Topic Options
#1465682 - 15/06/2018 18:58 NSW rainfall shortage from May 2018
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2116
Loc: Manilla, near Tamworth NSW
In May, some rainfall shortages at Manilla became "severe". In June, they may perhaps become "extreme".

One remarkable fact revealed by the graph is that no rainfall total, from one month to 360 months, rises above the median. This has not happened since 1947.
Details in my blog.
_________________________
Data are cheap; information is expensive!

Top
#1465719 - 16/06/2018 09:00 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Steve777 Online   content
Weatherzone Addict

Registered: 20/10/2011
Posts: 4230
Loc: Artarmon (Sydney North Shore)
It's been a very dry 12 months in Sydney, where lack or rain is not normally a problem.

Here are the rainfall numbers for Sydney Airport (66037) for the 12 months June 2017 - May 2018. The Sydney Airport station is on the shores of Botany Bay, about 8 km from the open ocean and exposed to often rain-bearing Southerlies.

The station has records going back to 1939:

Code:
	
Month (2017)	 Jun	 Jul	 Aug	 Sep	 Oct	 Nov	 Dec
Total Rainfall	113.6	18.0	27.2	 0.2	59.6	38.4	52.0
Avg Rainfall	124.2	69.6	76.8	59.7	69.7	80.4	73.6
				 			
% Average	  91%	 26%	 35%	  0%	 86%	 48%	 71%

Code:
Month (2017)   	 Jan	 Feb	 Mar	 Apr	 May	 Annual
Total Rainfall	 27.6	 92.2	108.8	 23.4	 17.0	 578.0
Avg Rainfall	 94.6	111.4	117.0	107.8	 96.0	1080.8
						
% Average	  29%	 83%	 93%	 22%	 18%	  53%


A few points to note:
1. The annual total (June - May) is just over half the annual average, less than the 5th percentile of the long term annual average (Jan - Dec).
2. Not one month reached its average
3, Four months recorded near average rainfall - June, October, February and March (all over 80%)
4. One almost rainless month - September
5. An extended 4 month dry spell from mid June to mid October during which only 52 mm fell compared to an expected (average) of 303 (i.e. 17% of average).

---

One feature of much of Sydney's rainfall over the past year or so is the way that it has been concentrated on the coast. An inland station like Bankstown (about 17 km West of the Airport) would have done even worse.

Top
#1465722 - 16/06/2018 09:51 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2116
Loc: Manilla, near Tamworth NSW
Steve, we agree that September 2017 was very dry. Here the rainfalls in October, November, December and February were all above normal. In your case, they were not quite up to normal.
_________________________
Data are cheap; information is expensive!

Top
#1465734 - 16/06/2018 13:26 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Kino Online   content
Weatherzone Addict

Registered: 10/08/2017
Posts: 2269
Loc: Wollongong, NSW, Aus
What’re the means/medians? Averages can be misleading.


Edited by Kino (16/06/2018 13:26)

Top
#1465736 - 16/06/2018 14:48 Re: NSW rainfall shortage from May 2018 [Re: Kino]
Steve777 Online   content
Weatherzone Addict

Registered: 20/10/2011
Posts: 4230
Loc: Artarmon (Sydney North Shore)
Originally Posted By: Kino
What’re the means/medians? Averages can be misleading.

A good question. With rainfall, like incomes, the average (mean) is often distorted by a minority of very high values. Here are the medians (middle values - half above, half below) for monthly rainfall at Sydney Airport (first line Jan --> Jun, second Jul --> Dec):
Code:
71.7	  82.5    85.7   81.4	 76.4   100.5   
51.7	  43.9    46.4   47.4	 66.8    59.8	

Annual: 1,045.8

EDIT - comment: monthly medians are about 80% of averages, although the annual median is only 4% less. It tend to balance out over longer periods.


Edited by Steve777 (16/06/2018 14:54)

Top
#1465737 - 16/06/2018 15:37 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Stormy3 Offline
Weatherzone Addict

Registered: 12/06/2013
Posts: 1720
Loc: Ellalong,10kms SW of Cessnock ...
Very much below here all the rain that has been around has been coastal.All creeks and cattle dams are dry here I am 10kms SW of Cessnock.
_________________________
https://www.facebook.com/supercell1
Click here for Ellalong live weathercam,The camera is facing west towards the Wollombi,Putty area,the video live stream will be online longer, if any storms or severe weather.

