al78
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Posts posted by al78
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I had a play on the NCEP NCAR composite plotting tool, and got out the surface pressure anomaly and 700mb geopotential height anomaly average over 1st April to 25th May. What we are experiencing seems to be part of a global wavetrain, with most of NW Europe under a ridge. There are regions either side (e.g. Eastern Arctic Canada) which have been under a trough, and I imagine there it has been a very wet spring. If the phase of this wavetrain had been shifted half a wavelength, the UK could be recording a record breaking wet spring, instead of a semi-arid one.
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21 hours ago, East Lancs Rain said:
I agree. Don't really want a northern blocking type summer like 2007, 2012 or the first half of June 2019 (which was absolutely diabolical) but don't really want a scorcher like 2006 or 2018 either. Somewhere in the middle would be nice.
Agreed. I picked exactly the wrong two week period to go on a backpacking trip in the Scottish highlands.
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Given how dry, warm and sunny April was in Scotland, coupled with the mild winter, will this mean less snow on the higher mountains in late Spring/early summer? I remember in 2017 there was barely a patch of snow even in the big corries of Braeriach where the semi-permanent patches can be found, but that was due to a lack of winter snow.
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On 02/05/2020 at 11:49, Mr Frost said:
April was fantastic! Sunniest ever and third driest on record. (Scotland)
That slow moving low and horrible full day of rain and November-like temperatures last Tuesday really bumped up the rainfall over central Southern England. Not surprised it ended up closer to average near me, that was the start of four consecutive wet days.
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On 24/04/2020 at 15:44, Scorcher said:
No stop trying to play this month down- other than 2007 and 2011 nothing compares in terms of the combination of sunshine and warmth. It's not about months 'having days like this' as yes in an average April you will get the odd nice day. What makes this month exceptional is the sheer number of days above 18C with sunshine- I certainly can't remember an April like this, 2007 and 2011 aside.
Exactly, it is also the amount of sunshine that is way above average. The coming week is going to knock the magnitude of the rainfall anomaly right down, but the last four weeks have been incredible for the time of year. It has felt like a cooler version of May and June 2018. In Horsham there has been one day last Saturday evening of heavy rain this month. To see how far from normal this month is, I will wait until HadCET, HadUKP have been updated then see where April 2020 ranks.
According to this Met Office timeseries (https://www.metoffice.gov.uk/pub/data/weather/uk/climate/datasets/Sunshine/date/UK.txt) April's with at least 200 hours of sunshine are rare, but there have been three in the last 15 years (2007, 2011, 2015). Prior to that, there have been only two since 1929 (1942 and 1984). Just because a random cluster makes something feel fairly common, doesn't mean it is. Perception is not fact.
I'll be glad for some rain this coming week. The heavy rain from a week ago Saturday mositened the soil on my allotment, but quickly dried out. Digging out the persistent perennial weeds is hard going on clay soil in a persistent dry spell, and replenishment of soil moisture will make this much easier.
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10 hours ago, Froze were the Days said:
April 2018 was 2c above the 1961-90 series and May 2.1c so that month couldn't have been very cold at times otherwise we wouldn't have got that anomaly (we know March was) and as for 'another cloudy' one re: summers...not sure about that as sunshine totals of recent summers are on the rise.
Are they? 2018 was a very sunny summer but I don't recall last year particularly standing out.
UK temperature, rainfall and sunshine time series
WWW.METOFFICE.GOV.UKTime series graphs of climate variables for previous months, seasons and yearsYou can select "summer" and "sunshine" to plot summer sunshine going back about 90 years, and apart from 2018, there is no increase in sunny summers over the last 20 years. The only real trend is an increase in high summer sunshine years from 1975 to 1996, followed by a slight drop off. The dreadful summer of 2012 stands out, and it looks like 2008 was duller than the flooding summer of 2007, probably due to the dreadfully dull August..
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13 hours ago, Roger J Smith said:
The AGW lobby have decided to assert that their signal has overwhelmed all other signals, which seems to me more of a political than a scientific proposition.
No it isn't, it is based on the best scientific conclusion from the available evidence and what we understand about the laws of physics. That is not to say there isn't internal variability which can mask or amplify the long term warming signal on short timescales, but internal variability does not contribute to a long term climate change. The only way the global climate can change is by a forcing, and human activities have been that forcing for the last 200 years.
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On 14/04/2020 at 13:26, Scorcher said:
The comparison between April 2010 and this month doesn't really stack up for me...only the sunshine is similar really.
This month has been much, much warmer so far- on a different planet in many ways.
