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Storm over Sth Ranges 16-10-05

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It started on the 15th with instability over the ranges firing up a few cells over the northern hot spots. This results of some very tight and intense rain cores were 18mm at Forreston. The next day (16th) dawned fine and warm and by early morning small puffs of convection began popping up over the southern hills. In a very short time this began to develop and draw into a single cell with some very impressive rotating updraughts on the base DIRECTLY overhead. Finally after a few rumbles of thunder and threatening to dump for some time, it did just that. 10 mm in a very short time at this location. Rain rate peaked at 63.5mm/h. In real terms that is not that heavy but for us it is and would be I say it is the highest rain rate I have recorded here. It is also extremely with a capital "E" unusual for such events to not only happen here as they did but to form directly overhead. Heavy rain cells often pass over coming from somewhere else and losing intensity in the process, but yesterday was rare indeed. In the few years I have been here I have never seen it develop and dump in this way "at this location". Did I mention how unusual this is?

The cell went from small precipitation shaft perhaps a km south of me to a visually impenetrable rain core overtop in 30 seconds. It then proceeded to follow the Bull Creek and Hack Ranges all the way to Mt Barker where by this time it had decayed significantly. It only peaked for a few minutes and had begun the death process as soon as it was born really. Totals for those in the core amounted to 10mm on average and there was reports of hail in some spots. The northerners can scoff at such piddly little cells which are commonplace out that way. But its a rare treat indeed down here. I snapped some pics as the day progressed which can be seen HERE

Left: Graph from the weather station showing rainfall. It certainly hit with a bang! It also had a significant impact on my local environment which can clearly be seen on the graphs here (opens in new window)

Left: Radar scan of the cell at its full intensity. Not large in real terms but extremely unusual in location and positioning. This was the best we saw from the system(s) that passed through over the next week or so. But it must be noted that the period from the 15th to the 22nd October was unusually wet and unstable statewide. The far north of the state was hammered by huge thunderstorms all week with some incredible falls over the northern centre's culminating in Oodnadatta being totally cut off by road. Severe hailstorms flattened crops near Ceduna and also in Western Australia. Such was the broad reach of the low. Locally on the 19th a rain band from the north delivered some pretty good falls of 25+mm to a very narrow strip that followed the Adelaide coastline and extended down to Victor Harbour. The hills got insignificant falls from this which in itself is unusual! Then on the 20th a band of rain over the northern suburbs and hills delivered falls in the 20mm mark. The southern ranges missed completely yet again with falls less than 4mm. By the end of the period pretty much everybody except perhaps the southeastern hills and flats had copped a drenching. Its timing was not so good for the hay farmers, but the croppers were smiling broadly.

The weatherzone forum of this event is worth a read. It was not yet over however and the northern spots were in yet again for a drenching while the moisture streams yet again missed the south eastern hills and flats.... More on this in the next event!

October Drenching 23-10-05 to 25-10-05

 

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After such a week of rain just a few days previous it was with incredulity that we viewed the models suggesting that it could all happen again!
But it did with a low south of KI delivering a wraparound rain band. The progged rain had some hills areas that were still at saturation point from the previous event on flood alert. The synoptic below shows the situation.

It began midday on the 23rd over the southern ranges. Isolated and very heavy rain cells began popping up on the radar. Strong winds buffeted as well. These small downpours soon coalesced into some solid CB cells delivering good falls to those in their way. I scored 19mm from this. I took some pictures of the cells from near Strathalbyn which can be seen HERE. But this was insignificant compared to what was to follow. As the low progressed east the wind turned SW (a terrible direction for this location due to the rain shadow from KI) and the wraparound approached. At approximately 12:30am a narrow arm of the wraparound exploded into action over the gulf and began drenching. The radar image below shows just how narrow this band was! Amazing stuff.

Some pretty serious totals resulted as this band backbuilt for most of the night. It stayed in this narrow line too and despite our recording 29mm to 9:00am yet again we missed the really serious falls which are very impressive indeed considering that most of this fell in less than 9 hours!! Check out the rain distribution below.

The Gawler and Para rivers broke their banks but with no real damage fortunately. Still flooding in late october!!! As the low progressed the moisture streams stayed narrow tending further south. Some more good totals were recorded on the 25th with Echunga the highest at 27mm. Yet again the streams just missed me with 14mm at home. So damn close, yet so far and a northern and central hills event - again!

The weekly rain bulletin is impressive.

The weatherzone forum of the event is also worth a read

Record Breaking October rains

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October 2005 has been an extraordinary month rainwise in SA. Up in my part of the ranges 158.25mm for October over 17 days. My highest October fall ever since records began here at this location in 1992. Next highest is 120mm in 1992 itself.
October average is 75.9mm so double the average.

But its not the highest October recorded in this area. In the 116 years of records from Meadows township such a total has been exceeded 4 times
178.1mm -1928
169.9mm - 1948
178.8mm - 1975
177.6mm - 1976
This oct is the 5th highest actually so certainly in the top 10% since records began. In other words this October fell ABOVE decile 9 or the 90th percentile! see this page for an explanation of deciles. This is not so common indeed!

Its also in stark contrast to October 2004 when only 16.7mm fell.

It is interesting that the highest official October fall that I have for my area is 215.3mm in 1928 from the now closed Bull Creek Station. What a year that must have been!

This now brings my yearly total to 841.9mm. We are now 50.9mm above average, quite a turnaround when we were 126.2mm BELOW average at the beginning of June. Since then we have had 706.1mm in those 5 months, 177.1mm more than average for the same period!.

This means that the first 5 months gave only 135.8mm! A mere 16% of the years total from the first 50% of the year! (to the end of october)

The following from the BOM monthly summary..

Rainfall totals in excess of 100 mm were reported from centres in the Lower North, Kangaroo Island, Adelaide Plains, County Light, Mount Lofty Ranges and Lower Southeast districts. The Western Agricultural and Upper North generally recorded totals below 50mm. The remaining districts reported totals between 50 and 100mm. Three stations in the Central Districts, Roseworthy Post Office, Freeling and Mt Bold Reservoir had their wettest October on record.

The highest "official" rainfall total for October was 221mm recorded at Woodhouse in the Mount Lofty Ranges. Unofficially was the rcording of 231.5mm at Summertown by Peter Wright who posts data on this very website. See his rainfall HERE.

Floods! 07-11-05

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Torrential rain in parts of the central and northern ranges result in the Gawler River flooding with millions of dollars of damage the result, amongst other happenings! Much happened in these few days - read the report and see the pics - HERE.

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