Central 12-month Rainfall Forecast

10 5 0
Jun 19
7
Jul 19
4
Aug 19
4
Sep 19
6
Oct 19
5
Nov 19
6
Dec 19
6
Jan 20
6
Feb 20
7
Mar 20
5
Apr 20
5
May 20
3
Rainfall deciles
10 Well above normal
8-9 Above normal
4-7 Near normal
2-3 Below normal
1 Well below normal

Issue Notes

ENSO status: Neutral (El Nino Watch)

Sea surface temperatures (SST's) showed a slight warming during May, and remain significantly warmer than average across the equatorial Pacific.

The Nino3.4 index lingered between 0.8 and 0.9 through the month of May. On the other hand, the Southern Oscillation Index (SOI) recorded a value of -0.9 in May, dropping back again into El Nino territory.

Current consensus suggests an El Nino pattern across the Pacific Ocean will continue through winter and spring, with all eight international models maintaining a warmer than average Pacific Ocean through the remainder of 2019, with a 50-60% chance of an El Nino developing again later this year.

The climate outlook for winter and early spring favours an overall below average rainfall outlook across southern Qld, NSW (mainly west of the Great Dividing Range), Vic, northeastern Tas and the southern SA and WA. A Positive IOD is now well established over the Indian Ocean, with five out of six international models exhibiting a moderate-to-strong event lasting until spring. During Positive IODs, central and southeastern Australia tend to see a reduction in rainfall amounts towards the second half of winter and first half of spring.

SST's along the eastern seaboard remain warmer than average, increasing the risk of extreme weather events such as East Coast Lows (ECLs), which activity reaches its peak in early winter. These can bring intense periods of rainfall east of the Great Dividing Range, leading to flash flooding.

Issued Jun 15

Forecast Explanation

Notes on the concept of deciles

If all the data in a record are ranked from lowest to highest they can then be divided into 100 equal blocks. These blocks are known as percentiles. The values that fall into the lowest 10% range (from 0 to 10%) are said to be in the first decile, those in the group 10+% to 20% are in the second decile, and so on. Those in the group 90+% to the maximum value recorded are in the 10th decile. The 50% value is a special one known as the 'median'. It is noteworthy since there is the same number of records above and below its value.

Deciles have been found to be very useful for analysing rainfall in particular as its distribution is not the normal bell-shape distribution but is skewed towards many low values with only a few high values. The deciles can be described in qualitative terms. A table is provided in the accompanying results.

Site search


Enter a postcode or town name for local weather, or text to search the site. » advanced search

Freezing start to Thursday

10:44 AEST Australia registered its lowest June temperature in eight years on Thursday morning as frost formed in every state and territory.

Help with Farmonline Weather