Rain and storm for Cpt pt 2

[absynth]

Vredehoek

 

[Gordon_R]

Bucketing down now

Some hail in the CBD a few minutes ago.

Both are typical of post-frontal conditions. Cold upper air is being pushed over humid and relatively warm surface air, triggering strong instability and isolated showers. The intensity of the rainfall is high (large droplets), but the duration of the showers are fairly short.

 

[FiestaST]

Thunder and lightning, get that washing out @airborne

 

[WAslayer]

Here we go with the hail in Kuils River...Looks like couscous falling from the sky..

Also some lightning and thunder..

 

[blaaislaai]

A huge piss and hail this side, within 5 minutes there's puddles I've never seen before.

 

[dualmeister]

Was that it?
I want a refund.

 

[RedViking]

Where is it snowing?

 

[dualmeister]

Where is it snowing?

3.7K views · 63 reactions | It was snowing at reception for a few minutes before stopping. We are expecting a lot of rain during the night and tomorrow. Please take the Weather warnings that was issued seriously and remain safe. There will be more

It was snowing at reception for a few minutes before stopping. We are expecting a lot of rain during the night and tomorrow. Please take the Weather warnings that was issued seriously and remain...

www.facebook.com

SEVERE WEATHER AND INFORMATION CENTRE SA | Snowfall at SUTHERLAND vic | Facebook

Snowfall at SUTHERLAND vic. of SUTHERLAND TELESCOPE............... 2026/05/10 - 10h08- SAST...... (acknowledgement SOLARIS)

www.facebook.com

 

[RedViking]

3.7K views · 63 reactions | It was snowing at reception for a few minutes before stopping. We are expecting a lot of rain during the night and tomorrow. Please take the Weather warnings that was issued seriously and remain safe. There will be more

It was snowing at reception for a few minutes before stopping. We are expecting a lot of rain during the night and tomorrow. Please take the Weather warnings that was issued seriously and remain...

www.facebook.com

SEVERE WEATHER AND INFORMATION CENTRE SA | Snowfall at SUTHERLAND vic | Facebook

Snowfall at SUTHERLAND vic. of SUTHERLAND TELESCOPE............... 2026/05/10 - 10h08- SAST...... (acknowledgement SOLARIS)

www.facebook.com

Where ?

 

[Gordon_R]

Where is it snowing?

Widespread parts of the Western Cape interior mountains. The most popular location is Matroosberg, outside Ceres. See my post from this morning:

Post in thread 'Rain and storm for Cpt pt 2'

May 10, 2026

It arrived as predicted, heavy rain strong winds that woke me up.. However, an hour later I was awakened by the sound of silence.. No more wind and no more rain.. Also not had the continuous down pour at all, just intermittent showers..

That was the first front. There is currently a gap in the weather (some sunshine too), but there will be further wind and showera this afternoon. The freezing level will drop further, producing snow at relatively low elevations (about 1200m). Tomorrow (Mon 11th) will be lots of rain, but less snow. See:

• Gordon_R

 

[ajax]

Stellenbosch University sent out a notice just now that classes are continuing as per normal tomorrow.
Guess schools won't be closing either.

 

[Gordon_R]

Stellenbosch University sent out a notice just now that classes are continuing as per normal tomorrow.
Guess schools won't be closing either.

As I have stated above, most of the heavy rain will fall in the mountains. This is also an extended event, so Monday morning will only be a 'normal' winter day. Things may change by late Monday evening, and could be worse by Tuesday.

Typical rainfall distribution for Mon 11th:


Note that winter rainfall closely follows areas of high terrain, as illustrated in this diagram:

 

[Rocco1]

The front on Sun 10th is a normal winter event. Mon 11th is a different animal altogether. A rapidly deepening low (called explosive cyclogenesis) will develop just south of CT, along with an inflow of moist sub-tropical air (an atmosperic river) will bring prolonged orographic rain.

Thanks for diving into the models and explaining the 2nd front/ jet stream of water. Yeah this front today has been underwhelming/just a usual winter front. The 2nd one is a far more interesting event.

The surprising thing is that tomorrow is warmer (no snow with NW the whole time and not SW etc) and how much continuous rain is forecast over the cape mountains over 24-48hrs , which differs quite a bit from a usual front, giving the significant rain forecasts. How are your forecasts for the low developing?
I am seeing a pressure of near 950 mbar low by Monday evening.

Heavy rain forecast for the Monday morning traffic, for anyone driving tomorrow - take note.

 

[RogueTr00per]

Here we go with the hail in Kuils River...Looks like couscous falling from the sky..

Also some lightning and thunder..

Same here for about 30 seconds, gonna have to check if there was any car bodywork damage :/

 

[konfab]

Attention everyone, according to the World Health organisation, you are advised to wear a hat tomorrow in Cape Town to protect yourself from UV radiation.

 

[Gordon_R]

Thanks for diving into the models and explaining the 2nd front/ jet stream of water. Yeah this front today has been underwhelming/just a usual winter front. The 2nd one is a far more interesting event.

The surprising thing is that tomorrow is warmer (no snow with NW the whole time and not SW etc) and how much continuous rain is forecast over the cape mountains over 24-48hrs , which differs quite a bit from a usual front, giving the significant rain forecasts. How are your forecasts for the low developing?
I am seeing a pressure of near 950 mbar low by Monday evening.

Heavy rain forecast for the Monday morning traffic, for anyone driving tomorrow - take note.

Not sure how rapid the deepening will be, but 1hPa per hour is explosive cyclogenesis. This is the chart for 2pm tomorrow (Mon 11th).


Edit: You can see a 6 hourly animation here: https://www.cpc.ncep.noaa.gov/products/international/cpci/data/00/gfs_mslp_precip_safrica.html

 

[Rocco1]

Not sure how rapid the deepening will be, but 1hPa per hour is explosive cyclogenesis. This is the chart for 2pm tomorrow (Mon 11th).

Edit: You can see a 6 hourly animation here: https://www.cpc.ncep.noaa.gov/products/international/cpci/data/00/gfs_mslp_precip_safrica.html

Looks like the tail is weakening, the water stream drops earlier in the models now around late afternoon Tuesday. also your model above shows a gap in the water stream post low, so prob less moiture in the stream now. from 300mm to 250mm 48hr max now in
mountains.


UPDATE: New models show low of only 965 and the accum rainfall is now max of 200mm over 48hrs, so already reduced quite significantly.

 

[Nerfherder]

Stellenbosch University sent out a notice just now that classes are continuing as per normal tomorrow.
Guess schools won't be closing either.

If there is one thing that kills a storm its closing schools.

Every damn time they do it the storm just blows over.
Anyway... the fact that they considered it and then just decided its fine... will end up being some kind of disaster.

 

[Rocco1]

Some schools in the Cape Winelands have closed.
Mainly in the Tulbach, Worcester, Ceres, Rawsonvillle area

 

[blaaislaai]

Yesterday I had no wind/gusts. This morning, as of right now it's quite hectic.