Monday, 30 April 2007 - Monthly Climate Summary for Victoria - Product code IDCKGC16R0

Victoria in April 2007
Finally, some rain

Summary

Finally, Victoria received useful rainfalls over a large swathe of the State. The exception was in the Central District and West Gippsland, which didn't have the benefit of the last weekend's downpour. Temperatures were above average. The reason for the rainfall is that, firstly, temperatures in the ocean off SW Western Australia have been below normal, allowing more active jet streams than usual to form as a result of the "Indian Ocean Dipole". Over the far eastern Pacific, cold waters are almost suggestive of a possible La Niņa.

In Melbourne, the average maximum temperature was 22.8 deg C (normal 20.6 deg C), whilst the average minimum was 12.3 deg C (normal 11.7 deg C). 22.8 mm of rain fell (normal 52.7 mm).

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Details

Falls of over 100 mm were recorded at some places, mostly towards the end of the month, especially in the northwest and far east of the State.

Rainfall

The heaviest recorded fall, overall, was 157.6 mm at Gabo Island Lighthouse. The driest overall was 13.8 mm at Omeo Comparison. The wettest single day 62.8 mm at Grampians (Mount William) on the 28th.

Some sites had their highest total April rainfall for at least 20 years.

Some sites had their lowest total April rainfall on record.

Some sites had their lowest total April rainfall for at least 20 years.

Temperature

Maximum temperature were more than 2 deg C above normal in the northwest, and around 1 deg C above average elsewhere. Minimum temperatures were mostly near average, but slightly above average in the northwest, and slightly below average in the east.

Maximum temperature

The hottest day was 32.0°C at Horsham Aerodrome on the 14th. The warmest days on average were 25.8°C at Mildura Airport, followed by 25.8°C at Ouyen (Post Office). The coolest days on average were 9.7°C at Mt Hotham. The coldest day was 5.0°C at Mt Baw Baw on the 23rd.

Minimum temperature

The coldest night was −2.4°C at Mt Hotham Airport on the 7th. The coolest nights on average were 3.6°C at Mt Hotham. The warmest nights on average were 14.6°C at Gabo Island Lighthouse, followed by 14.6°C at Wilsons Promontory Lighthouse. The warmest night was 18.1°C at Walpeup Research on the 11th.

Some sites had their highest April mean daily minimum temperature for at least 20 years.

Wind

The strongest wind gust was 104 km/h at Wilsons Promontory Lighthouse on the 28th.

Other phenomena

There were several days with thunderstorms, some with hail, during the month.

Synoptic situation

Blocking highs prevailed during the first two weeks. However, by the end of April, synoptic situations had become typical for late autumn, with westerlies and embedded fronts racing across the southern ocean.

Further information

Dr Harvey Stern
Climate Meteorologist
Victoria Climate Services Centre
Bureau of Meteorology
Phone (03) 9669 4956
Email climate.vic@bom.gov.au

Extremes

Hottest day
Highest temperature		 32.0°C at Horsham Aerodrome on the 14th
Warmest days on average
Highest mean daily maximum temperature		 25.8°C at Mildura Airport
25.8°C at Ouyen (Post Office)
Coolest days on average
Lowest mean daily maximum temperature		 9.7°C at Mt Hotham
Coldest day
Lowest daily maximum temperature		 5.0°C at Mt Baw Baw on the 23rd
Coldest night
Lowest temperature		 −2.4°C at Mt Hotham Airport on the 7th
Coolest nights on average
Lowest mean daily minimum temperature		 3.6°C at Mt Hotham
Warmest nights on average
Highest mean daily minimum temperature		 14.6°C at Gabo Island Lighthouse
14.6°C at Wilsons Promontory Lighthouse
Warmest night
Highest daily minimum temperature		 18.1°C at Walpeup Research on the 11th
Wettest overall
Highest total rainfall		 157.6 mm at Gabo Island Lighthouse
Driest overall
Lowest total rainfall		 13.8 mm at Omeo Comparison
Wettest day
Highest daily rainfall		 62.8 mm at Grampians (Mount William) on the 28th
Highest wind gust
 104 km/h at Wilsons Promontory Lighthouse on the 28th

