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There Is More To The Weather Than Whether It's Settled Or Unsettled

Thundery wintry showers


As time goes on I am fearing that the Model Output Discussion is going to degenerate into the usual summer fare, where the UK's weather is over-simplistically divided into two types: "settled" aka "good", and "unsettled" aka "bad".

The main problem is that the desire for "settled" weather, for most people, is tied in with images of clear blue skies, warm sunshine by day, and evenings spent in the garden with the barbeque going. Of course, high pressure can bring such weather, and many of us will have memories of that phenomenal spell at the back end of March this year.
But in fact we only need to think back to the last third of July 2011 for an illustration of how we can be "bitten" by being too simplistic about this association. The forecast models showed a fairly sustained settled period with high pressure close by to the west, and the model output thread was buzzing with posts insisting that we were in for a lot of barbeque-type weather. In reality, though, for many of us the spell turned out dry and cloudy with a chilly northerly wind which left those BBQs gathering dust indoors.

The problem is that for high pressure to bring us "BBQ weather", it really has to be in the right place. Here's one synoptic chart:
Let's be brutally honest, how many people would look at a chart like that and not think, "sustained settled spell- barbeque here we come"? In fact May 1991 was one of the dullest Mays on record as well as one of the driest and most settled.
Another stark counterexample occurred during June 1988. This was an often-forgotten warm sunny month across much of Scotland (leading into that infamous washout July) but also an often-forgotten dry cloudy one across most parts of England, characterised by high pressure in the wrong place:

Also, you don't actually need a sustained strong area of high pressure to bring this sort of "barbeque weather". The last week of June 2010, for instance, had a lot of this type of weather, but was only weakly anticyclonic:
And on relatively rare occasions, you don't even need any high pressure at all. I remember that in Tyneside (where in some summers, like last year's, we struggle to justify getting the BBQ out at all) I had a nice BBQ on the evening of the 4th July 1999:
...and how many people would see a chart like that and think, "oh dear, dull wet unsettled dross"? That spell in early July 1999 turned out generally warm and sunny but with sharp thundery downpours, so as long as you timed your BBQ well you were okay.

In fact it isn't all that unusual for the most "settled" spell of a month to end up being the cloudiest, if the unsettled weather is mainly bright and showery and the settled weather has high pressure in the wrong place. The dullest spell of this April so far was the relatively quiet one over Easter when high pressure (in the wrong place) ridged across from the west. It can even happen, more rarely, during a generally dull unsettled month (the dullest spell of August 2008, for many of us, was actually the relatively warm settled one near the end).

Some of it probably stems from how we were brought up. I know that when I was at school, we were taught, "high pressure is settled (good) weather, low pressure is unsettled (bad) weather".

I realise that, as a big fan of convective type weather, I am always going to be less enthusiastic than most others about sustained spells of high pressure (which have a habit of being convection-free). However, that consideration shouldn't affect the above analysis- I've deliberately looked at it from a "hoping for warm dry sunny BBQ weather" perspective, and shown how flawed/over-simplistic it is even from that perspective.


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Exactly. Settled or unsettled doesn't tell the whole story. It's all the different variaties that geographical features influence, the differences from location to location, night and day, winter and summer, all the different cloud types, weather types and transitions that comes with unsettled or settled. I'd prefer it if members in the Model Output Thread refered to the actual weather across the different regions of the UK instead of saying settled or unsettled. And of course, unsettled weather isn't always bad at all. For example, endless heavy rain and low cloud cover from depressions could be seen as bad weather but showery or even sunny spells in supposed unsettled periods can be better than even good scenarios that settled weather brings. There is indeed much more to British Weather than settled or unsettled.
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Also, for example, right now outside the skies are clear with just a few small clouds and there's no wind. We are supposed to be in an unsettled period right now yet what we've got now is better than some of the stuff that settled weather brings. If only we could have our weather switching from settled to unsettled periods with lots of varied weather that's often pleasant, seasonal and at times extreme.
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A fantastic read TWS! Even during that high pressure in March we had a lot of low cloud and fog for about 2 - 3 days.
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Of course it depends on where you live, any High Pressure with an Easterly flow, gives sunny or bright weather here, Even Last July tended to be quite bright here, even if wasn't wall to wall sunshine.

For us unsettled weather with Atlantic flows tends to be the worst, at any time of year, and that's why I don't particularly like it, I have no particular desire for convective activity either.

My preference for a summer would be to have over half the summer sunny or bright with daytime maxes over 20c. So in nutshell sunny and warm is my preference.
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I spent three years at Lancaster and I certainly recall a strong association between Atlantic flows and generally cloudy wet conditions there-. Slack, showery cyclonic conditions often gave a fair amount of sunshine and not many showers (Morecambe Bay tended to nullify convection, similar to the North Sea re. Tyneside, so Lancaster isn't great for convection/thunderstorm lovers either) but anything involving lots of fronts piling in off the Atlantic almost invariably gave frequent dull, wet and windy weather.
The general rule of thumb for anticyclonic weather was that anticyclonic/westerly types tended to be grey and drizzly (due to the moist tropical maritime air streaming in off Morecambe Bay) whereas high pressure combined with northerlies, easterlies or southerlies usually gave plenty of sunshine.

As a result I detected a stronger positive association between settled weather and sunshine in Lancaster than in Tyneside, although I identified two exceptions above. I would be even less keen on the "strong Azores High ridging into the south" scenario if I was still living over there as it tended to bring frequent grey drizzly weather to the Lancaster area.
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