Page 1 of 2 1 2 >
Topic Options
#1465682 - 15/06/2018 18:58 NSW rainfall shortage from May 2018
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
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 Offline
Weatherzone Addict

Registered: 20/10/2011
Posts: 4377
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: 2137
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 Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 2619
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 Offline
Weatherzone Addict

Registered: 20/10/2011
Posts: 4377
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: 1774
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 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: 10440
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:
October 2018 Rainfall: 104.6mm (October Avg. 90.8mm) // October 2018 Raindays: 7 (October Avg. 11.0 raindays)
Year-to-date Rainfall: 1184.8mm (Jan-Oct Avg. 1241.0mm) // Year-to-date Raindays: 104 (Jan-Oct Avg. 112.8 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: 2137
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: 2137
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: 3825
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: 2137
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: 2137
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: 2137
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
#1468008 - 30/07/2018 19:15 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW


Manilla is now in an extreme 5-month drought with little more rain than in the driest ever 5-month period from April to August 1888 (29 mm).
https://climatebysurly.com/2018/07/30/drought-fifth-month-july-2018/
_________________________
Data are cheap; information is expensive!

Top
#1468089 - 01/08/2018 10:15 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
If you are keeping count, you will have noticed that this undeniable evidence of an extreme 5-month drought at Manilla means that the five months of drought must have commenced with the month of March at the latest.
Yet I, for one, did not identify an oncoming drought at Manilla until May (as in the thread title).
This is a feature of droughts: they cannot be identified until they are already in progress. Even then, to identify a long-term drought requires more months of rainfall readings than to identify a short drought.
The thing is, the rainfall here was 26 mm in March and 18 mm in April. So the March-April mean of 22 mm, while it just qualified as a "severe" 2-month shortage, was very far from an "extreme" 2-month shortage.
Now, at the end of July, we can see that the 5-month rainfall total of 58 mm (an average rate of 11.6 mm per month) is not just a "serious" 5-month shortage, but one of the most extreme 5-month shortages in history!
_________________________
Data are cheap; information is expensive!

Top
#1468153 - 02/08/2018 16:57 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Steve777 Offline
Weatherzone Addict

Registered: 20/10/2011
Posts: 4377
Loc: Artarmon (Sydney North Shore)
Here's Sydney's rainfall for the year August 2017 to July 2018. The headline is "Dry":



The blue line is the actual monthly rainfall, the red line is the long term mean and the grey line is the median.

Sydney finished with 694 mm for the year, about 57% of average. Every month except June had below average rainfall, February and March were near average. September was almost rainless, very unusual in Sydney.

Much of the last year's rainfall came from Southerly influences, which dump lots of rain on the coast which doesn't penetrate inland. Sydney is located on a headland in the Harbour about 7 km from the open sea. Bankstown, about 25 km from the open sea, received just 330 mm for the year, semi-arid stuff, about 38% of the average.

Top
#1468416 - 06/08/2018 18:49 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 526
Loc: Pinjarra Hills, Qld
This is not directly related to the thread on rainfall shortage, but nonetheless relevant for drought as farmers would experience it.
There is a stark contrast in year to date estimates of potential and actual estimates of year to date evapotranspiration in BOMs AWRA model.
The year to date potential evapotranspiration estimate shows very high potential ET across much of NSW. Which means conditions have been favourable to dry out the landscape moisture.
http://www.bom.gov.au/water/landscape/#/...te/0/0/2018/1/1
The year to date actual ET estimates shows below average to very low estimates of actual moisture lost through ET.
http://www.bom.gov.au/water/landscape/#/...te/0/0/2018/1/1
The actual ET can be much lower than potential ET simply because there is no moisture left to be lost. That is you can't lose water to ET when there is no water left.
Root zone soil moisture estimates align to this.
http://www.bom.gov.au/water/landscape/#/...te/0/0/2018/1/1

I use the word estimates because it is mainly based on models👀

Top
#1468528 - 08/08/2018 21:54 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
Hi Flowin

Your three links go to BoM web pages showing an outline map and legend for (for example) "Root zone soil moisture", but they show no data at all.
What do you have to do to see the data?

When you said "Root zone soil moisture estimates align to this.", did you mean that it is the potential or the actual evaporation that aligns with the soil moisture?
_________________________
Data are cheap; information is expensive!

Top
#1468533 - 09/08/2018 06:25 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 526
Loc: Pinjarra Hills, Qld
Surly Bond,

Regarding the links. That seems odd as they show colour shading when I see them. You can click on the map and get a time series plot (for a point or catchment) and download the data as well (note though it says with compatible browsers Chrome, Firefox, Opera). The page also allows you to see daily value, monthly aggregation, or calendar year aggregation, and change the display between the numeric estimates (labelled 'actual') or relative which displays percentile ranks.

What I meant, in "root zone soil moisture align to this" is that the root zone is very dry which aligns to the observation that while potential ET is high, the actual ET is low because there is not much moisture left to be lost to ET.

For example near Dubbo (I clicked on pixel 32.00 deg S, 148.70 deg E) for July 2018 totals, Potential ET was about 98%ile rank, actual ET was about 2%ile rank, and root zone soil moisture was below 1%ile rank. Very dry conditions.
_________________________
Models are for estimating and gauges are for knowledge.

