or two.  And the rains intensified.  Clearly, wherever that wind shift came from, it gave the clouds above us another boost, to push an already memorable rain into historic proportions by helping generated the second two inches.  (I hope you logged the time of this important windshift in your weather diary yesterday.)

Here are some shots from that historic day, one that we will likely not live to see again:

5:54 AM. Stratocumulus clouds with a higher layer of clouds reddened in the sunrise that provided a rosy glow where there were break and thin spots in the overcast. The clouds are only maybe 2000 feet above the ground at 50 F (15 C) or so, incredibly warm-based.
5:54 AM. Stratocumulus clouds with a higher layer of clouds reddened in the sunrise that provided a rosy glow where there were break and thin spots in the overcast. The clouds are only maybe 2000 feet above the ground at 59 F (15 C) or so, incredibly warm-based.

 

6:32 AM.  This extraordinary shot.  "Huh" you say?  Its beginning to drizzle from these shallow Stratotumulus clouds, a RARE event in Arizona, though not unexpected when cloud bases are so warm, and therefore, contain so much water, water that is converted into larger than normal cloud droplets when then reach the Hocking threshold for collisions with coaslescence to occur.  Rare to see Hocking's threshold exceeded in our clouds!
6:32 AM. This extraordinary shot. “Huh,” you say? Its beginning to drizzle from these shallow Stratocumulus clouds over there by the Catalinas, a RARE event in Arizona.  When cloud bases are so warm, and therefore, contain so much water in them, water that is converted into larger than normal cloud droplets they can then reach the “Hocking threshold” (about 38 microns in diameter)  for collisions with coalescence to occur, and that in turn allows drizzle and rain drops to form without ice!  Rare to see Hocking’s threshold exceeded in our clouds!  The day could have ended right here and have been a happy, memorable one. True  drizzle even fell here in Sutherland Heights from these clouds just after 7 AM, too, and before the big rains hit.  Did you know that this process of rain formation, called collision-coalescence,  has produced the biggest rain drops ever measured, about a centimeter in diameter.  And that was in clouds that did not reach the freezing level! And, nearly all of that western Ghat rain is due to that mechanism, in hurricanes, too.  So, don’t need no ice for blinding rains when the air is so tropical as the air here was yesterday.  Ice in those tropical situations is often more like fluff icing on a rainy cake, to make a strange metaphor, than a real contributor to what falls on the ground.

 

7:17 AM.  Before long, heavier rains, this area fronted by a weak arcus cloud, were breaking out. With no thunder, and weak looking, stratiformy looking clouds, you do intuit that no ice may be involved, even if the rains are heavy.  Look how thick and fog-like it looks in that rain area.
7:17 AM. Before long, heavier rains, this area fronted by a weak arcus cloud, were breaking out. With no thunder, and weak looking, “stratiformy” looking clouds, you do intuit that no ice may be involved, even if the rains are heavy. Look how thick and fog-like it looks in that rain area.  About a half an inch fell out of this according to one “personal weather station” out there.

 

8:05 AM.  Outside of some brief true drizzle drops, it hasn't done anything here yet, but, "hey" this looks interesting as it approaches, though no rain was falling out of it.  Recall, too, that lower portions of cloud like this indicate an area of updraft feeding a Cumulus base.  Must be too shallow for rain to form....  Or was it?  This is going to be a VERY tedious blog today.
8:05 AM. Outside of some brief true drizzle drops, it hasn’t done anything here yet, but, “hey” this looks interesting as it approaches, though no rain was falling out of it. Recall, too, that lower portions of cloud like this indicate an area of updraft feeding a Cumulus base. Must be too shallow for rain to form…. Or was it?  This is going to be a VERY tedious blog today.
8:10 AM.  Look!  A little rain is falling out and its heading this way and that updraft area is holding up.  Maybe it will be enough to measure!
8:10 AM. Look! Just five minutes later, a little rain is falling out now and its heading this way and that updraft area is holding up. Maybe it will be enough to measure! (Note:  Here’s where the rain ball got rolling, to make another awkward metaphor; it dumped 0.22 inches in a few minutes as it unloaded on Sutherland Heights.  Note also that there is just stratiform (flat) and higher clouds behind this.  Didn’t look like much more was going to happen.  Perhaps it would be “too cloudy”  and cool for good rains, something we often hear around here, and is largely true.

OK, its pretty hard to take pictures of rain, but these two below were the best I could do, and I hope you appreciate it.  I have no idea why I took 85 pictures of heavy rain; they don’t look that great in retrospect, but it was exciting to be taking them…kind of lost control.

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9:28 AM. What Oro Valley looks like from Sutherland Heights when its raining two inches an hour. Photo looks west.
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Also taken at 9:28, but 21 photos earlier than the one above, of the runoff from a local resident’s roof when its raining two inches an hour. Wow, snapped 21 photos in a minute!  Hmmmmm… maybe some counseling is needed on self-control…

The rest of the day was truly history, and by afternoon, things were clearing out, and by late in the day left those usual, “memorable” scenes of our mountains decked in clouds.   The mountains seemed greener, washed up as it were, more than usual after good rains.

5:11 PM.  Residual Stratocumulus castellanus (because they have little turrets)  top "Sam" Ridge.
5:11 PM. Residual Stratocumulus castellanus (because they have little turrets) top “Sam” Ridge.
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6:08 PM. Another just a pretty scene of our well-washed mountains. Samaniego Peak got 4.59 inches yesterday, as mentioned before.

 

Today…..U of AZ mod run from 11 PM last night sez no rain around here today or tomorrow.  With the residual moisture we have, and clouds topping Samaniego Ridge this morning, it would be hard to imagine that early on in the day, later this morning that a few huge Cumulonimbus clouds won’t arise over the Cat Mountains before the drying takes hold.  So, we might see some great clouds right away, and then watch them wither as the dry air manifests itself.

In the longer term, yesterday’s 12 Z run was amazing since it had more heavy rains down the road,  a week or so out, with another “Norbert” like storm traveling up the Baja coastline.  Imagine!  And on last evening’s run at 5 PM AST, it has it in almost an identical trajectory as Norbert.  Check this out.  Never have seen that before, such a replication of something fairly strange in the first place.  I just saw this now, and am so excited am going to slip it here adding already to “blog excess” and “reader fatigue”:

Valid on September 18th at
Valid on September 16th at 5 PM AST, this duplicate of yesterday’s map!  UNBELIEVABLE!

 

 

 

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1In the southern peninsula region of India, east of the Ghats in during the time of the SW monsoon, there are giant thunderstorms with incredible LTG, but they’re more scattered around than the “24/7” monsoon rains in the Ghats, rains that can produce up to 300 inches in a month, though averages are closer to 100.