Geelong’s June rainfall was very gratifying, according to Lindsay Smail of Geelong Weather Services. Falls were above average virtually across the whole Geelong region, he said, ranging from 133.8 mm at West Barwon Dam (still 90% empty) to 41.1mm at Shelford. Within the urban area there were falls varying from 88.1mm at Leopold to 43 mm at Lara.
Rain fell in Geelong on a total of seventeen days, which is about average for June, Mr Smail said, and four of those days were responsible for 60 mm or about 80% of the total.
The outlook for winter rainfall is still good. The Southern Oscillation Index (based on El Nino measurements) is now rising steadily and above average falls can be predicted for this region in the next three monthly period. This does not necessarily mean each month will be above average, but that the seasonal total probably will be. Mr Smail said it already appeared that July would be receiving some good falls.
Geelong Weather Services has built up an accurate record of seasonal rainfall prediction in the past 18 months. Based on his research of computer forecast models, on April 13th Mr Smail predicted moderate falls for the rest of that month, and was correct. He then accurately forecast relatively dry conditions for the first three weeks in May, followed by “reasonable” falls until the end of the month. His prediction of a dry start to winter followed by rain at the end of June was interrupted by a good fall of 25 mm in the second week of June. But rain at the end of June confirmed his overall forecast.
Mr Smail hastens to point out that the computer prediction models are not his, but are developed from the National Centres for Environmental Prediction (NCEP) in the USA. “Nevertheless we have access to some fairly sophisticated information here which is just not available elsewhere”, he said.
June was slightly cooler than normal, with an average maximum of 13.8 degrees (compared to 14.3) and an average minimum of 5.6 (compared to 5.9). There were several minor “cold snaps” where the temperature at Mt Duneed Airport fell to 2 degrees or less. Temperatures between 0 and 2 degrees are regarded as a “light frost”. This happened on the mornings of the 10-11th, the 18-19th and the 28-28th. The temperature dropped to minus 1 on two occasions and only rose to 20 degrees on two days.
Within the Geelong urban area the temperature did not drop below 2 degrees on any occasion owing to the sheltering effect of the built-up environment – the so-called Urban Heat Island (UHI) effect, Mr Smail said.