Update Latest GFS model guidence as well as EURO (ECMWF)
Update #2 – 15 June 2015: The weather event in question has been subject to a lot of “flip-flopping” with forecast specifics changing slightly every few hours, making it difficult to pin point the exact conditions which can be expected, however with the system now almost here – the forecast is a bit more reliable. The first thing to note is that conditions remain far less optimistic for the Western Cape, than in the original post – with freezing levels dropping down to around 1600m in a few places, which will provide the opportunity for some possible light snowfalls on the higher mountains in the province.
The focus for snow now moves to the east. It’s possible that some places in the Northern Cape may experience some light snowfall, but the bulk of snow seems to be most likely in the northern parts of the Eastern Cape and once again Lesotho — on Wednesday. Freezing levels are very impressive over Lesotho in the latest GFS run, below 2000m in places. The real question however lies with the moisture, and should the band of moisture change in its timing, conditions could easily be less favourable for snow in that area.
Update #1 – 12 June 2015: As suggested in the original article, long term models tend to be very fickle and things can change dramatically between the runs. The latest 00z GFS shows this well, with conditions remarkably less favourable than those which were displayed the day before yesterday. The spaghetti models on Thursday were showing considerable variation between the GFS ensembles, and as per the latest run – the models are hinting at the freezing levels being much less impressive than before. While the original post shows freezing levels forecast to be under 1500 meters for a large portion of the province, the 00z run for Friday shows freezing levels barely dropping below 2000 meters.
We’ll continue to monitor the forecasts and see how the models progress over the course of the next 48 hours. By Sunday, there should be a fair bit more certainty over the forecast and as to whether or not this will really be a snow maker. It’s also worth noting that the models continue to show fairly widespread snow for Lesotho and northern parts of the Eastern Cape for next Wednesday.
Original Post – 10 June 2015
The GFS model is predicting an exciting week ahead starting on Tuesday the 16th June in the Western Cape. The forecast models are showing a 992hpa low pressure system to the far south of the country, strengthening considerably during the period from Tuesday into Wednesday with the low deepening to 976hpa by Wednesday. Despite the center of the low being around the -50 degree latitude, the system has impressive associated precip and cold air to the north of the center.
Early snow forecasts look very promising, though if we’ve learned anything this week it’s that forecast models are fickle and a slight change in the weather system can drastically change the outcome, though it is worth noting that cold fronts like the one in question tend to be easier to forecast than cut-off lows like that bringing snow to Lesotho tomorrow.
At this stage it looks like the real trick to having the forecast turn out as predicted at present will be the outcome of the freezing levels. Moisture is likely to not be too much of an issue, but the reason for the very impressive forecast snow totals is because of an extremely large area of sub-1500 meter freezing levels which extend up to the Northern Cape. The current forecasts from the 00z GFS (10 June) over at snow-forecast.com indicate that Sutherland looks to be the hot spot for chasers at this stage – though the forecast also currently suggests impressive totals early into Wednesday morning around Middleberg in the Eastern Cape.
Please note that this weather system is still a week away and details regarding the forecast by the models are likely to change over the coming days. We will do our best to keep you up to date with what they are showing – but at this stage this definitely appears to be worth keeping an eye on.