Exactly wet

Look, it has been raining a fair amount in Cape Town over the last few days. This is to be expected. Cape Town’s 3½ annual months of winter have begun and September and the spring that it allegedly brings with it seems a long way away right now.  
Kirstenbosch had over 50mm of rain yesterday and they’ve added to that with some frighteningly heavy stuff overnight.

So what will the rest of the week bring?
Step forward the South African Weather Service website:

Not great, hey?
But then check out that rain for tomorrow. A 30% chance of 6.8mm. 6.8. Six. Point. Eight.
Not six point five. Nor seven point zero.
Nope: to go with Steers’ infamous Wacky Wednesday – the day each week upon which one is able to purchase twice as many of last week’s least popular burger than one could have done last week for the same money as one would have spent on said burger the previous week if one actually had any inclination to buy it – SAWS have made tomorrow Super Accurate Tuesday.

I’ve done some rudimentary calculations and I reckon that to increase the height of the rainwater column collected in a standard pluviometer (which would have an 8″ or 20.32cm funnel arrangement), you would need around 67 large (3.6–5.1 mm) raindrops.
Now that might seem a lot, but when you think about how many raindrops fall in the average heavy shower (we’re talking literally hundreds of millions), it’s really not.

This suggests to me that either SAWS have invested heavily in highly accurate and expensive rain-measuring equipment (when really the money would have been better spent on a decent website) or, more likely, that they are just messing us around and we can actually expect a whole 7mm of rain tomorrow.

Meanwhile, in other weather news on the SAWS site, be on the lookout for NW winds gusting to 51.358kmh which may result in waves with heights in excess of 7.046m between Cape Columbine and a specific rock 1.967481km west of Plettenberg Bay.

2 thoughts on “Exactly wet

  1. I read your blog pretty much everyday (more than once) and i just felt the need to tell you that this article had me in stitches. I’m not quite sure why a topic as benign as the weather in Cape Town had such a profound effect on me, but i’m glad it did! The section on “rudimentary calculations” made my day.
    Love your work.
    .-= Siraj Savage´s last blog ..Cafe Caprice 2-for-1 burger special has started =-.

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