Heathrow didn't reach 22C once in the whole of April 2010 and only 3 days reached 20C. Away from the SE many places didn't even reach 20C.
I agree. In 2010 it seemed to take forever to properly warm up. 2010 was the year of northerly northerly northerly NORTHERLY wind week after week after week. I remember it for two reasons. Firstly, it was regularly a slog cycling in a NWly direction to work (10 miles) through spring, headwind after headwind after headwind. Secondly, flights were disrupted by ash from the Iceland volcano, again, thanks to the wind persistently blowing from that direction.
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On 17/04/2020 at 19:21, B87 said:
Was March really that dry? Heathrow recorded about 43mm of rain. The long term average is 42mm. Just because it all occurred in the first 2 weeks, with another 2 weeks of dry weather, doesn't make it a dry month.
E+W 58.4 mm according to HadUKP, which ranks it 125 out of 255 in the records going back to 1766. That is below the 1981-2010 average of 71.5 mm, although that climatology does include the incredibly wet March of 1981 (second wettest in the HadUKP record).
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On 15/04/2020 at 22:21, damianslaw said:
Yes in recent years can't think of many cases when a dry April has been followed by a dry May, but quite possibly 2018, May was very dry, April from memory wasn't that wet, though quite cool.
2018 had a wet April, followed by a drier than normal May (May 2019 was even drier). I remember it being extremely dry in my location (Horsham), I only remember it raining once or twice in the whole month. That was that first of three consecutive months with high pressure anchored right over the UK.
1974, 1977, 1978, 1980, 1982, 1990, 1995, 2010, 2011, 2019
These years had negative rainfall anomalies in April and May relative to 1981-2010 climatology, HadUKP England+Wales dataset. It is not that common. It is also uncommon to get both April and May wet, which suggests that locked in weather patterns for weeks at a time are rare in Spring.
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Looks like the summer-like weather will last into the first half of the Easter bank holiday, then a significant cool down from Monday back to near average temperatures. Still no sign of rain in my area, fortunately I haven't got any transplanted seedlings on my allotment that need watering (yet).
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On 04/04/2020 at 19:29, mb018538 said:
It’s pretty torturous - a week of sunshine and temps in the high teens/low 20s is exceptional for early April....and no one can fully enjoy it! Such a shame. Stay safe everyone.
You are allowed to go out for exercise. I cycled a couple of five mile laps around a route near me earlier this evening on (very) quiet country lanes (for anyone who lives near Horsham, Westons farm -> Barns Green -> Bax Castle pub -> Christs Hospital). Near perfect conditions for it.
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20 hours ago, cheeky_monkey said:
1997 was a decent summer (2nd hottest August on record)..as was 2019 i thought
I remember 1997, that was the first of three consecutive wet Junes, 1997 and 1998 recording over 100 mm of rain according to HadUKP (those two Junes were completely opposite strong ENSO phases). The following July's in those three years were much drier, then in August it turned wet again (not in 1998 though). I was at Reading uni from late 1996-mid 1999 and I distinctly remember the tendency of having a nice May followed by an awful June.
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Winter 2019/20 will go down as one of the more unpleasant ones, over five months of damp clag starting from the Autumn equinox. There was a bit of respite in January when it was dry and settled for a couple of weeks, but the punishment weather returned in February. Couldn't do any pre-spring preparation on my allotment as it was almost like a swamp at times. The worst was two names storms in three consecutive weekends, talk about a Swearing AGAIN-take for anyone who works standard office hours. March didn't start off much better, but has improved from the second week onward, and the last week has been excellent, pity it has to coincide with a nationwide lockdown restricting the ability to enjoy any nice weather.
Despite the lack of cold nights, I did come off my bike once at very low speed on black ice, when the weather did that nasty thing of raining during the day, then clearing and calming after sunset, allowing temperatures to drop to near freezing. fortunately it was on an empty estate road so no issue other than a painful little finger which got knocked sideways.
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On 03/03/2020 at 18:34, Sunny76 said:
Winter 19/20 was a stinker, but it still felt cold at times, probably due to all the wind and rain. It never felt really mild either.
I think the mildness was largely due to the lack of any cold nights, thanks to the near constant clag.
Spring 2020 | Moans, Ramps & Chat
in Spring Weather Discussion
Posted
Similar in that it was locked in for months , but the geopotential height anomaly through October 2019-February 2020 was indicative of a strong persistent positive NAO/AO signal, but with the centre of the low pressure anomaly shifted south over the UK, not a stagnant zonal wavetrain.