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Tuesday, 5 June 2002
MONTHLY CLIMATE SUMMARY - NSW REGIONAL OFFICE
Low rainfall for NSW during Autumn
Current Month Rainfall Statistics May 2002 The monthly total rainfall for May has been very much below average for much of NSW. The worst effected areas are found in the northern half of the State from the Upper West to the Northern Rivers Districts. Two significant systems during the month brought some semi wide spread falls around the southern districts. These rain bearing frontal systems occurred around the 14th to 15th of May and a second one around the 19th to the 21st of May. During these periods the rainfall did not penetrate very far north apart from residual showers around coastal plains and adjacent ranges in the days following. The later system brought snow to the snowy mountains and cold and wet conditions for a few days to the Central and Southern Tablelands and Southwest Slopes. Many areas in the north have received their lowest rainfall on record for May. See ftp://ftp.bom.gov.au/anon/home/ncc/www/rainfall/decile/month/colour/history/ns/2002050120020531.gif - Map 1
Previous 3 Month Rainfall Statistics March 2002 to May 2002 Rainfall has been very low in the NSW this Autumn - March to May 2002. For nearly all regions within NSW in the past three months the total rainfall has at least been of sufficient extent to avoid classification as 'Very Much Below Average'. That is, the total rainfall for the State has been above the 10th decile. However, most of the State, on an areal average, is below normal rather than being near normal conditions. That is in most areas the rainfall was below the 4th to 7th decile. There are a few isolated areas, fortunately of minor extent, where rainfalls are in the lowest category e.g. a small center west of Goulburn and another south of Coonabarabran. The 10th decile as a level is significant. If current conditions persist then severe to serious deficiencies may exist in the next three months. See ftp://ftp.bom.gov.au/anon/home/ncc/www/rainfall/decile/3month/colour/history/ns/2002030120020531.gif - Map 2 .
Previous Month Temperature Statistics May 2002 and March to May 2002 Mean maximum temperatures were above average by 1 to 2 degrees in the western districts and parts of the Riverina and Northwest Slopes and Plains, See ftp://ftp.bom.gov.au/anon/home/ncc/www/temperature/maxanom/month/colour/history/ns/2002050120020531.gif - Map 3 . The mean monthly minimum temperatures were mostly below average. A particularly cold center where minimum temperatures were around 2 to 3 degrees below average existed in the Northern Tablelands and Northwest Slopes. See ftp://ftp.bom.gov.au/anon/home/ncc/www/temperature/minanom/month/colour/history/ns/2002050120020531.gif - Map 4. Autumn mean maximum temperatures were mostly above average with the higher anomalies graduating to the west by 2 to 3 degrees above average. Autumn mean minimum temperatures were mostly near normal to slightly below average.
A note about deciles: Deciles are used to give an element (in this case rainfall) a ranking. Deciles are calculated by arranging the totals in ascending order (from lowest to highest), then splitting them into 10 equal groups (thus the groups are called deciles). The first group would be in decile range one, the second group in decile range two, etc, up to the highest annual totals (highest 10 per cent) being in decile range 10. See this website for more information: http://www.bom.gov.au/climate/glossary/deciles.shtml - http://www.bom.gov.au/climate/glossary/deciles.shtml
A note about temperature anomalies: The monthly mean maximum or minimum temperature anomaly is the difference, point by point across the State, of the long-term monthly mean temperature (maximum or minimum) with the current month's mean. Deciles are not used for maximum or minimum, but a direct difference in degrees.
Further information:
Matthew Bastin, Climate and Consultative Service, tel: (02) 9296 1522, e-mail: mailto:m.bastin@bom.gov.au - m.bastin@bom.gov.au
The latest rainfall and temperature maps: http://www.bom.gov.au/climate/austmaps/ - http://www.bom.gov.au/climate/austmaps/
A directory of Bureau services is available on poll fax: 1800 630 100
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