Top
#1465756 - 16/06/2018 18:26 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Seabreeze Offline
Weatherzone Moderator

Registered: 18/09/2005
Posts: 10370
Loc: South West Rocks, NSW
June 2017 to May 2018 rainfall here -



Slightly above average rain here over the past 12 months.
A very dry Jul-Sep period was followed by a rather wet Oct-Dec. A very wet March countered a moderately dry Jan-Feb.
The very wet December was courtesy of numerous thunderstorms, and March's high rainfall was from a coastal trough combining with a decent onshore flow on two separate occasions.

If there's no more rain for the rest of June here, the yearly (12-month) total will fall to be 5mm below average, or: 99.7% of the yearly average / 104.1% of the yearly median. The 3-month Apr-Jun period would be somewhat below average.

Btw, monthly means/medians will not cumulatively add up to the yearly mean/median. The yearly mean/median is calculated from the yearly rainfall amounts received, and isn't the sum of the monthly means or medians.
_________________________
South West Rocks, NSW Mid North Coast:
July 2018 Rainfall: 85.0mm (July Avg. 76.0mm) // July 2018 Raindays: 4 (July Avg. 8.1 raindays)
Year-to-date Rainfall: 982.4mm (Jan-Jul Avg. 1015.2mm) // Year-to-date Raindays: 77 (Jan-Jul Avg. 85.5 raindays)

Top
#1466171 - 20/06/2018 23:54 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2116
Loc: Manilla, near Tamworth NSW
As cited in weatherzone "Weather News" by Ben Domensino on June 20,
"...parched western NSW, where some places are experiencing their driest year to date in more than five decades."
That may be not nearly so bad as it seems.
At Manilla, which is likely to be typical, the last five decades were by far the most drought-free time in history.
_________________________
Data are cheap; information is expensive!

Top
#1466730 - 30/06/2018 18:41 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2116
Loc: Manilla, near Tamworth NSW
Updated to include June 2018:



Extreme rainfall shortages have now developed for the first time since the drought of 2002. This was the longest period free of extreme drought at Manilla in the record beginning 1883.

Details on my blog.
_________________________
Data are cheap; information is expensive!

Top
#1466734 - 01/07/2018 00:05 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Blair Trewin Offline
Weatherzone Addict

Registered: 13/07/2001
Posts: 3797
Loc: Melbourne, Australia
Originally Posted By: Surly Bond
As cited in weatherzone "Weather News" by Ben Domensino on June 20,
"...parched western NSW, where some places are experiencing their driest year to date in more than five decades."
That may be not nearly so bad as it seems.
At Manilla, which is likely to be typical, the last five decades were by far the most drought-free time in history.


The really extreme numbers are further west. Broken Hill has had only 18mm for the year so far.

Top
#1466759 - 01/07/2018 18:48 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2116
Loc: Manilla, near Tamworth NSW
Drifting into drought



Since around August 2016, a time that was very cold and very wet,we have been drifting into this drought. In late 2016, the drift was rapid. It reversed in early 2017, then resumed.
July data will show whether records for low smoothed rainfall anomaly and/or high smoothed day temperature anomaly will be broken.

More in this post on my blog.
_________________________
Data are cheap; information is expensive!

Top
#1467052 - 07/07/2018 17:04 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2116
Loc: Manilla, near Tamworth NSW
This graph shows how very few extreme droughts, such as this one, Manilla has had in recent decades.
Severe shortages are up to the 5th percentile, and extreme shortages are up to the 1st percentile.



This fifteen-year gap without extreme rainfall shortages from 2002 to 2018 is without precedent at this site. Earlier such gaps did not reach five years.
We never had it so good!
Up to now.


Edited by Surly Bond (07/07/2018 17:09)
_________________________
Data are cheap; information is expensive!

Top
#1467580 - 19/07/2018 10:55 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2116
Loc: Manilla, near Tamworth NSW
Extremely dry air, tending to prevent rain, is shown by record low dew points.
I calculate early morning dew points from minimum temperature and maximum relative humidity.
The lowest recent dew points were:
15/07/18: -10.6°;
16/07/18: -10.4°;
17/07/18: -10.9°.
These values were the lowest in my observations in nineteen years from April 1999.
They are thirteen degrees below my normal values for July.
_________________________
Data are cheap; information is expensive!

Top


Who's Online
4 registered (Kino, Lee@Hazo, Steve777, 1 invisible), 238 Guests and 3 Spiders online.
Key: Admin, Global Mod, Mod
Today's Birthdays
Aza1987, Dominic, NoRelationToNed, potato, Radar05
Forum Stats
29612 Members
32 Forums
23933 Topics
1494522 Posts

Max Online: 2925 @ 02/02/2011 22:23
Satellite Image