Ok, this is something I thought might be useful to catelog for people here. We often get guys like Southman and others each year asking if it's going to snow in Mossval, Bowral and other places. So I thought it might be a good idea to put up a few systems that have been known to dump in different areas and try and get a kind of catelog going. I think this could be a very useful thread and as systems approach people will be able to get an idea of what is about to happen. This first one I am putting up is a system that brought wide-spread snowfalls over the south-eastern ranges of NSW on the 27th August 2001. According to Andrew Miskelly's site, the "areas affected included the upper Illawarra, Southern Tablelands and south-east Central Tablelands." The distinguishing feature here is the south easterly airflow which enabled areas which don't normally get snow because of rain shadow to get it. I imagine that places like Jindy would benefit from this type of system. Anyway, there's one to start us off.
Here is the MSLP for the May 2000 dump that brought huge snowfalls up to 1metre over the alps. Notice the nice long SW fetch caused by the covergence of the high and low bringing up really cold polar air. This is very similar to what happened in the widespread snow event in July 65... http://www.bom.gov.au/cgi-bin/nmoc/nmocm...02.20000528.gif http://www.bom.gov.au/cgi-bin/nmoc/nmocm...02.20000529.gif Ok there are the links the BOM site wouldn't let me bring them up here. If anyone has a copy of the May 28 00 MSLP, feel free to post it.
Nice one spicy i like what you've shown here, perhaps this threaad should be sticky... We could catalogue this years systems? Probably need to be heavily monitored though, trying my hardest to not get sucked into a Murali Roast... On what is a very informative thread.
Thanks fletch. Here is the 1986 dump that produced snow to sea level over Victoria and Tasmania. You will notice that similar to the May 2000 dump, it has that long fetch of Soth to South Westerlies. and here is a link for the JulY 17, 1965 dump that blanketed much of NSW, including falls in the Hunter Region and the blue mountains with around half a metre of snow: http://www.theweather.com.au/people/amiskelly/snow/19650717/slp_196507170000.png If you click on that link, the surprising thing you will notice is that the pressure is very high over the regions where the snow fell (MSLP of around 1022), and there is a big fat high sitting over the country. There must have been some kind of upper level trough that brought the moisture in.
Interesting thing spice is the trailing high. Notice how the 2000,1986 and 1965 dumps all had very large highs trailing the system. 1032-1035 which are pretty decent sized highs. Looks quite similar to many of our current systems. Just need the whole lot to converge. Temp, moisture, correct isobar structure. Taipan
u guys need to look at blackheaths work pearce walker style this link is for the 1965 event in particular go walker
Quro, already done mate. My link 3 posts back links to the 1965 site you just linked again. I'm trying to get something up here in the forums that people in here can readily look at and view what the different systems do. Feel free to add some stuff, but I don't want a thread full of links. I want a thread with analysis and MSLP charts and discussion about them.
i think quro is suggesting there is no need to cover the ground already covered by Blackheath and A.Miskelly. Between them they've got the freak events covered. What would be interesting would be the next tier down, or even early season versus mid season.
yes please Jane... thanks in advance. Fantastic, so put them up.. I'm after all types of systems, but I wanted a few of the freak systems here so that the 100's of people that will visit this site and not the others will be able to see this stuff and learn it quick. We can refer to the thread and the systems to show people why certain systems hit certain areas well and other areas not so well, basically continuing from our discussion about different mountains and different aspects like Buller, BawBaw and why they differ from Falls etc. This is what I'm after.
Nice work spiceman and others I certainly dont know much about systems and the like but am learning lots..also i think this thread will be good for looking up old systems and comparing them to ones that are comming through etc.
