MONTHLY WEATHER REVIEW - ARMIDALE NSW

OCTOBER 2011

October 2011 was a cool, cloudy and wet month with light winds.
The rainfall total of 75.6 mm was 7 mm higher than the average with a number of moderate falls throughout the month. The heaviest falls were on the 15th and 25th - see details below.
Numerous cloudy days kept day temperatures well below normal, but overnight temperatures were close to normal. Temperatures exceeded 20 degrees on only 12 days.
Thunderstorm activity was a little higher than normal with storms on five days with only one storm producing hail.

There were only five frosts, one moderate and four light, as the frost season winds down.
Prevailing winds were light to moderate westerlies.

Noteworthy events:
1st & 2nd - A low pressure system and trough passing through New South Wales brought very chilly temperatures to the Northern Tablelands. The maximum on the 1st was 11.0C, and it was 9.0C on the 2nd, nine degrees below the average. It was showery on both days with rain totaling 15.2 mm over the two days which resulted in minor flooding in Dumaresq Creek in the early morning of the 3rd.

14th-15th - A low pressure trough passed through northern New South Wales bringing widespread rain to the Northern Tablelands. 19.8 mm was recorded at the city weather station from the afternoon of the 14th through to the following afternoon. Armidale airport received heavier falls totaling 33.0 mm for the same period.
25th - A trough moving through northern New South Wales generated widespread thunderstorms in the late afternoon and evening. A storm with hailstones up to 10 mm diameter and heavy rain struck between 5.30 and 6.00pm, with the main line of storms arriving between 8.30 and 9.30pm. These storms produced intense lightning activity and heavy rain. Rain totals from the storms: city: 17.2 mm, airport: 21.0 mm.

OCTOBER STATISTICS (long term averages in brackets):

Rainfall: 75.6 mm (68.4 mm)

Rain days: 10 (9)
2011 rainfall total Jan to Oct: 692.0 mm (615.7 mm)

Average maximum temp: 18.8 deg (20.5 deg)

Average minimum temp: 5.5 deg (5.6 deg)

Highest maximum temp: 24.6 deg on the 30th

Lowest maximum temp: 9.0 deg on the 2nd

Highest minimum temp: 11.5 deg on the 15th

Lowest minimum temp: -0.8 deg on the 1st

Fine sunny days: 12 (18)

Ideal weather days: 0 (2)

Days with thunderstorms: 5 (4)

Days with frosts: 5 (7)

Days with fogs: 4 (2)

Wind direction at 3pm & number of days:

Average daily evaporation: 2.8 mm (4.1 mm)

Thunderstorm details:

1st: 8.40-9.30am - moderate storm from NW
8th: 8.25am - slight storm from west; 12.50pm - thunder heard - no rain
25th: 5.00-5.30pm - thunder heard - no rain
5.30-6.00pm - moderate storm from west with heavy rain & hail 5.50-5.55pm
8.30-9.30pm - heavy storm from west with heavy rain
10.15-10.30pm - slight storm from west
28th: 2.40-2.50pm - thunder heard in north - no rain
30th: 1.30-3.00pm - thunder heard, 3.00-4.00pm - moderate storm from west, 4.00-4.30pm - thunder heard