Rain and storm for Cpt

[Mortymoose]

Looks like quite a bit of rain for the Cape this week....

 

[The_Mowgs]

Raining nicely again now.

 

[Gordon_R]

The outlook for this week is very mixed, with a moderate intensity cold-front predicted to hit CT on Tues 4th.

Several (but not all) models predict this system to evolve into a cutoff LOW by Thurs 6th, potentially bringing very heavy rain (50-100mm+) to parts of the Garden Route and Easter Cape.

Very cold conditions will prevail for most of this period, with widespread snow likely over parts of the Cape interior towards the end of the week.

 

[Geoff.D]

Just short of 17 mm measured at Dwarsberg and just over 6 mm at Constantiaberg last night. Good rains measured in Vredekloof also.

 

[Gordon_R]

The SAWS rainfall figures for August 2018 show slightly below average totals for the SW-Cape: http://www.weathersa.co.za//media/data/climate/nr_month_rai.pdf

Following a rather dry spell at the beginning of the month, a wetter period during the last ten days made up some of the difference: http://www.weathersa.co.za//media/data/climate/nr_10day_rai.pdf

Dam levels for the Cape Metropole have already shown a good increase to 65% (already noted during last week).

Edit: The increase during the week from Mon 27th to Mon 3rd was 4.0% to 65.9%: http://resource.capetown.gov.za/documentcentre/Documents/City research reports and review/damlevels.pdf

Edit: https://www.news24.com/SouthAfrica/...ger-zone-for-first-time-in-two-years-20180903

Cape Town's supply dams have just squeezed out of the City's defined "danger zone" as the recent rains have raised the combined water level to 65.9% of storage capacity.

The end of the defined "danger zone" is when the dam level rises above 65% at the end of the rainy season.

 

[3Gee]

Dam levels have shown another positive rise this week, pushing up from last week’s 65.3% to 65.9%. Levels may rise further as heavy rains are forecast to start from Tuesday onwards.

Water storage has continued to show healthy increases thus far into September since dam levels hit the 60% milestone in August. This is the first time in 18 months that dams have reached this high in water storage capacity.


http://www.capetownetc.com/cape-town/weather/dam-levels-rise-to-nearly-66/

 

[Geoff.D]

Drier than normal Spring Season for Western Cape and Gauteng

SAWS released a map today showing the above Provinces can expect below normal rains while parts of Northern, Eastern Cape and KZN can expect above normal rains.

 

[cenredash]

Drier than normal Spring Season for Western Cape and Gauteng

SAWS released a map today showing the above Provinces can expect below normal rains while parts of Northern, Eastern Cape and KZN can expect above normal rains.

Do we have stats for SAWS maps per month and their "hit" rate of correctly predicting the amount of rains .. ?

 

[Scooby_Doo]

What would our dam levels have been now if we were using water similar to last season?

 

[Geoff.D]

Do we have stats for SAWS maps per month and their "hit" rate of correctly predicting the amount of rains .. ?

Weather forecasting is not a contest. It is a service where those that try to forecast are continually improving their prediction models. So it is irrelevant of how often their predictions are correct or not. It is about us all being given an idea of what to expect. It is NOT about spot on accuracy.

 

[Geoff.D]

What would our dam levels have been now if we were using water similar to last season?

Yes I guess the Capetonians should be asking themselves that question --- those that allowed the usage patterns to slip that is.

 

[noxibox]

I expect more slippage once the temperatures start to rise. The flat charges for water and electricity mean that people's rates accounts have escalated dramatically, so an extra few kilolitres at R30 each is not going to make a big difference. They've also now created a situation where your effective per kilolitre cost goes down by using more, up to a point.

What would our dam levels have been now if we were using water similar to last season?

Overall usage was probably about 100 million litres more per day, but about 40 million litres a day now comes from alternative sources. So it's likely the dam levels would be more even with last year's usage, but still quite low. Which points to the importance of getting the augmentation projects fully operational as soon as possible, because restrictions are not sustainable. Those projects should already have been supplying 150 million litres a day.

 

[AchmatK]

so an extra few kilolitres at R30 each is not going to make a big difference.

