Category: Commentary

The initial front from Storm Migeul gave us steady rain from 07.00 to until 13.30 on Friday producing 11.1mm. Another three hours, from just before 05.00 to 07.50 Saturday morning, from the back end of the weather front, gave another 5.2mm making a twenty-four hour rainfall total of 16.3mm, the wettest day since 9th May.

On Friday the thermometer hovered around 12C until the afternoon, when the cloud began to thin, producing 2.8 hours of sunshine and a maximum of 17.6C late in the day at 17.05, which was 2.6C below average.

The wind, initially from the north east, veered into the south east as the depression slowly moved northwards circuiting anticlockwise, as low pressure systems do, thus the change in wind directions as the day progressed.

The minimum overnight was 10.0C being 0.1C below average.

Saturday morning arrived with the hang back of cloud and the wind from the south west as Miguel moved off towards Norway.

Update on Saturday at 18.10: forecast strong winds from Storm Miguel were modest today with the peak gust reaching 26mph at 12.15 although moderating over past three hours. A cool day with another below average maximum of 16.2C (-4.0C).

Storm Miguel, named by the Spanish meteorological Organisation on Wednesday, arrived in the early hours of Friday with light showers between 01.30 and 02.15, which gave a rainfall total for the last twenty-four hours of 2.1mm. Friday morning arrived overcast, after initial brightness, with the first rain drops from the depression observed at 07.00 and steady rain began just before 07.30.

The centre of the deep depression is currently over Jersey but the barometer is falling rapidly, currently reading 1002.8mb. This is the lowest barometric pressure for a month and indicates that the depression is heading towards the UK with the rain radar indicating several hours of rainfall, which will be welcomed by local gardeners.

Thursday gave us 10.9 hours of welcome sunshine that meant the temperature eased upwards a little to reach 18.2C, but still 2C below average. The minimum overnight was 8.8C. recorded at 00.40. Subsequently the temperature began to rise as the thicker cloud from Storm Miguel began to drift towards the UK, the thermometer having recovered to 10.6C at 08.00 Friday.

Update on Friday at 15.00: the steady rainfall that fell between 07.00 and 13.35, from Storm Miguel, amounted to 11.1mm. The temperature was depressed around 12C all morning with a little brightness in the afternoon, which lifted that to 14.1C. The centre of the depression is now over southern England with the barometric pressure currently reading 998.2mb, the lowest in a month.

Update at 18.45: further showers arrived from the south just after 6pm. Late afternoon strong sunshine raised the temperature further to a maximum of 17.6C at 17.05, still below average.

I commented yesterday that summer showers, when they arrive from the south or west seem to track around the area giving Marlborough a miss, and yesterday was another example. At 16.30 the rain radar showed two modest sized intense showers developing to the south west but at 16.45 the radar clearly showed them passing to the west and east on a northeasterly track. So no rain again on Wednesday.

The maximum temperatures have been dropping over the past five days with maxima of 25.6C, 22.3C, 19.3C, 18.3C and 17.7C on Wednesday. Last night was the coldest this month when the thermometer dropped to a minimum of 5.8C, which was a significant 4.3C below the average.

Thursday saw the sun shine brightly after dawn with the thermometer, following the cold start, recover to 13.1C at 08.00.

Another day with mixed weather on Tuesday with 5.8 hours of sunshine, broken by occasional very light showers in the afternoon that only amounted to 0.9mm, which soon evaporated. The gardens are still awaiting a good soak with the last substantial rainfall a month ago.

The changeable weather continues under the influence of the Atlantic depressions that continue to advance from the west producing sunshine and light showers as the weather fronts approach and cross the country. As on numerous previous occasions I have watched the rain radar and seen the showers approach from the south or west and watched them skirt the area. I think the topography of the area deflects rain showers, but not rain bands, around the higher ground.

It was cooler again with the thermometer also below average (-1.9C) with a maximum of 18.3C.

The UV level yesterday fell back into the ‘high’ category after the previous three days when it soared into the ‘very high’ category.

Another below average minimum occurred with the thermometer falling to 9.2C (-0.7C) in the early hours of Wednesday.

Wednesday brought blue skies after dawn and strong sunshine that lifted the temperature to 13.2C at 08.00. A lovely morning, if a little breezy.

A depression is crossing the country today, Tuesday, with more lining up for the coming days as they arrive having developed over the Atlantic. The result is a succession of weather fronts that produce depressed temperatures from a regime of sunshine and showers, as on Monday.

The current barometric pressure, with a reading of 1007.7mb, is the lowest since 18th May.

The maximum yesterday was 19.3C, which was almost 1C below the 35-year average with occasional very light showers that only amounted to 0.3mm.

Overnight the thermometer fell away to a minimum of 9.1C in the early hours at 01.02, also almost 1C below average.

Tuesday saw a bright start, no sunshine, with spots of rain at 08.00 at which time the thermometer had recovered to 11.8C.

Weather report for May and Spring 2019
It was a cool May with the mean temperature just below average. The statistics show that although the daytime temperatures were in fact above average they were offset by the many cold nights that meant the mean minimum was 1.1C below average. There was only one air frost, -1.2C on the 5th, but several nights gave a ground frost with no evidence above ground, especially during the early days of May.

Warm air brought to us on a south-westerly air flow from Iberia meant a warmer end to the month with the warmest night on the 31st with a minimum of 13.9C, which was 6.8C above the 35-year average.

Although the last month of Spring was below average, the season was warmer than normal (+0.8C) with a mean of 9.71C. It is interesting to analyse the data since my station began recording in 1984 and find that Spring of that year was exceptionally cold with a mean of 6.83C. Investigating the statistics for that year I found that March was 2.1C below average, April 1.1C lower than average and May a significant 2.2C below the current average. By contrast, the Spring of 2011 produced a mean of 10.51C, the warmest from my records.

For that particularly cold Spring of 1984, hard frosts occurred on the 2nd and 4th of April with the thermometer falling to -6.0 and -5.0C. This followed a cold March that produced 11 air frosts, the coldest of which was -3.5C on the 29th.

Contrasting 1984 with the warmest Spring in 2011, although a hard air frost measuring -6.3C was recorded on 8th March 2011, no air frost occurred after 26th March or for the whole of April and May.

Although the examples above cover the past 35 years, the graph for this period shows an almost continuous rise in the mean temperature with the exception of the cold Springs in 1996 and 2013.

Rainfall in May 2018 was concentrated on three days, the 7th – 9th, when over half the month’s precipitation fell and 6.2mm, 14.4mm and 14.0mm respectively was recorded. The total rainfall for the month almost equalled the average with 59.5mm when the average is 61.0mm. There were only 6 days classified as wet days when the precipitation was equal to or greater than 1mm and 21 dry days in May.

The trend of drier than average rainfall continues into 2019. The rainfall for 2018 was 62mm below the 35-year average with 783mm. The first five months of 2019 have produced a total of 301mm a deficit of 55mm compared to the 35-year average. However, set against that figure must be the loss through evaporation from ground sources and plant life, the equivalent rainfall of 237mm.

The year of 2018 was not the driest I have recorded, as that occurred in 1996 with 594mm of precipitation, whereas six years later, in the very wet year of 2002, 1146mm was recorded.