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Records

Record lowest total April rainfall
Total rainfall
for April 2007 (mm) 		Previous lowest
for April		 Years of
record		 Normal for
April
Scoresby Research Institute 18.4 18.7 in 1958 55 68.6
Noojee (Slivar) 16.2 24.8 in 1993 26


Highest total April rainfall for at least 20 years
Total rainfall
for April 2007 (mm) 		Most recent higher
for April		 Years since
higher		 Normal for
April
Walpeup Research 76.6 100.9 in 1970 37 26.5
Ouyen (Post Office) 82.3 82.6 in 1971 36 26.6
Horsham (Polkemmet) 67.4 104.8 in 1974 33 30.3
Longerenong 63.2 118.3 in 1974 33 29.0


Lowest total April rainfall for at least 20 years
Total rainfall
for April 2007 (mm) 		Most recent lower
for April		 Years since
lower		 Normal for
April
Wilsons Promontory Lighthouse 24.6 11.8 in 1962 45 84.1
Moorabbin Airport 16.8 8.2 in 1963 42 61.6


Highest April mean daily minimum temperature for at least 20 years
Mean daily minimum
temperature
for April 2007 (°C) 		Most recent higher
for April		 Years since
higher		 Normal for
April
Cape Otway Lighthouse 13.2 13.3 in 1919 88 11.9
Mildura Airport 11.6 12.3 in 1980 27 10.5
Casterton Showgrounds 9.8 10.4 in 1980 22 9.1
Horsham (Polkemmet) 9.1 9.9 in 1980 22 8.8


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Summaries

 In the following table, certain key sites have been highlighted to make them easier to identify.

