Atlantic Air returns

After the extreme heat of the Continental Air on Friday, more moderate weather arrived on Saturday as Atlantic Air was brought on westerly winds. The peak temperature was above average with 22.4C maximum (+1.4C). This was 10C down on the Friday peak.

It was another dry day with 8.4 hours of sunshine and the UV level reaching Very High again.

A much cooler night was to follow as the thermometer dropped to 8.3C early on Sunday morning that arrived with variable sunshine through broken cloud.

July 2020 review

A distinctly below average month

A conveyor belt of moist air from the Atlantic greeted the new month brought on brisk southwest winds. This meant cool days with maxima several degrees below the 36-year average. By the 5th it felt more like autumn with the maximum 5C below average accompanied by strong winds from the west that gusted to 31mph.

There followed three dismal days, gloomy and damp, from the moist Atlantic air on winds from the southwest that were relatively light, a maximum gust of 17mph. Interestingly and quite unusually were the almost identical maxima on four days, 19.6C, 19.5C, 19.6C and 19.7C on the 6th to the 9th respectively.

Although there have been storms forming in the Atlantic during the 2020 season that started on 1st June, the Saharan sand that brought minute particles westwards across the Atlantic to the eastern seaboard of America, are thought to have reduced the energy in them during that period. Storm Edouard formed on the 5th, moving north eastwards towards the UK. This was the earliest named “E” storm on record.

Storm Fay formed in the Caribbean on the 10th but slowly faded as it drifted northwards to the eastern seaboard of America. This was the earliest 6th Atlantic named storm formation on record. It was the first storm in recorded history to make landfall in Florida four times as it zigzagged up the coast. There followed Storm Gonzala that eventually disappeared in the Caribbean but Storm Hanna was identified on the 21st that then developed into a hurricane before landfall in Texas on the 25th, knocking down part of President Trump’s wall between the US and Mexico, later downgraded to a Storm. At no time was the predicted track of these storms northeastwards towards the UK as Storm Edouard in June.

The Atlantic Hurricane season is from 1st June to 30th November. Due to the unusually warm ocean water this year, which acts as fuel for hurricanes, it is predicted that the 2020 season will see an exceptional number of storms and hurricanes with Hurricane Isaias fast developing on the 30th being the ninth storm this season when the average is 12 storms.

No storms here but a very gloomy day on the 15th with a maximum 5.3C below the average and barely a sight of the sun.

There followed an improved period as the barometric pressure rose, with many fine days that produced maxima of 24.2C and 23.2C on the 17th and 18th respectively. However, during the early morning of the 17th fog formed that limited visibility to 200m but had evaporated by 08.00. Interestingly the thermometer read 15.2C at 08.00 on three consecutive mornings.

The nights of the 20th and 21st were distinctly chilly as under clear skies the thermometer fell steadily to 5.8C and 6.0C respectively being some 6C below the 36-year average.

An unsettled period arrived on the 23rd with several depressions passing close to or over the north of the country for several days bringing disturbed weather on a south westerly breeze and not at all summerlike. The maximum temperatures slowly fell day by day with increasing frequency of showers producing 17.7mm on the 25th, making it the wettest day in July and since 18th June.

The 27th opened with a bang with thunder at 07.25 as another wide rain band crossed the country. This was preceded by a brief flash of lightning but nowhere near the record set in October 2018 when satellite technology confirmed a single flash of lightning stretched from NE Argentina across southern Brazil and then over the Atlantic measuring 709km, termed a megaflash. Also confirmed this month was a lightning flash in 2019 over Argentina that lasted 16.73 seconds.

By night, thanks to a duvet of thick cloud, the minimum temperatures were well above average, 16.2C on the 25th was the warmest night being 4.3C above the average.

A temporary ridge of high pressure brought a hot end to the month with a peak of 32.9C on the 31st making it the warmest day since 19th July 2006. The 25th July in 2019 was close to this high with a peak of 32.6C.

With below average sunshine and solar energy just 95% of the long term average it was not surprising to find that overall July was a cool month with a mean temperature 0.5C below the 36-year average. Rainfall amounted to 56.6mm being 3mm below average, however, there was a deficit of moisture as the equivalent rainfall of 93.3mm was lost to the atmosphere through evaporation from ground sources and plant life.