This Yahoo news item 23 Sep 2013 – Strong winds bring down trees and powerlines in Perth and South West – says at the end – [The Bureau of Meteorology says the front will hit early this evening and last most of the night.
The Perth metropolitan area has recorded its wettest September for more than 90 years.
So far this month Perth has recorded 129 millimetres of rain – making it the wettest September since 1923.]
There is a major error in those last two sentences and I find it amazing that such a simple issue as rainfall can get so garbled – particularly in the Perth media. Many 10 year old children with a www connection and a copy of Excel could provide Yahoo with relevant basic rainfall statistics.
Here is a list of the wettest Septembers for Perth – both Perth Metro (1993-current) and Perth Regional Office (1876-1992). Chris Gillham has information about BoM Perth weather stations.
The ridiculous statements on Yahoo completely ignore the fact that in September 1973 Perth had 146mm rain – so that is the first “record” hurdle that 2013 has to jump.
Then in 1971 September saw 183.8mm rain and it will take truly exceptional rain for the rest of this month to top that.
So where does Yahoo get their 90 years from ??
I notice that on 19 Sep PerthNow had a factual article – Perth on track for wettest September in 40 years.
So it is puzzling that a few days later Yahoo come up with their nonsense.
It is also worth noting that in my reading for this article I never saw Perth Hills rain referred to – yet that has such economic importance for Perth water supply. Of course Perth Hills rain is much higher than Perth rain. Somebody has the Perth media well trained.
Just had a look at Bickley, the only hills location on the Elders website. September MTD total 281.8mm. 55mm over the previous record (since 1969) of 226.9mm.
www.eldersweather.com.au/dailysummary.jsp?lt=site&lc=9240
Mandurah also had a record 140.8mm. Previous record 97.4mm. Although records only go to 2002. Bunbury and Margaret River also had record rainfall this month. (All on the coast for those not familiar with WA) Cape Leeuwin was far from a rainfall record, but records go back to 1907. Nowhere outside the SW coastal and hills was close to a rainfall record.
Busselton didn’t have a record, but they are in something of a rain shadow when winds are from the SW.
Clearly the rain was due to increased cold fronts, rather than mid-level disturbances, which tend to cause more rain inland. The weather feature the CSIRO were/are so confident would decrease with AGW. Although one month does not make a trend.
Comments emailed to me –
ABC TV weather in WA on Monday night accurately reported Perth Metro having 129.2mm but also said it was the wettest Perth September in 90 years. I’d researched the Perth history that day and was watching the 7pm news over dinner when the announcer said wettest in 90 years … nearly threw my broccoli at the TV screen.
Two different media sources citing 90 years certainly indicates it was information from the BoM rather than a single media error. There’s nothing about Perth rainfall in recent BoM media releases so I must assume it was either passed to the media verbally by a BoM employee or was possibly added on to one of the regular weather update bulletins the BoM issues to all media. Another possible scenario is that The West Australian published that Yahoo page on Monday afternoon, got it all wrong, and the ABC spotted it and quoted The West Australian via Yahoo in Monday evening’s news. Having worked WA’s mainstream media for a couple of decades, it wouldn’t surprise me if our amateur monopoly press can’t research and if our national broadcaster then looks at other amateur media as an information source.
The West Australian story via Yahoo also says in its final sentence that “the average for the month is 81”. The September mean rainfall at Perth Metro is 87.5mm and at Perth Airport it’s 72.2mm, so I have no idea where 81mm comes from. The average of 87.5 and 72.2 is 79.1mm, so even a weird station average wouldn’t make sense.
Note from Ed: The average September rain for Perth Metro merged with Perth Regional Office – 1876-2012 is 81.2mm