Summer 2021 General Discussion

Bucketing down in S Wexford

just day last week i was sweating the mickey off myself and now look 😙 chilly & wet

irish weather heh!

We usually get 1 day.

Must be Climate Change.

The radar this morning does not accurately describe the intensity of the showers whatsoever. About half an hour ago it was utterly lashing and nothing more than a blue spec even on the netweather radar.

Cannot agree whatsoever, the colouring used by Met Eireann makes it very difficult to distinguish between heavier and lighter rainfall. Much prefer Netweather.

Just put together a chart showing the relationship between 850-hPa temperatures (T850) and maximum surface (1.5-metre) air temperatures (Tmax) before, during and after the recent heatwave. The T850 figures are from the 11Z Valentia soundings and I chose Gurteen as suitable station as it's not a million miles from Kerry but more importantly it's well away from the influence of sea breezes. It's also in a natural setting, away from any possible artificial influences.

Also shown are the daily sunshine hours for Gurteen. Obviously, the longer the sunshine the higher the temperature, and this also influences the relationship between T850 and Tmax.

The general rule of thumb is to add 15 degrees to T850 to get Tmax, but there are tonnes of caveats to that, namely the time of year (sun angle and duration), cloudiness, soil moisture, altitude of the station, lapse rate below, surface pressure, etc. However, it's clear that once the warm airmass and cloudless days were in place (from July 16th), Tmax went from 11.4 degrees above T850 on that first sunny day (>10 hours of sunshine) and rose to 13.8, 14.0, 15.8, 14.2, 15.6, 15.7 degrees above on the next six days.

Obviously this is just Gurteen and stations further west and northwest squeezed the extra couple of degrees out of it, being even more removed from the easterly sea breeze.

Castor Bay were only launching balloons at 23Z. All of its T850s were a degree or so lower than those of Valentia but those extra degrees were also squeezed out there too. That's the cumulative effect of multiple days' heat and also maybe less of a sea breeze influence from the short sea track from northern England.

Besides the persistence and high temperatures during the heatwave obviously, what I find quite impressive about July 2021 was how the sunshine total dramatically rose because of that very sunny period.

For the first 13 days, Dublin Airport had only 35 hrs of sun which was on par with July 2020 and was exceptionally dull. However, despite this, the monthly total in the end managed to reach 190 hrs which is Dublin's sunniest July since 2013. Still below April and May of this year but I was impressed just how much it had risen because of one (remarkable) sunny period.

In terms of the national mean, July 2021 was the warmest since 2013 at 16.8c (2013 = 17.0c) and was on par with that of July 2006, but just ever so slightly cooler (by 0.15c) than that of July 1983. July 1995's monthly mean of 17.1c remains the one to beat.

Data from Met Eireann.

the coming week is going to be sh1t 😕

looks like the 9 day scorchio was our summer

From Met Eireann "On this day 2nd of August 1995, Oak park recorded the highest temperature for the month of August of 31.5°C"

Same in Galway, but I am enjoying watching the (painfully light) rain falling. Makes for a pleasant change and will do plant and tree life some good.

Just bringing this back up as the Armagh temperature did not pass quality checks and the Castlederg 31.3C is the new official record for Northern Ireland - in spite of that paving.