Top
#1469871 - 01/09/2018 00:22 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Steve777 Offline
Weatherzone Addict

Registered: 20/10/2011
Posts: 4377
Loc: Artarmon (Sydney North Shore)
The good rain news for Sydney is that so far this September (since 9:00 yesterday) we have already exceeded last September's rainfall by a factor of 10.

The bad news is that in last September Sydney was virtually rainless, recording just 0.2mm.

Like July, August across Sydney was very dry, with most sites recording about 10-15% of average.

Top
#1469874 - 01/09/2018 04:53 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Long Road Home Offline
Meteorological Motor Mouth

Registered: 08/10/2007
Posts: 8573
Loc: Northern Beaches Syd
Nicely done Steve, looking at things from a 'glass half full' perspective. Pardon the pun laugh

Top
#1469914 - 01/09/2018 15:34 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW


August rain prevented six-month totals from approaching the record of 43 mm set in 1888.

https://climatebysurly.com/2018/09/01/drought-sixth-month-august-2018/
_________________________
Data are cheap; information is expensive!

Top
#1470618 - 11/09/2018 19:09 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
I have drafted a graph like the one above (August 2018) projected for September using dummy rainfall totals.
Remarkably, the September total (8.8 mm up to the 11th) will have to exceed 17 mm to avoid breaking a record for rainfall deficiency.
The record, which has stood since 1912, is the 15-month total of 404 mm. That is a rate of only 27 mm per month: just half of the average monthly rate.
_________________________
Data are cheap; information is expensive!

Top
#1470941 - 19/09/2018 11:51 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
"This lack of moisture in recent months has caused some places in western NSW to experience one of their driest years to date on record.
Broken Hill's running annual total of 24.6mm as of 9am on Wednesday was its lowest to this point in the year since 1927 and the second lowest in more than 120 years of records.
Wanaaring's 45.8mm of rain to date is its lowest total to this point in the year since 1982.
Further east, Parkes was only up to 137.4mm as of 9am on Wednesday, making this its driest year to date since 1902 and the second driest on record."

- weatherzone Weather News Ben Domensino, Wednesday September 19, 2018

These near-record low figures for the year to date (8.6 months) agree with the shape of my August graph for Manilla (above). I have the 5- and 6-month rainfall totals as the most extremely low percentile values on the graph.
Unless there is normal rainfall this month, Manilla's 9-month total will also be extremely low, but not record-breaking. The 15-month total may break a record (thus, below the 0.1th percentile).
_________________________
Data are cheap; information is expensive!

Top
#1471678 - 30/09/2018 17:05 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
September figures for Manilla show that rainfall in the last 15 months is not just extremely low, it is the lowest ever recorded.



A serious shortage at a duration of 20 years has also appeared, for the first time since 1949.

https://climatebysurly.com/2018/09/30/record-15-month-drought-in-2018/
_________________________
Data are cheap; information is expensive!

Top
#1471688 - 30/09/2018 18:05 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Steve777 Offline
Weatherzone Addict

Registered: 20/10/2011
Posts: 4377
Loc: Artarmon (Sydney North Shore)
Sydney did a bit better in September, with most places finishing about average (broadly defined) in what is admittedly the driest month of the year. The following are rainfall figures, with percentages being of median and average.

Sydney OH: 51.0 mm, 98%, 75%
Bankstown : 94.4 mm, 220%, 277%
Parramatta: 31.0 mm, 87%, 60%
Richmond : 18.4 mm, 62%, 42%

Good rains fell across much of Sydney on the 8th, with Bankstown, which had been very dry this year, scoring a bullseye. However, Sydney's North didn't do so well. Parramatta is about 15 km North of Bankstown, about the sane distance inland. It missed out on the good falls of the 8th.

Top
#1471864 - 02/10/2018 18:21 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
The Bureau of Meteorology "Drought" maps now include September data, for example:
http://www.bom.gov.au/jsp/awap/rain/inde...18month&area=ns

On these maps, the greatest rainfall deficiencies in the area of the "North-west Slopes and Plains" match well to my "Rainfall Shortage" graph (above). The Bureau does not present analysis of 15-month deficiencies, which happen to be the most extreme deficiencies at Manilla just now. However, the 18-month deficiencies on the maps are much worse than the 12-month deficiencies, as on my graph.
Deficiencies for other durations also agree with my graph to a large extent.
_________________________
Data are cheap; information is expensive!

Top
#1471904 - 03/10/2018 06:49 Re: NSW rainfall shortage from May 2018 [Re: Surly Bond]
DerekHV Offline
Weatherzone Addict

Registered: 12/02/2010
Posts: 1187
Loc: Aberglasslyn (Maitland) NSW
We are not yet into restrictions with Hunter Water, and will require a few more months of low rainfall for that to be the case.
Still, we will see what happens with the upcoming event in the next few days, as long term rain forecasts were not good.


Top
Page 1 of 2 1 2 >


Who's Online
8 registered (red earth, Lee@Hazo, DDstorm, Mad Elf #1.5, Perfect Storm, Timbuck, Jimi, Homer), 353 Guests and 0 Spiders online.
Key: Admin, Global Mod, Mod
Today's Birthdays
bradmac, Eager2beastormchaser, Go The Cows, Roland
Forum Stats
29681 Members
32 Forums
23978 Topics
1500759 Posts

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