Lol. Try R142 per kilolitre for any usage above 10kl at level 6 tariffs. I really don't see usage going drastically up unless they drop to a lower tariff bracket.

 

[Gordon_R]

15mm in gauge in Kenilworth up to 7.30pm (rain abating slightly now).

About 20mm on SAEON Constantiaberg and Dwarsberg (so far).

 

[noxibox]

Lol. Try R142 per kilolitre for any usage above 10kl at level 6 tariffs. I really don't see usage going drastically up unless they drop to a lower tariff bracket.

And why does increasing usage require exceeding 10.5kl? It is already the case that those using low amounts can reduce their cost per kilolitre by using more water. If it were me and I was currently using 3kl I'd happily double or even triple that usage, because I've been given an incentive to do so. Up to 6kl the effective price actually goes down the more you use. From there up to 10kl it stays relatively flat, but as a percentage of what you're paying already the additional water isn't that much.

 

[Geoff.D]

And why does increasing usage require exceeding 10.5kl? It is already the case that those using low amounts can reduce their cost per kilolitre by using more water. If it were me and I was currently using 3kl I'd happily double or even triple that usage, because I've been given an incentive to do so. Up to 6kl the effective price actually goes down the more you use. From there up to 10kl it stays relatively flat, but as a percentage of what you're paying already the additional water isn't that much.

That is what happens when you fiddle with pricing models the way the authorities have done. And, having now introduced a connection fee into the equation, the way we all interpret an plot the per unit cost has to change. It is not strictly correct to do the calcs the way your are doing.
A t the end of the crises, will the connection fee be removed again? I don't think so. That will remain. Only then can one get back to a truly proportional to use cost.

But we digress. This debate should continue in the other thread rather.

 

[Geoff.D]

The current pattern is the first truly cape weather of old, a very slowly moving front that is going to linger for a few days.

 

[Gordon_R]

There were good falls of rain near the mountains: 24.5mm overnight in our gauge in Kenilworth. SAEON Dwarsberg reported 48mm up to midnight, and about half that early this morning (total close to 75mm overnight). SAEON Constantiaberg somewhat less, and SAEON Cederberg (further inland) got significantly less.

It is still raining lightly over CT, and will do so intermittently for a day or two. Dam levels are starting to creep up again, though runoff will initially be slow due to limited soil moisture.

The Berg River Dam reached 97% this morning, and could easily be full by the end of this week: http://www.dwa.gov.za/hydrology/Unverified/DetailStageFlow.aspx?Station=G1R004FW&Type=Flow

Heavy rain is likely tomorrow (Thurs 6th) from the development of a cutoff low, though the peak intensity has shifted more towards the coastal areas of the Eastern Cape (earlier predictions showed further inland).

Widespread snow is likely at high elevations over the next few days, extending to parts of the Drakensberg by Fri 8th.

Edit: A few impressive SAWS rainfall numbers (stations near the mountains) during the 24 hours to 8am on Wed 6th: http://www.weathersa.co.za/media/data/climate/nr_daily_rai.pdf
Highest include Kirstenbosch 50mm, Jonkershoek 27mm, Grabouw 23mm, Wellington 23mm, etc.

 

[Icemanbrfc]

There were good falls of rain near the mountains: 24.5mm overnight in our gauge in Kenilworth. SAEON Dwarsberg reported 48mm up to midnight, and about half that early this morning (total close to 75mm overnight). SAEON Constantiaberg somewhat less, and SAEON Cederberg (further inland) got significantly less.

It is still raining lightly over CT, and will do so intermittently for a day or two. Dam levels are starting to creep up again, though runoff will initially be slow due to limited soil moisture.

The Berg River Dam reached 97% this morning, and could easily be full by the end of this week: http://www.dwa.gov.za/hydrology/Unverified/DetailStageFlow.aspx?Station=G1R004FW&Type=Flow

Heavy rain is likely tomorrow (Thurs 6th) from the development of a cutoff low, though the peak intensity has shifted more towards the coastal areas of the Eastern Cape (earlier predictions showed further inland).

Widespread snow is likely at high elevations over the next few days, extending to parts of the Drakensberg by Fri 8th.

Thanks for the update Gordon...

 

[Alan]

sitting here catching some rays while it buckets down with hail.....