SIGNIFICANT WEATHER - APRIL 1996

Summary Tropical Cyclones Thunderstorms Wind Flooding Temperature Rainfall

SUMMARY

Tropical cyclone OLIVIA at the beginning of the month caused extensive property damage and produced severe wind gusts in Western Australia and South Australia. Heavy rains resulting from ex-tropical cyclone OLIVIA were experienced in Western Australia, Victoria and Tasmania as the system moved towards the Bight.

TROPICAL CYCLONES

Western Australia

Tropical cyclone OLIVIA formed in the Timor Sea on the 5th while located approximately 370 kilometres to the north of Kalumburu. The cyclone moved on a westwards path and slowly intensified and was upgraded to a category 4 cyclone on the 9th. During the 10th tropical cyclone OLIVIA turned towards the southsoutheast and accelerated toward the west Pilbara coastline, crossing the coast that evening. The system then tracked just to the west of Pannawonica and Paraburdoo then headed towards the southsoutheast and weakened.

Severe property damage occurred on Barrow Island where numerous buildings and equipment were damaged. Damage was also reported at Mardie Station. At Pannawonica fifty houses were damaged and power supplies disrupted. Minor damage was reported from Karratha, Dampier, Tom Price and Paraburdoo. The tidal surge at Barrow Island produced some severe coastal erosion. A wind gust of 267 km/h was recorded on Varanus Island, north-east of Barrow Island and 257 km/h at Mardie Station, this being the second highest recorded on the Australian mainland. The Kimberley received general rains from OLIVIA, with Cygnet Bay reporting 84mm on the 9th. Notable rainfall registrations in the 24 hours to 9am on the 11th were recorded at Yalleen 117mm (south-east of Mardie) and Wickham 114mm. As the system moved on a south-easterly path towards the Great Australian Bight parts of the Murchison, Goldfields and Eucla also recorded heavy rains.

THUNDERSTORMS

Queensland

A thunderstorm cluster formed near an upper low and caused torrential rain and severe local flooding in the Yaamba area during the 23rd. The 24 hour total ending 9am on the 24th was 480mm, most of which fell in the 6 hour period between 10am and 4pm.

New South Wales

On the 11th at Mannering Park (Hunter) 2cm hail stripped foliage. On the 27th at Bellbrook (Mid-North Coast), there was 2cm hail but no reports of damage.

FLOODING

Victoria

On the 11th heavy rainfall mainly in the middle, south eastern and eastern suburbs of Melbourne caused local flooding which disrupted traffic and delayed train services. Prahran recorded 52mm of rain in 24 hours. Major roads were flooded due to blocked drains. On the 18th heavy rainfall caused the Watts Creek at Healsville to overflow flooding the caravan park.

Tasmania

Heavy rainfall on the 17th to the 19th caused flooding in the Huonville area and flash flooding in Hobart suburbs. Although not of the same magnitude of the February floods the event attracted considerable media attention.experienced in the Meander River Valley with access to the town of Meander affected on the 16th.

WIND

Tasmania
Gales affected all areas of Tasmania on the 2nd, although most damage occurred in the north of the State. Yachts broke their moorings and some houses were damaged by falling trees. Gusts were reported to 131 km/h at Maatsuyker Island. A storm that occurred near Meander on the 3rd blew rooves off houses and farm buildings and uprooted trees.

South Australia

Gale force winds on the 12th associated with ex tropical cyclone OLIVIA brought down tree branches across Kangaroo Island. Wind gusts of 106 km/h were reported at Cape Willoughby. Rough seas were generated in Boston Bay near Port Lincoln by strong north to northeast winds. The waves stirred up sediment which resulted in killing a large proportion of stock in tuna farms located in the bay. Losses have been estimated as high as$60 million.

Western Australia

Trees and a building in the Midland area suffered minor damage during a period of strong winds as a cold front passed over the Perth metropolitan area on the 19th.

TEMPERATURE

Lowest Mean Maximum Temperature for April

                           Previous          Years of
     Station      Actual   Lowest    Year    Record
                    øC       øC     
Victoria
     Mangalore    18.0     18.6      1995       37

                            Previous          Years of
     Station        Actual  Lowest    Year    Record
                     øC      øC     
Tasmania
     Hobart A/P     15.5    15.7     1965       37
     Maatsuyker Island
                    12.4    12.6      1965      60

                            Previous         Years of
     Station       Actual   Highest  Year    Record
                     øC       øC     

Queensland
     Collinsville    20.0   18.9     1983       33
     St Lawrence     20.4   20.1     1968       55

                      Previous          Years of
     Station  Actual  Lowest    Year    Record
                øC      øC     
Victoria
     Donald      7.7     7.8    1977      30

                                       Previous            Years of
     Station        Actual   Date      Highest    Year     Record
                      øC                 øC
Queensland
     Brisbane AMO    34.3      1        33.6       1973      47
     Gympie          35.6      1        34.5       1973      32
     Richmond        38.9      6        38.7       1983      39
     Clermont        36.5      6        36.4       1980      34
     Urandangie      40.4      6        40.0       1980      34
     Windorah        39.2      7        38.6       1979      30

                                    Previous            Years of
     Station     Actual   Date      Lowest     Year     Record
                  øC                  øC
Queensland
     St George    16.3     30        16.9       1983      35
     Surat        17.6     30        18.3       1962      31
     Bollon       16.9     30        17.7       1983      38

                                    Previous           Years of
     Station     Actual   Date      Highest   Year     Record
                   øC                 øC
Queensland
     Isisford    24.2      9          23.9    1958       32
     Longreach   25.0      9          24.4    1983       31

                                    Previous            Years of
     Station     Actual   Date      Lowest     Year     Record
                   øC                 øC
Queensland
     Gympie      4.8       13        5.6        1983      32
     Kingaroy    1.5       13        2.0        1983      40
        

RAINFALL

Highest Monthly Rainfall on Record for April

                              Previous             Years of  
       Station     Actual     Highest     Year     Record
                   mm           mm
Queensland
     Yaamba(Fitzroy River)
                  539.2      481.4      1928       98
Tasmania
     Taroona      189.4       96.9      1974       32
Northern Territory
     Inverway     184.0      134.4      1961       38
     Riveren      242.6       79.2      1985       28
     Rosewood     157.2      140.5      1939       102     

                                   Previous            Years of 
     Station            Actual     Lowest     Year     Record
                          mm         mm
New South Wales
     Tia(Highrent)       3.2         5.8      1980       35     
     Cape Byron          5.2        36.6      1953       45
     Buladelah           6.4        13.2      1956       90
     Comboyne           14.8        21.4      1973       90
     Port Macquarie      7.4        14.2      1896      155
     Taree               1.1         3.9      1935      114
     Wauchope            5.0         5.7      1896      105

            
                                   Previous            Years of
     Station     Actual   Date      Highest   Year     Record
                   mm                 mm
Queensland
     Yaamba (Fitzroy River)        
                  480.2    24        256.0    12/1990     98

Note: Some statistical records mentioned in this report are based on data that have yet to be fully validated.