There’s 76/77 (polar vortex year) again.
By Paul Homewood
As we know, California is going through a serious drought at the moment. But how does it compare with earlier droughts in the 20thC? Let’s start by checking the rainfall stats for the last 12 months, August to July.
This last 12 months is the third driest August – July on record, behind 1976/7 and 1923/4.
One of the things that has exacerbated the drought is that we have now had three dry years on the trot. When 3-year trends are plotted, the latest period is slightly drier than 1974-77 and 1928-31.
However, looking at the longer term 60-Month chart, the longest NOAA provide, we find that many previous periods have been much drier. Perhaps the most serious and long running drought was during the 1920’s and 30’s.
The blue lines, by the way, are trends lines (not means). As the legend shows, precipitation trends…
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