danm
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Posts posted by danm
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51 minutes ago, CryoraptorA303 said:
There is no "usually" about it, there have been plenty of times when we've had these conditions in late April and colder. April is a chaotic month with no "should be", it can be below freezing overnight and snowing or 29°C at this time of year, and anything inbetween.
I agree, there is no "should be". An average is an average, sometimes colder, sometimes warmer. The problem isn't so much the temperatures - we've had cold spells in April before - it's the persistence of the duller and wetter than average weather that's the main problem. We just can't seem to get a stretch of dry and sunny weather at the moment. I accept that in late Autumn and winter, it's what the weather is like at that time of year, but by now you'd hope we would get something more consistently dry and sunny. The SSW definitely put a wrench in things and hasn't helped. I dreaded the talk at the end of Feb of an imminent SSW, knowing this would be the exact result of it. Not snowy mid March nirvana as many on the Mod thread were hoping for, but a perpetuating northern blocking pattern, shunting troughs into the mid latitudes giving us dull and damp weather.
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B87 yeh i think it's highly likely that the late season SSW has perpetuated northern blocking. Low pressure is just getting stuck at mid latitudes.
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lassie23 hard to say for sure, northern blocking is actually pretty common at this time of year, but I do think the SSW has enhanced and prolonged this pattern.
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raz.org.rain warm, wet and thundery according to those charts.
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6 minutes ago, B87 said:
Here's an absolute joke of a forecast going into May. Extreme dullness, wet and only a handful of days approaching average. Will feel more like October than May with the complete lack of sun.
Considering the May average is about 18c for London, temperature wise we look OK next week according to this with 17c to 19c. The problem is it also looks pretty unsettled...
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1 minute ago, MP-R said:
We'll have to agree to disagree then, but it's a well known issue. Same in summer. High pressure but with cool upper air often sees infill problems. When the upper air warms up with pressure still high, you'll often get cloudless conditions.
The reason i'm arguing against that is we can get brilliant sunshine under a high in mid winter with cold upper air.
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4 minutes ago, MP-R said:
Sure, the centre was, but pressure was still very high over most of the UK. We need to get rid of the cold upper air. The weekend's set up with 850s of say 5-10 would've been much sunnier nationwide.
Yeh i don't think upper air temps had anything to do with the cloud, that was more to do with the positioning of the high.
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Just now, danm said:
the high was centred over western Ireland so here in the east and over much of mainland UK in fact, we were on the eastern edge of the high, where pressure was lower. Not to mention an onshore breeze off the North Sea. You can have cold upper air temperatures too and brilliant sunshine, so long as pressure is high enough to kill off cloud formation and also not having an onshore breeze dragging in low cloud.
Adding to this, our issue is also being surrounded on water on all sides. The only way to get crystal clear blue skies in this county is if a high is slap bang over us with 1025-1030mb pressure, or having a SE’erly airflow from off the near continent which drags in dry air, or from a northerly airstream in mid winter as we had in Jan.
It’s much easier in continental locations as low cloud getting dragged in off a cold sea is much less of an issue.
1 minute ago, SunnyG said:Looks like we are getting a repeat of last year's weather but worse than last year's. What decent weather there will be, it's going to be in the west and we here in the east will get cold cloudy weather for the foreseeable. There are zero signs it's gonna change in May.
It’s not looking particularly good in the west either.
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MP-R the high was centred over western Ireland so here in the east and over much of mainland UK in fact, we were on the eastern edge of the high, where pressure was lower. Not to mention an onshore breeze off the North Sea. You can have cold upper air temperatures too and brilliant sunshine, so long as pressure is high enough to kill off cloud formation and also not having an onshore breeze dragging in low cloud.
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7 minutes ago, In Absence of True Seasons said:
2 / 3 hours of sun this morning and now in comes the cloud, like clockwork. No doubt it'll all clear again this evening after dinner-tine lol.
We genuinely need the starts to align in this country to get an actually sunny, or even mostly sunny day. Utterly infuriating.
...we just need higher pressure. Things like infill, or clouding over, or afternoon showers will keep happening whilst we have relatively low pressure in charge. We need a solid high at or above 1025-1030mb. We haven't had that for any length of time since early January.
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Derecho I'm sure that's coming our way. Forecast is for some rain later.
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Well a proper sunny morning! Shame it won’t last though…
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41 minutes ago, richie3846 said:
I've saved a screenshot shot of B87's calculation table for future reference. Very useful. I'm thinking a lot of the ongoing discussions about sunshine over the years, may have been unintentionally misleading and pessimistic because of this discrepancy. I'd say this topic needs bringing to the forefront from time to time, to remind people of the adjustments, and to check their sources of information for raw or adjusted data, where that is possible.
Yes exactly, I just don’t understand why the Met Office only publish the raw figures but not the corrected ones. Without that calculation you can never really know the exact actual sunshine hours for a particular location, unless you look at the anomaly maps which give a percentage range.
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55 minutes ago, B87 said:
They do, but only on the maps. They should have the actual values available without having to FoI request them.
They really should release the actual figures. The raw numbers that are displayed on their own website plus others like meteociel and weather online are wrong and misleading. Still don’t understand why they don’t, considering they show the actual ranges on the anomaly maps.
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B87 strange why they don’t publish the true, corrected values…..
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B87 thanks! Why does the Met Office not publicly display the corrected values? Or do they up to a certain year?
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B87 an ok thanks. The thing is, on the met office and metociel pages they seem to have the raw sunshine totals, not the corrected values. Where do we see the corrected values?
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Just now, B87 said:
It was a few hours below the average. It's only really because of June that it got anywhere near the average.
Heathrow was 3 hours shy of the 1991-2020 average. I think we can probably call it an average year for sunshine!
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B87 btw where do you get your annual and monthly stats from?
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TwisterGirl81 5% either side of average is “about” average I suppose.
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B87 I’m actually surprised we had 7 months out of 12 with above average sunshine in London last year.
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To highlight Spring sometimes resulting in better weather in the west compared to the east (often due to the increased likelihood of northern blocking at this time of year, and easterly winds that favour the west more than the east), I checked the average sunshine totals for April versus July.
In April, many western areas average a very similar amount of sunshine to the south and east:
By mid Summer, the south and east averages significantly more sunshine than the north and west:
You can also see this for Spring as a whole compared to Summer as a whole:
This is largely down to high pressure being far more frequently centred to the north/NW or west of the UK during Spring than at any other time of year, which will always favours sheltered western and NW'ern areas.
Add in a late season SSW that increases the chances of northern blocking even more, and this pattern probably becomes even more accentuated.
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20 minutes ago, Alderc 2.0 said:
looking at output I think mean maxes in the south will be dragged down quite a bit. GFS doesn’t have temps getting much 10-12C for the next and only 12-15C Monday and Tuesday. Then apart from the 1st nothing above 15C until the 9th which would be incredibly poor.
Yep that' possible. I was more referring to the month so far, which to date has run a little above average.
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7 minutes ago, B87 said:
The forecast has plenty of days below 15c, which will help to drop that average though.
Maybe, but you did say that it's only been warm because of the mean so far this month, but we've actually run a little above average for max temps over the first 23 days of the month. Yes, that will likely drop a little as we get to the end of the month, so maybe finishing marginally below average.
Moans, ramps and banter
in Spring Weather Discussion
Posted
Let's hope so.