Summary statistics for April 2007
Maximum temperatures
for April
(°C)		 Minimum temperatures
for April
(°C)		 Rainfall
for April
(millimetres)
Mean for
April
2007		 Diff
from
normal		 Highest for
April
2007		 Mean for
April
2007		 Diff
from
normal		 Lowest for
April
2007		 Total for
April
2007		 Normal
for
April		 Rank of
April
2007		 Fraction of
April
normal
North Mallee (district 76)
Mildura Airport 25.8 +2.3 31.4 14th 11.6 +1.1 8.1 7th 34.0 24.2 high 140%
Ouyen 25.8 +2.3 31.9 14th 10.8 +0.9 5.9 16th 82.3 26.6 very high 309%
Walpeup Research 25.2 +2.2 31.3 11th 12.0 +1.7 7.0 6th 76.6 26.5 very high 289%
South Mallee (district 77)
Hopetoun Airport 25.2 31.9 14th 9.9 5.6 20th 32.4
Swan Hill Aerodrome 24.9 31.3 14th 9.7 7.2 4th 51.8
North Wimmera (district 78)
Nhill 24.2 +2.3 31.5 14th 9.3 +0.8 2.7 6th 42.6 29.0 high 147%
Nhill Aerodrome 24.7 31.9 14th 10.4 3.8 6th 37.8
Warracknabeal Museum 24.7 31.4 14th 10.4 5.6 6th 36.6 32.8 high 112%
South Wimmera (district 79)
Edenhope Airport 23.2 30.7 10th 10.2 4.2 6th 41.4
Grampians 14.7 21.5 13th 7.6 2.6 6th 109.8
Horsham 24.4 +2.8 31.6 14th 9.1 +0.3 4.2 6th 67.4 30.3 high 222%
Horsham Aerodrome 24.1 32.0 14th 8.4 2.0 6th 89.8
Kanagulk 23.0 30.1 14th 9.8 4.7 18th 58.6
Longerenong 23.9 +2.1 31.1 14th 9.3 +0.7 3.0 6th 63.2 29.0 very high 218%
Stawell Aerodrome 22.7 29.4 14th 9.3 5.1 8th 68.4
Lower North (district 80)
Charlton 24.1 30.3 14th 10.2 7.4 6th 28.8
Echuca Aerodrome 24.6 +2.2 30.9 14th 9.6 −0.1 5.9 17th 32.4 35.3 normal 92%
Kerang 25.1 +2.5 31.6 14th 10.5 +0.5 7.9 4th 29.3 32.1 normal 91%
Kyabram DPI 24.1 +2.7 30.0 14th 10.0 +1.2 6.0 17th 29.0 43.7 low 66%
Upper North (district 81)
Bendigo Airport 22.8 28.2 14th 9.0 4.6 6th 45.8
Shepparton Airport 24.4 29.4 14th 9.1 5.3 7th 32.8
Tatura Inst Sustainable Ag 23.8 +2.4 29.1 14th 8.7 +0.3 4.7 20th 31.4 42.0 normal 75%
Yarrawonga 25.1 29.9 13th 10.3 7.5 17th 25.6
Lower Northeast (district 82)
Beechworth Woolshed 24.1 27.7 11th 7.2 3.6 20th 34.9
Benalla Airport 24.4 28.7 13th 9.2 4.7 21st 23.3
Corryong Airport 24.1 28.7 15th 5.8 1.4 26th 77.4
Dartmouth Reservoir 23.2 27.0 15th 8.1 5.0 9th 38.6
Hunters Hill 18.9 22.8 11th 10.1 5.8 7th 76.0
Rutherglen Research 24.9 +2.8 28.6 11th 7.4 −0.1 3.3 26th 25.6 45.8 normal 56%
Strathbogie 20.9 25.0 13th 6.5 1.1 26th 42.4 72.7 low 58%
Wangaratta Aero 24.7 28.5 13th 7.0 2.5 26th 38.0
Upper Northeast (district 83)
Edi Upper 23.3 27.4 11th 10.2 6.5 1st 59.5
Falls Creek 11.5 16.0 9th 4.4 −0.8 7th 45.0
Mount Buller 11.3 15.3 13th 5.0 −0.4 6th 44.8
Mt Hotham 9.7 13.6 13th 3.6 −1.2 6th 83.0
Mt Hotham Airport 15.6 20.4 13th 3.7 −2.4 7th 25.4
Omeo 19.8 25.8 15th 5.7 −0.3 7th 24.0
Omeo Comparison 25.4 15th 5.7 +0.6 0.3 9th 13.8 50.2 very low 27%
East Gippsland (district 84)
Combienbar AWS 18.7 25.5 18th 10.1 7.3 26th 76.2
Gabo Island Lighthouse 20.1 +1.0 23.0 15th 14.6 +0.7 12.2 26th 157.6 91.6 high 172%
Gelantipy 17.4 24.5 15th 7.6 3.2 7th 39.0
Lakes Entrance 19.9 25.4 15th 10.2 5.4 9th 72.4
Mallacoota 20.5 25.6 18th 12.4 9.8 10th 82.6
Mt Nowa Nowa 19.3 27.7 14th 11.6 8.2 6th 145.0
Orbost 20.8 28.8 14th 10.5 5.9 13th 93.4
Orbost 21.5 +0.1 29.0 14th 9.4 −0.2 5.2 13th 93.9 79.8 normal 118%
Point Hicks 20.8 +1.0 27.3 18th 13.6 +0.4 11.4 25th 44.9 87.4 low 51%
West Gippsland (district 85)
Bairnsdale Airport 20.6 29.6 14th 8.6 4.2 8th 39.2
East Sale Airport 21.0 +0.6 28.0 14th 8.8 −0.1 4.3 7th 53.2 52.9 normal 101%
Morwell 21.8 28.4 14th 9.2 2.8 7th 33.6
Mt Baw Baw 11.4 16.2 14th 5.1 −0.3 6th 18.4
Mt Moornapa 18.6 27.3 14th 10.9 7.5 26th 58.6
