Topic: 1950:- Extremely wet year for E NSW

[bondiman]

I'm trying to find out more information re the "wet" 1950 for NSW, mainly coastal Sydney, have searched Google and Yahoo, but they dont seem to lead to "good" guides, can anyone point me in the right direction re links, websites etc that I may have missed out on. Thanks.

[Michael Bath]

You can access synoptic weather maps for that year (and others) from this webiste:
http://www.wthrman.com/

then click "synoptic maps since 1948"

The BoM has archived rainfall maps going back many decades too - access them from here:

http://www.bom.gov.au/silo/products/ClimMaps.shtml

1950 rainfall totals map attached

[Jimmy Deguara]

Welcome Bondiman,

Yes 1950 was an extremely wet year and from what I recall set some records for eastern NSW for monthly records and also daily records. I think it was this year that Dorrigo recorded some phenomenal falls of rain and set these records. Anyone can elaborate more on this?

Regards,

Jimmy Deguara

[wthrman]

The website (www.wthrman.com) also has an article on the June 1950 rain events; it's one that I wrote, with some scanned copies of original hand-drawn (in pencil) synoptic maps. From the main page, click on Research then I think it's the last item on the screen that follows. The upper pattern was similar to June 2007, as of course was the count of ECLs (the same at 5).

I have all the daily rainfall readings for that month. According to these, Dorrigo had 1417.3mm for the month, of which 970mm fell in 72 hours (23rd-25th inclusive).

[mitch]

From what I can tell from this website: http://www.bom.gov.au/climate/current/soihtm1.shtml ,1950 may of been a la-nina year. For the entire year the SOI was positive indicating a possible la-nina event. Generally the higher the SOI, the more chance of rainfall (especially over SE Australia). Also interseting to note, the SOI was at its highest in June. A la-nina could have assisted in creating this massive amount of rainfall.

[wthrman]

According to this site :

But just how large must the value of the index be, and for how long must it persist in order for an El Niño or La Niña  to be identified? On these points different researchers have different ideas and there is no single method used to identify events. However, a common method in use is based on the NINO 3.4 Index, which is the departure in monthly sea surface temperature from its long-term mean averaged over the NINO 3.4 region. In this method, an El Niño or La Niña event is identified if the 5-month running-average of the NINO 3.4 Index exceeds +0.4  deg. C (for El Niño; -0.4 deg. C for La Niña) for at least 6 consecutive months (see Trenberth, 1997 in Links and References). The 5-month running-average (data is averaged over 5-month, overlapping periods incrementing one month at a time) is used to smooth out variations in sea surface temperature not associated with  ENSO.

Notice that it's defined by SST anomalies (and so expressed in °C), not by the SOI (although of course the SOI is affected by those anomalies).

There is a table of La Nina/El Nino years on the same page from which it would appear that 1950 was a La Nina year. Interestingly, it wasn't among the top 10 listed further down that page.

[Jimmy Deguara]

Keith,

Is it possible to post a few exmaples for this of what you are trying to portray in regard to the 1950 even - even some embedded examples of the maps so that this thread looks realistic? I am interested in this particular year's June event as well given its similarity as you say to June last year.

Kind regards,

Jimmy Deguara

[wthrman]

Hi Jimmy and everyone,

The following charts are a selection from the ones I have posted in the online article previously mentioned (I had to do a bit of resizing to get them within the image size limit):


6th June

7th June

8th June

11th June

15th June

19th June

23rd June

26th June

29th June

25th June..500Mb reanalysis plot (courtesy http://www.nws.noaa.gov/ )

The synoptic patterns in June 2007 were of course not completely identical to the 1950 event except in very broad terms, but were similar in the way these storms followed one after the other, and also the area affected most (NSW mid north coast southward).  I also thought the upper patterns in 2007 were from time to time almost identical especially with the bulge southward over Australian longitudes.

The maps are hand drawn originals. It's possible to make out the station plots although you can't read them due to the small image size. Most are drawn in pencil (I realise that thumbnails would probably have been a better posting option but I wasn't able to work out how to do that..haven't done this here before).

The following is a list of the highest rainfalls received in NSW for June 1950:

HORNSBY MWSDB   719.6 MIDDLECOVE   722.3 BURRAWANG (RANGE STREET)   728.2 LINDFIELD WEST   732.9 BEECROFT   738.4 PYMBLE (CANISIUS COLLEGE)   777.3 LORNE (LORNE ROAD)   783.9 GORDON GOLF CLUB   786.4 KILLARA (METRO)   792.6 TURRAMURRA (KISSING POINT ROAD)   796.1 DARKES FOREST (KINTYRE)   800.9 ROSEVILLE BOWLING CLUB   807.1 MIRANDA (BLACKWOOD ST)   807.6 OLNEY STATE FOREST   810.6 MADDENS CREEK   818.1 CONCORD GOLF CLUB   855.6 KANGAROO VALLEY (MAIN RD)   856.9 ELANDS POST OFFICE   871.8 HELENSBURGH (SAWAN ST)   967.7 COMBOYNE POST OFFICE   1024.6 DORRIGO   1452.4

[Jimmy Deguara]

Thanks so much for that Keith - that is an extensive description easily covering the whole month.

Those are impressive figures for Sydney region as well other parts of the coastline. Hard to imagine that some regions had more in the month that we normally have in a year out in the western suburbs.

The east coast lows in some cases had very deep and excellent pressure gradients. But as per usual, when the bomb or intensify, out they go into the Pacific.

Regards,

Jimmy Deguara

[Michael Bath]

Thanks for that info Keith - very interesting.

When comparing to June 2007 - have a look at an earlier topic on the subject which includes MSL and upper charts.

regards, Michael

[bondiman]

Sorry about the late reply, had forgotten about this (D'oh)

Bewdy guys for the information  :-)

So 5 or 6 ECL's were recorded in June alone? (Same for June last year), Every month bar August & December exceeded the average by considerable margins, has this been repeated since then? 1988, 1989 & 1990 seems to come fairly close.