Rain and storm for Cpt

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BTTB said:
While we had some strong winds and flooding across the Cape, I only measured 36mm across the two days.
Good rain and welcome thank you, but the way people report of social media you would think we were hit by a huge storm.
What I see is blocked drains, broken branches and the odd tree that falls over is fairly normal for the Cape Winter weather.
The South Easter can blow a gale, yet the trees seem used to it, but let it blow a strong North Westerly and we have damage to property and trees.
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Wind direction can make a big difference to the effect on structures. The area where I live is subject to severe turbulence downwind from Table Mountain, which is what does the most damage. Look at the tank lid I just posted, turbulence is the only way to explain that!
chrisc said:
8 trees blown down in Plumstead and Diep River
Some streets still without electricity
Council had the trees cut up yesterday before 6.00, when it gets dark

Last storm a few years back, the steel roof of a garage flew through the air and hit my solar water heater and roof. About R32k damage

This time nothing to speak of
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It was a 'normal' winter storm, which caught some unprepared. Very little other damage reported:
www.news24.com

Power outages, uprooted trees and floods: Mopping up after Cape Town deluge | News24

The City of Cape Town and its residents are mopping up after a two-day deluge and very cold weather.
www.news24.com www.news24.com
genetic said:
@Gordon_R Isn't there a 7 or 12 year or so cyclic rainfall pattern between rainy seasons and relatively dry seasons?
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Sorry, I'm not into numerology. Weather is mostly random and unpredictable...
Geoff.D said:
26kg weight for 1.2m diameter disc would equate to about 200 N/msq.

Looking up that on a chart for wind load means a wind speed of 20m/s would be enough to lift and flip the lid off, which is 72 km/h thereabouts.

Nothing if what we heard is correct that the wind was gusting up to 100 - 150 km/h in CT.
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Correct (I did a ballpark estimate). The point is that measured wind speeds are horizontal. The question is how do you get a vertical wind speed of 20m/sec? See my comment on turbulence and downwind effects from the mountain.
 
Ja well in the satellite antenna business and working at altitude ( Hillbrow tower for years), I can attest to wind updrafts at the tower of up to 200 km/hr! So, while one could spend plenty of time speculating, it just needs a few factors to be perfectly aligned for the most amazing things to happen.
In the old days when the Hartebeeshoek Satellite first opened, we used to routinely "park" the antennas when the wind reached certainly velocities to limit damage to the tracking motors (36m diameter antennas).
The first time I was sent stats on the windloadings in a typical summer storm at HBH I would not believe them either.

BTW did you see my previous comment on that lid, asking if the workmen had maybe shifted the lid to access water? If the lid was partially off the tank for any reason, it could easily have been flipped up enough for the wind to take it and blow it away as if it was a feather.
 
Edited my post above, it was actually 51mm that fell here at my spot in Cape Town, I forgot that I threw out Friday's 15mm from my rain gauge.
15+36 = 51mm.

Good rains, thank you man upstairs, all welcome.
 
genetic said:
There's this eNCA report of mass flooding and destruction, and the only thing they can show is the same tree that's been posted over social media over and over. They even report from that tree!


Cape Town is definitely not used to storms we used to have. This is just a standard winter front - and we need more fronts!
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Also not natural to pave around trees, creates abnormal root development.

Winter is not over yet. The worst winters are those that drag on through September, October and even into November.
I recall circa 1996/7, 26 days of rain in September alone which carried on with intermittent cold fronts right up to December. On the 1st of December we joked we may have a white Christmas and in that moment the South Easter said hello and winter was over.
Its the Cape, you can have 4 seasons in one day, still great though.
 
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BTTB said:
Also not natural to pave around trees, creates abnormal root development.

Winter is not over yet. The worst winters are those that drag on through September, October and even into November.
I recall circa 1996/7, 26 days of rain in September alone which carried on with intermittent cold fronts right up to December. On the 1st of December we joked we may have a white Christmas and in that moment the South Easter said hello and winter was over.
Its the Cape, you can have 4 seasons in one day, still great though.
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Not going to lie Cape Town in that condition looks a a lot like parts of parts of Durban on a normal day.
 
BTTB said:
Also not natural to pave around trees, creates abnormal root development.

Winter is not over yet. The worst winters are those that drag on through September, October and even into November.
I recall circa 1996/7, 26 days of rain in September alone which carried on with intermittent cold fronts right up to December. On the 1st of December we joked we may have a white Christmas and in that moment the South Easter said hello and winter was over.
Its the Cape, you can have 4 seasons in one day, still great though.
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that's what i was thinking.
 
BTTB said:
Also not natural to pave around trees, creates abnormal root development.

Winter is not over yet. The worst winters are those that drag on through September, October and even into November.
I recall circa 1996/7, 26 days of rain in September alone which carried on with intermittent cold fronts right up to December. On the 1st of December we joked we may have a white Christmas and in that moment the South Easter said hello and winter was over.
Its the Cape, you can have 4 seasons in one day, still great though.
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I remember in 2006 - 2008 the winters produced similar results... Soaking rains! I guess what I'm getting at is that our current drought is cyclic and not a result of long-term climate change. I long for those long rainy showers that last more than a few hours or a day or so.
 
Geoff.D said:
BTW did you see my previous comment on that lid, asking if the workmen had maybe shifted the lid to access water? If the lid was partially off the tank for any reason, it could easily have been flipped up enough for the wind to take it and blow it away as if it was a feather.
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In his post he said the pic was 2017.. so unless they moved the lid back then, it was likely untouched..
 
WAslayer said:
In his post he said the pic was 2017.. so unless they moved the lid back then, it was likely untouched..
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The fundamental problem was that the lid was only held in place by gravity. I can't say more, but in hindsight it should have been secured. Other tank lids were unaffected, and this really was a freak event. The position of the tower block had some effect on turbulence. If it was a more serious incident, a proper forensic study would be justified.

Edit: More storm updates:
1. I heard from a friend that some roofs were damaged in Betty's Bay. They also suffer from mountain turbulence when the wind is from the NW.
2. Just spoke to someone who lives in Harfield Village (Claremont). Their roof was damaged at 2am on Saturday morning, and they had to get someone to deal with rain-water ingress.
3. Walked through PnPay Rosmead (no photos). Looks like false-ceiling boards got water damage, roof itself is intact.
4. Heard from another neighbour that an old oak tree fell in Newlands, damaging some cars.
 
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saor said:
Joh, from rain to this lekker sunny day.
Go for a walk/run/ride!
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Will be a good time to pick some shrooms. I found some porcini and pinerings in Newlands, but only half a packet. Now that things have warmed up a bit there should be more.
 
Defiler said:
Will be a good time to pick some shrooms. I found some porcini and pinerings in Newlands, but only half a packet. Now that things have warmed up a bit there should be more.
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Pick wisely? Are they easy to differentiate the good stuff from the KillYouDead stuff?
 
Still early days, but numerous model forecasts are showing a significant weather event for the SW-Cape (only), starting on Thurs 9th. Expect cold, wet and windy conditions, with snow possible.

This chart shows the predicted rainfall for the 7 days up to Fri 10th:

totp_week1_s[20200704-11].gif
 
Gordon_R said:
Still early days, but numerous model forecasts are showing a significant weather event for the SW-Cape (only), starting on Thurs 9th. Expect cold, wet and windy conditions, with snow possible.

This chart shows the predicted rainfall for the 7 days up to Fri 10th:

View attachment 869795
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Good - get your rains, but keep your cold temperatures there - I don't want it anywhere near GP :laugh:
 
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