Weather Watch: Prolonged dry spell could cause concern
PUBLISHED: 08:14 04 July 2019 | UPDATED: 08:44 04 July 2019
My previous dire warnings regarding the possibility of an impending drought, have for the time being been alleviated by a decidedly wet June whose rainfall total of 116.9mms was double the long-term average.
However a further prolonged dry spell during the remainder of the summer could again cause concern.
Although the coolest June since 2015, the average temperature was slightly above normal, with warm spells at the beginning and end of the month mitigated by some particularly cool days mid-month.
The 10th and 11th were especially autumnal, with maxima below 14C and a rainfall total of 48.4C. Thunder was heard on the 10th and 19th.
The record-breaking heatwave that encompassed much of western Europe at the close of the month barely affected the British Isles with the highest recorded maximum of 34C at Heathrow being again suspect, due to the exposure of the thermometers in proximity to expanses of tarmac and the exhaust gases of aircraft.
The extreme continental European heatwave has been widely reported as due to climate change - and a prelude to a future warmer world.
This assertion is hard to quantify - although there are always major uncertainties when attempting to fully understand the enormously complex global atmospheric system. Great heat was often recorded in the past, for example in June 1773 it became so excessively hot in England that horses were dying on the roads.
Bizarrely, another indicator of very high temperatures on the near-continent was the fact that swarms of lucusts invaded parts of southern England on the 4th August 1748, and devoured vegetable crops.
For the considerable time our sector of the northern hemisphere has been dominated by marked undulations in the path of the jet stream. This causes surges of warmth from the south to alternate with cool, and often unsettled conditions from the north.
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This sequence was well-illustrated in June, with maxima exceeding 40C over much of western Europe, whilst western Russia was afflicted with temperatures 10C below normal.
By the beginning of July, with the slow eastward movement of the loops in the jet stream, European temperatures returned to normal and the Moskovites could at last again bask in warmth.
Diminution of Arctic pack ice has been suggested as the cause of the unusual weather - if so, as stated past records of similar extremes would indicate that we are merely experiencing natural variability.
Statistics for June 2019:
- Total rainfall: 116.9mms (219% of average)
- Wettest day: 41.8mms 10th
- Days with rain: 13
- Coolest day: 13.5C 11th
- Warmest day: 29.4C 29th
- Lowest minimum: 8.0C 9th
- Average temperature: 15.5C (1.2C above normal)