Dry spring heralds a hot summer

WEATHER: The Bureau of Meteorology (BOM) has said that lower than average rainfall during Spring, experienced in the Yass Valley, is a result of the El Nino influence, and is likely to mean greater fire risk during summer.

Yass received just 19.7mm of rain in September, well below the mean of 56.8mm.

In October, Yass received 30.2mm, and in November 85.7mm (more than September and October combined). However, our total spring rainfall was still well below the mean (based on historical data from 1898 – 2011); our spring total was 135.6mm, with the mean 177.9mm.

The lower than average rainfall was accompanied by high day time temperatures. The highest in October (31.6 degrees Celsius) and November (37.5) where close to the highest on record, 32.7 and 39.5 respectively.

According to BOM, lower than average Spring rain in the Southern Tablelands is tracking with the influence of the present El Nino affect. The affect is even more significant this cycle, as it’s combined with a positive Indian Ocean Dipole (IOD) event.

A positive IOD year is characterised by cooler than normal water in the tropical eastern Indian Ocean, near Indonesia, and warmer than normal water in the tropical western Indian Ocean, near Africa. A positive IOD sea surface temperature pattern often results in a decrease of rainfall over parts of Australia.

Other weather statistics that characterised spring in the Yass Valley were:

• Predominantly calm conditions, with winds peaking at 24km/h (NNW) on November 18.
• Our biggest spring rainfall was recorded as 34mm on Monday November 2 (Note: Yass weather records, taken at the Rural Fire Service, are generally not recorded on weekends).
• In September, we twice recorded the lowest temperature of 0.0, on September 2 and September 24. But this was higher than the September lowest mean temperature of -3.9.

The outlook for the Yass Valley for December to February, according to forecasting by the BOM, is higher than mean temperatures. Rainfall is predicted to be close to the mean during this period.

After a promising start to spring, we’ve had less than average rainfall which means greater fire risk during summer. PHOTO: Katharyn Brine