After a dryish start to the month as well as to spring generally, the end came with a climactic boom, surprising many. November saw most of Geelong end up with over 120 mm, well over double the average.
In a remarkable downpour, the 24 hours ending at 9 am on Sunday 27th saw over 100 mm fall in Geelong’s eastern suburbs and the Bellarine Peninsula. At the Racecourse in Breakwater (90 mm in 24 hours), 27 mm was dumped between 1 pm and 2 pm on the Saturday. Although most of the urban area was not quite as deluged, the severe flash flooding event caused clean-up problems right across town.
It was actually a November record for Geelong’s highest 24-hour rainfall. The previous one was 63 mm set in 1978.
However Geelong has had much worse flash floods in the past, and several other occasions in which more than 100 mm fell in a 24-hour period (even in 1896). The most recent were the 128 mm which fell at South Geelong in January, 2005, and the 130 mm at Grovedale in February of the same year. On those occasions there was massive storm and flood damage.
This time the event was caused by an intense, deepening low pressure system which had developed in Northern Victoria after retrogressing from the northeast. As it moved southeastwards, the inner eastern flank found the Geelong – Bellarine Peninsula area in the firing line. Then the system caught up with the district again as it continued south-eastwards and the “wrap-around” effect and cloudband passed right over this part of the state. The result is now in the record books. These systems are to be expected in this region from time to time, especially in spring – summer, and the storm season is well and truly underway at the moment.
As far as spring as a whole is concerned, the district around Geelong and the Bellarine Peninsula ended up with well above average rainfall. Urban Geelong recorded 217 mm compared with the average 154 mm. Total year-to-date rain is 664 mm compared to the 11-month average of 485 mm. The Bureau’s spring outlook predicted only around a 40% chance that the area would get normal rains. The Otways has not fared quite as well but has still received close to average over spring (80% of normal), and the catchments remain around 87% full with a normal decline expected over the holiday period.
TEMPERATURES AND WIND
Geelong’s daily temperatures for November and for spring generally were well above average: by about a degree overall. November’s average daily maximum was 23.3 degrees C and daily minimums 12.0 degrees C. Taking into account the site differences between the new, more urban-oriented station and the old one, we could conclude that Geelong was about 1.5 degrees C warmer than normal in November. This trend tends to counteract the somewhat cooler temperatures noted in the first half of the year.
There were 3 days over 30 degrees C this November (the normal is 2.0) and the top reached was 36.8 C on the 18th. Lowest maximum was 15.2 C on the 2nd. Warmest overnight minimum was 18.2 C on the 18th and lowest was 7.8 C on the 5th.
There was one strong wind day with over 60 kph gusts, the 30th, although a suspected tornado may have caused damage just west of Skipton during a storm on the 9th. This has to be confirmed. In Geelong there were six thunder days and one severe storm (26th).
The Bureau of Meteorology’s outlook for summer is that the region has a less than 40% chance of receiving normal rainfalls over the next 3 months. This outlook is questioned by several independent researchers who point to the poor record of previous outlooks as well as the very positive conditions for east coast rain in Australia owing to the currently strengthening La Nina and the warming of both the Southern and Indian Oceans.