FYI: Monthly Climate Summary for Canberra - October 2009 [SEC=UNOFFICIAL]

The following is provided for the information
of subscribers (and as an addition to the annual summary provided in the
Annual Bird Report): http://www.bom.gov.au/climate/current/month/act/summary.shtml

Canberra has cloudy, cool October

·        Close to average rainfall
·        Cool to cold days with below average maximum temperatures
·        Coolest October since 2003
·        Mild nights, close to average minimum temperatures
·        Second cloudiest October on record (6.9 hours of sunshine per day)

Rainfall

Canberra Airport recorded a total rainfall of 42.4 mm during the month, which is below the historical average of 62.1 mm. This is now the 10th consecutive October with below average rainfall in the ACT and makes it the longest continuous period of below average October rainfall since Canberra records commenced in 1939. Higher falls were recorded in southwestern parts of the city where Tharwa's total was 78.4 mm and Tuggeranong 75.2 mm. Canberra Airport recorded 14 raindays during the month, which is the highest for October since 1976 (when 18 raindays). Normally Canberra would expect around 10 raindays in October.

A number of low pressure troughs during the month with associated thunderstorms caused the majority of the rain over the ACT. The most active was on the 25th when a combined surface and upper low caused thunderstorms and heavy showers in the ACT, especially over the southern ranges.

October monthly totals in Canberra suburbs ranged from a high of 75.2 mm at Tuggeranong AWS in the southwestern suburbs to a low of 41.8 mm at Cook in Belconnen. Higher falls occurred on the ACT ranges where Corin Dam recorded a monthly total of 126.0 mm.

Temperatures

In a marked contrast to September, days were cool and cloudy in the ACT during October. The mean maximum (daytime) temperature at Canberra Airport was 19.0 °C, which is 0.4 °C below the historical October average of 19.4 °C, making it the coolest October since 2003. There were 12 'cold' days (maximum temperature below 16 °C), twice the average of 6 days. It is the highest number of cold days in October since 1986 (when 14 days below 16 °C). The coldest day was 11.3 °C on the 7th, the lowest maximum temperature in October since 23 October 1999. Snow fell in Cooma - Monaro districts south of the ACT on the 7th as well as on the ACT ranges.

Nights were generally cool to mild and close to the October historical average. The mean minimum temperature at Canberra Airport was 6.6 °C, or 0.5 °C above the October historical average of 6.1 °C. Canberra Airport recorded only 4 frosts during the month (minimum temperature below 2 °C) below the normal 7 frosts for October. The lowest temperature in Canberra suburbs was -0.3 °C at the airport on the 9th. The lowest in the ACT was -3.6 °C at Mount Ginini AWS on the 16th.

Wind

Following a marked persistence in W-NW winds in the ACT last month, there was a significant change to predominantly E to S winds during October and a noticeable lack of the usual NW wind. Morning winds were E to S up to 52% of the time compared to the usual 20% from this direction. The highest wind gust in Canberra was 65 km/h at Canberra Airport on the 12th and the highest in the ACT was 80 km/h at Mount Ginini AWS on the 14th.

Other phenomena

There were 3 thunderstorms in the ACT during October, on the 2nd, 11th and 25th. Thunderstorms both on the 2nd and 25th caused some local moderate falls, the highest 24 hour totals being 29.4 mm at Tralee (to 9am on the 3rd) and 25.8 mm at Tharwa (to 9am on the 26th), both in southern regions of the city. Just over the NSW border at Googong Dam, one of Canberra's water catchment reservoirs, 39 mm was recorded in a storm on the 25th, the highest daily fall in the ACT area for the month.

Relative humidity at 9am averaged 72% which is the highest for October since 1992. Due to the increased humidity and rainfall around the ACT, Canberra Airport recorded 5 fogs during October (6th, 7th, 20th, 29th and 30th), twice the historical average and the highest number of fogs for October since 1977. Visibility was briefly reduced to 100 metres on the 6th and 200 metres on the 7th.

October was a cloudy month with several consecutive days having virtually no sun. Only about 3 hours of sunshine was recorded over the 3 days from the 3rd to the 5th. The monthly average was 6.9 hours per day which is the 2nd lowest October monthly total on record for Canberra Airport. The lowest is 6.7 hours per day in 1992. The historic average for October is 8.7 hours per day.********************************************************************** IMPORTANT: This e-mail is intended for the use of the addressee and may contain information that is confidential, commercially valuable or subject to legal or parliamentary privilege. If you are not the intended recipient you are notified that any review, re-transmission, disclosure, use or dissemination of this communication is strictly prohibited by several Commonwealth Acts of Parliament. If you have received this communication in error please notify the sender immediately and delete all copies of this transmission together with any attachments. **********************************************************************