Snow Watch 2017

25 Jan 2017 08:38 - 17 May 2017 08:04 #70753 by JonWells
JonWells created the topic: Snow Watch 2017
This is the official thread for Snow Watch 2017. Feel free to post pictures, information, questions and reports about the snow conditions in the Drakensberg for 2017. The idea is to keep track of the snowfalls, pool information about where the snow is for those that want to go see it, and simply to have a place to express the joy and experiences you may have had if you have witnessed the grandeur of the Dragon clothed in white.

Historical Snow Watch threads:
2009
2010
2011
2012
2013
2014
2015
2016

2017 Snowfalls:

1. 12-14 May - Large frontal system drops moderate to heavy snow across the the entire Drakensberg high ground. Snow fell to around 2000m in some places, and areas like Sani Pass and Afriski reported depths of up to half a metre. Details
Last Edit: 17 May 2017 08:04 by JonWells.

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20 Feb 2017 16:13 #70940 by JonWells
JonWells replied to: Snow Watch 2017
Yr.no is suggesting a small chance of some light snow/sleet on Thabana Ntlenyana from late tomorrow :

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12 Apr 2017 09:55 - 12 Apr 2017 10:35 #71355 by Dave
Dave replied to: Snow Watch 2017
Hey folks. Snowreport.co.za is forecasting some light snow over the weekend in the Central and Northern Berg, but none of the other weather services is. Could someone with decent meteorological knowledge please give an opinion on this? I'm quite keen to go but not kitted out for snow.
Last Edit: 12 Apr 2017 10:35 by Dave. Reason: Grammar

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12 Apr 2017 10:22 #71356 by JonWells
JonWells replied to: Snow Watch 2017
Hi Dave, earlier on in the week there did seem to be a small chance of some light snow on the very highest peaks this weekend, but this chance seems to have faded away with the latest forecasts.

It is however likely to turn quite cold on the escarpment from Saturday with temperatures dropping below freezing at night.
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12 Apr 2017 10:34 #71358 by Dave
Dave replied to: Snow Watch 2017
Thanks, Jon. I am prepared for the cold.

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09 May 2017 12:55 #71527 by JonWells
JonWells replied to: Snow Watch 2017
For a number of days now the long term forecasts have been chopping and changing between showing snow and no snow for the Drakensberg this coming weekend. As the event is now only 3 days away, which normally means the forecast begin to become more reliable, it it interesting to note the drastic increase in the amount of forecast snow. The current windguru forecasts are suggesting snow totals in excess of 90cm for the Southern Berg escarpment, and up to 30cm in the North. Freezing levels in the south are currently forecast to drop as low as 2400m, which could indicate a chance of snow down to around 2000m. Whilst this forecast may yet change once again, its certainly a system worth keeping an eye on!
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10 May 2017 10:40 - 10 May 2017 10:40 #71534 by tiska
tiska replied to: Snow Watch 2017
I had a look at the forecast from the US global weather forecast model (NCEP GFS). The forecast shown is for 1300 on Saturday 13th May made from 10 May. The visualisation of the data is via the Earth Nullschool site. The colour is temperature and the lines are winds, both at 700 hPa.

The tell-tale sign of cold weather is a very well developed cold front followed by a strong ridging high which is well south of southern Africa. The anticyclone feeds the cold, post frontal air northwards from about 45 degrees south in the Southern Ocean. The GFS system is showing temperatures of about -3 degrees at 700 hPa pressure level in the model (corresponding with about 3000 m) near Giants Castle. The extent of the potential snow event depends on the maintenance of a strong feed of southerly flow of cold, moist air from the southern oceans through a deep layer in the atmosphere, say over 4000m deep. This in turn depends on how intense and slow moving the ridging high is behind the cold front. Whether there is deep cloud above escarpment height also depends on the upper air westerly wave structure which is best shown from plots higher up in the atmosphere near 200 hPa and can't be seen in the attached plot at 700 hPa.

I have watched the forecast for Saturday over the last day or so. It looks to me like the flow forecast for Saturday from the Southern Ocean is not originating as far south as it was in the forecast for Saturday made from yesterday's model run. How cold the air is depends sensitively on the track and strength of that ridging anticyclone.

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Last Edit: 10 May 2017 10:40 by tiska.
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10 May 2017 10:49 #71535 by ghaznavid
ghaznavid replied to: Snow Watch 2017
Interesting. Trying to convert what you said into English - the cold front is likely to be smaller than predicted? Or am I misunderstanding.

My meteorology knowledge is limited to matric level, and that wasn't as recent as it used to be!

"Getting to the top is optional. Getting down is mandatory." - Ed Viesturs

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10 May 2017 14:10 #71547 by tiska
tiska replied to: Snow Watch 2017

ghaznavid wrote: Trying to convert what you said into English - the cold front is likely to be smaller than predicted?


No, not quite. That's why I wrote: "The extent of the potential snow event depends on the maintenance of a strong feed of southerly flow of cold, moist air from the southern oceans through a deep layer in the atmosphere, say over 4000m deep."

Look at the animation evident here:
earth.nullschool.net/#2017/05/13/1200Z/wind/isobaric/700hPa/overlay=temp/orthographic=-339.82,-36.18,1863/loc=22.241,-24.439
No English required to see the flow moving towards the Berg from the Southern Ocean.
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10 May 2017 14:14 #71548 by ghaznavid
ghaznavid replied to: Snow Watch 2017
That animation makes much more sense, thanks!

"Getting to the top is optional. Getting down is mandatory." - Ed Viesturs

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