These reports are done as time permits. Further information will be added to them periodically.
September 26th and 27th, 2009:
With the Wagga weather balloon sounding showing 500hPa temperatures of about -31.5C on the 26th, it was clear this was a pretty cold air mass for late September. 700hPa temperatures were around -12C and 850hPa temps came in at about -1.5C. That's impressive stuff, except for one thing, the relative humidity in the mid levels looked patchy on this same sounding. So, whilst there was potential for snow to fairly low levels, cells would be isolated or scattered in nature. Blackheath had some nice sleet and large flaked snow showers from 7pm to 7:30pm on Saturday night but they soon returned to light, spitty rain after that. NB: The new Terry Hills Radar seems to be very good at detecting light showers. Next morning at about 5am my wife woke me and outside were nice grainy snow showers falling in temps of around -0.5C. We had a dusting here in town and the intermittant snow showers continued until about 7am.
I hit the road to the Oberon Plateau at about 6am and got there just after 7am. The snowline was down to about 800M and snow showers would have fallen to about 700M. The snow cover was mostly light though until about the 1100M mark. Oberon township had about 3 or 4cm and higher up around Shooters Hill there was 5cm to 7cm at a guess in the less exposed areas. Some of the drifts were notably deeper than that. So, a late season fall in what has been a pretty poor snow season. Thank goodness we got something in the end.
July 15, 2009:
This cold outbreak was showing fairly good potential on the charts but it was certainly far from a classic system. There was no tight pressure gradient so strong winds, a common phenomenon in most cold outbreaks, were virtually non-existent. The appealing feature was fairly cold upper temps and good mid level moisture, which can combine to bring good snowfalls. Whilst this setup did have some impact on the Central Tablelands (Mt Trickett had around 5cm) most of the action went further north where they had nice light snowfalls in the Guyra area. Blackheath had sleet and hail on Wednesday night but no snow. The upper cold pool associated with the surface low was quite strong but its focus, as you can see on the satellite image above, was mainly around Guyra.
July 3rd, 2009:
This system was never looking overly strong on the forecasting models from the outset but with the chance of a surface low interacting with an upper cold pool there was always the possibility of something interesting happening. That possibility never really developed into anything too impressive this far north as the air mass just wasn't cold enough through the layers. Think of a balloon floating up from the surface to a place high in the atmosphere: you really need it to be at least -28C at the 500hPa level in the atmosphere and about -9C or colder at the 700hPa layer to provide the potential for decent snow this far north. That is just a guide and other atmospheric scenarios can bring snow but its a guide that works fairly well.
Have a look at the Sydney Sounding link above and you will see that whilst it was approaching -28C at the 500hPa layer, it was around -8C at 700hPa and about 1C at 850hPa. That just not a cold enough airmass to bring good snow to our region, except for across the highest ground above 1200 metres. The air mass would have been a bit colder over the Oberon Plateau than this Sydney Weather Balloon Sounding shows but its still indicative of outcomes.
At about 3:30am on Friday the 3rd, I was awoken by heavy splats on the window. The temp was around 2.5C and the resulting precipitation was sleet and some fairly decent amounts of it. It never got quite cold enough for snow although there were some soggy flakes in the mix. Sunny Corner (and no doubt the Oberon Plateau) were experiencing snow at around the same time and the amounts were in the 2cm to 5cm range and perhaps a bit more in exposed spots. So, the trend of this winter continues, cold fronts without a lot of punch. The climate has certainly changed up here in the last ten to fifteen years, cold fronts are not penetrating this far north as often. Perhaps mid to late July will give us some better results.
June 9th and 10th - 2009:
Well, lets be honest, it wasn't exactly a system to write home about (or email home about) but it gradually built up to be quite good in the end, not for the amount of snow but for the cold days. Have a look at the Mount Boyce AWS link above to see just how chilly it has been over recent days. There was a nice build up of about 5 to 10cm of snow on the Oberon Plateau above 1150 metres with regular snow showers throughout the 9th and into the early morning of the 10th. Sleet and hail fell in Katoomba and Blackheath on the morning of the 9th but not in any large quantities. Later that evening more sleet occured in Blackheath with some of the showers looking quite good with some soggy snow flakes in the mix.
By around 5am on the 10th there was light snow falling in Blackheath but it was certainly light and was never going to settle. The 10th was a very cold day barely reaching 3C for a maximum with wind-chill reaching -11C. Frosts are certain to follow over the next few days. NB: It got to -3C at my place on the morning of the 11th. So, not a great system for Blackheath in the context of snow but it has been cold and the ski fields have at least been well covered for the start of the season. Snow will always be a marginal event in Blackheath but lets hope the next system is a little less marginal and a bit more snowy!