If this one on the weekend comes off we could see snow again in places like Mossvale, Bowral, the Upper Illawarra etc because of the SE airstream. There is a nice size fetch of very cold air that will combine with an East Coast low and it will be an interesting one to watch.
what about the 1984 system that had snow all the way up to Qld I was coming back from Perisher and had sleet falling at Fairfield in sydney when i woke the next morning centre point tower had snow on the roof and the hume highway /new england were all closed snow was even falling on the darling downs from memory the temp was -32 at 9000 ft i was really lucky to have left when i did as the hume was closed for 4 days i think that snow was falling down to 250m or so the resorts did not get much from this and the fletch was quite similiar to 1981
remembering that southerly fetch makes me excited. VERY excited!! oops i think i had a little prefrontal there
23rd June, see below. We had snow in North Central Victoria to about 150m ASL from that system, we even got the morning off school to make snowmen & throw snowballs as none of us had ever seen it before! Apparently that was the second time in recorded history that it has snowed and settled in the region, the previous being some time in the 1880/90's (got a chart for that one!? ). From http://www.bom.gov.au/lam/climate/levelthree/c20thc/temp4.htm :
Just found more info... There was a book published to commemorate the falls in 1981 (in St.Arnaud), and from it it says that falls also happened July 15 1909, Aug 16 1900, and some time in 1895 and 1882. Certainly snow to low level seemed more prevalent in those days! So can anyone dig up some charts for then!!! Perhaps there is at least some BOM observational data for some parts of the country for the July 15 1909 event that could put together a partial picture?
Thanks to Djon for the animation. Here are three systems that went through from 27th April to 7th May in 1960. They delivered a bucket load of snow basically 150cms in a week and a half. Over 115cms fell between the 2nd of May and the 8th of May. I've put the Spencer's creek depths below taken from Dave's thread, as well as a list of the pressure on the dates in question and the animation. 1960 Spencer's Creek Depths 1960-04-20 0.0 1960-04-27 33.8 1960-04-30 40.4 1960-05-02 32.0 1960-05-09 148.8 1960-05-13 165.9 1960-05-16 201.7 1960-05-20 168.7 1960-05-23 167.4 1960-05-30 163.1 1960-06-06 160.0 1960-06-09 166.6 1960-06-14 181.1 1960-06-17 216.7 1960-06-20 214.1 1960-06-23 213.1 1960-06-27 211.1 1960-07-04 242.3 Hobart Pressure <div class="ubbcode-block"><div class="ubbcode-header"> Code:</div><div class="ubbcode-body ubbcode-pre" style="height: 150px;"><pre> 1960-05-01 00:00:00 1014 1960-05-01 06:00:00 1007 1960-05-01 12:00:00 1006 1960-05-01 18:00:00 1000 1960-05-02 00:00:00 997 1960-05-02 06:00:00 998 1960-05-02 12:00:00 1004 1960-05-02 18:00:00 1003 1960-05-03 00:00:00 1010 1960-05-03 06:00:00 1006 1960-05-03 12:00:00 1005 1960-05-03 18:00:00 999 1960-05-04 00:00:00 994 1960-05-04 06:00:00 988 1960-05-04 12:00:00 988 1960-05-04 18:00:00 986 1960-05-05 00:00:00 988 1960-05-05 06:00:00 985 1960-05-05 12:00:00 983 1960-05-05 18:00:00 983 1960-05-06 00:00:00 985 1960-05-06 06:00:00 983 1960-05-06 12:00:00 985 1960-05-06 18:00:00 986 1960-05-07 00:00:00 989 1960-05-07 06:00:00 992 1960-05-07 12:00:00 996 1960-05-07 18:00:00 997 1960-05-08 00:00:00 997 1960-05-08 06:00:00 999 1960-05-08 12:00:00 1004 1960-05-08 18:00:00 1009 1960-05-09 00:00:00 1012 1960-05-09 06:00:00 1011 1960-05-09 12:00:00 1013 1960-05-09 18:00:00 1014 </pre></div></div>
Most of our snow comes from the Northwest. Cold fronts rotate clockwise around a low(highs rotate anticlockwise) and the highs are usually positioned further north than the lows. As the cold front approaches, the relative locations of the high & low produces a northwesterly air flow. A cold front is the boundary between warm and cold air, and the main cloud band PRECEEDS the cold front. If the low is sufficiently far south, the air behind the cold front will feed enough cold air into the system to produce snow ahead of the front rather than rain. In this map you can see the winds are from the northwest, but the feed behind the front is far from the south. The rain band is just ahead of the front, so the bulk of the snow comes from the northwest. Here is a scenario where it would rain instead: The relative positions of the highs (highs generally further south) and lows means the air is coming from much further inland, so the cloud band preceeding the front would be rain. Compare the two maps I've posted. PS If you look at all of the cornices in the snow country, you can see that the wind was coming from the Northwest.