Noojee 21.1 27.5 14th 6.7 3.0 24th 16.2
Wilsons Promontory Lighthouse 18.2 +0.9 23.6 10th 14.6 +1.5 12.7 5th 24.6 84.1 very low 29%
East Central (district 86)
Bundoora 22.6 28.9 10th 9.7 5.0 26th 24.6
Cerberus 21.5 28.1 10th 10.3 4.4 12th 25.8
Coldstream 22.6 27.9 13th 6.2 1.1 26th 23.0
Cranbourne Botanic Gardens 21.8 28.0 10th 10.2 7.4 26th 23.0
Dunns Hill 18.3 24.2 13th 10.6 7.4 6th 29.6
Essendon Airport 22.5 28.9 10th 10.3 5.5 26th 23.6 52.2 low 45%
Frankston AWS 20.8 26.2 14th 12.6 9.2 12th
Kilmore Gap 19.1 24.7 14th 10.1 6.7 4th 34.8
Melbourne Airport 22.2 +2.1 28.3 10th 10.4 +0.1 6.2 26th 29.6 48.8 normal 61%
Melbourne Regional Office 22.8 +2.2 29.3 10th 12.3 +0.6 8.3 26th 22.8 52.7 low 43%
Moorabbin Airport 22.2 +2.0 29.6 14th 10.0 −0.8 5.3 25th 16.8 61.6 very low 27%
Phillip Island Penguin Reserve 21.0 27.3 10th 10.3 3.5 12th 22.2
Rhyll 21.3 27.3 10th 13.8 10.8 13th 24.4
Scoresby Research Institute 22.3 +2.4 28.1 10th 9.2 −1.4 3.4 26th 18.4 68.6 lowest 27%
Viewbank 22.9 28.6 14th 9.8 4.8 26th 20.0
Wonthaggi 21.9 +2.3 28.0 10th 10.9 +0.6 5.5 12th 26.0 77.4 very low 34%
West Central (district 87)
Avalon Airport 21.6 30.1 10th 10.3 5.3 26th 27.4
Geelong Airport 21.5 29.6 10th 10.5 5.9 26th 21.2
Laverton RAAF 22.0 +1.4 29.4 10th 10.3 +0.2 4.2 26th 32.4 50.5 normal 64%
Point Wilson 19.5 26.0 14th 13.9 11.0 8th
Sheoaks 21.1 28.0 14th 9.7 4.1 7th 21.6
North Central (district 88)
Castlemaine Prison 22.1 +1.8 27.4 14th 9.1 +1.8 4.4 5th 61.6 47.9 normal 129%
Eildon Fire Tower 20.8 25.8 13th 10.5 6.8 4th 18.0
Lake Eildon 23.5 +3.0 28.0 13th 8.3 +0.2 4.5 26th 17.0 68.5 low 25%
Mangalore Airport 23.6 +2.2 28.4 14th 9.5 +0.7 5.3 26th 19.8 45.0 low 44%
Maryborough 22.9 +2.0 28.2 13th 9.2 +0.4 5.4 17th 53.0 44.5 normal 119%
Redesdale 22.3 27.4 14th 8.6 5.4 7th 46.2 47.8 normal 97%
Western Plains (district 89)
Ararat Prison 21.9 +2.7 29.7 14th 7.6 +0.1 2.4 8th 60.0 49.0 normal 122%
Ballarat Aerodrome 20.4 +2.5 26.3 14th 8.2 +0.3 2.6 17th 26.4 55.1 low 48%
Lookout Hill 15.8 22.4 13th 8.3 3.8 6th 74.2
Westmere 22.0 29.6 14th 8.1 2.4 13th 38.0
West Coast (district 90)
Aireys Inlet 20.3 29.7 10th 12.7 9.6 12th 35.8
Cape Nelson Lighthouse 19.1 28.8 9th 13.5 10.8 20th 52.8
Cape Otway Lighthouse 18.3 +0.5 26.4 10th 13.2 +1.3 8.2 12th 45.8 75.1 normal 61%
Casterton 22.5 30.3 13th 10.0 3.7 4th 36.8
Casterton Showgrounds 22.5 +2.0 30.7 10th 9.8 +0.7 4.5 4th 29.7 43.7 normal 68%
Colac 20.6 28.5 10th 10.7 7.8 17th 22.0
Hamilton Airport 21.9 29.9 14th 9.5 4.7 4th 46.2
Mortlake Racecourse 22.2 30.4 14th 9.3 1.9 7th 51.4
Port Fairy AWS 20.8 30.7 14th 12.0 6.9 20th 46.6
Portland 19.7 27.7 9th 10.9 7.0 8th 61.6
Warrnambool Airport Ndb 21.5 30.7 14th 9.7 2.7 12th 50.2
Weeaproinah 17.2 24.3 10th 10.1 6.8 12th 61.4 162.0 very low 38%

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Notes

This statement has been prepared based on information available at 11 am on Monday 30 April 2007. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Normals are long-term means based on observations from the years 1961 to 1990. They are not shown for sites with less than 20 years of record in that time, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of "normal" rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, normal in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of normal shows how much rain has fallen this time as a percentage of the long-term mean.

Further information

Dr Harvey Stern
Climate Meteorologist
Victoria Climate Services Centre
Bureau of Meteorology
Phone (03) 9669 4956
Email climate.vic@bom.gov.au