AcCLIMATise - A DAFWA project September 2007

The Season to Date

At the beginning of the season we had:

• Neutral El Nino conditions
• A strengthening sea surface temperature gradient in the Indian Ocean
• Good early rains, tracking at seasonal cumulative decile 7-9.

By September:

• The season's cumulative rainfall has retreated to average and below - at Mt Madden down to decile 2
• A fluctuating frontal pattern
• Indicators that a La Nina event could still develop in 2007, giving improved chances of an average spring rainfall
• Strong crops in the Esperance coastal areas due to warmer conditions, soil moisture and little disease (eg: the Cox site at Neridup)
• Crops in the mallee areas becoming more reliant on stored soil moisture (eg: the Graham site at Salmon Gums)

Seasonal Outlook

Spring falls in the Eastern Wheatbelt will depend on:

• The strength of the low pressure systems moving into our region
• The Northwest Sea Surface Temperature Gradient. This weakened in June and the longer it remains depressed, the less chance there is of above average

DAFWA produced an experimental outlook map based on analogue years (1952, 1970 and 1995) with similar conditions, reflects this outlook - that is, average to below average rainfall for August to October.



The National Climate Centre (BofM) is a little more optimistic:

• They see the chances of exceeding the median rainfall for the September to November period are between 55 and 60% in southwest WA (see map below)
• In years with ocean patterns like the current, about six springs out of ten are expected to be wetter than average in this part of the country, while about four out of ten are expected to be drier
• See www.bom.gov.au and follow the links - water & land - rainfall - 3 month outlook.

The DFAWA May Growing Season Outlook is available on line at www.agric.wa.gov.au/climate. This will be updated on 13 September. The above comments are largely drawn from the August Outlook.

Sites to be monitored for the season

Click on each site for a detailed report from that site. Return to AcCLIMATise intro