I've done some other animations like the 1960 system above for some systems inclduding the low level 1981 system : <a href='http://snow.barratt.com.au/misc/Aus.SLP.1981062100.1981062700.gif'>1981 Low level snow SLP animation 482kB</a> I have put together a program to easily generate these so if there are any other systems that are worth looking at let me know. At the moment I have systems from 1951 (x2), 1960, 1965, 1981, 1986, 2000, 2001, and 2003. I have done SLP here, but can also do the likes of air temperature at different levels. Also would be good to do some composites (eg SLP & 1000-500mb thickness). These charts are generated from the NCEP data at http://www.cdc.noaa.gov/.
Much thanks to Jane O'Neil who got the charts from the 81 and 84 dumps. Here is the 84 dump that occurred 2nd to 4th July: You can see why it snowed all the way to Queensland. Once again that great big southerly fetch of cold air brought up by the converging low and high together. It is really obvious what to look out for for a dump of snow.
I'm no weather guru so this may be a silly question but is the current weather patttern that the Australian snow fields are experiencing going to flow to the snow fields in NZ (Cardrona/TC, Remarks etc) as I'm headed over there next Friday (13th) and the snow looks a bit average at the moment..Cheers
Originally posted by Dijon I would like to see the 86 system, do you have it on your website? Also the 74 storm that hit sydney would be of interest. thanks
There was a huge storm (ECL) in Sydney in 78. Ran all night. That would be worth seeing; July timeframe. I lived in St Ives at the time and every street was littered with trees down - it was the worst I had ever seen until a twister ripped through a narrow corridor about 87 and stripped trees of every leaf.
Time to clean out this thread and keep the excellent examples of the systems and then lock it and make it sticky for this coming winter.
Would be good to clean it up, but not lock it. I have a few systems I have been meaning to add to it, but haven't had time as yet. I should before the start of the season though!
Can a mod please clean up this thread? Ie delete all the posts that dont have useful information... (including this one)
Victorian low 31/1/05 - 5/2/05 Since this was a (very) significant summer snow system I thought this should go in here. A summary page containing links to animations, snow cams, and radar images can be found <a href='http://snow.barratt.com.au/weather/systems/2005-01-31.2005-02-05/index_html'>here.</a>. Here is a satellite image, analysis chart, and snow cam from this front : <a href='http://snow.barratt.com.au/weather/systems/2005-01-31.2005-02-05/index_html'> <img src='http://snow.barratt.com.au/weather/systems/2005-01-31.2005-02-05/IDE00035.20050204145935.jpg'> <img src='http://snow.barratt.com.au/weather/systems/2005-01-31.2005-02-05/IDX0894.20050203115616.gif'> <img src='http://snow.barratt.com.au/z/snowcams/200502/buller1.20050203142002.jpg'> Mt.Buller - Bourke St. </a>
Thought I might put this here as it directly relates to winter systems and how they develop. The upper level Long Wave patterns have significant influence on surface snow bearing systems. You are looking at an image of the Southern Hemisphere with Australia upside down near the bottom. Now have a look at the grey/white coloured shading marked 5400 and observe how it meanders its way around the globe, moving up and down in waves. These long wave troughs (colder air moving over southern Australia) are in the upper atmosphere, this is the region that drives and strongly influences the weather at the surface. Its when these long wave troughs (approximately the areas of grey shading) peak over the south east of Australia and short waves (even colder, smaller pools of air that move into the LWT like a swirling eddy) slide into them, that good surface weather patterns favouring cold outbreaks can form. Imagine the long wave troughs as large, ocean waves peaking and breaking onto the shore. When these long waves peak and "break" onto the south east of Australia with short wave disturbances within them, you then have potential for cold outbreaks at the surface. You can see in the image above that a Long Wave Trough is peaking to the south of Perth (the 5400 line is roughly where the LWT is). This means that the strongest frontal weather at the surface would typically form near Perth underneath this long wave pattern and the ski fields would 'generally' miss out as they are under the