After what can only be described as a dull summer severe weather wise for majority of the Western Cape it seems as though something exciting may be on the door step, a cut-off low pressure system is forecast to develop from a steep upper air trough and position itself over the Western Cape, bringing very interesting conditions to the surrounding areas. A cut off low is often associated with severe weather, and in summer it usually brings thunderstorms due to the nature of the air it pulls in.

Temperatures are to remain hot over the next 4 days, as high as the upper 30s in places, but with that said there are forecasts for very heavy rain. The latest GFS model guidance is showing some very wet conditions over the Western Cape interior with rainfall exceeding 60mm in 24 hours in places.

These conditions will be brought by the presence of a black south easter, one of the weather events caused by a cut-off low, if positioned correctly with the high pressure ridge. While Cape Town itself may well see some thunderstorm activity from Monday night through to Thursday majority of rainfall will be in the interior. Here's to hoping something happens in Cape Town, because it has been entirely too long without any decent activity for a storm chaser in these parts.

It should also be noted that these cut-off lows can bring severe thunderstorms to the central parts of S.A and in the NE.

Photograph: Lightning Strikes Over Stellenbosch- Photo by Eric Palmer

This summer has seem some fairly unusual weather thus far. Usually temperatures in the Western Cape soar between the months of January and February and historically are the hottest months for Cape Town, though this year while January had some rather warm days it was more mild than one would expect for that month. February has started off well below the average for Cape Town with temperatures being in the low to mid 20s for majority of the time- this is far below the expected low 30s which one typically experiences at this time of the year.

It is interesting to note that while Cape Town has been well below average that just inland in places like Worcester, while temperatures haven't been quite as hot as expected for February, it has been quite a lot hotter than Cape Town with temperature differences of around 8 degrees on many days, compared to the usual difference of around 3-5 degrees.

There have been a few weak cold fronts to push through the Western Cape in the past few weeks, but were short events. The general weather pattern is much closer to Autumn than to Summer. In the summer months Cape Town generally has a primarily off-shore flow with the famous South-Easter making it's presence felt on majority of days, this seems to not be the case late this summer, with an on-shore wind pattern seeming to remain in effect.

The long range models at the moment continue showing a very very mild February with temperatures seeming to hover around the mid 20s. Could it be that was are already transcending into Autumn? It's very possible given the steadiness of this moderate weather and the long range model forecasts, though one cannot discount that it is just a period of cooler weather and that we may still see some true summer conditions coming.

As many of you know, the Garden Route area along the Southern Cape are suffering the effects of a strong drought. And while they would love the unset of an early winter, conditions as mentioned above are consisting of weak cold fronts which have very little impact with only a few mm of rainfall being produced.

Another interesting fact to note is the lack of strong troughs this summer, while the central parts of the country were receiving some good thunderstorms generated by troughs fairly recently these trough systems are far weaker than the usual January and February troughs- they are not dipping down south as they often do at this time of the year, this is another reason for the Southern Cape drought situation, they often benefit from the deep trough systems which pass from west to east across S.A and dip down into the southern regions.

The fact is the Cape usually sees 2-3 thunderstorms in the summer months from deep dipping trough systems, but this year we haven't had any true such events. Granted there was some thunderstorm activity on the 9th of February but this was due to a very weak trough interacting with a weak front and not the result of a purely subtropical trough.

We should have another month or 2 before the seasons truly switch to winter-type patterns (though earlier if this weather is an indication of an early Autumn). Autumn is typically the best time of year for thunderstorms in the Western Cape around Cape Town. April has been the month that I have noticed tends to be most active, when the first cut-off lows begin moving in, while temperatures aren't that low yet.

The first update in quite some time, I trust everyone had a good Christmas and New Years. We are now into 2010, a year which has received much hype in South Africa due to the FIFA World Cup which will be taking place in about 6 months.

2010 may also be an interesting year for weather developments in South Africa. As I reported a couple months ago the South African Weather Service installed the countries first doppler radar stations and they have been testing the systems for a month or so now, meaning we may well see the introduction of the doppler radar for public usage some time this year. It may well also be integrated with the FIFA World Cup, should severe squall lines be evidence in close proximity.

Just inland along the Garden Route they will be hoping for plenty rain and soon too as droughts are currently very harsh in some areas and they are in dire need of some relief.

2009 was an interesting year in South Africa and brought some very rare and interesting weather events, several tornadoes up country as well as at least 4 seperate occasions of mammatus clouds in the Western Cape- a weather feature which tends to be rarely seen at all in these areas.

Internationally it will be remembered as the year Vortex 2, the worlds largest scientific tornado research experiment took place. While they did not manage to intercept many tornadoes there was 1 case where they managed to document a strong tornado from birth until it's death. This tornado became noted as the tornado that managed to supply the most scientific data out of any tornado in the past.

Hurricane season was also noteable, but for it's lack of activity. 2009 was a very quiet year in the Atlantic and if I recall correctly there was no US hurricane landfall and only minimal storms. Great news for residents, but boring news for the hurricane trackers.

Looking ahead to 2010 let's see what we get. Tornado season in the US begins in 3 months and hurricane season in 6 months...

This was the last real chase day as I was leaving the next day so we went all out and clocked over 400km of distance over a period of about 5 hours or so. We were targetting some intense cells to the north east of Pretoria, but there were some neat isolated cells to the south east first so I opted to head SW to see how that cell does before heading north so we headed towards the SE cell where you can see pictures below of the large beautiful crisp convection that was present at this storm, but after the photos the storm started weakening so we then headed up north for an hour or so until we reached Bela-Bela and then headed east behind the storm and this is where it got interesting... Little to our knowledge we had already entered Limpopo and a few kilometers back and then into Mpumalanga, it was my first time visiting the provinces.

The GPS we were using had one of the roads as a tar road, and it was our only way to our destination so we took it (let's just say it wasn't tar). We were passing along side a township on a narrow 8 kilometer road, the road was in terrible condition with huge holes and ditches in it- it was a very rough ride.

 It was clear that the storm had just passed through the area as flash flooding was evident as can be seen in the photographs below. We were in an Opel Corsa so there was a very real chance of us getting stuck... Things got even worse after that as the road we were planning to get on was closed for retarring and we had to go in the opposite direction along the sides of the half tarred road for about another 10 kilometers or so- it was a wonderful feeling to get back onto the tarred road. We then tracked under the storm as we entered an area of much better moisure as could be seen in the lowering of the clouds in some of the photographs. We also managed to come across a much needed garage (of a name which we'd never heard). The photos with the bright foreground are the result of a ray of sunshine shining through onto the fields infront of us, made for a great photo opportunity. We also encountered some heavy rain on our way back to Pretoria.

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