LAST week’s blocking situation involving a stationary deep Southern Ocean low pressure, an intense high-pressure system in the Bight and persistent well-below normal temperatures at Alice Springs began to break down last weekend.
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This occurred as the intense high-pressure system moved over southern Victoria.
This gave Melbourne one of its highest barometer readings on record for May with a reading of 1037.2mbs last Saturday, May 16.
Following a high barometer reading last month of 1037.1mbs in Melbourne it has set up an interesting situation.
Looking at previous cases of high barometer readings of above 1034mbs occurring in April and May of the same year, there were cases of this is 1868, 1889, 1890, 1916, 1920, 1934, 1955, 1987, 1999, 2003 and 2012.
The first one, 1868, was a bad drought year but all the rest had a winter season wetter than average conditions generally in our regions. Of particular interest are the cases 1889 and 1920.
In 1920 the barometric pressure reached 1037mbs in April and May in Melbourne like it did this year and this was the only other occasion in the past 153 years of records in Melbourne this happened. There was heavy rain in our regions a week later after the high barometer reading of 1038mm in May 1920.
In 1889 heavy rain fell in North East Victoria four days after the high barometer reading in Melbourne and very heavy rain at Coonabarabran nine days later, then moderate to heavy rainfalls generally in our regions at the beginning of June.