influence of that strong Long Wave Ridge (brown/red shading over Tassie). Long Wave Ridges tend to encourage the formation of surface high pressure systems. The LWT typically moves east very slowly at around 8 knots per day but can remain stationary or even move west (retrograde). Shortwaves (even colder, smaller pools of air breaking off in the upper atmosphere) within the long wave patterns tend to move east proportional to the average wind speed at the 700mb level. If you have an idea of how to plot the Long Wave patterns, it can really help in understanding where surface fronts will generally move to. I am not suggesting you can't get snow at the surface without the LWT being nearby but the strongest surface systems will usually occur near (and roughly underneath) the LWT. You don't have to be a meteorologist to plot and understand the basics of the LWT/LWR but in doing so, you will see more clearly which fronts have the potential to reach the ski fields. I can remember as a boy in the car often asking, "Mum, are we there yet? Are we there yet?" Until, one day mum gave me a map to work it out for myself. If you can identify ridges and troughs in the upper atmosphere, you will have more of an idea of what surface pattern will strengthen or weaken as it reaches the Alps. Mets and others, please feel free to add to or correct my thoughts here. I'm just trying to help folk do a bit of basic forecasting work themselves. You can plot the LWT at either of these links: http://nomad3.ncep.noaa.gov/cgi-bin/pdisp_avn.sh http://nomad1.ncep.noaa.gov/cgi-bin/pdisp_avn.sh How to plot: On the first page Control File: select the latest analysis file or forecast file. Options: Leave blank. Overlap: select 'single variable'. Plot Type: select 'map' Click 'next page' Variable one: select '5WAVH' Level: leave as is. Extra operation 1: Leave as is. Time: select the time you want to go out to, within the limits of the control file, of course. Map Projection: select 's hemi' Draw: select 'shaded and lines' Plot size: suite yourself with this selection. Leave other variables alone for now. Click on 'Plot' More server links here if the others change or are down: (but these can also be down when overloaded) http://www.australiasevereweather.com/links/ozcharts.htm Head to the GFS links on the above page.
A "cuf off low" system is the ideal system for snow provided it is in the right location The a "cut off low" is only "cut off" to a certain extent, but there are ALWAYS isobars that will drag air from elsewhere. If it is further south (e.g. over Tassie) the clockwise circulation will drag in colder air and snow. e.g. In this example, you can see the cold feed: On the other hand, if it is further north (right over the top of the alps, it will often drag in air from northern NSW and rain: The pressure is important. Generally if it is the correct location (generally over Tassie), then the lower the pressure, the more snow there will be, because the lower the pressure, the more moisture will be present int he system. Also, the system will tend to move more slowly than a fast moving cold front.
Snow will fall if there is moisture and a sufficiently low temperature. In the middle of winter, a pressure like 1015hPa will produce very little snow because there is very little moisture. On the other hand if the pressure is very low, say less than 1000hPa, then there is usually also a lot of moisture. If the low is in the right place, there will be an injection of cold air so we get LOTS of snow. This is NOT the MIDDLE of winter. I've found (after taking records from 1984 - 1997) that before about mid July, and after early September, we can get reasonably high falls of snow with pressures of around 1008-1015hPa. However, we don't often get big dumps in mid winter with pressures greater than 1005hPa. So pressure DOES matter. You can see in 2003 that on each occasion, the snow increases when the pressure dips below 1000hPa, as long as it is in the right place: 4 times below 1000hPa in 2003. June 6, 40cm: June 27, rain: July 24, 100cm+: August 24, 45cm:
Can someone please update this with the two snow bearing systems we have had so far - which have been highly unusual!
Mahtoh & Co Sep 2005 - Feb 2006 snow producing systems are now up to date in the good ol' System Summary Thread .... It's not sticky anymore so pray for regular snow this year or the thread may be buried from time to time between good systems... best bet in that case is just check one of the Blocking High Hysteria Threads
